336 
AWUS01 KWNH 190159
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-190700-

Mesoscale Precipitation Discussion 0164
NWS Weather Prediction Center College Park MD
958 PM EDT Thu Apr 18 2024

Areas affected...sern MO/nern AR into lower OH Valley and nwrn TN

Concerning...Heavy rainfall...Flash flooding possible

Valid 190157Z - 190700Z

SUMMARY...Short term training of thunderstorms from west to east
may result in localized flash flooding from 2-3 inches of rain.
The threat will extend through 07Z for portions of southeastern MO
into northeastern AR, and eastward into the lower OH Valley and
northwestern TN.

DISCUSSION...Infrared imagery and 01Z surface observations helped
identify a cold front extending from a surface low in west-central
IL, southwestward into northwestern AR. A line of thunderstorms
was located in southeastern IL, well out ahead of the cold front,
arcing southwestward into southeastern MO (with gaps in intensity)
where the line was more coincident with the frontal boundary.
While the presence of hail may be over-inflating MRMS rainfall
estimates, peak rainfall rates were averaging between 1-2 in/hr
over the past few hours according to MRMS data.

The cold front is forecast by the model consensus to continue a
steady movement toward the southeast through at least the first
half of the night, limiting flash flood concerns just considering
movement of the boundary. However, given radar trends and short
term extrapolation of the leading line of thunderstorms in IL,
moving out ahead faster than the portion of the line in MO, there
could be some portions of the convective line that orient parallel
to mean steering flow, supporting at least a short period of
training. Where/if this occurs, rainfall rates of 1-2 in/hr could
result in 2-3 inches of rain in roughly a 2 hour window. 925-850
mb winds from the SSW at 01Z were focusing the best low level
moisture transport up the MS River Valley and this axis is
expected to edge eastward over the next few hours while gradually
veering through 06Z. The flash flood threat is expected to
decrease beyond 06Z with reducing instability and veering low
level flow, in line with the hires model consensus, but trends
will be monitored for changes to the forecast evolution.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LMK...LSX...LZK...MEG...OHX...PAH...SGF...

ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC...

LAT...LON   38238735 38058667 37598622 36728621 36268650 
            36078727 35988819 35858968 36099170 36619216 
            36699211 37039149 37349083 37748961 

711 
AWUS01 KWNH 182122
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-190100-

Mesoscale Precipitation Discussion 0163
NWS Weather Prediction Center College Park MD
521 PM EDT Thu Apr 18 2024

Areas affected...Arklamiss into north-central MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 182119Z - 190100Z

Summary...Localized but likely flash flooding to persist while
translating east for another few hours into central MS through
00Z. Rainfall rates over 2 in/hr can be expected.

Discussion...21Z radar imagery continued to show a west-east axis
of thunderstorms extending from the eastern AR/LA border into
central MS, with MRMS hourly rainfall totals over 2 inches at
times. MRMS-derived rainfall over the past 6 hours (ending 21Z) is
near 10 inches along the southern Ashley/Chicot County border, and
while MRMS rainfall matches a Wunderground.com station just west
of Eudora, AR with 5.74", this region resides within the melting
layer of the 3-nearest WSR-88Ds, and uncertainty exists with the
actual highest rainfall totals given a lack of ground truth.
Regardless, significant rainfall has fallen within a relatively
short period of time near the AR/LA/MS border with ongoing flash
flooding.

A mid to upper level shortwave was observed to be moving east
along the central AR/LA border with diffluent flow downstream.
Radar/infrared imagery downstream of the shortwave into central MS
has shown some signs of losing organization over the past hour.
Despite that fact, the environment will continue to favor training
heavy rain for the next 1-3 hours to the north of an outflow
boundary analyzed from northern LA into central MS with 20-35 kt
of SSW 925-850 mb flow in northern LA overrunning the rain-cooled
airmass. While some near term weakening of the low level flow will
be possible, MLCAPE estimates just south of the outflow boundary
were 1000 to 2000+ j/kg via the 21Z SPC mesoanalysis and as the
shortwave aloft continues to advance toward the east, areas of
heavy rain with training will shift downstream into portions of
central MS through 00Z. Peak rainfall rates over 2 in/hr will
remain possible at times and and an additional 2-5 inches is
expected for localized areas through 00Z or 01Z.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   33628913 33538823 33068814 32418824 32268905 
            32339032 32579130 33049166 33379130 33529039 
            

503 
AWUS01 KWNH 181659
FFGMPD
MSZ000-LAZ000-ARZ000-182100-

Mesoscale Precipitation Discussion 0162
NWS Weather Prediction Center College Park MD
1258 PM EDT Thu Apr 18 2024

Areas affected...southeastern Arkansas, western Mississippi, and
northeastern Louisiana

Concerning...Heavy rainfall...Flash flooding likely

Valid 181657Z - 182100Z

Summary...Localized flash flood threat continues across the
discussion area through 21Z.

Discussion...A robust band of training convection continues along
the AR/LA border region near/just north of an axis from Lake
Providence to Bastrop.  Radar estimates of 3-5 inches of rainfall
have been observed with this band so far.  Surface observations
suggest that a maturing cold pool has developed in vicinity of the
storms, which should aid in a continued focus for convective
development through the early afternoon.  Meanwhile, southwesterly
850mb flow continues to help maintain a fetch of 1500+ J/kg SBCAPE
and 1.8 inch PW values into the region, supporting robust and
efficient updrafts.  Upstream, satellite/radar imagery continues
to suggest updrafts near/east of Shreveport, likely associated
with a mid-level shortwave trough near TXK.  This suggests that
continued development of convection will likely continue for at
least a couple more hours (potentially through 21Z) on the western
flank of ongoing convection.  At least 1 inch/hr rain rates are
likely to be maintained during this period.

Models and observations suggest that the overall scenario
supporting flash flooding should shift to the east at some point -
especially once the shortwave trough over the TXK area shifts
eastward and mid/upper subsidence can develop in its wake.  This
process will take a few hours to unfold, however.  Flash flooding
potential will continue - especially where heavier rainfall has
already occurred across the discussion area.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...LMRFC...NWC...

LAT...LON   33939112 33849012 33348978 32649024 32509183 
            32399281 33319293 33739223 

222 
AWUS01 KWNH 181413
FFGMPD
MSZ000-LAZ000-ARZ000-181812-

Mesoscale Precipitation Discussion 0161
NWS Weather Prediction Center College Park MD
1012 AM EDT Thu Apr 18 2024

Areas affected...northern Louisiana, southern Arkansas, and
western Mississippi

Concerning...Heavy rainfall...Flash flooding possible

Valid 181412Z - 181812Z

Summary...A band of convection has deepened very near the
Arkansas/Louisiana border region over the past hour.  These cells
are oriented favorably for training and heavy rainfall,
potentially posing a spotty flash flood risk through 18Z.

Discussion...The combination of confluent/convergent low-level
flow (in the 850mb layer) and a stout shortwave trough across
northeast Texas was contributing to development of robust
convection along the AR/LA border region over the past hour.  The
cells are oriented favorably parallel to mid/upper steering flow
for training, and while rain rates so far are peaking at around
0.5 inch/hr, ~2000 J/kg SBCAPE and 1.5 inch PW values should
eventually support higher rain rates especially as convection
continues to train across the area.

Observations and SPC Mesoanalyses suggest that this axis of
convection could persist for a few hours as 1) the mid-level wave
providing ascent continues to approach the area and 2) convergence
on the nose of a 35kt 850mb low-level jet upstream across
southeast Texas both contribute to ascent for deep convective
development through 18Z or so.  An isolated flash flood risk is
expected especially where convective training can boost rain rates
into the 2-2.5 inch/hr range.  FFGs are in the ~2.5 inch/hr range,
and may be exceeded in a few spots as storms mature.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...LMRFC...NWC...

LAT...LON   33989137 33959011 33588961 32948967 32369123 
            32229317 32589377 33189367 33609325 33889245 
            

279 
AWUS01 KWNH 172233
FFGMPD
NYZ000-PAZ000-MDZ000-WVZ000-OHZ000-180400-

Mesoscale Precipitation Discussion 0160
NWS Weather Prediction Center College Park MD
633 PM EDT Wed Apr 17 2024

Areas affected...eastern OH, WV, MD Panhandle into western PA and
far western NY

Concerning...Heavy rainfall...Flash flooding possible

Valid 172232Z - 180400Z

Summary...The potential for a quick inch or two of rain may
produce localized flash flood concerns across portions of the
Appalachian Plateau into the central Appalachians through 04Z.
While total rainfall is not expected to amount to much, the region
contains above average soil moisture and elevated creeks/streams
from heavy rainfall within the past 2 weeks.

Discussion...22Z radar imagery across the Upper OH Valley showed a
band of thunderstorms located along and ahead of a cold front
moving through east-central OH. Farther east, thunderstorm
coverage was in the process of expanding near a stationary front
that extended from NW to SE across western PA. The warm sector was
characterized by MLCAPE of 500 to over 1000 J/kg as seen on the
22Z SPC mesoanalysis, confirmed with the 21Z PBZ sounding,
although instability in WV was still below 500 J/kg with the cold
front still well west of the region. Several Wunderground.com
observing sites have reported 0.5 to 1.0 inches of rain in 15
minutes with the line of thunderstorms as they've moved through
over the past 1-2 hours, but the forward progression of the cold
front has limited total rainfall to 1 to 1.5 inches in localized
spots across the area.

Given mean steering flow from the WSW and a tendency for the line
of thunderstorms, south of the apex, to align with the mean wind,
training potential has increased for some locations in central to
southeastern OH. MLCAPE of about 500 to 1000 J/kg is forecast by
the RAP to advance eastward with the progression of the cold front
and some weak instability will remain after sunset, especially
across WV where 0-2 km moisture is expected to remain highest
relative to northern locations. Additional thunderstorm
development will be possible near/south of the southern edge of
the existing line as it moves into WV with possible short term
training resulting in high rainfall intensities over a time frame
of up to 1-2 hours. Northern locations from west-central PA into
western NY may experience two rounds of heavy rain, first with the
ongoing discrete cells and second as the front approaches from the
west after 00Z.

The region from eastern OH into western PA and WV has received 4-8
inches above average rainfall over the last 2 weeks, leaving
portions of the area with increased soil moisture and elevated
waterways. A quick 1-2 inches of rain may result in localized
flash flooding through the early overnight.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BUF...CLE...CTP...ILN...LWX...PBZ...RLX...

ATTN...RFC...MARFC...NERFC...OHRFC...NWC...

LAT...LON   42517894 42277803 41247762 40127798 39597849 
            38308010 38228151 38328192 39018300 39668308 
            40498196 41828134 42307991 

168 
AWUS01 KWNH 161756
FFGMPD
MNZ000-IAZ000-NEZ000-SDZ000-162132-

Mesoscale Precipitation Discussion 0159
NWS Weather Prediction Center College Park MD
155 PM EDT Tue Apr 16 2024

Areas affected...northeastern Nebraska, far southeastern South
Dakota, and far western Iowa

Concerning...Heavy rainfall...Flash flooding likely

Valid 161732Z - 162132Z

Summary...A nearly stationary complex of storms continues to
produce 1-2.5 inch/hr rain rates and has done so for several
hours. Flash flooding is likely through 21Z.

Discussion...An axis of convection has remained nearly stationary
across northeastern Nebraska over the past 3-4 hours while
producing periods of 1-2.5 inch/hr rain rates at times.  The
convection is generally oriented along a line from Yankton, SD to
Norfolk, NE to Columbus, NE, with backbuilding on its southern
flank continuing to support nearly stationary and erratic movement
with the complex.  Easterly low-level flow was maintaining a fetch
of near 60F dewpoints into the area of convection.  Meanwhile, an
outflow boundary has matured along the rainfall axis and southerly
flow aloft continues to help the complex maintain its very slow
motion along with backbuilding.  Cold temperatures aloft also
support moderate surface-based instability in the pre-convective
environment near the storms, further supporting robust updrafts.

The ongoing scenario will change little over the next couple
hours, with spots of 1-2.5 inch/hr rain rates continuing over the
area through 19Z.  Thereafter, convective trends are a bit
uncertain and will depend on evolution and propagation of the cold
pool.  Given the proximity of the mid/upper low and cold air
aloft, it appears that at least some threat of heavier downpours
will persist through most of the afternoon even though the cold
pool is likely to begin shifting slowly northeastward over the
course of the afternoon.  Another 1-3 inches of precipitation is
possible atop the nearly 2-5 inch totals that have already
developed (estimated per MRMS).  Flash flooding is likely in this
scenario.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FSD...GID...LBF...OAX...

ATTN...RFC...MBRFC...NWC...

LAT...LON   43819772 43649624 42789562 41609592 41359773 
            41909853 

089 
AWUS01 KWNH 161421
FFGMPD
MOZ000-MNZ000-IAZ000-KSZ000-NEZ000-SDZ000-161800-

Mesoscale Precipitation Discussion 0158
NWS Weather Prediction Center College Park MD
1021 AM EDT Tue Apr 16 2024

Areas affected...eastern Nebraska, southeastern South Dakota,
northeastern Kansas, northwestern Missouri, and western into
central Iowa

Concerning...Heavy rainfall...Flash flooding possible

Valid 161420Z - 161800Z

Summary...Bands of convection are resulting in prolonged rain
rates (including 2+ inch/hr rates at times) across the discussion
area.  Areas/spots of flash flooding are possible through 18Z this
morning.

Discussion...Over the last hour or so, a couple of dominant
convective bands have taken on a favorable orientation for
training despite relatively fast steering flow and storm motions.
One of these bands extended from near Yankton, SD to near
Columbus, NE, with rightward-moving structured embedded and
assisting in both 1 inch/hr rain rates and 2-2.5 inch/3-hr rain
rates beneath the band.  This area was continuing to ingest
surface-based parcels due to southeasterly low-level flow and near
60F dewpoints beneath very cold air aloft (-20C at 500mb),
contributing to relatively efficient rain rates.  Local FFGs in
the 1.5 inch/hr range were being approached on a localized basis,
suggesting a continued flash flood risk as long as convection
remains rooted near the surface.  Some cells were moving northward
toward cooler surface air, however, which may weaken storms and
lower rain rates as they drift into southeastern South Dakota.

Southeast of this area, a second band of more robust convection
extended from near Clarinda in southwest Iowa through Topeka, KS.
These cells are also training and fostering areas of nearly 2
inch/hr rain rates due to favorable orientation to south-southwest
steering flow aloft.  Stronger buoyancy in this area was also
contributing to slightly stronger/deeper updrafts per satellite
imagery.  These storms were also lifting northward toward a
low-level boundary and stable air across central Iowa, although
ascent/forcing aloft may sustain training cells toward the Des
Moines, IA area after 16Z or so.

Models suggest that warm advection/destabilization will develop
northward into areas of central/northwestern Iowa over time,
resulting in a broader spatial opportunity for deep, training
updrafts and heavy rain rates.  Areas of 1-2 inch/hr rain rates
are expected to approach FFG thresholds over the discussion area
on at least a spotty basis through 18Z or so.  The threat could
persist beyond 18Z, although model trends seem to indicate a
faster forward progression of convection (and less training)
through the afternoon hours.  This scenario will be re-evaluated
for another potential MPD after 18Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...DMX...EAX...FSD...ICT...MPX...OAX...SGF...TOP...

ATTN...RFC...ABRFC...MBRFC...NCRFC...NWC...

LAT...LON   44399753 44339634 43329360 41849265 39539264 
            38389370 38069443 38039543 39329568 40479675 
            42379784 43669793 

035 
AWUS01 KWNH 160631
FFGMPD
MNZ000-IAZ000-NEZ000-SDZ000-161200-

Mesoscale Precipitation Discussion 0157
NWS Weather Prediction Center College Park MD
231 AM EDT Tue Apr 16 2024

Areas affected...Southeast SDak...Northeast NEB...Northwest
Iowa...

Concerning...Heavy rainfall...Flash flooding possible

Valid 160630Z - 161200Z

SUMMARY...Slow moving, locally intense thunderstorms may produce
some widely scattered spots of 2"+ rainfall precursory to stronger
wave and additional thunderstorms approaching toward daybreak
across the Mid-Missouri Valley.  Some low-end incidents of flash
flooding may be possible; but will at least set the stage for
increasing risk later this morning.

DISCUSSION...GOES-E 10.3um EIR and WV suite imagery depict a
broadening/cooling convective complex within the highly diffluent
western branch of the upper level jet across the Mid-Missouri
River Valley providing excellent outflow aloft to maintain
convective development.  In the lower levels, well defined surface
stationary front across the SDak/NEB line angles south through the
river valley into northwest MO, delineating moist air with low to
mid 60s Tds in the warm sector compared to 30s/40s north of it. 
Stronger shortwave of main closed low has shifted into the central
High Plains advancing toward the area and the low level jet has
responded with solid confluence in the sfc to boundary layer
region enhancing convergence at the frontal zone across NE NEB;
flux of 45-50kts and the enhanced moisture along the boundary
continues to provide solid flux through overall moisture
values/depth is limited to 1.25-1.3", but will steadily increase
toward 1.5" by late morning.

Highly unstable mid-levels (MUCAPES of 2000-2500 J/kg) are
resulting in the stronger updrafts and given the flux into the low
levels has been initially resulting in hail and cold pool
generation, steepening the front.  Deep layer flow supports north
to northwest cell motions; however, it is the anchoring of the
frontal zone and initiation spots that will aid back-building
regenerative updrafts capable of increasingly efficient rainfall
production.  Rates of 1.5"/hr may become closer to 2" with time
and strengthening approaching mid-level forcing toward 12z.  Still
the overall duration may result in localized spots of 2-3" and may
induce an instance of flash flooding in the vicinity (just north)
of the stationary front until that time, and therefore is
considered possible for the Mid-Missouri Valley through 12z.


Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...DMX...FSD...OAX...

ATTN...RFC...MBRFC...NWC...

LAT...LON   44079726 43629627 42919546 42379515 41389503 
            40989595 42029717 42889827 43319861 43909835 
            

328 
AWUS01 KWNH 160324
FFGMPD
SDZ000-160730-

Mesoscale Precipitation Discussion 0156...Corrected
NWS Weather Prediction Center College Park MD
1123 PM EDT Mon Apr 15 2024

Corrected for Resent for spelling errors

Areas affected...Western to South-central South Dakota...

Concerning...Heavy rainfall...Flash flooding possible

Valid 160250Z - 160730Z

SUMMARY...Very high moisture flux over outflow boundary is
resulting in efficient rainfall production and with slow forward
propagation may pose higher rainfall totals (2-3") capable of
inducing localized incident(s) of flash flooding.

DISCUSSION...Rapid surface cyclogenesis is occurring just south of
the Black Hills of SD where a 989mb low was noted.  Very strong
isallobaric wind response is generating very high southeasterly
and easterly confluent low level flow across the central Plains
into SDak.  Upon this, moisture has been channeled into a tongue
across northeast NEB angled into western NEB.  Given surface winds
of 30-35kts and 850mb flow and winds at the boundary layer of
50-60kts, moisture flux has been very strong.  Initial rounds of
thunderstorms generated cold pools from drier mid-level air in
place subsequently resulting in favorably oriented outflow
boundaries to the flow to support additional rapid convective
development along the isentropic ascent.

Combined with natural low level barrier in the Black Hills low
level winds remain highly convergent resulting in sufficient
moisture flux into the developing storms for fairly efficient
rainfall production (updraft loading) given the overall drier
environment. While UDX RADAR suggests modest hail generation, KDP
field also supports downdrafts with fairly decent rainfall
generation while supporting 1.5-2"/hr estimates.  Forward
propagation should be effective in eastward cell motions, but
current trends suggest stronger mid to upper level divergence
channel toward the northwest and north is supporting downshear
updraft columns maintaining a bit longer duration for heavier
rainfall to accumulate before the outflow boundary presses too far
east and generates another updraft cycle further west.  As such,
north/south oriented lines of enhanced rainfall should be expected
over the next few hours with slow eastward advancement before
approaching shortwave from the southeast triggers a stronger
complex further upstream robbing the best environmental moisture
flux.  As such a few lines of 2-3" totals are possible over the
next 3-4hrs slowly advancing eastward into central SDak.

While the soils have been dry, the shear magnitude of rainfall and
naturally lower FFG values north of the Sand Hills, suggest these
2-3" totals in 1-3hrs may induce a localized flash flooding
incident or two through 08z and considered possible.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABR...UNR...

ATTN...RFC...MBRFC...NWC...

LAT...LON   45210237 45080119 44099989 43499991 43290028 
            43370099 43720166 43600249 43340304 43470358 
            44050378 44830337 

830 
AWUS01 KWNH 160250
FFGMPD
SDZ000-160730-

Mesoscale Precipitation Discussion 0156
NWS Weather Prediction Center College Park MD
1050 PM EDT Mon Apr 15 2024

Areas affected...Western to south-central South Dakota...

Concerning...Heavy rainfall...Flash flooding possible

Valid 160250Z - 160730Z

SUMMARY...Very high moisture flux over outflow boundary is
resulting in efficient rainfall production and with slow forward
propagation may pose higher rainfall totals (2-3") capable of
inducing localized incident(s) of flash flooding.

DISCUSSION...Rapid surface cyclogenesis is occurring just south of
the Black Hills of SD where a 989mb low was noted.  Very strong
isallobaric wind response is generating very high southeasterly
and easterly confluent low level flow across the central Plains
into SDak.  Upon this, moisture has been channeled into a tongue
across northeast NEB angled into western NEB.  Given surface winds
of 30-35kts and 850mb flow and winds at the boundary layer of
50-60kts, moisture flux has been very strong.  Initial rounds of
thudnerstorms generated cold pools from drier mid-level air in
place subsequently resulting in favorablely oriented outflow
boundaries to the flow to support additional rapid convective
development along the isentropic ascent.

Combined with natural low level barrier in the Black Hills low
level winds remain highly convergent resulting in suffficient
moisture flux into the developing storms for fairly efficient
rainfall production (updraft loading) given the overall drier
environment. While UDX RADAR suggests modest hail generation, KDP
field also supports downdrafts with fairly decent rainfall
generation while supporting 1.5-2"/hr estimates.  Forward
propagation should be effective in eastward cell motions, but
current trends suggest stronger mid to upper level divergence
channel toward the northwest and north is supporting downshear
updraft columns maintaining a bit longer duration for heavier
rainfall to accumulate before the outflow boundary presses too far
east and generates another updraft cycle further west.  As such,
north/south oriented lines of enhanced rainfall should be expected
over the next few hours with slow eastward advancement before
approaching shortwave from the southeast triggers a stronger
complex further upstream robbing the best environmental moisture
flux.  As such a few lines of 2-3" totals are possible over the
next 3-4hrs slowly advancing eastward into central SDak.

While the soils have been dry, the shear magnitude of rainfall and
naturally lower FFG values north of the Sand Hills, suggest these
2-3" totals in 1-3hrs may induce a localized flash flooding
incident or two through 08z and considered possible.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABR...UNR...

ATTN...RFC...MBRFC...NWC...

LAT...LON   45210237 45080119 44099989 43499991 43290028 
            43370099 43720166 43600249 43340304 43470358 
            44050378 44830337 

632 
AWUS01 KWNH 121256
FFGMPD
MEZ000-MAZ000-NHZ000-121845-

Mesoscale Precipitation Discussion 0155
NWS Weather Prediction Center College Park MD
855 AM EDT Fri Apr 12 2024

Areas affected...Northern New England

Concerning...Heavy rainfall...Flash flooding likely

Valid 121245Z - 121845Z

SUMMARY...Heavy showers over the next several hours combined with
snowmelt over the higher terrain is likely to result in areas of
flash flooding going through early this afternoon.

DISCUSSION...A deep layer trough of low pressure continues to
advance into the Northeast U.S. this morning with a surge of
strong warm air advection and moisture transport lifting up across
much of New England. In fact, a warm front continues to surge
northward across the interior of New England which is yielding the
arrival of a notably warm/moist airmass in off the western
Atlantic Ocean.

The early morning CIRA-ALPW data shows the LPW in the SFC/700mb
layer exceeding the 95th percentile of climatology, and this will
play a key role in conjunction with a southerly low-level jet of
50 to 60+ kts in driving efficient rainfall processes for elevated
rainfall rates. The CIRA-LVT magnitudes below 700 mb are
particularly strong right now nosing up across areas of
central/eastern MA and southern NH, with magnitudes exceeding 300
kg/m/s.

Radar imagery shows a batch of heavy shower activity including a
few thunderstorms riding northward across eastern MA and RI which
will likely get up into areas of central/southern NH and
especially southwest ME over the next few hours. A nose of
instability is associated with this area of convection with MUCAPE
values of as much as 500 to 1000 J/kg, and this coupled with the
efficient moisture column is driving rainfall rates of as much as
1"/hour with the stronger convective cells, although much of this
rainfall is tending to fall in as little as 30 to 45 minutes in
some cases.

Overall, the latest hires model guidance including the HRRR and
overnight HREF members appear to be a bit underdone with the
ongoing areas of heavy rain. The expectation is that rainfall
rates and coverage of heavy rain may increase going through
midday, and especially for areas of western and southwest ME. An
additional 2 to 3 inches of rain may occur locally, and especially
if some of the convective bands of eastern MA begins to locally
train over the same area into portions of western ME.

Snowmelt is a major concern at least locally up across the White
Mountains this morning in central and northern NH, and adjacent
areas of western ME with very warm air and high dewpoints
overrunning the remaining snowpack. Aside from this, the region in
general is quite sensitive with very moist/wet soil conditions.
Therefore, collectively, the arrival of additional heavy rainfall
over northern New England will encourage notable concerns for
runoff problems and flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BOX...CAR...GYX...

ATTN...RFC...NERFC...NWC...

LAT...LON   45626963 45446879 44726860 44166908 43597018 
            42807104 42857174 43387198 44007195 44767124 
            45347058 

277 
AWUS01 KWNH 121248
FFGMPD
MEZ000-MAZ000-NHZ000-121845-

Mesoscale Precipitation Discussion 0155
NWS Weather Prediction Center College Park MD
846 AM EDT Fri Apr 12 2024

Areas affected...Northern New New England

Concerning...Heavy rainfall...Flash flooding likely

Valid 121245Z - 121845Z

SUMMARY...Heavy showers over the next several hours combined with
snowmelt over the higher terrain is likely to result in areas of
flash flooding going through early this afternoon.

DISCUSSION...A deep layer trough of low pressure continues to
advance into the Northeast U.S. this morning with a surge of
strong warm air advection and moisture transport lifting up across
much of New England. In fact, A warm front continues to surge
northward across the interior of New England which is yielding the
arrival of a notably warm/moist airmass in off the western
Atlantic Ocean.

The early morning CIRA-ALPW data shows the LPW in the SFC/700mb
layer exceeding the 95th percentile of climatology, and this will
play a key role in conjunction with a southerly low-level jet of
50 to 60+ kts in driving efficient rainfall processes for elevated
rainfall rates. The CIRA-LVT magnitudes below 700 mb are
particularly strong right now nosing up across areas of
central/eastern MA and southern NH, with magnitudes exceeding 300
kg/m/s.

Radar imagery shows a batch of heavy shower activity including a
few thunderstorms riding northward across eastern MA and RI which
will likely get up into areas of central/southern NH and
especially southwest ME over the next few hours. A nose of
instability is associated with this area of convection with MUCAPE
values of as much as 500 to 1000 J/kg, and this coupled with the
efficient moisture column is driving rainfall rates of as much as
1"/hour with the stronger convective cells, although much of this
rainfall is tending to fall in as little as 30 to 45 minutes in
some cases.

Overall, the latest hires model guidance including the HRRR and
overnight HREF members appear to be a bit underdone with the
ongoing areas of heavy rain. The expectation is that rainfall
rates and coverage of heavy rain may increase going through
midday, and especially for areas of western and southwest ME. An
additional 2 to 3 inches of rain may occur locally, and especially
if some of the convective bands of eastern MA begins to locally
train over the same area into portions of western ME.

Snowmelt is a major concern at least locally up across the White
Mountains this morning in central and northern NH, and adjacent
areas of western ME with very warm air and high dewpoints
overrunning the remaining snowpack. Aside from this, the region in
general is quite sensitive with very moist/wet soil conditions.
Therefore, collectively, the arrival of additional heavy rainfall
over northern New England will encourage notable concerns for
runoff problems and flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BOX...CAR...GYX...

ATTN...RFC...NERFC...NWC...

LAT...LON   45626963 45446879 44726860 44166908 43597018 
            42807104 42857174 43387198 44007195 44767124 
            45347058 

704 
AWUS01 KWNH 120524
FFGMPD
NYZ000-PAZ000-MDZ000-VAZ000-WVZ000-121100-

Mesoscale Precipitation Discussion 0154
NWS Weather Prediction Center College Park MD
123 AM EDT Fri Apr 12 2024

Areas affected...Western NY...Western to Central PA... Adj
Northwest MD...Far Eastern WV...

Concerning...Heavy rainfall...Flash flooding possible

Valid 120530Z - 121100Z

SUMMARY...Some threat for flash flooding continues overnight due
to training storms across complex terrain, though overall coverage
and magnitude will be diminishing with time.

DISCUSSION...GOES-E WV shows a potent southern stream shortwave
lifting north across S West Virginia at this time being kicked
from the base of the larger scale polar trough lifting out of the
Cumberland Plateau (ahead of the undercutting jet in the Tennessee
Valley).  So combined with the stronger DPVA along/ahead of the
wave, broadening diffluence across the Allegheny Plateau and
steepening mid-level lapse rates with CAA aloft keeps an
environment for scattered thunderstorms.  While much of the
temperature/dewpoint depressions have fallen to near zero; modest
moisture of upper 50s and low 60s have streamed northward through
the terrain, with CIRA LPW denoting very anomalous moisture in the
sfc-850 and modest 850-700mb layers still advecting across central
PA into south-central Upstate NY with providing ample moisture
flux to any ongoing lingering convection.  At this time, profiles
still support some 200-300 J/kg of MUCAPE to allow for some
vertical development to maintain/weaken slowly in the region of
continued best ascent.  Rates of up to .75" are possible with
smaller convective elements, but more likely .25-.5"/hr rates will
remain with those remaining cells...so duration is going to remain
key for any potential flash flooding downstream into W NY, central
PA. 

Given the terrain of central PA remains favorably oriented to deep
layer steering (near parallel) and low level flow still suggests
some orthogonal easterly component along/ahead of the shortwave;
there remains some potential for training.  As such, high-res CAMs
and last WoFS runs suggested a few stripes of 1-2" totals remain
especially across along and east of the track of the mid-level
shortwave (which appears to be crossing W PA)...placing best
potential from Bedford to Potter counties. 

Though this is not very much rainfall; however, given recent
saturated ground conditions (200-300% of normal in last 2 weeks)
across complex/steep terrain; FFG values are well below normal and
within range of exceedance given 1-2" potential.   As such, cannot
rule out a spot or two of flash flooding through the overnight
hours and flash flooding is considered possible...even as the
overall trend of intensity and coverage continues to diminish.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BGM...BUF...CLE...CTP...LWX...PBZ...

ATTN...RFC...MARFC...NERFC...OHRFC...NWC...

LAT...LON   43147858 43017775 42597727 41847683 40587658 
            39577682 39297850 40357926 41637968 42427946 
            42987905 

349 
AWUS01 KWNH 112344
FFGMPD
NYZ000-PAZ000-MDZ000-VAZ000-NCZ000-WVZ000-OHZ000-KYZ000-120543-

Mesoscale Precipitation Discussion 0153
NWS Weather Prediction Center College Park MD
744 PM EDT Thu Apr 11 2024

Areas affected...portions of Pennsylvania, West Virginia, western
Virginia, and western Maryland

Concerning...Heavy rainfall...Flash flooding likely

Valid 112343Z - 120543Z

Summary...A focused axis of training convection is resulting in a
prolonged period of 0.25-1.00 inch/hr rates.  Areas of flash
flooding (locally significant) are likely to continue through 05Z.

Discussion...Recent convective trends have exhibited a focused
axis of convection extending from near BKW (Beckley, WV)
north-northeastward to near Pittsburgh Metro.  The band was
aligned with strong deep layer convergence on the western side of
strong, southerly 850mb flow over the Mid-Atlantic.  The band was
also oriented parallel to strong south-southwesterly steering flow
aloft and immediate downstream of a mid-level wave providing
forcing for ascent across the area.  500 J/kg SBCAPE and 1.3 inch
PW values were also located within the pre-convective airmass
across the region supporting the ongoing convection.  The net
result of the pattern was an elongated axis of 1-2 inch rainfall
totals over the past 3 hours (estimated per MRMS) along with
occasional spots of 1 inch/hr rates, all exceeding FFG thresholds
across the area and resulting in excessive runoff (locally
significant near the Pittsburgh area).

The ongoing scenario will persist over the next 4-6 hours, with
only a slow translation eastward of the band of convection during
that timeframe.  This will result in a continued risk of flash
flooding across the discussion area.  Although slight boundary
layer cooling may occur ahead of the band, ascent/cooling aloft
associated with the mid-level wave centered over Kentucky and
continued warm advection ahead of the band should maintain at
least 500 J/kg SBCAPE ahead of the convective band.  Ongoing flash
flood impacts are expected to continue through 05Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BUF...CLE...CTP...JKL...LWX...MRX...PBZ...RLX...
RNK...

ATTN...RFC...LMRFC...MARFC...NERFC...OHRFC...SERFC...NWC...

LAT...LON   42077899 41977785 41117744 39457746 37927863 
            36667984 36258102 37428231 38408286 39148216 
            40438105 41138046 41917963 

018 
AWUS01 KWNH 111811
FFGMPD
PAZ000-VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-120010-

Mesoscale Precipitation Discussion 0152
NWS Weather Prediction Center College Park MD
210 PM EDT Thu Apr 11 2024

Areas affected...Portions of the Upper OH Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 111810Z - 120010Z

SUMMARY...Some expansion of shower and thunderstorm activity is
expected this afternoon through early this evening with pockets of
heavy rainfall rates. This coupled with moist antecedent
conditions may result in some instances of flash flooding.

DISCUSSION...GOES-E IR/WV imagery shows a strong mid-level trough
and an associated frontal zone currently crossing through the
Mid-South and taking aim on the OH Valley. Strong forcing
associated the energy aloft coupled with a gradually destabilizing
boundary layer out ahead it will set the stage for gradually
expanding areas of locally heavy showers and thunderstorms over
the next several hours.

Already the regional dual-pol radars show broken areas of shower
activity impacting large areas of the Upper OH Valley. Overall,
the instability profiles are rather modest though with MUCAPE
values of 500 to 1000 J/kg, with the greatest pooling of this seen
nosing up across central/eastern KY and western WV. However, over
the next few hours, some additional boundary layer destabilization
is expected which will drive an increase in convective coverage,
and the latest GOES-E visible satellite imagery does show some
areal breaks in the cloud cover facilitating an uptick in diurnal
heating.

Effective bulk shear values of locally 40 to 50 kts working in
tandem with the instability, and rather moist low-levels should
favor some relatively organized convective cells capable of
producing heavy rainfall rates. PWs across the broader OH Valley
region are on the order of 1.5 to 2 standard deviations above
normal, and the latest CIRA-ALPW data shows mid-level moisture
relatively concentrated over areas of eastern KY, central/eastern
OH and western WV which will tend to support somewhat greater
rainfall efficiency this afternoon. Rainfall rates across these
areas may reach as high as 1.5"/hour with the stronger cells and
this is supported by the consensus of the 12Z HREF guidance.

Some localized repeating/training of cells will be possible by
late afternoon as the convection attains greater levels of
organization, and with these heavier rates, some localized swaths
of additional rainfall reaching 2 to 3 inches will be possible.

The antecedent conditions are locally rather sensitive, with moist
soils and locally elevated streamflows. So, the additional
rainfall threat this afternoon may encourage some more notable
runoff concerns and potential for flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CLE...ILN...JKL...LMK...MRX...OHX...PBZ...RLX...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON   41858084 41727983 41197931 40787921 39927947 
            39088009 38118110 36908234 36118301 35778361 
            35768402 36148493 37178521 38638458 40068366 
            41238235 

700 
AWUS01 KWNH 110755
FFGMPD
SCZ000-FLZ000-GAZ000-111330-

Mesoscale Precipitation Discussion 0151
NWS Weather Prediction Center College Park MD
354 AM EDT Thu Apr 11 2024

Areas affected...Eastern FL Panhandle...Southern GA...Ext.
Southern SC...

Concerning...Heavy rainfall...Flash flooding possible

Valid 110800Z - 111330Z

SUMMARY...Continued broad area of heavy rainfall, rain-rates of
2"+/hr and localized streaks of 2-5" totals in 3-4 hrs may result
in additional isolated possible flash flooding/rapid inundation
conditions through morning downstream of ongoing flooding in
Central FL panhandle/SW GA.

DISCUSSION...As main surface to upper-low start to vertically
stack further NW across the Low Mississippi Valley; a subtle
shortwave has rounded the base of the closed low and is starting
to lift northeast across the central Gulf generally along/ahead of
core of deepening dry slot across S MS, AL at this time.  Combined
with a diffluent weak dual jet streak centered over S GA is
providing highly favorable mid to upper-level ascent pattern. 
This is manifesting at the surface with sharpening gradients and
increasing warm air advection across the eastern Gulf pressing
warm moist air further north into central GA with 60-70kts of
850mb flow along/ahead of the dry slot.  This narrowed the deep
moisture plume with 2-2.2" total PWats at the coastline, expanding
to 1.75-2" as far north as central GA.  While lapse rates are
flattening, the strength of isentropic ascent and flux convergence
into ongoing convective clusters will keep rainfall efficiency
fairly high with 2"/hr rates likely through daybreak. 

At the surface, the favorable upper-level pattern has supported a
weak surface inflection to develop southwest of Panama City, while
upstream high-falls/dry slot has surged the cold front further
east providing strong directional convergence for some surface
based convection along/near the Big Bend region. Though individual
cell motions are increasing with a ENE trajectory, continued
convergence upstream will support some backbuilding and slow
northward shift in cell motions to allow for repeat/training
streaks to develop across the eastern FL panhandle into southern
GA.  This should allow for some streaks of 2-5" totals to
accumulate. 

While the cells/training environment is moving further into
drier/swampier ground conditions, the intensity of the rain from
such moisture flux, may still provide a possible localized
incident or two of flash (or more likely rapid inundation)
flooding through the early morning hours.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CHS...FFC...JAX...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON   32978123 32388041 31698098 30208234 29568321 
            29748359 29938396 29938415 30128469 31678342 
            32508244 

574 
AWUS01 KWNH 110201
FFGMPD
FLZ000-GAZ000-ALZ000-110815-

Mesoscale Precipitation Discussion 0150
NWS Weather Prediction Center College Park MD
1000 PM EDT Wed Apr 10 2024

Areas affected...Florida Panhandle, Southeast Alabama & Southwest
Georgia

Concerning...Heavy rainfall...Flash flooding likely

Valid 110215Z - 110815Z

SUMMARY...
Widely scattered instances of flash flooding likely to continue as
convection capable of rainfall rates to 1.5 inches per hour
continue across portions of the Deep South. Locally considerable
flash flooding may develop in the hardest hit areas if heavier
convection redevelops late tonight, with new instances of flash
flooding possible.

DISCUSSION...
An MCS slowly tracking along the northeastern Gulf Coast continues
to generate a large area of light to moderate rain. Embedded
convection is locally producing heavy rain to 1.5 inches per hour
over the central Panhandle near Tallahassee and on the
back/northwest side of the precipitation shield towards Pensacola
and south-central Alabama.

Storm total rainfall has broadly averaged between 2 and 5 inches
across the Florida Panhandle, southeast Alabama, and southwest
Georgia. Local totals near the southeast corner of Alabama
southwest into the north-central Panhandle are over 6 inches for
storm total rainfall. This rainfall has already resulted in flash
flooding across these areas.

Through the early morning hours, expect the line of heaviest
rainfall embedded within the middle of the rainfall shield from
west of Tallahassee into the southwest corner of Georgia to
continue slowly weakening. The heaviest embedded convection will
become more cellular, originating from the Gulf, and tracking
northeast. The cellular convection will be more likely to train as
it moves into the Panhandle from the Gulf. The slow eastward
progress of the entire mass of rain will support continued steady
rain over much of the MPD area through 0830Z, with the back edge
gradually moving southeast across southeast Alabama and the far
western Panhandle.

There remains considerable uncertainty how much convection will
move into the Gulf Coast from the Gulf, as thusfar most of the
heaviest convection has remained offshore. Most of the CAMs
continue to suggest the convection will move ashore, but the CAMs
have done quite poorly depicting that northward move up until now.
Convection with marginally higher rainfall rates has successfully
moved inland along the back/western edge of the rainfall shield,
likely due to added forcing from the advancing upper level
shortwave, and should this pattern continue that should diminish
the time any one area sees embedded convection capable of
producing new flash flooding. Meanwhile, the ongoing steady rain
will enable ongoing flooding to continue through the overnight,
worsening should heavier convection move over the hardest hit
areas.

Wegman

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...JAX...MOB...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON   32278419 31948292 31098293 30288354 29968384 
            29648477 29588519 30328635 30268727 31278671 
            32078515 

573 
AWUS01 KWNH 102029
FFGMPD
FLZ000-GAZ000-ALZ000-MSZ000-110230-

Mesoscale Precipitation Discussion 0149
NWS Weather Prediction Center College Park MD
429 PM EDT Wed Apr 10 2024

Areas affected...Central to Northeastern Gulf Coast

Concerning...Heavy rainfall...Flash flooding possible

Valid 102030Z - 110230Z

SUMMARY...
Heavy rainfall to 2 inches per hour will continue to shift east
down the I-10 corridor into this evening. Widely scattered
instances of flash flooding are possible.

DISCUSSION...
A mature MCV is tracking east along the Gulf Coast this afternoon.
The leading edge of the MCV contains the heaviest rainfall, with
rates locally approaching 2 inches per hour from Eglin AFB (KEVX
radar). These strongest thunderstorms have become more progressive
in the past few hours, which in turn is diminishing the flash
flooding threat as compared to a few hours ago across Louisiana.

Behind the main line of storms tracking east across the Florida
Panhandle, numerous showers and thunderstorms featuring
considerably lower rainfall rates continue from east of Pensacola
west through most of coastal Mississippi. While rates for most
areas barely reach 1 inch per hour, the slow movement of the
parent MCV itself is making for multiple hours of this moderate
rainfall to hit areas behind the initial line of storms. The
result has been numerous instances of flash flooding from
Louisiana to coastal Alabama earlier today. The MCV continues to
draw upon abundant Gulf moisture with PWATs exceeding 2 inches.
Instability has been decreasing along the Gulf coast, generally
under 1,000 J/kg.

As the MCV pushes east, most of the heaviest rainfall behind the
initial line of storms is now mostly off the coast. Much of the
CAMs guidance suggests these heavier cores will either translate
east, eventually impacting the Panama City area, or begin to lift
back north towards the coast, which may impact areas as far west
as Pensacola late this afternoon into this evening. Regardless,
expect multiple hours of moderate to occasionally heavy rain, with
any training cells developing in deep southwesterly flow further
locally enhancing the flooding threat.

Soils in this area started out the day a bit drier than normal,
and with the initial line of storms producing by far the heaviest
rainfall in the entire MCV moving faster to the northeast, think
the broad scale flash flooding threat is now diminishing,
especially the further east into the Florida Panhandle and Georgia
you go. However, the potential for the heaviest rains behind the
initial line of storms to move back onshore into the Florida
Panhandle followed by training cells keeps the flash flooding
threat elevated, especially given the history this MCV has of
producing flash flooding.

Wegman

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   31888607 31778441 31478360 31098354 30388384 
            30108412 29648515 30298632 30208790 30278912 
            30858903 31648773 31828706 

268 
AWUS01 KWNH 101819
FFGMPD
ALZ000-MSZ000-102218-

Mesoscale Precipitation Discussion 0148
NWS Weather Prediction Center College Park MD
218 PM EDT Wed Apr 10 2024

Areas affected...Central to Northeast MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 101818Z - 102218Z

SUMMARY...Additional heavy showers and thunderstorms over the next
few hours should maintain the threat for areas of flash flooding,
and especially with wet/saturated soil conditions. Conditions
should gradually improve by late this afternoon.

DISCUSSION...Radar imagery shows a very strong MCV advancing
east-northeast across central MS which is connected to the
long-lived QLCS that has been sweeping across the Gulf Coast
states over the last several hours. Areas of heavy rain showers
and thunderstorms are still occurring in conjunction with the MCV
itself, although cloud tops are gradually warming across the
region which is suggestive of a general weakening trend.

The energy associated with the MCV is becoming well-detached from
the pooling of better instability and low-level jet forcing
situated closer to the central Gulf Coast, and this should
facilitate a further weakening of the rainfall rates/trends for
central to northeast MS heading through the late afternoon hours.

Nevertheless, rainfall rates of as much as 1" to 1.5" are still
occurring with some of the stronger embedded convective cells
within the larger scale convective mass, and at least for a few
more hours, these rains will be falling on areas that have already
had excessive rainfall and flash flooding.

The latest HRRR guidance suggests additional rainfall totals of 1
to 2 inches with isolated heavier amounts being possible going
through late this afternoon, and this may still focus some
concerns for more short-term flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...MEG...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   34618853 34308815 33748819 33278833 32698893 
            32658991 33189034 34418936 

360 
AWUS01 KWNH 101733
FFGMPD
LAZ000-ARZ000-TXZ000-OKZ000-102332-

Mesoscale Precipitation Discussion 0147
NWS Weather Prediction Center College Park MD
132 PM EDT Wed Apr 10 2024

Areas affected...Southeast OK...Northeast TX...West-Central to
Southwest AR

Concerning...Heavy rainfall...Flash flooding likely

Valid 101732Z - 102332Z

SUMMARY...Slow-moving showers and thunderstorms are expected going
through the afternoon hours with locally heavy rainfall rates.
This coupled with wet antecedent conditions from recent heavy
rainfall should foster scattered instances of flash flooding over
the next several hours.

DISCUSSION...A deep upper-level trough and an associated closed
low continues to gradually eject east across the southern Plains
en route to the Lower MS Valley. Stronger forcing aloft coupled
with steepening mid-level lapse rates and a moist boundary layer
pooled near a frontal zone will be key to facilitating an
additional expansion of showers and thunderstorms going through
the afternoon hours.

MUCAPE values are on the order of 500 to 1000 J/kg locally, with
aid from 700/500 mb lapse rates of 7.0 to 7.5+ degrees C/KM. Some
additional mid-level cooling is expected especially over southeast
OK, west-central to southwest AR, and northeast TX over the next
few hours and this coupled with at least modest boundary layer
heating and some frontal convergence should gradually allow the
convection currently over southern OK and northern TX to focus
farther off to the east.

The 12Z HREF guidance shows strong agreement in depicting
slow-moving convective cells given rather weak steering currents,
but also supports some localized concerns for smaller-scale
training convective bands. Already dual-pol radar trends show
areas of heavy showers and thunderstorms producing localized 1 to
1.5"/hour rainfall rates, and especially over the eastern suburbs
of the Dallas-Forth Worth metropolitan area where some relatively
organized bands of convection have set up.

Rainfall totals going through late this afternoon may reach 2 to 4
inches with isolated heavier amounts with these slower moving
areas of showers and thunderstorms. This coupled with the wet
antecedent conditions from recent heavy rainfall will likely
result in at least scattered instances of flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   35689386 35359291 34489246 33479263 32409354 
            31739522 31709681 32409761 33849763 34959668 
            35639510 

717 
AWUS01 KWNH 101442
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-102040-

Mesoscale Precipitation Discussion 0146
NWS Weather Prediction Center College Park MD
1041 AM EDT Wed Apr 10 2024

Areas affected...Central/Eastern LA...Central/Southern
MS...Southwest AL...Far Western FL Panhandle

Concerning...Heavy rainfall...Flash flooding likely

Valid 101440Z - 102040Z

SUMMARY...Extremely heavy rainfall rates from organized areas of
showers and thunderstorms will maintain a significant threat for
flash flooding over the next several hours heading into the
afternoon. Areas of considerable to high-impact flash flooding are
expected along and near the I-10 corridor, including multiple
major metropolitan areas from New Orleans to Mobile.

DISCUSSION...The latest GOES-East IR satellite imagery in
conjunction with dual-pol radar continues to show a very
impressive cold-topped convective mass associated with strong QLCS
activity advancing east across the central Gulf Coast region. The
complex remains well-organized out ahead of a deepening area of
low pressure near the northwest Gulf Coast, and will continue to
advance off to the east over the next several hours while
promoting multiple hazards including severe weather and flash
flooding.

Radar imagery shows a well-defined MCV advancing through southwest
MS currently, and the energy/forcing associated with this
continues to help channel a strongly convergent and very moist
southerly low-level jet of 40 to 50+ kts up out of the northern
Gulf of Mexico and into large areas of eastern LA and southern MS.
Enhanced moisture and instability transport associated with this
is interacting with a west/east oriented stationary front draped
east across the region and ahead of the aforementioned deepening
low center.

MLCAPE values of 1000 to 2000 J/kg are focused currently along and
south of this boundary, with the greatest nose of instability
generally aimed into southeast LA including the New Orleans
metropolitan area. This coupled with enhanced vertical shear has
facilitated the development and expansion of numerous areas of
convection across eastern LA and far southern MS over the last 1
to 2 hours including some supercell activity which is all focused
out ahead of the main QLCS axis upstream.

PWs of 1.5 to 1.75+ inches are in place, and with the degree of
instability and shear focusing along the stationary front,
enhanced rainfall rates of 2" to 3"/hour will be likely as the
more organized convective cells evolve over the next several hours
off to the east.

The main concern over the next 3 to 6 hours will be the threat for
convection becoming aligned in a west-southwest to east-northeast
fashion across southeast LA through southern MS and gradually into
southern AL inclusive of the I-10 corridor. Enhanced training of
very heavy showers and thunderstorms is expected locally, and some
major metropolitan areas from New Orleans eastward to Mobile
should closely watch out for the threat of extremely heavy
rainfall rates and storm totals over the next several hours.

Areas farther north across central MS and west-central AL will
also become a focus for areas of heavy rainfall, but with
instability more limited here, the rates should be a bit lower.

An axis of 4 to 8 inches of rain cannot be ruled out across areas
of southeast LA through southern MS and into southwest AL by later
this afternoon. Lesser amounts of 2 to 4 inches are expected
farther north and generally north of the aforementioned stationary
boundary.

Flash flooding is likely across the region, and areas of
considerable to high-impact flash flooding are expected locally
and especially where the greatest areas of cell-training occurs.
This includes a notable threat to the I-10 corridor and the urban
corridors along it.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...LCH...LIX...MOB...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   32768853 32488756 31748689 30558696 30058888 
            29698952 29439041 29479138 29689197 29959212 
            30959160 31559145 32069104 32608969 

157 
AWUS01 KWNH 101217
FFGMPD
ALZ000-MSZ000-LAZ000-101815-

Mesoscale Precipitation Discussion 0145
NWS Weather Prediction Center College Park MD
815 AM EDT Wed Apr 10 2024

Areas affected...Central to Northeast MS...Far Western to
Northwest AL

Concerning...Heavy rainfall...Flash flooding possible

Valid 101215Z - 101815Z

SUMMARY...Broken areas of showers and thunderstorms will continue
to advance off to the east this morning, and a combination of
heavy rainfall rates and locally sensitive soil conditions may
foster some instances of flash flooding through midday.

DISCUSSION...A broken band of heavy showers and thunderstorms
continues to advance off to the east early this morning across
areas of central and northern MS. The activity is somewhat
progressive in nature, including a couple of small-scale bowing
segments, but the activity continues to foster heavy rainfall
rates with some localized areas of repeating cell-activity.

The downstream airmass across eastern MS and western AL is only
weakly unstable with MUCAPE values of as much as 500 J/kg, but a
relatively strong southerly low-level jet of 30 to 40 kts is
forecast to remain in place which will continue to encourage
rather focused moisture transport from the Gulf of Mexico.

This coupled with a gradual increase in boundary layer instability
and the arrival of warm front downstream from strengthening low
pressure near the northwest Gulf Coast should favor at least a
broken axis of convection across areas of central to northeast MS
which will gradually advance into west-central to northwest AL by
early afternoon.

The southern part of the MPD area which has already locally seen
some flash flooding this morning may come under the influence of
stronger and more organized convection impacting areas farther
south down into LA, and this area will need to be monitored for a
more focused and renewed threat of flash flooding.

Generally the rainfall rates with the ongoing broken activity will
tend to be somewhat mitigated by the relative lack of instability,
but some of the stronger convective elements may still produce
some 1 to 1.5"/hour rates, with pockets of additional totals
through early afternoon of 2 to 3 inches. Given the wet antecedent
conditions, these additional rains may foster some instances of
flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...HUN...JAN...MEG...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   34558809 34338757 33598768 32688840 32048939 
            31729048 32279108 33149017 34168914 

019 
AWUS01 KWNH 100933
FFGMPD
MSZ000-LAZ000-TXZ000-101430-

Mesoscale Precipitation Discussion 0144...Corrected
NWS Weather Prediction Center College Park MD
532 AM EDT Wed Apr 10 2024

Corrected for minor northeastward expansion of MPD area

Areas affected...southeastern TX into central/southern LA and
southwestern MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 100927Z - 101430Z

Summary...Heavy rain is expected to expand eastward into portions
of south-central LA with scattered to numerous areas of flash
flooding through 14Z, some of which could be considerable to
severe with life-threatening impacts.

Discussion...A persistent area of training from the southern Piney
Woods region of TX into western LA has resulted in an areas of 5
to 10+ inches of rain over the past 12 hours, extending from
Hardin and Tyler counties into western Vernon and Beauregard
parishes. Radar imagery at 09Z showed the west to east axis of
training, occurring just north of a combined outflow/stationary
front, has begun to lift north over the past hour, ahead of an
approaching, forward propagating convective line moving east from
a Conroe to Houston to Freeport line. The VAD wind profile from
KHGX at 09Z indicated southerly winds of 30-40 kt in the 2-5 kft
AGL layer, ahead of the convective line, a 10 kt increase since
two hours earlier. The strengthening low level flow, just ahead of
a surface low and southward extending cold front near Houston, has
likely helped to shift the axis of ongoing training to the north
over the past hour.

As a potent mid-level trough over western TX continues to advance
east this morning, increased large scale ascent (including
strengthening divergence and diffluence aloft) will shift eastward
from eastern TX into western LA. An ongoing axis of elevated
convergence in the 925-850 mb layer, crossing the Sabine River
from SW to NE, is likely to be disrupted as the upper trough and
preceding convective line advance eastward this morning.
Overrunning low level flow of 30-40 kt will translate eastward
into LA over the next few hours, tapping a notable region of 1000
to 2000+ J/kg MLCAPE located off of the upper TX and LA coast,
supporting continued heavy rainfall. Mean steering flow will be
oriented from SW to NE, but west to east mean translation of the
heavy rainfall axis is expected which should result in continued
training, with rainfall rates of 1-2 in/hr, locally 2 to near 3
in/hr. Additional rainfall totals of 3-5 inches (locally higher)
are expected through 14Z, which is likely to extend a significant
flash flood threat eastward from southeastern TX into portions of
central/southern LA. Any overlap of heavy rain which has fallen
over the past 12 hours will maintain a risk of considerable or
major flash flooding with the Sabine River Valley, and possibly
eastward into portions of central or south-central LA.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HGX...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   32199146 31869063 31259029 30558992 30158962 
            29798980 29609040 29729173 29739326 29509480 
            29789521 30389498 31029423 31419344 

936 
AWUS01 KWNH 100929
FFGMPD
MSZ000-LAZ000-TXZ000-101430-

Mesoscale Precipitation Discussion 0144
NWS Weather Prediction Center College Park MD
528 AM EDT Wed Apr 10 2024

Areas affected...southeastern TX into central/southern LA and
southwestern MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 100927Z - 101430Z

Summary...Heavy rain is expected to expand eastward into portions
of south-central LA with scattered to numerous areas of flash
flooding through 14Z, some of which could be considerable to
severe with life-threatening impacts.

Discussion...A persistent area of training from the southern Piney
Woods region of TX into western LA has resulted in an areas of 5
to 10+ inches of rain over the past 12 hours, extending from
Hardin and Tyler counties into western Vernon and Beauregard
parishes. Radar imagery at 09Z showed the west to east axis of
training, occurring just north of a combined outflow/stationary
front, has begun to lift north over the past hour, ahead of an
approaching, forward propagating convective line moving east from
a Conroe to Houston to Freeport line. The VAD wind profile from
KHGX at 09Z indicated southerly winds of 30-40 kt in the 2-5 kft
AGL layer, ahead of the convective line, a 10 kt increase since
two hours earlier. The strengthening low level flow, just ahead of
a surface low and southward extending cold front near Houston, has
likely helped to shift the axis of ongoing training to the north
over the past hour.

As a potent mid-level trough over western TX continues to advance
east this morning, increased large scale ascent (including
strengthening divergence and diffluence aloft) will shift eastward
from eastern TX into western LA. An ongoing axis of elevated
convergence in the 925-850 mb layer, crossing the Sabine River
from SW to NE, is likely to be disrupted as the upper trough and
preceding convective line advance eastward this morning.
Overrunning low level flow of 30-40 kt will translate eastward
into LA over the next few hours, tapping a notable region of 1000
to 2000+ J/kg MLCAPE located off of the upper TX and LA coast,
supporting continued heavy rainfall. Mean steering flow will be
oriented from SW to NE, but west to east mean translation of the
heavy rainfall axis is expected which should result in continued
training, with rainfall rates of 1-2 in/hr, locally 2 to near 3
in/hr. Additional rainfall totals of 3-5 inches (locally higher)
are expected through 14Z, which is likely to extend a significant
flash flood threat eastward from southeastern TX into portions of
central/southern LA. Any overlap of heavy rain which has fallen
over the past 12 hours will maintain a risk of considerable or
major flash flooding with the Sabine River Valley, and possibly
eastward into portions of central or south-central LA.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HGX...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   31849202 31649106 31229053 30558992 30158962 
            29798980 29609040 29729173 29739326 29509480 
            29789521 30389498 31029423 31419344 

919 
AWUS01 KWNH 100734
FFGMPD
MSZ000-LAZ000-101215-

Mesoscale Precipitation Discussion 0143
NWS Weather Prediction Center College Park MD
333 AM EDT Wed Apr 10 2024

Areas affected...central MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 100731Z - 101215Z

SUMMARY...Training of thunderstorms may produce flash flooding
across portions of central MS through 10Z. Rainfall rates of 1 to
2 in/hr are expected with additional totals of 2-4 inches through
12Z.

DISCUSSION...07Z radar imagery across the Lower MS Valley showed
an eastward advancing MCS with higher values of reflectivity
oriented from the northern LA/MS border into central LA. Weakening
reflectivity and warming cloud tops were noted downstream across
eastern MS into northern AL where instability was absent or very
limited. An outflow boundary (perhaps coincident with a stationary
front) was located just west of MEI to south of JAN to just north
of HEZ at 07Z.  Elevated instability was estimated to be 500-1000
J/kg to the north of the outflow boundary but lowered with eastern
extent via the 07Z SPC mesoanalysis.

As the upstream SW to NE line of thunderstorms approaches MS over
the next 1-3 hours, there will be the potential for training and
possible redevelopment of thunderstorms just ahead of the main
line, located near/north of the outflow boundary. Rainfall rates
of 1-2 in/hr will be possible, which may overlap with 3-5 inches
of rain which impacted portions of the Jackson metro over the past
6 hours. The greatest uncertainty is the availability of
instability due to an overall warming of cloud tops on infrared
satellite imagery over central MS over the past 1-2 hours,
although renewed influx of instability from the south will
possibly continue to support higher rates where training is able
to materialize. Flash flooding will be possible over the next few
hours.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...MEG...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   33708872 33428831 32448857 32108971 32099088 
            32829117 33329070 33688942 

042 
AWUS01 KWNH 100358
FFGMPD
MSZ000-LAZ000-TXZ000-100915-

Mesoscale Precipitation Discussion 0142
NWS Weather Prediction Center College Park MD
1157 PM EDT Tue Apr 09 2024

Areas affected...southeastern TX into south-central LA and western
MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 100356Z - 100915Z

Summary...Training of heavy rain is expected to impact portions of
southeastern TX into south-central LA through 09Z. Localized
rainfall rates near/over 3 in/hr are expected and 6-hr totals of 3
to over 6 inches will be possible. Some significant flash flooding
may occur.

Discussion...Regional radar and infrared satellite imagery at
0330Z showed an MCS advancing over the Lower MS Valley with
upstream training of thunderstorms along its southwestern flank in
southeastern TX. Observed rainfall rates within the axis of SW to
NE training in southeastern TX have been observed near 3 in/hr and
2 to 4 inches have already occurred over Hardin and Tyler counties
within the past 3 hours. Thunderstorms over southeastern TX into
western LA were forming along a low level convergence axis in the
925-550 mb layer, with steering flow parallel to the convergence
axis, supporting training. SPC mesoanalysis data from 03Z showed
ample MLCAPE of 1500 to 2500+ J/kg over southeastern TX with
little to no inhibition.

925-850 mb winds are forecast by the RAP to maintain a southerly
fetch with 25-35 kt speeds slowly translating east into western LA
over the next few hours, but with the convergence axis remaining
in roughly the same place for at least the next 2-4 hours. A
concern for significant rainfall totals and possibly significant
flash flooding comes from expected upstream development, already
underway with a forward propagating cell just west of College
Station and additional development in the vicinity of San Antonio.
The eastward movement of a mid/upper level trough over West Texas
is expected to allow for increasing thunderstorm development
within the instability pool over southeastern TX near a stationary
front analyzed west to east across central/southeastern TX into
LA.

While the axis of ongoing training along the Sabine River may
begin to shift east with time, additional upstream development is
likely to support the development of training from west to east
near the stationary front from portions of southeastern TX into
south-central LA. Rainfall rates of 2 to near 3 in/hr will be
possible at times and 6-hr totals through 09Z are expected to
climb into the 3 to 6 inch range, with localized totals higher
than 6 inches possible. These high rainfall totals are expected to
result in scattered to numerous areas of flash flooding, some of
which could be tied associated with considerable impacts.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HGX...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   32929142 32719065 32359058 31649080 30679185 
            30119266 29729348 29349521 30339573 31039453 
            32419374 

105 
AWUS01 KWNH 092054
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-100315-

Mesoscale Precipitation Discussion 0141
NWS Weather Prediction Center College Park MD
453 PM EDT Tue Apr 09 2024

Areas affected...Ark-La-Tex into northern LA, southern AR, and
west-central MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 092115Z - 100315Z

Summary...Scattered to numerous instances of flash flooding likely
with widespread additional totals of 1-2" (and localized totals of
2-4"). Some significant flash flooding is possible.

Discussion...An MCS has gained better organization across portions
of eastern TX over the past several hours, producing hourly
rainfall totals of 1-2" in association with the primary bow echo
(per MRMS estimates). The mesoscale environment looks to remain
favorable for maintaining the MCS, as a strong (but slowly waning)
LLJ transports ample moisture northward from the Gulf the a
shortwave trough aloft providing 50-70 kts of deep layer shear.
The primary bow echo looks to continue to progress towards the ENE
at 40-50 kts, nearly parallel with an associated quasi-stationary
surface front (as well as the 850-300 mb mean flow). Backbuilding
of convection along the southwestern flank of the MCS will
continue to allow for training of heavy rainfall rates, which may
lead to hourly totals to reach as high as 3" locally. As a result,
some localized 2-4" totals are expected along the southwestern
flank of the MCS, favoring areas near and south of Shreveport.
Should the bow echo maintain its structure as it travels generally
eastward, than these higher totals may extend as far east as
northeast LA into the west-central MS (most prominently depicted
by the ARW and HRRR solutions).

While north-central LA is the most favored corridor for intense
convection (directly along the gradient of favorable instability
with MU CAPE of 500-1500 J/kg), areas just to the north (from
northwest LA into southern AR and the MS Delta) remain the most
saturated from prior rainfall (with FFGs generally < 2"). While
the MCS should begin to favor a southeast drift (as mature MCSs
tend to migrate to the warm side of the stationary front), the
northern flank (and possibly north bookend vortex) can still
produce very heavy rainfall, resulting in localized hourly totals
of 1-2" (but generally limited to 2" due to less favorable
training). This will likely result in scattered to numerous
instances of flash flooding, given relatively widespread totals of
1-2" (and more localized totals of 3-4"). Given the wet antecedent
conditions across much of the region, some significant instances
of flash flooding are possible.

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HGX...JAN...LCH...LZK...MEG...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   34309061 32988997 31989082 31049376 31259500 
            32089489 32629493 32749433 32969415 33349382 
            33639249 

424 
AWUS01 KWNH 091802
FFGMPD
TXZ000-OKZ000-100000-

Mesoscale Precipitation Discussion 0140
NWS Weather Prediction Center College Park MD
201 PM EDT Tue Apr 09 2024

Areas affected...Portions of the TX Panhandle into Northwest TX

Concerning...Heavy rainfall...Flash flooding possible

Valid 091800Z - 100000Z

SUMMARY...Showers and thunderstorms going through the afternoon
hours may produce a few localized pockets of flash flooding.

DISCUSSION...The latest GOES-W WV suite shows a well-defined
upper-level trough and associated closed low gradually edging east
into the southern High Plains.

Areas of showers and thunderstorms are already impacting portions
of the TX Panhandle through northwest TX, and some additional
expansion of this activity in a broken fashion is expected this
afternoon as stronger DPVA/jet-forcing around the eastern flank of
the upper low interacts with a nose of elevated instability
inclusive of a pool of relatively high mid-level lapse rates.

MUCAPE values of as much as 500 to 1000 J/kg are expected to be
generally nosed up across eastern portions of the TX Panhandle and
adjacent areas of northwest TX going through the afternoon hours,
and with a relatively concentrated area of low to mid-level
moisture in place and large scale ascent, some of the convective
elements this afternoon will be capable of producing rainfall
rates of 1 to 1.5 inches/hour.

Despite the elevated nature of the convection, rather strong shear
profiles will encourage some degree of convective organization,
and the cells will tend to be relatively slow-moving and capable
of repeating over the same area. Consequently, at least some
localized swaths of rainfall totals reaching 2 to 4 inches will be
possible.

The 12Z HREF guidance does indicate some low-end probabilities of
seeing 3-hour FFG exceedance with the additional rainfall this
afternoon, and given the locally slow cell-motions, some localized
pockets of flash flooding will be possible.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AMA...LUB...OUN...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON   35240140 35210027 34699968 34099961 33600003 
            33290095 33240197 33560288 34400301 34950237 
            

355 
AWUS01 KWNH 091527
FFGMPD
TXZ000-092125-

Mesoscale Precipitation Discussion 0139
NWS Weather Prediction Center College Park MD
1125 AM EDT Tue Apr 09 2024

Areas affected...Central and Eastern TX

Concerning...Heavy rainfall...Flash flooding likely

Valid 091525Z - 092125Z

SUMMARY...Very heavy showers and thunderstorms including concerns
for additional cell-training will continue across areas of central
and eastern TX. Additional areas of flash flooding are likely, and
locally significant flash flooding is possible.

DISCUSSION...The GOES-East IR satellite imagery shows an expansive
axis of cold-topped convection associated with very heavy showers
and thunderstorms focusing across areas of central and eastern TX,
with the more robust convective growth over the last hour seen
generally along a line from near Burnett through Waco and up into
the Corsicana area. Some rainfall rates with this activity are
reaching into the 2" to 3"/hour range.

The activity continues to locally organize and focus in response
to the nose of a moist southerly low-level jet of 30 to 40 kts
overrunning a quasi-stationary front generally oriented west/east
across the region. A well-defined and substantial pool of
instability is noted near and south of the front, which includes
MLCAPE values of 1500 to 2000+ J/kg across the Hill Country.

This moderate to strongly unstable airmass coupled with focused
low-level moisture convergence and increasingly divergent flow
aloft ahead of a deeper layer trough/closed low ejecting east into
the southern High Plains is expected to favor a continuation and
localized expansion of convective activity over the next few hours.

Many areas across northern and eastern TX have already seen heavy
rainfall and flash flooding early this morning, and additional
very heavy rainfall totals are expected over the next few hours
which may total as much as 4 to 6 inches with isolated heavier
amounts not out of the question where any cell-training occurs.

The greatest likelihood for this is along the aforementioned
corridor from near Burnett through Waco and into Corsicana.
Adjacent areas of central and eastern TX near and north of the
front are likely to see heavy rainfall as well with somewhat
lesser totals at least through mid-afternoon. Upstream convection
approaching from the TX Panhandle and northwest TX will also need
to be closely monitored as that activity associated with the
leading edge of the upper-trough will promote eventually a renewed
heavy rainfall/convective threat to the Dallas metropolitan area.

Additional areas of flash flooding are likely, and locally
significant flash flooding will be possible given the very heavy
rainfall rates reaching as high as 2" to 3"/hour, enhanced storm
totals, and sensitive ground conditions including urban runoff
considerations.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EWX...FWD...HGX...OUN...SHV...SJT...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   33959889 33569750 33259634 33189548 32889422 
            32079412 31529529 30919680 30339788 30279863 
            30809880 31659842 32319860 32889931 33579944 
            

832 
AWUS01 KWNH 090926
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-091525-

Mesoscale Precipitation Discussion 0138
NWS Weather Prediction Center College Park MD
525 AM EDT Tue Apr 09 2024

Areas affected...eastern TX into southern AR/northern LA

Concerning...Heavy rainfall...Flash flooding likely

Valid 090925Z - 091525Z

SUMMARY...A relatively narrow axis of heavy rain is expected to
become better organized near or a little after 12Z with areas of
training from SW to NE focusing from portions of central TX into
the Arklatex and portions of southern AR/northern LA. 2 to 4 inch
totals are expected by 15Z, although locally higher cannot be
ruled out.

DISCUSSION...Regional reflectivity across northeastern TX showed a
weakening cluster of thunderstorms advancing past the DFW
Metroplex at 0900Z with outflow preceding it from near LNC to MKN.
To the east and southeast of the Metroplex, regional reflectivity
showed overrunning showers and thunderstorms, with a recent uptick
in intensity since 08Z. This newer activity was located to the
north of an effective stationary front which extended WNW from
southern LA into east-central TX. The recent uptick in intensity
to the north of the effective stationary front appears to be
related to an increase in elevated instability as seen in SPC
mesoanalysis of MUCAPE, due to increasing low level moisture
(sfc-700 mb) as seen on Layered Precipitable Water (LPW) imagery
from CIRA. LPW and water vapor imagery also showed the presence of
a shortwave located southeast of Big Bend, TX, advancing toward
the northeast along with higher levels of moisture in the 700-500
mb layer.

Expectations are for an increase in thunderstorms along the
leading edge of low level moisture return, focused in the 925-850
mb layer, with roughly 20-30 kt of southerly flow. The low level
convergence axis is forecast by recent runs of the RAP to extend
from near GTU to JDD to TXK at 12Z as low level wind fields
gradually strengthen ahead of an eastward advancing closed low
over AZ/NM. The 08/09Z SPC mesoanalysis showed 500 to 2000+ J/kg
ML and MU CAPE over east-central TX, with some relatively weak
areas of CIN south of the Metroplex.

The advection of low to mid-level moisture from the south into
central/eastern TX through the morning is expected to help reduce
CIN and moisten initially dry mid-levels. Simulated reflectivity
from the HRRR has been consistent with the development of an axis
of thunderstorms near the low level convergence axis, focusing the
potential for training and repeating storms from central into
northeastern TX and near the AR/LA border, perhaps developing near
or just after 12Z. Some of that development appears to be ongoing
over far northeastern TX.

Portions of this region have received an estimated 1 to 4+ inches
since 21Z (multi-sensor MRMS estimates) and the addition of an
additional 2-4 inches would result in renewed flash flood
concerns. There is some uncertainty with coverage of 2-4 inch
totals with recent HRRR cycles trending downward with QPF through
the mid/late morning, however, the setup looks favorable for heavy
rain developing later this morning with rainfall rates of 1-2
in/hr.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EWX...FWD...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   34399209 34279117 33949073 33269098 32899165 
            32379342 31999465 31389616 30629763 31119805 
            32409683 33649463 34319279 

530 
AWUS01 KWNH 090447
FFGMPD
ARZ000-TXZ000-OKZ000-090915-

Mesoscale Precipitation Discussion 0137
NWS Weather Prediction Center College Park MD
1247 AM EDT Tue Apr 09 2024

Areas affected...northern TX into southeastern OK

Concerning...Heavy rainfall...Flash flooding possible

Valid 090446Z - 090915Z

SUMMARY...Locally repeating rounds of thunderstorms will pose a
threat for flash flooding across northern/northeastern TX into
southeastern OK through 09Z. 2 to 4 inches of rain with rainfall
rates of 1-2 in/hr are expected, although localized rates over 2
in/hr cannot be ruled out.

DISCUSSION...Thunderstorms were ongoing at 0415Z from northern TX
into and across the Red River Valley, primarily north of I-20,
located on either side of a slow moving cold front that extended
from eastern OK into northern TX. Many of these cells contained
large hail and severe winds but sufficient shear and instability
were supporting supercell organization and locally enhanced
rainfall intensities. For example, a cell in northern Parker
County was recently associated with ~1 inch of rain in 20 minutes
but average cell movement of 20 to 30 kt toward the northeast to
east has limited storm total rainfall.

Synoptic scale lift was occurring with height falls out ahead of a
mid-level closed low located over southern AZ, moving toward the
east. MLCAPE was estimated to range from 500 to 2000 J/kg at 04Z
along and just ahead of the front in northern TX via SPC
mesoanalysis data along with PWATs of 1.1 to 1.6 inches.
Additional storms are expected near/ahead of the cold front and
just north of a rain-cooled outflow boundary located west-east
across the DFW Metroplex over the next few hours. Expanding
thunderstorm coverage with cell mergers and locally repeating
rounds of thunderstorms are expected to produce 1-2 in/hr rates
with totals of 2-4 inches in a few places. Flash flooding will be
possible, especially with urban overlap of higher rates.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   35129484 34619445 33679446 32989549 32609734 
            32639866 33339889 34019786 34819620 

172 
AWUS01 KWNH 090354
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-090920-

Mesoscale Precipitation Discussion 0136
NWS Weather Prediction Center College Park MD
1154 PM EDT Mon Apr 08 2024

Areas affected...northeastern TX to AR/LA border

Concerning...Heavy rainfall...Flash flooding likely

Valid 090353Z - 090920Z

Summary...A threat for flash flooding is likely to continue for
parts of northeastern TX into northern LA/southern AR and possibly
western MS. Rainfall rates ranging between 1-3 in/hr and
additional totals of at least 3-5 inches are expected through 09Z.

Discussion...0330Z radar imagery from northeastern TX into
northern LA showed ongoing heavy rain with rainfall rates via
local Wunderground networks showing hourly accumulations of 1 to 3
inches over the past couple of hours. There was an axis of higher
reflectivity observed to be oriented roughly west to east across
the region near and just south of I-40, located just north of an
elevated convergence axis centered near 850 mb as seen on area VAD
wind plots at 03Z, supported by 850 mb peak southerly winds near
50 kt as sampled by KLCH, converging toward southeasterly 850 mb
winds at KSHV near 20 kt. PWATs varied across TX into LA but were
2+ standardized anomalies above average, measuring 1.9 inches on
the 00Z KLCH RAOB.

The Arklatex and nearby locations were, and are expected to
remain, under a favorable upper level divergence max positioned
within the right entrance region of a 110 to 130+ jet extending
from northern AR/southern MO into the OH Valley, and...to a lesser
extent...left exit region of an upper jet max crossing the Rio
Grande Valley into eastern TX. Latest RAP forecasts and infrared
satellite trends indicate some potential for the low level axis of
convergence to migrate northward over the next few hours, but
steering flow nearly parallel to that convergence axis will
support an extended period of training with heavy rain. MUCAPE is
currently highest over western locations, but some expansion of
instability to the east is possible through the overnight. Hourly
rainfall of 1-3 inches should be expected at times along with
additional totals of at least 3 to 5 inches in some locations by
~09Z. Areas of ongoing flash flooding are expected to expand in
coverage overnight as these higher rates overcome drier antecedent
conditions, with an immediate focus along the I-40 corridor from
near Tyler, TX into Ruston and perhaps Monroe, LA.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...JAN...LZK...SHV...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   33629358 33599191 33349096 33109057 32519061 
            32189147 32029268 32009465 31879663 32409688 
            33059606 

131 
AWUS01 KWNH 031900
FFGMPD
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-040000-

Mesoscale Precipitation Discussion 0135
NWS Weather Prediction Center College Park MD
259 PM EDT Wed Apr 03 2024

Areas affected...portions of northern VA into Washington DC, MD,
DE, southeast PA, and NJ

Concerning...Heavy rainfall...Flash flooding possible

Valid 031900Z - 040000Z

Summary...Localized rainfall rates up to 1"/hr may lead to
isolated instances of flash flooding through the evening.

Discussion...A surface low will track northeastward across
northern Mid-Atlantic this evening, with localized rainfall rates
up to 1"/hr possible with the strongest convection. While not
particularly intense, these rates may overwhelm localities that
have already seen up to an inch or so of rain over the past 24
hours. Saturated soils and lowered capacity to handle runoff could
particularly lead to more impacts in the populated I-95 corridor
from Washington D.C. to Newark (where FFGs are as low as a quarter
to a half inch per hour).

While instability is the main limiting factor preventing more
intense convection, there may still be a thunderstorm or two (most
likely near the Delmarva Peninsula, where MU CAPE is >500 J/kg)
that manages to form. Elsewhere across the outlook area,
precipitable water values of 1.0-1.4 inches (above the 90th
percentile per SPC sounding climatology) combined with ample large
scale moisture transport and warm air advection from the northward
expanding warm sector will fuel heavy showers with briefly high
rainfall rates that could lead to some instances of nuisance level
flooding.

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AKQ...BGM...CTP...LWX...OKX...PHI...

ATTN...RFC...MARFC...NERFC...NWC...

LAT...LON   41337470 41307443 41107402 40857404 40707412 
            39977396 38807459 37627561 37587683 38117733 
            38997696 39787636 41007519 

130 
AWUS01 KWNH 030538
FFGMPD
NYZ000-PAZ000-MDZ000-VAZ000-WVZ000-OHZ000-031137-

Mesoscale Precipitation Discussion 0134
NWS Weather Prediction Center College Park MD
138 AM EDT Wed Apr 03 2024

Areas affected...western/central Pennsylvania, portions of West
Virginia, western Maryland, and eastern Ohio

Concerning...Heavy rainfall...Flash flooding likely

Valid 030537Z - 031137Z

Summary...A persistent warm conveyor will continue to produce
areas of 0.25-0.75 inch/hr rain rates across the discussion area
through 12Z.  Flash flooding remains likely with this scenario.

Discussion...A warm/moist conveyor continues to result in
widespread precipitation across the discussion area - particularly
in western and central Pennsylvania.  This warm conveyor will
continue to foster low-level convergence and warm advection into
the discussion area due to continued deepening of a low over the
western Great Lakes.  Widespread areas of 0.25-0.75 inch/hr rain
rates continue, and are highest where MUCAPE is maximized across
West Virginia and Maryland.  Furthermore, the region has
experienced widespread 1-4 inch rainfall totals in the past 24
hours, resulting in wet ground conditions and low FFGs areawide
(as low as 0.25 inch/hr in spots).  As warm advection continues
across the region, it is not out of the question for rain rates to
exceed (perhaps double) 1-hour FFG thresholds at times, especially
where instability can redevelop due to cooling mid-level
temperatures from west to east over the next several hours.

The ongoing scenario for precipitation is not expected to change
substantially through 12Z, with periods of rainfall resulting in
another widespread 1-2 inches across the discussion area.  Flash
flooding remains likely.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BUF...CLE...CTP...LWX...PBZ...RLX...

ATTN...RFC...MARFC...NERFC...OHRFC...NWC...

LAT...LON   42097844 41777730 40787697 39817718 39197830 
            38467981 38638175 39638210 40618178 41278136 
            42048019 

347 
AWUS01 KWNH 030430
FFGMPD
GAZ000-ALZ000-030700-

Mesoscale Precipitation Discussion 0133
NWS Weather Prediction Center College Park MD
1230 AM EDT Wed Apr 03 2024

Areas affected...northern Georgia

Concerning...Heavy rainfall...Flash flooding likely

Valid 030428Z - 030700Z

Summary...Convective cluster near Atlanta Metro has produced an
axis of 2-3 inches of rainfall, and upstream convection over
east-central Alabama could produce another two inches of rainfall
through 07Z or so.  Flash flooding is likely in this scenario.

Discussion...An earlier convective cluster across northwestern
Georgia gained organization over the past hour while traversing
areas from near Carrollton to southern Atlanta Metro to near
Conyers, producing a narrow band of 2-3 inches of rainfall.  An
impressive 2.41 inch of rainfall was measured in an hour at KATL
with this cluster.  On its current trajectory, that complex should
reach Athens and may continue to produce 1-2 inch/hr rain rates
through 06Z.

Upstream, another cluster of convection (favorably oriented to
fast west-southwesterly steering flow aloft) was producing
localized training and rain rates in the 1-2 inch/hr rain rates. 
That complex should affect areas recently that recently
experienced the 2-3 inch rainfall totals.  It is not out of the
question for some parts of the region to experience 4-5 inch
totals from both complexes through 07Z tonight.

Given recent convective trends, flash flooding appears likely in
this scenario.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...GSP...

ATTN...RFC...SERFC...NWC...

LAT...LON   34338329 34038297 33698298 33278361 32938494 
            33018561 33298586 33798557 34108475 

520 
AWUS01 KWNH 030308
FFGMPD
NCZ000-SCZ000-GAZ000-ALZ000-030907-

Mesoscale Precipitation Discussion 0132
NWS Weather Prediction Center College Park MD
1108 PM EDT Tue Apr 02 2024

Areas affected...portions of Alabama, Georgia, and western South
Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 030307Z - 030907Z

Summary...Convective coverage was expanding across Alabama and
west-central Georgia, and 1+ inch/hr rain rates were beginning to
approach urbanized areas near Atlanta, GA and south of Birmingham,
AL.  Isolated instances of flash flooding are possible through 09Z.

Discussion...The combination of broad low-level confluence across
the discussion area and upper difluence was resulting in maturing
convection across southwestern/central Alabama and west-central
Georgia over the past couple of hours.  SPC mesoanalyses indicated
that storms were located in an unstable, yet weakly capped
environment characterized by ~1500 J/kg SBCAPE, 1.5-2 inch PW
values, and strong vertical shear/flow aloft.  The flow aloft was
keeping most convection progressive in nature, although convective
orientation (more parallel to flow aloft) in a couple areas was
resulting in training and rain rates exceeding 1 inch/hr - 1) west
of Atlanta Metro (near Carrollton, GA) and 2) over Talladega
National Forest near west of Selma, AL.  FFG thresholds are
generally in the 2.5 inch/hr range across most of the discussion
area (locally lower in urban areas), suggestive of an isolated
flash flood threat where ground conditions are relatively
sensitive in the short term.

Over time, three factors should contribute to a continued, gradual
expansion of convective coverage through the night, including 1)
an approaching mid/upper jet stream across currently across
southeast Texas, 2) increasing low-level flow/persistent low-level
confluence across the unstable airmass in place across the
discussion area, and 3) destabilization into portions of northern
Georgia and upstate South Carolina, where ground conditions are
somewhat more sensitive for flash flood potential (lower FFGs). 
Each of these factors suggest a continued risk of areas of rain
rates approaching 2 inches/hr (especially where training is
pronounced) along with a gradually increasing, yet isolated flash
flood risk.  Again, this risk is focused mainly from central Al
into the Atlanta Metro area in the near term, but should spread
northeastward into more of the southern Appalachians over the next
3-6 hours.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...CAE...FFC...GSP...HUN...MOB...MRX...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   35258189 35078113 34448096 33768130 32828228 
            31998411 31338615 31358751 31598812 32118815 
            33078753 33818682 34658598 34928464 35218307 
            

974 
AWUS01 KWNH 022326
FFGMPD
PAZ000-MDZ000-VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-030525-

Mesoscale Precipitation Discussion 0131
NWS Weather Prediction Center College Park MD
725 PM EDT Tue Apr 02 2024

Areas affected...Portions of the OH/TN Valleys into the Central
Appalachians

Concerning...Heavy rainfall...Flash flooding likely

Valid 022325Z - 030525Z

SUMMARY...Broken clusters of heavy showers and thunderstorms will
continue through the remainder of the evening and into the
overnight hours. A combination of heavy rainfall rates and locally
sensitive/saturated soil conditions will likely result in at least
scattered areas of flash flooding.

DISCUSSION...The late-day GOES-E IR satellite imagery in
conjunction with dual-pol radar shows broken clusters of heavy
showers and thunderstorms advancing across portions of the OH/TN
Valleys, with the more organized/stronger convective cells seen
focused over areas of northern KY and southwest OH, with
additional corridors of stronger storms also noted moving up from
central TN into southeast KY. The activity continues to be driven
by instability pooling northeastward well ahead of a cold front
and with a relatively moist southwest low-level jet of 40 to 50
kts in place.

MLCAPE values over northern KY and southwest OH have risen to as
much as 1000 to 1500 J/kg, with somewhat lesser values noted
farther southeast over eastern KY and WV where earlier convection
has acted to stabilize the boundary layer to an extent. Over the
next few hours, some resurgence of instability off to the
northeast back into areas of the central Appalachians is expected,
and with rather strong effective bulk shear parameters still in
place and deeper layer forcing arriving ahead of the upstream
upper-level trough, at least broken coverage of heavy showers and
thunderstorms can be expected.

Recent HRRR runs coupled with the experimental WoFS guidance
suggest rather strong confidence in continuing to see some linear
swaths of heavy rainfall associated with locally training areas of
convection. Rainfall rates embedded within the stronger and more
organized bands/clusters of thunderstorms are expected to reach
1.5" to 2"/hour heading through at least the remainder of the
evening hours while instability and shear remain conducive for
organized and sustainable updrafts. Thus, some additional rainfall
totals may reach as high as 2 to 4 inches heading through at least
the midnight time frame.

Many areas across especially central and eastern OH, northern KY,
central and northern WV, and western PA will be very sensitive to
the additional heavy rainfall threat over the next several hours
given how wet/saturated the soil conditions are. There are likely
to be scattered areas of flash flooding as a result, with locally
enhanced pockets of runoff expected. This will include an urban
flash flood threat. Areas farther south down into southern KY and
northern TN will be a bit more tolerable to the additional
rainfall, but even here, there may be at least some isolated flash
flooding concerns given the rather high rainfall rates and pockets
of cell-training.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CLE...CTP...ILN...JKL...LMK...MRX...OHX...PBZ...
RLX...

ATTN...RFC...LMRFC...MARFC...OHRFC...NWC...

LAT...LON   41667971 40987861 39887896 38688017 37928114 
            36828284 36398434 36338534 37088600 38248509 
            39598353 40848221 41478113 

771 
AWUS01 KWNH 021943
FFGMPD
PAZ000-WVZ000-OHZ000-KYZ000-INZ000-030140-

Mesoscale Precipitation Discussion 0130
NWS Weather Prediction Center College Park MD
342 PM EDT Tue Apr 02 2024

Areas affected...Much of the Upper OH Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 021940Z - 030140Z

SUMMARY...Increasing coverage of showers and thunderstorm activity
going through the afternoon and evening hours will set the stage
for renewed concerns for flash flooding.

DISCUSSION...In the wake of morning convection, and with diurnal
heating resuming across large areas of southern IN and through
much of central/southern OH, the airmass across the region will be
destabilizing rather quickly over the next couple of hours. This
will set the stage for new areas of heavy showers and
thunderstorms, which inclusive of severe weather concerns, will
also be capable of producing sufficient levels of additional
rainfall for a renewed flash flooding threat.

A strong upper-level trough and associated area of surface low
pressure will be traversing the OH Valley and portions of the
Great Lakes region through the afternoon and evening hours, and
this will drive a cold front steadily off to the east. MLCAPE
values on the order of 1000+ J/kg are nosing northeast up across
southern IN currently just ahead of the cold front, and this
coupled with strong vertical shear and pockets of locally focused
surface moisture convergence aided by a southwest low-level jet of
40 to 50 kts will favor an increase in the coverage of heavy
showers and thunderstorms over the next few hours. This will
especially be the case as the downstream boundary layer along and
south of a west/east oriented warm front continues to destabilize.

The more organized pockets of convection, which should gradually
include some supercells and linear convective segments, will be
capable of producing rainfall rates that reach 1.5" to 2"/hour.
The relative moist environment with PWs approaching 1.25 inches
and the strong and sustainable updrafts within the stronger cells
will be key contributors to the locally enhanced rates.

Some localized training of these convective cells will be possible
as the activity gradually expands in coverage, and this may
produce some linear swaths of 2 to 4 inches of rain where this
occurs. Given the heavier rains earlier in the day and last night,
many areas across the broader Upper OH Valley are rather sensitive
to any additional heavy rainfall. Therefore, additional concerns
for flash flooding will exist heading into the evening hours.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CLE...ILN...IND...IWX...LMK...PAH...PBZ...RLX...

ATTN...RFC...OHRFC...NWC...

LAT...LON   41408056 41117933 40317917 39747951 39458021 
            39158163 38998330 38528519 37688714 37998776 
            39148693 39948580 40658442 41208242 

689 
AWUS01 KWNH 021733
FFGMPD
VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-INZ000-022300-

Mesoscale Precipitation Discussion 0129
NWS Weather Prediction Center College Park MD
132 PM EDT Tue Apr 02 2024

Areas affected...much of KY and surrounding portions of WV, Middle
TN, and southern OH

Concerning...Heavy rainfall...Flash flooding possible

Valid 021730Z - 022300Z

Summary...Narrow swaths of 2-4" of rainfall may occur through
mid-afternoon, possibly resulting in isolated to scattered flash
flooding.

Discussion...Relatively disorganized convection is ongoing early
this afternoon across a broad warm sector, encompassing much of
the MS/OH/TN Valleys. Some of the most efficient multicell
clusters have developed across the OH/TN Valley over the past
several hours, producing up to 1"/hr accumulations across portions
of northern Middle TN and south-central KY. This convective
activity looks to track into the wake of an earlier bow echo which
raced across portions of northern KY, southern OH, and much of WV
this morning, resulting in 0.5-1.0" of rainfall locally (and
pre-saturating soils across much of the region). The mesoscale
environment is characterized by 500-1000 J/kg of ML CAPE (and
increasing by as much as 300-600 J/kg over the past 3 hours),
precipitable water values of 1.1-1.6 inches (near or above the
90th percentile, per SPC sounding climatology), and ample deep
layer shear of 50-60 kts.

While convection within the open warm sector is expected to remain
somewhat disorganized through mid-afternoon (primarily due to the
lack of a focusing mechanism), cells may still take on an
increasingly linear orientation (from WSW to ENE with the deep
mean flow) that would allow for localized training through
mid-afternoon. This could result in narrow swaths as high as 2-4"
through mid-afternoon, as suggested by 12z HREF 40-km neighborhood
exceedance probabilities of 20-50% and 5-10% for 2" and 3"
thresholds, respectively. These totals would meet or exceed
associated short-term (3-hr) FFGs of 1.5-2.5", suggesting that
isolated to scattered instances of flash flooding are possible
(particularly over northern portions of the outlooked area, where
localized 0.5-1.0" totals occurred this morning).

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ILN...JKL...LMK...MRX...OHX...PAH...RLX...RNK...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON   39108161 38938060 37948045 37518155 37178259 
            36758386 36348501 35898650 35908754 36558772 
            37458707 38178590 38718424 38938289 

979 
AWUS01 KWNH 020608
FFGMPD
OHZ000-KYZ000-INZ000-ILZ000-MOZ000-021200-

Mesoscale Precipitation Discussion 0128
NWS Weather Prediction Center College Park MD
207 AM EDT Tue Apr 02 2024

Areas affected...southern through eastern Missouri,
southern/central Illinois, southern/central Indiana, portions of
Kentucky, and southwestern Ohio

Concerning...Heavy rainfall...Flash flooding possible

Valid 020606Z - 021200Z

Summary...A series of convective complexes were merging/growing
upscale while producing 1+ inch/hr rain rates in spots.  These
trends will continue through the next 3-6 hours, posing flash
flood potential across the discussion area.

Discussion...A series of forward propagating, linear convective
segments have began to grow upscale over the past 1-2 hours,
forming a large convective complex that extends from southwestern
Missouri (near Springfield) to near Saint Louis to near Terre
Haute, IN.  The complex was forming a relatively extensive outflow
that merges with a synoptic warm front across Illinois and
Indiana.  Meanwhile, the pre-convective environment supporting the
ongoing activity was characterized by approximately 1000 J/kg
SBCAPE and strong southwesterly inflow along a 45-60 knot
low-level jet axis emanating from the Ozarks.  Convergence along
the nose of this jet and strong low-level warm advection will
likely maintain deep convection through at least 12Z this morning.
 The orientation of convection, however, with outflow generally
parallel to west-southwesterly steering flow aloft will allow for
areas of localized training and rain rates exceeding 1 inch/hr. 
These rates were generally less than FFG thresholds (around 1.5
inch/hr), and a slow but notable rightward component of motion
relative to flow aloft was allowing for heavier rainfall to move
toward drier soils nearer the Ohio River. 

The ongoing scenario should support at least a modest flash flood
risk over the next few hours.  Areas of convective training should
continue through 12Z that could support rain rates exceeding 1.5
inches/hr at times, with low-lying and/or sensitive areas
potentially experiencing excessive runoff.  A lengthy duration of
heavier rainfall could also result in 2 inch amounts over a three
hour period that would also contribute to flash flood concerns
(with 2 inch/3 hr FFG thresholds noted across the area).  The
leading edge of the expanding MCS should reach southwestern Ohio
areas by 09Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ILN...ILX...IND...LMK...LSX...PAH...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON   40128421 39508371 38888386 38138510 37008853 
            36609172 36719324 37569334 38339232 39269039 
            39848844 40078547 

536 
AWUS01 KWNH 020233
FFGMPD
ILZ000-MOZ000-ARZ000-OKZ000-KSZ000-020630-

Mesoscale Precipitation Discussion 0127
NWS Weather Prediction Center College Park MD
1033 PM EDT Mon Apr 01 2024

Areas affected...northeastern OK/southeastern KS into MO and far
northwestern AR

Concerning...Heavy rainfall...Flash flooding possible

Valid 020231Z - 020630Z

Summary...A threat of flash flooding will continue from portions
of northeastern OK/southeastern KS into southwestern/central MO
and far northwestern AR through 07Z. Multiple rounds of heavy rain
with areas of training are expected to result in some 2 to 3+ inch
totals through 07Z.

Discussion...Regional radar imagery at 02Z showed a cluster of
thunderstorms over eastern MO into central IL and a second cluster
over central OK into southeastern KS. Additional storms were noted
ahead of a cold front, approaching central OK. Embedded MCVs were
noted within some of the convective clusters, advancing toward the
northeast. An elongated outflow boundary was observed on 02Z
surface observations just south of the convection and just south a
line connecting STL to JLN to TUL to OKX. SPC mesoanalysis data
from 02Z indicated ML and MU CAPE remained in the 500 to 1500 J/kg
range from northeastern OK into central MO, along with PWATs of
1.1 to 1.5 inches.

DPVA ahead of an approaching mid-level shortwave over KS/OK/west
TX, low level flow of 30-50 kt (850 mb) ahead of an eastward
advancing cold front approaching from central OK along with
divergent and diffluent flow aloft will be enough to maintain
forcing for continued convection over at least the next few hours
from OK into the mid-MS Valley. Multiple rounds of convection
near/north of the outflow boundary will have the greatest
potential for 1-2 in/hr rainfall rates and training from SW to NE
or WSW to ENE given similarly oriented steering flow aloft. An
additional 2 to 3 inches (locally higher) is expected to maintain
a threat of flash flooding from the lower Plains into the Midwest.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EAX...ICT...LSX...LZK...OUN...PAH...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...NWC...

LAT...LON   39159028 38298921 37429034 36319285 35429577 
            35759702 36259701 37159574 37709451 38419310 
            38819218 

225 
AWUS01 KWNH 020009
FFGMPD
OHZ000-KYZ000-INZ000-ILZ000-020600-

Mesoscale Precipitation Discussion 0126
NWS Weather Prediction Center College Park MD
808 PM EDT Mon Apr 01 2024

Areas affected...south-central IL/IN into far southwestern OH

Concerning...Heavy rainfall...Flash flooding likely

Valid 020007Z - 020600Z

Summary...Training of heavy rain from west to east is expected to
produce at least localized flash flooding from a quick 2-4 inches
of rain. The greatest threat will exist across south-central IL/IN
through 06Z.

Discussion...Regional radar imagery at 2330Z showed two supercells
in eastern MO, just south of I-70 along with a linear segment
oriented west to east, crossing I-55 about 20 miles south of
Springfield, IL. These thunderstorms were located along or just
north of a rain-cooled outflow boundary that extended WSW to ENE
through Saint Louis. The rain-cooled outflow was acting as the
effective warm front within an axis of 500 to 1000+ J/kg MLCAPE
via the 23Z SPC mesoanalysis.

As a mid to upper-level trough axis continues to advance eastward
across the central/southern Plains, low level inflow across the
outflow boundary will increase over the next few hours. 25-40 kt
of southerly flow in the 925-850 mb layer will increase
overrunning while upper level divergence increases within the
right-entrance and left-exit regions of dual jets at 250 mb
downstream of the main upper trough axis to the west. Increasing
thunderstorm coverage is expected to expand from west to east with
time. Steering flow quasi-parallel to the low level axis of
forcing should support some areas of training, especially as
upstream convection over west-central MO approaches. 1-2 in/hr
rainfall rates and 2-4 inches in 2-3 hours is expected to produce
at least a few areas of localized flash flooding with the threat
expanding east with time through 06Z.

Localized thunderstorm development will be possible south of the
warm front into southern portions of IL/IN over the next few
hours, but coverage and the potential for flash flooding does not
appear as great compared to locations farther north.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ILN...ILX...IND...LMK...LSX...PAH...

ATTN...RFC...NCRFC...OHRFC...NWC...

LAT...LON   40368794 39998512 39318455 38868483 38418648 
            38348868 38948996 39968960 

510 
AWUS01 KWNH 012104
FFGMPD
ILZ000-MOZ000-OKZ000-KSZ000-020300-

Mesoscale Precipitation Discussion 0125
NWS Weather Prediction Center College Park MD
503 PM EDT Mon Apr 01 2024

Areas affected...northern OK, southeastern KS into central MO and
western IL

Concerning...Heavy rainfall...Flash flooding possible

Valid 012100Z - 020300Z

Summary...Increasing coverage of thunderstorms from the eastern
KS/OK border into MO and western IL may produce flash flooding
from 2-4 inches of rain through 03Z. Multiple rounds of storms are
expected for a few locations with rainfall rates possibly
exceeding 2 in/hr.

Discussion...Regional radar imagery at 2030Z showed a small
cluster of thunderstorms to the east of I-35 in northern
OK/southern KS, tracking toward the northeast. Rainfall was more
stratiform over central MO, but a few areas of embedded
thunderstorms with higher reflectivity values were observed to the
north of I-70 near Marshall and east of St. Joseph. These storms
were forming partially in response to an ejecting positively
tilted mid-level trough axis translating eastward across the
southern High Plains. SPC mesoanalysis data from 20Z showed a
broad swath of MLCAPE between 1000-2000 J/kg within the warm
sector of a frontal cyclone with a surface low located in far
northwestern MO, but with CIN remaining across many locations due
to a capping inversion located between 850-700 mb.

Expectations are for an increase in thunderstorm coverage across
MO later this afternoon/evening, as a result of 1) northeastward
thunderstorm translation from the OK/KS border and 2) new
development across the region as CIN continues to erode with low
to mid-level height falls moving eastward in association with the
aforementioned trough over the southern High Plains. Shear
parameters are plenty supportive of organized cells with an
expected movement of individual cells off toward the northeast in
general, but with more of an eastward translation to thunderstorm
clusters, allowing for possible training of heavy rain from WSW to
ENE.

Additional thunderstorm development is anticipated over central to
northern OK around 00Z, ahead of the rapid eastward advancement of
a secondary cold front just entering the TX Panhandle at 20Z,
forecast to catch up to the dryline later this evening. The
anticipated secondary development of thunderstorms may pass over
some of the same locations that received rainfall from the ongoing
round near the eastern OK/KS border. Rainfall rates of 1-2 in/hr
are likely with localized potential for rates exceeding 2 in/hr.
The result of the two rounds of thunderstorms along with potential
for short term training within each individual round may result in
some flash flooding with 2-4 inches of rain through 03Z.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EAX...ICT...ILX...LSX...OUN...SGF...TOP...TSA...

ATTN...RFC...ABRFC...MBRFC...NCRFC...NWC...

LAT...LON   40179256 40169085 40148986 40058912 39588904 
            39198958 38749028 38349107 37839249 37359403 
            36289690 36819746 38439578 39869410 

719 
AWUS01 KWNH 010909
FFGMPD
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-011307-

Mesoscale Precipitation Discussion 0124
NWS Weather Prediction Center College Park MD
508 AM EDT Mon Apr 01 2024

Areas affected...portions of Maryland, Delaware, far southern
Pennsylvania, and the District of Columbia

Concerning...Heavy rainfall...Flash flooding possible

Valid 010907Z - 011307Z

Summary...Bands of west-to-east moving convection are producing
spots of 0.5-0.75 inch/hr rain rates across far northern Virginia,
with slightly lower rates near Washington, D.C.  These rates could
cause a few areas of flash flooding (especially in urban areas)
through morning rush hour and midday.

Discussion...A fairly focused band of convection has continued
through the night along a warm frontal zone extending from
southern Ohio through northern Virginia this morning.  Along this
frontal zone, mostly elevated convection has materialized, with
support for updrafts coming primarily from convergence on the nose
of strong 850mb flow amid marginal/weak instability.  The
orientation of this convergence/instability axis was generally
parallel to westerly flow aloft, however, allowing for training. 
Observations and MRMS suggest focused axes of 0.4-0.75 inch/hr
rain rates have materialized from near Winchester, VA to near
Gaithersburg, MD over the past 1-2 hours.

Over time, eastward movement of this band of convection will allow
for migration into areas of the DC/Baltimore urban corridor, where
FFGs are considerably low (in the 0.5-0.75 inch/hr range).  This
should cause at least isolated flash flood potential to emerge
across low-lying and sensitive areas over the next 2-3 hours. 
FFGs are also likely to be exceeded in spots.  The northward
movement of the warm front and aforementioned convergence zone may
be mitigating factors for a larger, more widespread flash flood
threat, with heavier precipitation expected to shift toward the
MD/PA border region through mid-morning.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AKQ...CTP...LWX...PHI...

ATTN...RFC...MARFC...NWC...

LAT...LON   39887731 39617556 38817506 38627512 38697636 
            39167791 39497877 39757823 

601 
AWUS01 KWNH 010456
FFGMPD
AZZ000-CAZ000-011054-

Mesoscale Precipitation Discussion 0123
NWS Weather Prediction Center College Park MD
1256 AM EDT Mon Apr 01 2024

Areas affected...portions of Arizona

Concerning...Heavy rainfall...Flash flooding possible

Valid 010454Z - 011054Z

Summary...A few slow-moving thunderstorms continue to develop
across southwestern Arizona, with local rain rates approaching 1
inch/hr on an isolated/spotty basis.  This pattern could continue
for a few more hours this evening/overnight, prompting isolated
flash flooding.

Discussion...Very cold temperatures aloft (-24 to -28C at 500 hPa
per SPC Mesoanalysis) continues to support isolated to scattered
convective development across the discussion area.  The
temperature profiles were supporting areas of 250-750 J/kg of
surface-based CAPE amid 0.7 inch PW values and weak steering flow
aloft (especially in western Arizona), supporting slow storm
motions.  One cell nearly stalled recently approximately 70 miles
east of BLH/Blythe, CA, which has promoted local rain rates
approaching 1 inch/hr.  Satellite imagery indicates strong ascent
entering the discussion area from the west in tandem with a couple
of mid-level shortwave troughs across the northwestern Baja
Peninsula and Lower Colorado River Valley.  This pattern aloft is
supporting ongoing convection, and should continue to do so for at
least another 3-4 hours despite slow boundary layer cooling during
that time.

As mid/upper disturbances continue to travel eastward, it is not
out of the question that the Phoenix Metro and surrounding areas
could experience locally heavier rain rates tonight.  Local FFGs
are only in the 0.75 - 1.50 inch/hr range and the lower end of
that range could be exceeded especially where local cell
mergers/cold pool generation support prolonged rainfall from
stalled or erratically moving cells.  Sensitive and/or urbanized
areas are most likely to experience impacts, although the isolated
nature of the convection through the night suggests that the flash
flood risk should remain isolated through 10-11Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FGZ...PSR...TWC...VEF...

ATTN...RFC...CBRFC...CNRFC...NWC...

LAT...LON   35291346 35221237 34211153 32921142 32231171 
            31921252 32301383 33041494 34371501 35181440 
            

484 
AWUS01 KWNH 312325
FFGMPD
CAZ000-010520-

Mesoscale Precipitation Discussion 0122
NWS Weather Prediction Center College Park MD
725 PM EDT Sun Mar 31 2024

Areas affected...southern CA

Concerning...Heavy rainfall...Flash flooding possible

Valid 312323Z - 010520Z

Summary...A localized flash flood threat will continue across
southern CA through 05Z, from near Los Angeles/San Bernardino into
the San Diego metro areas, with potential for 0.5 to 1 inch of
rain in an hour or less.

Discussion...GOES West visible imagery at 23Z showed a persistent
axis of surface convergence that was located west-east through the
Channel Islands, just north of San Clemente Island before turning
southward and parallel to the coast, roughly 10-20 miles west of
the San Diego County coastline. Recent outflow has been noted to
be pushing across San Clemente Island on visible imagery but some
degree of convergence remained to its north. This feature has been
an active focus for showers and thunderstorms for the past several
hours, located just northeast of a surface low, located roughly
150 miles west of the northern Baja Peninsula via visible
satellite imagery. This area of southern CA was beneath the center
of a mid to upper-level low/trough with weak storm motions, ~5 kt,
using 0-6 km AGL mean layer winds as a proxy for cell motions.

As the southern portion of the parent upper trough slowly edges
southeastward over the next 6 hours, low level onshore flow from
the south to southwest will continue to favor the likelihood of
cells containing heavy rain between the coast and the Peninsular
Ranges over the next few hours. It is unclear the future location
or existence of the surface convergence axis just offshore, but
given its proximity to the coast, it seems reasonable that showers
and embedded thunderstorms will continue to impact coastal
locations of Orange into northern San Diego County in the short
term, focusing near an estimated wave along the boundary west of
NFG within an axis of instability containing a few hundred J/kg of
MLCAPE. Forecasts of MLCAPE from the RAP support values up to ~500
J/kg lingering just offshore of San Diego County through 06Z with
low level onshore flow (weak as it may be) maintaining a fetch
from the instability reservoir onto land. Slow moving to nearly
stalled showers and thunderstorms will have the potential to
produce high rainfall rates of 0.5 to 1 inch in an hour or less,
supporting a lingering but localized flash flood threat into the
night for southern CA. The focus is expected to be in Orange and
San Diego counties, but cannot rule out some activity farther
north into Los Angeles County as well.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34371803 34111742 33731690 33291659 32681644 
            32411645 32261692 32391758 33161814 33661886 
            34271864 

106 
AWUS01 KWNH 312147
FFGMPD
CAZ000-010330-

Mesoscale Precipitation Discussion 0121
NWS Weather Prediction Center College Park MD
546 PM EDT Sun Mar 31 2024

Areas affected...western Transverse Ranges of southern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 312143Z - 010330Z

Summary...A few slow moving showers/thunderstorms will be capable
of producing high rainfall rates of 0.5+ in/hr across western
portions of the Transverse Ranges through ~03Z. Localized flash
flooding will be possible with potentially higher impacts over
areas which received heavy rain over the past 48 hours and/or
sensitive burn scars.

Discussion...GOES West visible imagery at 2130Z showed the
southern and low level portion of a slow moving, vertically
stacked low about 150 miles southwest of Los Angeles. This low was
slowly moving east and in the process of opening up but weak
steering flow was located beneath and northeast of the low center.
Visible imagery and local radar imagery from KVBX showed numerous
showers over the southern Coastal Ranges into the western
Transverse Ranges where the 0-6 km AGL mean wind was from the
north at 5-15 kt. Daytime heating has allowed for the development
of weak MLCAPE, less than 500 J/kg per 21Z SPC mesoanalysis data,
which was supporting ongoing shower activity across the region.

An increased risk for flash flooding this afternoon/evening will
come from the fact that steering flow is fairly similar in
direction and magnitude to low level inflow from the north, which
could promote some slow moving and/or training cores of heavy
rain. The weak instability and modest moisture (PWATs 0.5 to 0.8
inches) should limit updraft strength but isolated thunder could
still occur over the next few hours. The slow movement of heavy
rain cores could allow for rainfall rates to exceed 0.5 inches in
an hour or less. Due to heavy rain which has impacted Santa
Barbara and Ventura counties over the past 2 days, with over 5
inches reported in portions of the Santa Ynez and San Rafael
Mountains, sensitivity to flooding has increased in addition to
already sensitive burn scar regions. Localized rainfall totals
through 03Z of 1-2 inches will be possible, but with much of the
rainfall falling over a relatively short period of time. A
reduction of any lingering instability after sunset should reduce
the threat for flash flooding but conditions will need to be
monitored for a lingering threat beyond 03Z.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   35362017 34871943 34731904 34451880 34161879 
            33981905 34131948 34221991 34332048 34592073 
            35022086 35312060 

745 
AWUS01 KWNH 311652
FFGMPD
CAZ000-312300-

Mesoscale Precipitation Discussion 0120
NWS Weather Prediction Center College Park MD
1251 PM EDT Sun Mar 31 2024

Areas affected...Southern California...

Concerning...Heavy rainfall...Flash flooding possible

Valid 311700Z - 312300Z

SUMMARY...Widely scattered thunderstorms capable of 1-1.5" hourly
totals continue to pose a risk for localized flash flooding late
this morning into the afternoon. 

DISCUSSION...Persistent narrow updraft, shallow thunderstorms have
persisted near a stubborn effective stationary front from
southeast of Santa Cruz Island to Santa Catalina bending southward
about 10-20 miles off the San Diego county coastline. CIRA LPW
continues to show enhanced moisture of .75" (for a non-AR plume)
pooled along the boundary with solid surface to boundary layer
confluence centered along and near Santa Catalina. With steep
lapse rates and cold air advection aloft maintaining above normal
unstable airmass with MUCAPE values of 750 J/kg.  The combination
has seen persist convective towers along the frontal zone
eventually shearing bringing light to moderate rainfall ashore
across SE LA, Orange and W San Diego counties.  However, limited
eastward progression of the boundary has limited the offshore more
intense rain rates of .5-1"/hr from coming ashore...still
conditions remain favorable for additional upstream development on
the front.

GOES-WV suggests the upstream vorticity center is a the base of
the longer wave trof axis but still appears to be digging south
rather than rotating northeast.  This continues to provide a
favorable upper-level divergence pattern and DPVA to maintain
thunderstorms but has not allow for westerly low level flow to
dislodge the stationary front.  However, there remain a majority
of Hi-Res CAMs suggesting this eastward advancement, which would
allow for isolated cells to produce .75-1.5" totals in short
duration and given already saturated soils with 0-40cm saturation
near 75-80%; well above normal (and impermeable urban conditions),
suggest any stronger rates than .5"/hr could result in rapid
run-off and localized flash flooding into the afternoon hours. 
While best convergence parameters remain just offshore, proximity
and potential for eastward moving cells into the area of concern,
will keep a threat of localized flash flooding possible through
23z.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34301826 34211778 33931722 33291662 32871648 
            32581651 32571717 32801737 33381773 33471805 
            33041813 32791844 32981864 33501863 34051866 
            34241859 

229 
AWUS01 KWNH 311102
FFGMPD
CAZ000-311700-

Mesoscale Precipitation Discussion 0119
NWS Weather Prediction Center College Park MD
701 AM EDT Sun Mar 31 2024

Areas affected...Southern California...

Concerning...Heavy rainfall...Flash flooding possible

Valid 311100Z - 311700Z

SUMMARY...Potential for slow, perhaps stationary widely scattered
shallow thunderstorms with capability of 1-1.5"/hr totals will
continue to pose focused, highly localized flash flooding
potential this morning.

DISCUSSION...GOES-W WV and EIR suite depicts the seasonally
anomalous deep closed low (2-3 std dev) continues to wobble
southwest of the Channel Islands.  The core vorticity center
continues to be well defined along the south-southwest edge of the
larger circulation starting to press eastward.  This, in
combination with exiting subtropical jet streak through the Desert
Southwest continues to provide a favorable ascent pattern aloft
across the California Bight into Southern California;  while in
the lowest levels south to southeasterly confluent flow enhanced
by topographic channeling of the flow along the coastal region
continues to provide ample but focused moisture convergence from
the Santa Barbara coast toward NW LA county coast.  WV/EIR loop
also depicts the old occlusion boundary is starting to sag
southward across central CA with the nose of a jet streak starting
to press southwestward out of the central Sierra.  This will
further accelerate low level winds and moisture convergence but
with limited mid-level steering given the axis of the mid-level
trof lies across the northern channel islands through the southern
Sierra Nevada/Tehachapi Range. 

CIRA LPW denotes modest remaining moisture along this low level
confluence axis with Sfc-700mb moisture near .5-.7", combined with
steep/cold mid-level lapse rates (likely to further steepen with
DPVA associated with rounding shortwave); instability of 750+ J/kg
will continue to support stronger updrafts capable of vertical
moisture loading with up to 1.5-1.75"/hr. This may result in a
spot or two of 1-2" totals across SE Santa Barbara, Ventura into W
LA county where cells may be near stationary at apex of the
mid-level pivot/trof aloft. Further south coverage should be
greater in the southwesterly flow regime aloft from LA to San
Diego county, cell motions may limit duration a bit...but the risk
for intense cores still will result in potential for localized
flash flooding concerns through the morning into the evening. 

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34862024 34581868 34261755 33301680 32521680 
            32541787 33071932 33602006 34182049 34672068 
            

170 
AWUS01 KWNH 310345
FFGMPD
CAZ000-310943-

Mesoscale Precipitation Discussion 0118
NWS Weather Prediction Center College Park MD
1144 PM EDT Sat Mar 30 2024

Areas affected...coastal areas of southern/southwestern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 310343Z - 310943Z

Summary...A few heavier downpours along coastal areas were
producing 0.5+ inch/hr rain rates in spots near land areas.  A
conditional, yet locally significant flash flood risk will exist
with this activity for the next several hours.

Discussion...A very slow-moving mid/upper low continues across
offshore waters (centered approximately 125 mi west of Vandenburg
AFB, CA currently).  Very cold temperatures aloft has enabled
areas of 500+ J/kg MUCAPE to develop over open waters and near
immediate coastal areas per SPC mesoanalyses.  Additionally, weak
onshore wind fields (both at the surface and aloft) were promoting
upright, yet slow-moving convection to affect mainly offshore
areas.  One cell in particular, however, has made landfall near
Santa Barbara, CA over the past hour or so and produced impressive
rain rates (locally exceeding 1.5 inch/hr), potentially
contributing to a locally significant flash flood threat in that
area.

The ongoing scenario should continue for at least a few more hours
- and perhaps beyond 09Z tonight.  Mostly cellular convection will
continue to move slowly northeastward and approach coastal areas,
potentially resulting in a few spots of very heavy rain rates and
excessive runoff at times over land/coastal areas.  Instability
profiles may not support development of these cells very far
inland, although sensitive/urbanized coastal areas (and burn
scars) could experience flash flooding as weak onshore flow
maintains ~500 J/kg SBCAPE near the coast through the nighttime
hours.  Flash flood potential should stay isolated, however, and
remain dependent on cells that can make it onshore and persist for
any length of time.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...MTR...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   36172120 35752073 35082016 34701953 34311861 
            33831785 33451736 32731702 32601718 33161803 
            33761898 34061977 34472056 34912097 36112175 
            

842 
AWUS01 KWNH 300854
FFGMPD
CAZ000-302051-

Mesoscale Precipitation Discussion 0117
NWS Weather Prediction Center College Park MD
453 AM EDT Sat Mar 30 2024

Areas affected...portions of southern California

Concerning...Heavy rainfall

Valid 300851Z - 302051Z

Summary...A landfalling atmospheric river will gradually shift
southeastward across southern California through 21Z.  Areas of
hourly rain rates approaching 1 inch will continue to pose a
flood/flash flood risk during that time.

Discussion...A landfalling atmospheric river continues across
southern California currently.  The greatest integrated water
vapor transport was focused into the Transverse Ranges as of
0830Z, with several areas of 0.25-0.6 inch/hr rain rates observed
and estimated per MRMS from Santa Barbara through Los Angeles
Counties.  Local rain rates approaching 1 inch/hr were also
observed. The atmospheric river was located on the southeastern
periphery of an anomalously deep and slow moving upper low
centered about 150 mi west of San Francisco.

This low and attendant atmospheric river will make slow
southeastward progress today, with heavy rainfall eventually
focusing along the eastern Transverse Ranges, Peninsular Ranges,
and lower-elevation areas near Los Angeles and San Diego.  The
heaviest rainfall (including hourly rates of 0.25-0.9 inches) and
peak IVT will continue to focus along the Transverse Ranges
through the next 4-6 hours, before focusing across the Peninsular
Ranges (and San Diego metro area) between 12-21Z today.  With the
atmospheric river expected to maintain its intensity today,
multiple hours of moderate to heavy rainfall are expected
(especially in terrain-favored areas).  0.25-0.9 inch/hr rain
rates will remain likely where IVT is maximized.  Storm totals of
1.5-2.5 inches (locally higher) are possible through 21Z, which
should continue to foster at least an isolated flood/flash flood
risk especially in low-lying, sensitive areas.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...PSR...SGX...VEF...

ATTN...RFC...CNRFC...NWC...

LAT...LON   35261923 34991773 34621690 33891616 33121613 
            32611627 32521701 32801740 33481812 34161938 
            34482032 35052000 

423 
AWUS01 KWNH 292340
FFGMPD
CAZ000-300920-

Mesoscale Precipitation Discussion 0116
NWS Weather Prediction Center College Park MD
739 PM EDT Fri Mar 29 2024

Areas affected...south-central CA coast into the Transverse Ranges

Concerning...Heavy rainfall...Flash flooding possible

Valid 292338Z - 300920Z

Summary...Heavy rain and possible flash flooding will affect
portions of the south-central CA coastline into the Transverse
Ranges this evening and tonight. Peak hourly rainfall of 0.7 to
~1.0 inches is expected along with 2 to 3 (perhaps a little
higher) inches of storm total rainfall through ~09Z.

Discussion...Visible satellite imagery from GOES West showed a
well-defined cloud pattern depicting a cyclone just off of the
north-central CA coast with an occluded/cold front nearing San
Francisco Bay at 23Z. Peak hourly rainfall in and around the Santa
Cruz Mountains over the past couple of hours has been in the 0.25
to 0.50 inch range. Water vapor imagery showed a closed mid to
upper-level low centered about 250 miles to the WNW of SFO with
strongly diffluent flow located east and southeast of the low
center. The closed low was tracking toward the southeast, helping
to keep the occluded/cold front moving along in a fairly
progressive fashion but short term heavy rain was still impacting
portions of the CA coast.

While the progressive nature of the occluded/cold front is
expected to continue through the night given no upstream impulses
observed on water vapor imagery to indicate stalling or slowing of
the front, locally intense short term rainfall rates are still
expected for portions of the CA coast into the Transverse Ranges
later tonight. Despite some wavering up/down, peak IVT values of
400-500 kg/m/s are likely to remain fairly steady through 09Z
along the coast and locations just inland but any instability
should remain low (<250 J/kg), lowering convective potential.
Nonetheless, strong forcing and low level winds becoming
orthogonal to the axis of the Transverse Ranges should favor
hourly rainfall totals over 0.5 in/hr at times within the axis of
highest IVT, with localized hourly totals near 1 inch possible.
Farther north, the duration of heavy rain is expected to be
shorter, limiting storm total rainfall into the 1 to 2+ inch
range. The Transverse Ranges will see the greatest potential for
rainfall totals in the 2 to 3 inch range through 09Z (although
spotty totals just over 3 inches may occur) along with the longest
duration of 0.5 in/hr rates, perhaps as much as 2-3 hours for any
given location within the terrain. The relatively quick addition
of 2-3 inches may result in excess runoff for a few locations from
the south-central CA coast into the Transverse Ranges with the
axis of heavy rain forecast to be located just west the Los
Angeles metro at 09Z.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...MTR...

ATTN...RFC...CNRFC...NWC...

LAT...LON   36382169 36312154 35872109 35592066 35482044 
            35282015 35081977 34931948 34821925 34801891 
            34801874 34721844 34361848 34011886 34221964 
            34432071 35292145 36032186 36262184 

327 
AWUS01 KWNH 280716
FFGMPD
VAZ000-NCZ000-SCZ000-281315-

Mesoscale Precipitation Discussion 0115
NWS Weather Prediction Center College Park MD
316 AM EDT Thu Mar 28 2024

Areas affected...eastern North Carolina, northeastern South
Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 280715Z - 281315Z

Summary...Convection has consolidated into bands with nearly 2
inch/hr rain rates just northwest of Wilmington recently.  These
trends are expected to continue for the next 3-6 hours, posing an
isolated flash flood threat.

Discussion...The onset of slightly stronger forcing for ascent
aloft (associated with mid-level waved embedded in southwesterly
flow aloft) and convergence along a surface boundary extending
from near ORF to near CRE was resulting in an increasingly focused
band of convection just northwest of Wilmington recently.  The
storms are in a very moist environment (1.5 inch PW values), with
elevated instability and orientation of the convection (parallel
to flow aloft) supporting training and 2-2.5 inch/hr rain rates. 
These rates are falling on ground conditions characterized by 2.5
inch/hr FFGs, suggestive of an evolving flash flood threat with
the convection near Wilmington in the next hour or so.

Models/observations suggest a continued trend for increasing
convection (and perhaps upscale growth) through the next 3-4 hours
particularly along the surface boundary.  As this occurs, the
coverage of flash flood potential should increase especially where
training is most pronounced.  Eventually, upscale growth and
movement of the front should allow for propagation of storms
toward open waters of the Gulf Stream that should effectively end
the flash flood threat.  This process is expected to evolve
through 12-13Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AKQ...CHS...ILM...MHX...RAH...

ATTN...RFC...SERFC...NWC...

LAT...LON   36617628 35977524 34537560 33147924 33398005 
            34137967 35127877 36227730 

535 
AWUS01 KWNH 260403
FFGMPD
ALZ000-MSZ000-LAZ000-261000-

Mesoscale Precipitation Discussion 0114
NWS Weather Prediction Center College Park MD
1201 AM EDT Tue Mar 26 2024

Areas affected...Portions of Central/Eastern LA through
Central/Southern MS and Western AL

Concerning...Heavy rainfall...Flash flooding possible

Valid 260400Z - 261000Z

SUMMARY...Additional isolated to widely scattered instances of
flash flooding will be possible heading through the overnight
hours from a well-organized line of showers and thunderstorms with
very heavy rainfall rates.

DISCUSSION...The latest radar imagery shows a broken QLCS oriented
in a southwest to northeast fashion from portions of central LA
through central MS. The northern portion of this convective line,
generally near and northeast of Jackson, MS, has been tending to
bow a bit more progressively off to the east which has tended to
mitigate the rainfall totals somewhat despite the very organized
structure of the convection.

However, the portion of the line that involves areas of central LA
into at least southwest MS has been slower moving and over the
last 1 to 2 hours has begun to exhibit some short-term training
character. This is occurring as the convection becomes aligned
more parallel to the deeper layer southwest flow out ahead of an
upper-level trough moving into the MS Valley. There is a fair
amount of instability lurking out ahead of the southwest portion
of the QLCS across eastern LA and southwest MS where MLCAPE values
are still on the order of 1000 to 1500+ J/kg. This coupled with a
strong and convergent low-level jet of 50 to 60 kts and 50+ kts of
effective bulk shear is likely to support QLCS sustenance over the
next several hours that will be capable of producing very heavy
rainfall rates.

The PWs have risen to locally 1.5 to 1.75 inches, and this coupled
with the favorable thermodynamic environment and strong
shear-enhanced updrafts should help support rainfall rates that
occasionally reach or exceed 2"/hour. The latest 00Z HREF guidance
appears to be under doing the convective organization of the
strong cluster of cells south of Natchez, MS and north of New
Roads, LA. This activity in particular is rather slow-moving, but
is exhibiting some very cold overshooting top activity within the
last hour, and is likely producing rainfall rates of 2.0 to
2.5"/hour.

The larger scale convective threat should overall continue to
advance downstream across central and southern MS and will
eventually get into areas of western AL. The southwest flank of
the line that still impacts portions of central/eastern LA and
southwest MS will generally have the greater cell-training
potential. Some rainfall totals of 2 to 4 inches with isolated
heavier amounts will be possible where this occurs.

Additional isolated to widely scattered instances of flash
flooding will be possible as a result, and this will include the
more sensitive urban locations where runoff will be more
pronounced.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...LIX...MEG...MOB...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   33798801 33508751 32608764 31368871 30588956 
            30379000 30249075 30409141 30739167 31049168 
            31549131 33168966 33678888 

477 
AWUS01 KWNH 252240
FFGMPD
MSZ000-LAZ000-ARZ000-260438-

Mesoscale Precipitation Discussion 0113
NWS Weather Prediction Center College Park MD
639 PM EDT Mon Mar 25 2024

Areas affected...central/eastern Louisiana into southern/central
Mississippi

Concerning...Heavy rainfall...Flash flooding possible

Valid 252238Z - 260438Z

Summary...Localized training/cell mergers are supporting spots of
2 inch/hr rain rates at times - especially in central Louisiana. 
These heavier rain rates should translate eastward, posing an
isolated flash flood threat especially in sensitive/urbanized
areas.

Discussion...A couple of SSW-NNE oriented convective bands have
materialized over central Louisiana over the past 2-3 hours.  The
bands have generally organized along and ahead of a remnant
outflow from prior convection that was currently located from near
SRC (Searcy, AR) to near BPT (Beaumont, Texas).  Over the past
half hour or so, this outflow has made enough eastward progression
to undercut some of the central Louisiana convection, with
remaining storms likely elevated but leveraging just enough
instability aloft to maintain heavy rainfall atop areas that have
experienced 2-3 inches of rainfall.  Rates in most areas have
fallen below areal FFG thresholds (generally holding in the 2.5-3
inch/hr range), and much of the flash flood threat has remained
fairly isolated.  These trends should keep the flash flood threat
isolated in the short term.

Over time, convection will continue to translate eastward,
eventually crossing the Mississippi River as surface-based storms
generally from US 82 southward.  As this occurs, models suggest
limited opportunity for training to develop especially where 1)
surface-based instability exists to support deeper/stronger
updrafts and 2) where the eastward-moving outflow boundary can
slow its forward progression, allowing for more opportunity for
training/repeating and cell mergers.  This scenario (which should
support 1.5+ inch/hr rain rates) is most likely to unfold along an
axis from near Alexandria, LA to Jackson, MS through the evening. 
These rates are still likely to fall below one- and three-hour FFG
thresholds except on an isolated basis, and flash flood potential
should remain isolated and localized near urban and/or low-lying
areas.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LCH...LIX...LZK...MEG...SHV...

ATTN...RFC...LMRFC...SERFC...WGRFC...NWC...

LAT...LON   33929033 33658911 32848885 32078885 31588926 
            30789116 30419309 31039324 31819297 32879217 
            33629127 

733 
AWUS01 KWNH 250042
FFGMPD
TXZ000-OKZ000-250600-

Mesoscale Precipitation Discussion 0112
NWS Weather Prediction Center College Park MD
841 PM EDT Sun Mar 24 2024

Areas affected...west-central to north-central TX

Concerning...Heavy rainfall...Flash flooding possible

Valid 250038Z - 250600Z

Summary...Potential training of thunderstorms from SW to NE over
west-central to north-central TX may lead to localized flash
flooding through 06Z. Rainfall rates of 1-2 in/hr and totals of
2-3 inches will be possible.

Discussion...00Z regional radar imagery over the Southern Plains
showed an elongated line of thunderstorms with cells that were
largely contiguous, extending from northwestern TX into western
portions of the Edwards Plateau, located out ahead of a cold
front/dryline. Individual cells were observed to be moving briskly
toward the NE or ENE at 30-40 kt, not posing a flash flood threat
by themselves given their progressive forward motion. However, new
cells were in the process of organizing over west-central TX
between I-10 and I-20, with some orientation from SW to NE. These
cells were forming within a region of approximately 500-1000 J/kg
MLCAPE and 0.7 to 1.0 inches of precipitable water (00Z SPC
mesoanalysis).

It appears cells to the north will develop/move farther east more
quickly relative to those to the south given extrapolation of
short term trends in radar and forecast boundary movement via the
RAP. Despite nocturnal cooling of the boundary layer (low level
development of CIN), there should be sufficient lift associated
with the cold front and with the approach of an upper-level max in
divergence (left exit region of a RAP-estimated 150-170 kt upper
level jet streak from northern Mexico into western TX), coupled
with 20-40 kt of southerly flow at 850 mb into the boundary or
rain-cooled outflow, to support continued thunderstorm development
over west-central TX into the early overnight. Alignment of
thunderstorms from WSW to ENE will be parallel to the mean
steering flow and set up potential training of 1-2 in/hr rainfall
rates across a portion of west-central to north-central TX. If
training is able to persist long enough, localized 2-3 inch totals
could occur which may produce localized flash flooding given flash
flood guidance of 2.5 to 3+ inches in 3 hours over the region.
This scenario is partially dependent on sufficient instability
lingering long enough to support higher rainfall rates, but it
appears at least an isolated threat for flash flooding will exist
through about 06Z.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EWX...FWD...MAF...OUN...SJT...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   33849619 33579574 32659605 31699747 30749895 
            30450031 30490112 31120135 31540101 31960044 
            32759911 33439772 33779671 

862 
AWUS01 KWNH 231855
FFGMPD
MEZ000-MAZ000-NHZ000-RIZ000-VTZ000-CTZ000-NYZ000-NJZ000-240100-

Mesoscale Precipitation Discussion 0111
NWS Weather Prediction Center College Park MD
254 PM EDT Sat Mar 23 2024

Areas affected...southern New England, southern New York state

Concerning...Heavy rainfall...Flash flooding possible

Valid 231848Z - 240100Z

Summary...Areas of 0.25-0.7 inch/hr rainfall rates are spreading
northeastward into southern New England.  These rates are expected
to persist for around 3-5 hours or so, resulting in at least minor
flood/flash flood issues through 01Z.

Discussion...A relatively focused areas of heavy rainfall
continues to migrate northeastward along and ahead of a
strengthening low-level cyclone centered over Maryland.  The area
of heavier rain continues to be supported by strong convergence on
the nose of a stout (70 kt) low-level jet extending from open
waters east of the Mid-Atlantic into Long Island, NY.  Over the
past several hours, areas of 0.5-0.7 inch/hr rain rates have been
noted, resulting in a number of road closures and creeks entering
flood stage especially across eastern Pennsylvania and New Jersey.

The area of heavier rain appears to be shifting northeastward into
southern New York State and Connecticut while expanding across
Rhode Island and southern Massachusetts.  This pattern will likely
result in about a 3-5 hour period of heavier rainfall across the
discussion area, with totals reaching the 1-2.5 inch range during
that time.  These totals are likely to approach FFG thresholds
(generally in the 2-2.5 inch/hr range/locally lower in urban
areas) on at least an isolated basis.  Widespread areas of minor
flood impacts are expected, and isolated flash flood instances are
possible in this regime.  Current trends suggest that heavier
rainfall should end across southern New York state/Long Island by
around 21Z, while persisting across eastern Massachusetts/Rhode
Island and vicinity through 01Z.  Given warm advection across
areas of southern New Hampshire, a few areas of snow-melt-induced
excess runoff cannot be completely ruled out.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ALY...BGM...BOX...GYX...OKX...PHI...

ATTN...RFC...MARFC...NERFC...NWC...

LAT...LON   43637084 42527001 41416983 40217166 40367419 
            40967464 41637453 42587355 43407207 

510 
AWUS01 KWNH 231427
FFGMPD
MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-232026-

Mesoscale Precipitation Discussion 0110
NWS Weather Prediction Center College Park MD
1027 AM EDT Sat Mar 23 2024

Areas affected...portions of Maryland, , Washington DC, New
Jersey, eastern Pennsylvania, southern New York, and southwestern
New England

Concerning...Heavy rainfall...Flash flooding possible

Valid 231426Z - 232026Z

Summary...A long-duration, moderate to heavy rain event is
unfolding generally along the urban corridor of I-95 from
Washington DC through New York City.  Areas of 0.25-0.5 inch/hr
rain rates should continue to spread northeastward with time,
causing issues with excessive runoff.

Discussion...Recent radar mosaic imagery/MRMS indicates widespread
areas of moderate to heavy rainfall, with the heaviest of rates
(0.25-0.7 inch/hr) focused along an axis from Washington DC and
Chesapeake Bay north through the Philadelphia Metro area.  These
rain rates are focused within an axis of low-level convergence on
the northwestern edge of a stout, south-southeasterly 850mb
low-level jet just east of the Mid-Atlantic.  A low-level cyclone
(centered over central Virginia) was also contributing to the
strength of the low-level jet, and should strengthen while
migrating north-northeastward toward eastern Pennsylvania over the
next 6 hours.  Heavier rain rates will continue to shift
north-northeastward in tandem with this low, eventually spreading
into more of Philadelphia, New Jersey, southern New York
(including New York City), and southwestern New England through
21-22Z.

As the rain rates continue (and modestly increase) through 21Z,
they will overspread sensitive, urbanized areas, encouraging
runoff.  Widespread areas of minor flood impacts are expected, and
isolated flash flooding is possible.  3-hour rainfall totals of
1-1.5 inches should approach or locally exceed FFGs across the
region (which happen to be highest in populated areas near the
I-95 corridor), again supporting localized flash flood potential.
Much of the heavier rainfall (and associated flash flood risk)
should wane across Maryland and Washington DC after around 17Z,
while ramping up across the northeastern half of the discussion
area (New Jersey into southern New York) in the 17-21Z timeframe.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AKQ...ALY...BGM...BOX...CTP...LWX...OKX...PHI...

ATTN...RFC...MARFC...NERFC...NWC...

LAT...LON   42127298 41627222 40697217 39417356 37807535 
            37447607 38497701 38807707 39287733 39797703 
            41167531 41947391 

821 
AWUS01 KWNH 231331
FFGMPD
FLZ000-231630-

Mesoscale Precipitation Discussion 0109
NWS Weather Prediction Center College Park MD
930 AM EDT Sat Mar 23 2024

Areas affected...metropolitan areas of southeastern Florida

Concerning...Heavy rainfall...Flash flooding likely

Valid 231330Z - 231630Z

Summary...Areas of training convection are producing spots of 2-3
inch/hr rain rates over parts of the Everglades.  This activity
will spread into populated areas of southeastern Florida soon,
prompting localized flash flooding.

Discussion...A lead convective cluster was located over Miami
currently.  Upstream from that cluster, an axis of west-southwest
to east-northeast oriented storms were located over the Everglades
and just north of the Florida Keys.  SPC Mesoanalysis and radar
mosaic imagery shows that the storms are in an abundantly moist,
unstable environment (2000 J/kg SBCAPE and nearly 2 inch PW
values), supporting efficient rainfall processes within the
storms.  Additionally, a few of the storms are
orienting/developing parallel to flow aloft, enabling 2+ inch/hr
rain rates to develop despite relatively fast storm motions.

MRMS has already estimated a band of 2+ inch/hr rain rates over
the Everglades and areas west of the Miami metro area.  On their
current trajectory, these rates should spread eastward and impact
the metro area, with sensitive/urbanized areas experiencing an
increased flash flood threat beginning in the next few minutes. 
At least 1-2 hours of heavier downpours are expected, and wet
soils/antecedent conditions should also support excessive runoff
at times.  Flash flooding will become likely for a few hours today.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...KEY...MFL...

ATTN...RFC...SERFC...NWC...

LAT...LON   26458097 26377980 25727937 24947991 24598117 
            25068198 26118179 

502 
AWUS01 KWNH 222313
FFGMPD
FLZ000-230500-

Mesoscale Precipitation Discussion 0108
NWS Weather Prediction Center College Park MD
713 PM EDT Fri Mar 22 2024

Areas affected...southern FL Peninsula and the Keys

Concerning...Heavy rainfall...Flash flooding possible

Valid 222312Z - 230500Z

Summary...Flash flooding will be possible across portions of
southern FL, including the FL Keys, through 05Z. Rainfall rates
with an approaching MCS may exceed 2 in/hr along with localized
totals of 3-5 inches (perhaps locally higher).

Discussion...GOES East infrared and regional radar imagery at
2230Z showed an MCS to the southwest of the southern FL Peninsula.
The coldest cloud tops and bulk of lightning strikes have been
advancing toward the southeast, missing Key West by 50-100 miles
to the west. However, ship observations showed a 1006 mb low was
located ~110 miles west of Key West and moderate to heavy rain
with embedded thunderstorms were occurring north of the low within
a low level warm advection regime...north of an estimated warm
front extending across the Keys (though ongoing convection was
making the exact frontal placement difficult). Farther east, a
supercell was observed over Biscayne Bay, tracking north near the
barrier island marking the eastern edge of the bay. Warm rain
processes were dominating this cell given the lack of recent
lightning data and relative warm tops on infrared imagery. Short
term trends indicate this cell may impact Key Biscayne and
portions of Miami/Miami Beach in the short term with rain rates of
1-2 in/hr if it is able to survive. According to the SPC
mesoanalysis, MLCAPE has not changed much since 18Z across
southern FL, with the northern extent of the 500 J/kg contour
reaching North Key Largo, coinciding with precipitable water
values of 1.7 to 2.0 inches.

As a mid-level closed low/trough over the Lower Mississippi Valley
continues to track east into the early overnight hours, large
scale lift will overspread FL, including increasing
divergence/diffluence aloft. 925-850 mb layer southerly flow will
likely increase at least another 10 kt from their present 25-30 kt
values across southern FL, ahead of the approaching surface low
west of Key West through 03-06Z. Widespread heavy rain will
translate into southern FL from the west but additional convective
development will be possible in advance as increasing moisture
transport and CAPE overspread southern FL over the next few hours.
Rainfall rates over 2 in/hr will be possible on a localized basis,
especially with organized cells given favorable shear profiles,
with storm totals of 3 to 5+ inches, perhaps focused near the Keys
or the southern Everglades. There will be localized potential for
higher rates along the urban southeastern corridor as well.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...KEY...MFL...

ATTN...RFC...SERFC...NWC...

LAT...LON   26758023 26547979 26107953 25007990 24308110 
            24178187 24438223 24848210 25428157 25918090 
            26628050 

632 
AWUS01 KWNH 221754
FFGMPD
FLZ000-222200-

Mesoscale Precipitation Discussion 0107
NWS Weather Prediction Center College Park MD
153 PM EDT Fri Mar 22 2024

Areas affected...FL Keys into southeastern FL

Concerning...Heavy rainfall...Flash flooding possible

Valid 221752Z - 222200Z

Summary...An increased risk of localized flash flooding will exist
across the FL Keys into southeastern FL over the next few hours.
Hourly rainfall totals of 1-2 inches will be possible, but cannot
rule out isolated rates over 2 in/hr where favorable
instability/forcing overlap.

Discussion...Regional radar and visible satellite imagery showed
an MCS extending from offshore of southwestern FL into the
southern Peninsula with an embedded circulation/low located over
the southern Everglades at 1730Z. An outflow enhanced effective
front extended southwestward from the low over the open water and
southeastward through the Upper Keys with surface dewpoints in the
upper 60s across the region near and south of the boundary.
Precipitable water values were 1.6 to 1.8 inches from the 12Z MFL
and KEY soundings which displayed high relative humidity
throughout the column and freezing levels of 12.5 to 14.0 kft.
Therefore, the environment was supportive of efficient rainfall
production despite relatively low instbility; the 500+ J/kg MLCAPE
contour only covering the Keys, with lower values to the north.
Rainfall over the past 3-4 hours has resulted in 0.5 to almost 2
inches of rain in the southern Miami suburbs with hourly totals
near 1 inch over the past 1-2 hours.

Moderate (~20-30 kt) low level warm advection ahead of the
meso-low will continue to allow for steady moderate to locally
heavy rain across the urban southeastern corridor over the next
few hours as it tracks southeastward, in addition to general
overrunning of the boundary in place just south of the region. The
greatest focus for higher rainfall intensities will exist just
ahead of the meso-low with possible training of heavy rain from
west to east mostly over the Everglades but the expected axis of
training may clip the the southeastern urban corridor as well,
with 1 to 2+ in/hr. Embedded convective elements will locally
increase hourly rainfall over 1 inch elsewhere across the region
with additional totals of 1-3 inches possible through 22Z. Farther
south where instability is a bit higher, greater potential will
exist for hourly rainfall of 1-2 inches, with locally higher rates
possible but the progressive southeastward movement of the MCS
should limit short term additional rainfall totals with this
initial round of storms across much of the Keys. However,
additional rounds of heavy rain are expected later this evening
with additional MPDs possible.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...KEY...MFL...

ATTN...RFC...SERFC...NWC...

LAT...LON   26478041 26417988 25667990 24818047 24378135 
            24448195 24698202 25128196 25558136 

509 
AWUS01 KWNH 212109
FFGMPD
TXZ000-OKZ000-220245-

Mesoscale Precipitation Discussion 0106
NWS Weather Prediction Center College Park MD
508 PM EDT Thu Mar 21 2024

Areas affected...Southern Oklahoma to Northern Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 212107Z - 220245Z

Summary...Isolated flash flooding is possible across portions of
southern Oklahoma into northern Texas as a shortwave trough moves
eastward near the Red River and convection begins to grow upscale
in coverage and intensity this afternoon.  Localized rainfall
totals of 2 to 4 inches remains possible where cell motions are
reduced close to the ejecting trough/low.

Discussion...Radar showed convection beginning to grow either side
of the Red River in proximity in the vicinity of a pair of
shortwave troughs, a weak dryline in the area, and a
quasi-stationary front located to the north. 

The HRRR runs from late this morning and this afternoon have been
showing run to run differences in placement of the heaviest
rainfall...but a consistent theme has been for the axis of
heaviest rain to be along and immediately south of the track of
the trough where greater surface-based instability should result
from better daytime heating/steeper low/mid level lapse rates. 
Surface flow is fairly weak into the region and 850 mb flow is
modest...15 to 20 kts at best as shown by latest VWPs from the
Gulf coast region northward into central/eastern Texas...but the
flow was favoring moisture transport ahead of the trough/low. 

Flash flood guidance was generally at or above 2.5 inches per hour
and closer to 3 inches per 3 hours hour across MPD area. Thinking
is that localized maximum rainfall amounts of 2 to 4 inches are
possible should the cells slow down in response to the approach of
the upper system...so instances of flash flooding rainfall may
occur but should be isolated in coverage.

Bann

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON   34559881 34469786 34129710 33559663 33179667 
            32769690 31929791 31349894 31300006 31920005 
            32909947 33469953 34319984 

569 
AWUS01 KWNH 161458
FFGMPD
TXZ000-161730-

Mesoscale Precipitation Discussion 0105
NWS Weather Prediction Center College Park MD
1057 AM EDT Sat Mar 16 2024

Areas affected...a small portion of south Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 161456Z - 161730Z

Summary...A cluster of mostly nearly surface-based convection
located just south of San Antonio is producing a quick 1-2 inch
rainfall totals amid localized training/repeating.  This cluster
could persist eastward toward areas that received heavier rain
totals (near/west of Houston) over the next few hours, posing an
isolated flash flood risk.

Discussion...A cluster of cells just south of San Antonio has
gained modest organization over the past hour or so, and is
establishing a cold pool and associated gust front over Karnes
County.  The orientation of the cold pool was generally
perpendicular to 20-30 knot southerly flow at 850mb, and surface
temps/point forecast soundings suggest that this activity could be
only slightly elevated while benefiting from appreciable (7-7.5
C/km) mid-level lapse rates.

The longevity of this activity is a bit unclear, although
satellite/radar presentation suggest potential eastward
persistence of the complex along with some degree of upstream
backbuilding.  This would result in a few areas of 1-2 inch/hr
rain rates continuing for at least a couple of hours, posing an
isolated flash flood risk especially in sensitive or urban areas.
The rates generally fall below FFG thresholds in most of the area,
further suggesting only an isolated threat in the near-term. 
Farther east (closer to the Houston Metro area), heavy rainfall
from last night's convection (exceeding 3-4 inches) has resulted
in reduced FFGs and wet soils, so a slightly higher flash flood
risk could exist in this area.  A few spots of urban runoff could
also occur if the upstream flank of the cluster happens to drift
into the San Antonio area through 17Z or so.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CRP...EWX...HGX...

ATTN...RFC...WGRFC...NWC...

LAT...LON   30369633 30109541 29699494 29029518 28439647 
            28359808 28869967 29449970 30019899 30269791 
            

156 
AWUS01 KWNH 160655
FFGMPD
TXZ000-161200-

Mesoscale Precipitation Discussion 0104
NWS Weather Prediction Center College Park MD
254 AM EDT Sat Mar 16 2024

Areas affected...Deep South Texas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 160700Z - 161200Z

SUMMARY...Strong moisture flux into mature complex along front
should maintain efficient rainfall production with 2-3"/hr rates
through late overnight period.  Muddled steering flow may allow
for some slow cells motions and localized totals over 4" and
result in possible flash flooding through daybreak.

DISCUSSION...Goes-E 10.3um EIR depicts a mature convective complex
across Deep South Texas with overshooting tops to -70C indicative
of solid unstable inflow.  06z surface fronts continues to slowly
sag southward from near VCT to CRP to BKS and ZPY providing a
solid moisture convergence boundary and now as low level flow
continues to veer, is also generally confluent but becoming
increasingly orthogonal to the boundary providing continued
isentropic ascent even as low levels may be starting to
stabilize/cap.  RAP analysis and GOES AMVs suggest weak upper
level flow is favorably oriented toward weak outflow jet to the
northeast and satellite imagery denotes that fact with some
transverse banding filaments noted along the far
fringes...however, this favorable region appears to be lifting
away.  As such, a delicate balance appears to remain in place with
mid-level steering also starting to veer and support northeasterly
motion to internal updrafts with the complex as well.   However,
solid inflow suggests southeastward propagation and so, the
complex is expected to continue to be slow moving along the
frontal zone.

Total moisture values have ticked up to near 2" through depth, but
surface to boundary layer values per CIRA LPW continue to rise
being well over 1" below 850mb and Tds into the mid 70s.  While
winds are in the 15-20kt range, there remains solid
confluence/convergence to the boundary to allow for enhanced
moisture flux for continued efficient rainfall production;
generally between 2-3"/hr though HRRR 15-minute totals of
1.5-1.75" have been forecast.   As noted earlier, overall slow
cell motions appear to be allowing for increased localized totals
with spots of 4, perhaps 5" plausible within the next few hours.
While FFG values are high/soils dry, few soil conditions can
infiltrate this amount in short-time, so much could run off and
induce localized flash flooding concerns.  

Uncertainty remains with stronger isentropic ascent along the
upstream portion of the frontal zone and the Sierra Madre.  Given
veering steering, this may present back-building and then repeat
cell tracks across S Zapata, Starr county and then downstream with
areas that may have already seen 2-4" locally.  If this were to
manifest spots over 6" are possible and flash flooding would
clearly be more likely, but as for now; there are mixed signals
that this will occur.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BRO...CRP...

ATTN...RFC...WGRFC...NWC...

LAT...LON   28589703 28319646 27829705 27499720 27059732 
            26709730 26439769 26099828 26379907 26699933 
            27319954 27449866 27939785 

195 
AWUS01 KWNH 160202
FFGMPD
TXZ000-160730-

Mesoscale Precipitation Discussion 0103
NWS Weather Prediction Center College Park MD
1002 PM EDT Fri Mar 15 2024

Areas affected...Lower Rio Grande Valley of Texas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 160200Z - 160730Z

SUMMARY...Broad downdraft supercells with large hail and intense
rainfall rates to cross the Rio Grande with left-splits and
upscale development into a broader complex into the overnight
period.  Highly focused and slow cell motions may result in
2-3"/hr totals and possible flash flooding.

DISCUSSION...GOES-E and regional RADAR mosaic denotes a pair of
broad updraft supercells along the Mexican side of the Rio Grande
continuing to translate slowly along the instability axis.  Slow
southward sagging cold front is aiding moisture flux convergence
into the theta-E axis that is banked up along the Sierra Madre
Oriental/Serranias del Burro, with Tds of low to mid-70s and
return southeasterly flow parallel to the axis along the Rio
Grande at 20-25kts resulting in total PWats of 1.25 to 1.6 from
south to north.  Elevated mixed layer at 700-500mb from the
south-southwest has allowed for very steep lapse rates and
therefore continued very high instability of 2500-3500 J/kg of
CAPE for cells to utilize.   While this profile provides for hail
production, the ample deeper layer moisture (generally up to
800mb) and solid flux will allow for accompanying intense rainfall
production as well with 2-3"/hr rates possible.

The uncertainty resides in a couple of factors; (1) Duration,
though broad updrafts and slow right moving cell motions may allow
for 30-45 minutes of intense rainfall production overall totals
may still be a the lower threshold of the higher capacity soil
conditions in the region per FFG values of 3"/hr and 4"+/3hr.  (2)
Location, current trends are for continued strong easterly flow
through the theta-E axis into the upslope region of the Sierra
Madre keeping upstream redevelopment along the terrain and with
deep layer effective bulk shear over 60kts...cells are more likely
to turn right along the axis resulting in training more so on the
Mexico side of the boarder. However, left splitting updrafts are
likely throughout the cycle and likely limited in duration moving
away from the best moisture flux, still may remain potent enough. 
 (3) Upscale growth,  while models are less aggressive on this
scenario, there are suggestions in the WV/EIR loops and RADAR
mosaic for development to be filling in allowing for a larger
mesoscale complex to develop over the next few hours.   The RAP
hints as some increased divergence along the lower Rio Grande in
the next few hours with shortwave ridging developing.  This may be
manifest out of the strength of the updrafts and mesoscale outflow
jet or some combination with the upper-jet/closed orientation to
the NW across S NM/W TX.  Either way, any upscale growth would
favor an eastward migration resulting in intense rates into South
Texas.

Bottom line, strong cells with rainfall intensity to rapidly
overwhelm even dry soils may result in rapid runoff and possible
flash flooding in and around the Rio Grande Valley through the
early overnight period with low confidence in precise placement.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BRO...CRP...

ATTN...RFC...WGRFC...NWC...

LAT...LON   28169931 27969888 27519846 26629816 26099788 
            26039833 26389913 26869945 27309960 27649980 
            27869998 28030005 28119992 

338 
AWUS01 KWNH 151926
FFGMPD
TXZ000-160125-

Mesoscale Precipitation Discussion 0102
NWS Weather Prediction Center College Park MD
325 PM EDT Fri Mar 15 2024

Areas affected...Portions of South-Central to Southeast TX

Concerning...Heavy rainfall...Flash flooding possible

Valid 151925Z - 160125Z

SUMMARY...Showers and thunderstorms will be developing and
expanding in coverage over the next several hours. Very heavy
rainfall rates and locally slow cell-motions are expected to drive
concerns for isolated to widely scattered instances of flash
flooding.

DISCUSSION...The latest GOES-East visible satellite imagery is
showing an increasingly unstable boundary layer across much of
south-central to southeast TX as strong diurnal heating occurs in
conjunction with the pooling of low-level moisture out ahead of a
slow-moving cold front.

MLCAPE values have increased to as much as 2000 to 3000 J/kg and
the latest CIRA-ALPW data shows a strong concentration of moisture
in the SFC-850 layer. This coupled with frontal convergence and
relatively strong shear parameters should set the stage for the
development and expansion of rather organized convective activity,
including a mix of multicell and supercell thunderstorms. Already
the latest dual-pol radar in conjunction with satellite imagery is
showing areas of convective initiation underway.

Rainfall rates with some of the stronger and more organized cells
may reach 2.5"/hour, and with rather slow cell-motions expected,
some rainfall totals may reach 3 to 5 inches in as little as 2 to
3 hours. The 12Z HREF guidance was somewhat indeterminate on the
location of the heaviest rainfall, but recent runs of the HRRR
guidance have been trending wetter and generally favor an axis
from east of San Antonio to north of Victoria and potentially in
time getting into the western suburbs of the Houston metropolitan
area going through 00Z (7PM CDT).

The convective threat will also in time extend farther west to
areas closer to the Lower Rio Grande Valley including areas such
as Uvalde and Cotulla as the cold front continues to edge
southward and interacts with what should be a strongly unstable
boundary layer heading through the late-afternoon and early
evening hours. Isolated to widely scattered instances of flash
flooding will be possible given the expected high rainfall rates
and short-term storm totals.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CRP...EWX...HGX...LCH...

ATTN...RFC...WGRFC...NWC...

LAT...LON   30619504 30399443 29859440 29489453 28889561 
            28359754 28109913 28180006 28650055 29170021 
            29489934 29839793 30379648 

213 
AWUS01 KWNH 150854
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-151400-

Mesoscale Precipitation Discussion 0101
NWS Weather Prediction Center College Park MD
453 AM EDT Fri Mar 15 2024

Areas affected...Southern AR...Northwest MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 150850Z - 151400Z

Summary...Favored training of deep convection for the next several
hours may result in additional totals of 2-4". Scattered instances
of flash flooding are likely.

Discussion...Resurgence of deep convection is well underway over
the Ark-La-Tex and downstream portions of southern Arkansas, as
seen by GOES-East infrared cold cloud tops. This is occurring
along an outflow boundary on the southwestern flank of a decaying
MCS, but a favorable environment should encourage increased
training over the next several hours. This mesoscale environment
is characterized by ML CAPE of 1000-2000 J/kg, PWATs of 1.5-1.8
inches (near the max moving average, per SHV sounding
climatology), and deep layer shear of 30-50 kts. In addition, a
highly favorable coupled overlap of 850 mb convergence (moderate
southwesterly low-level moisture transport) and 250 mb divergence
(diffluence downstream of subtropical jet streak over south TX and
within the right-entrance region of polar jet streak over the
northeast US) is likely to maintain deep convection. Convection
has already begun to train from WSW to ENE, and southern AR into
northwest MS are favored to see the most precipitation over the
next 3-5 hours.

The 00z HREF has a better handle of the ongoing convection than
more recent HRRR runs, suggesting localized totals of 2-4" through
15z (per the HREF PMM). The corresponding 3" neighborhood
exceedance probabilities are as high as 30-50% (maximized through
12z), but much of this rainfall has likely already occurred (with
MRMS indicating 2-3" hourly totals over the past hour) as CAMs are
often too slow with these dynamic convective processes. Even
still, given the favored environment with continued training of
convection, expect additional amounts of at least 1-3". This is
likely to result in scattered instances of flash flooding over the
next several hours, despite relatively high FFGs of 2.5-3.5".

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...SERFC...NWC...

LAT...LON   34518884 33528894 32768986 32669231 32659359 
            32679423 32769472 33149490 33749447 34239314 
            34199060 

804 
AWUS01 KWNH 150154
FFGMPD
TNZ000-MSZ000-LAZ000-MOZ000-ARZ000-TXZ000-OKZ000-150730-

Mesoscale Precipitation Discussion 0100
NWS Weather Prediction Center College Park MD
953 PM EDT Thu Mar 14 2024

Areas affected...Northeast TX...Southeast OK...Arkansas...Eastern
TN...Northern MS...

Concerning...Heavy rainfall...Flash flooding likely

Valid 150155Z - 150730Z

SUMMARY...Expanding linear convective complex favorably oriented
to the deep layer steering flow will allow for areas of intense
rainfall rates over 2"/hr and streaks of 3-5" resulting in likely
incidents of flash flooding across Northeast TX into Western TN
overnight.

DISCUSSION...GOES-E 10.3um showing a cooling and expanding
convective complex from the Red River of SE OK and NE TX across AR
nosing toward W TN at this time.  Internally, numerous
overshooting tops dotting the center of the complex with -70C
indicating maturing/strong updrafts within the favorably unstable
environment across the warm sector.  To exacerbate the issue,
orientation of the overshooting tops denote the growing concern
for favorable mergers and training cells; this is related to the
exiting of a mid-level shortwave/mature MCV racing across the
Mid-Mississippi Valley into S IL.  As a result, the associated
meso-high blow echo is orienting the outflow boundary toward the
strengthening southwesterly LLJ and southerly/nearly orthogonal
surface flux across central AR.  Ample low level moisture with Tds
in the upper 60s to low 70s with modestly steep mid-level lapse
rates results in ample unstable air with CAPE values still in the
2000-3000 J/kg range (even in an elevated nature).

As such, strong moisture flux/strong updrafts (as noted by the
instability and overshooting tops) suggest increasing moisture
flux and rainfall efficiency, with hourly rates up to 2"/hr in the
cores, though 15-minute rainfall totals of 1-1.3" are likely given
00z HRRR and additive WoFS totals.  While a mid-level jet is
translating over the top of the complex now, increasing cell
motions, but as noted, weak inflection lifting northeast through
the flow should allow for some timing (2-4hrs) of favorable
training orientation before weak height-falls and right entrance
upper level dynamics allows for some forward (southeast)
propagation of the line/complex after 07z).   As a result, of the
efficient rain and training, streaks of training cells mainly out
of SE OK across central AR will allow for streaks of 3-5" totals
and continue likely flash flooding...given the longer duration
potential there.

However, other streaks further downstream into W TN/NW MS as well
as favorable upstream/back-building near the nose of the
EML/Western Gulf LLJ confluence across NE TX, may support similar
rates but shorter duration for spots of 2-4" and possible
incidents of flash flooding as well.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...JAN...LZK...MEG...OHX...OUN...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   36338831 36068758 35368774 33959029 32469541 
            32719744 33869742 35309502 35949260 36249043 
            

562 
AWUS01 KWNH 142210
FFGMPD
OHZ000-KYZ000-INZ000-ILZ000-MOZ000-150351-

Mesoscale Precipitation Discussion 0099
NWS Weather Prediction Center College Park MD
609 PM EDT Thu Mar 14 2024

Areas affected...east-central Missouri, central/southern Illinois,
central/southern Indiana, northern Kentucky, western/central Ohio

Concerning...Heavy rainfall...Flash flooding possible

Valid 142151Z - 150351Z

Summary...Relatively fast-moving storms are favorably oriented for
training/repeating and a quick 1-1.5 inches of rainfall in
localized spots.  This could result in an isolated flash flooding
across the discussion area through 03Z this evening.

Discussion...Scattered convection continues to deepen and
intensify across east-central Missouri and western Illinois.  The
storms are exhibiting primarily a cellular mode, but are oriented
along WSW-ENE axes (from Springfield, IL westward to south of
Columbia, MO and also south through southwest of Saint Louis)
generally parallel to fast flow aloft.  A limited amount of
training has been observed, which has enhanced rain rates to close
to 1 inch/hr in spots (per MRMS) despite relatively fast storm
motions (30-40 knots).  Another east-west oriented band was
located across central Indiana (Kokomo to south of Fort Wayne)
that was oriented favorably for training.  Additionally, a cluster
of more mature cells/lines were located across south-central and
southwestern Missouri that will move eastward through the
discussion area over the next several hours.

The downstream airmass has heated and destabilized sufficiently to
support deep convection through at least 03Z this evening.  That
airmass is characterized by areas of 1000-3000 J/kg SBCAPE
(highest in Missouri) and 1-1.3 inch PW values.  The airmass will
continue to support deep convection along with localized training,
cell mergers, and occasional spots of 1-1.5 inch rainfall rates. 
These rates will approach FFG thresholds (generally in the 1-2
inch/hr range - lowest across portions of Ohio, Kentucky, and
eastern Indiana). NASA Sport soil moisture values indicate
widespread, dry antecedent conditions that will need to be
overcome by training convection (espcially in Illinois).  The
aforementioned scenario suggests that an isolated/spotty flash
flood risk should materialize through 03Z especially where
convective training is most pronounced.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CLE...ILN...ILX...IND...IWX...JKL...LMK...LOT...
LSX...PAH...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON   41108389 39608290 38408346 37428675 37088888 
            37308997 38589111 39699114 40628891 40998669 
            

339 
AWUS01 KWNH 142153
FFGMPD
OHZ000-KYZ000-INZ000-ILZ000-MOZ000-150351-

Mesoscale Precipitation Discussion 0099
NWS Weather Prediction Center College Park MD
553 PM EDT Thu Mar 14 2024

Areas affected...east-central Missouri, central/southern Illinois,
central/southern Indiana, northern Kentucky

Concerning...Heavy rainfall...Flash flooding possible

Valid 142151Z - 150351Z

Summary...Relatively fast-moving storms are favorably oriented for
training/repeating and a quick 1-1.5 inches of rainfall in
localized spots.  This could result in an isolated flash flooding
across the discussion area through 03Z this evening.

Discussion...Scattered convection continues to deepen and
intensify across east-central Missouri and western Illinois.  The
storms are exhibiting primarily a cellular mode, but are oriented
along WSW-ENE axes (from Springfield, IL westward to south of
Columbia, MO and also south through southwest of Saint Louis)
generally parallel to fast flow aloft.  A limited amount of
training has been observed, which has enhanced rain rates to close
to 1 inch/hr in spots (per MRMS) despite relatively fast storm
motions (30-40 knots).  Another east-west oriented band was
located across central Indiana (Kokomo to south of Fort Wayne)
that was oriented favorably for training.  Additionally, a cluster
of more mature cells/lines were located across south-central and
southwestern Missouri that will move eastward through the
discussion area over the next several hours.

The downstream airmass has heated and destabilized sufficiently to
support deep convection through at least 03Z this evening.  That
airmass is characterized by areas of 1000-3000 J/kg SBCAPE
(highest in Missouri) and 1-1.3 inch PW values.  The airmass will
continue to support deep convection along with localized training,
cell mergers, and occasional spots of 1-1.5 inch rainfall rates. 
These rates will approach FFG thresholds (generally in the 1-2
inch/hr range - lowest across portions of Ohio, Kentucky, and
eastern Indiana). NASA Sport soil moisture values indicate
widespread, dry antecedent conditions that will need to be
overcome by training convection (espcially in Illinois).  The
aforementioned scenario suggests that an isolated/spotty flash
flood risk should materialize through 03Z especially where
convective training is most pronounced.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CLE...ILN...ILX...IND...IWX...JKL...LMK...LOT...
LSX...PAH...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON   41108389 39608290 38408346 37428675 37088888 
            37308997 38589111 39699114 40628891 40998669 
            

273 
AWUS01 KWNH 141939
FFGMPD
MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-150136-

Mesoscale Precipitation Discussion 0098
NWS Weather Prediction Center College Park MD
338 PM EDT Thu Mar 14 2024

Areas affected...much of southern Missouri, much of northern
Arkansas, eastern/southeastern Oklahoma, and a small part of north
Texas

Concerning...Heavy rainfall...Flash flooding likely

Valid 141936Z - 150136Z

Summary...Ongoing, mature MCS across eastern Oklahoma is prompting
localized flash flood concerns while moving toward hillier
terrain/lower FFGs in Arkansas/southern Missouri.  Additionally,
redevelopment along the southwestern flank of this MCS remains
likely later this afternoon as a front surges southward over
central Oklahoma.  The flash flood risk will increase over time.

Discussion...A mature MCS continues along an axis from near
Joplin, MO to near Ada, OK.  The complex has picked up forward
speed over the past hour as expected, although embedded
LEWPs/rotation has enabled occasional spots of 2-2.5 inch/hr rain
rates to develop at times that have exceeded local FFGs.  The
airmass downstream of this MCS remains moist and strongly
unstable, although low-level wind fields are weakening slightly
and should continue to do so through the evening.  This general
regime (with occasional 2+ inch/hr rain rates in spots) should
continue to translate east-northeastward in tandem with the MCS,
resulting in occasional/spotty flash flood potential across
northern Arkansas and southern Missouri through 01Z.

Perhaps a greater flash flood threat may materialize across
southeastern Oklahoma and adjacent areas of western Arkansas with
time.  A remnant outflow over the area (partially reinforced by
lingering convection/updrafts across south-central through
east-central Oklahoma) is likely to interact favorably with a
dryline (just west of I-35) and a surging cold front moving
through central Oklahoma) to reignite convection through the
evening.  The 15Z HRRR seems to have a handle on this scenario,
and suggests that a greater coverage of 2+ inch/hr rain rates
should materialize as storms orient more favorably for training
through the afternoon and early evening.  Pending convective
trends, a small, targeted Moderate Risk area may need to be added
to the ERO should increased flash flood potential materialize.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EAX...FWD...ICT...LSX...LZK...MEG...OUN...PAH...
SGF...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...WGRFC...NWC...

LAT...LON   38709255 38389061 37249013 35979069 35019242 
            33709429 33039660 33139814 33449846 34539789 
            35489699 37279480 38129398 

792 
AWUS01 KWNH 141645
FFGMPD
MOZ000-ARZ000-TXZ000-OKZ000-142043-

Mesoscale Precipitation Discussion 0097
NWS Weather Prediction Center College Park MD
1244 PM EDT Thu Mar 14 2024

Areas affected...central/eastern Oklahoma, far north Texas, and
far western Arkansas

Concerning...Heavy rainfall...Flash flooding possible

Valid 141643Z - 142043Z

Summary...Scattered thunderstorms will continue to expand in
coverage through the afternoon.  Despite relatively dry antecedent
conditions, at least an isolated flash flood risk will exist where
convective training can materialize.

Discussion...Robust convective development has occurred along a
surface dryline extending from near Norman, OK to near Wichita
Falls, TX.  The storms are in a strongly unstable environment,
with steep lapse rates aloft and convergence along the
aforementioned dryline enabling rapid development amid negligible
forcing for ascent aloft.  In their current state, storms are
oriented generally parallel to southwesterly flow aloft and not
propagating off of their current axis.  This suggests at least a
limited opportunity for isolated flash flood potential to unfold
over the next few hours as training boosts rain rates above 1
inch/hr in a few spots.

Eventually, storms will begin to forward propagate due to maturing
cold pools, allowing for a slightly more eastward component of
motion.  Despite this, an abundant pool of instability and
continued convergence along low-level boundaries should allow for
some degree of continued redevelopment (and perhaps backbuilding)
generally along a zone from Ardmore to Talequah despite modestly
rising geopotential heights.  A mix of cells and linear segments
is expected.  The flash flood risk is expected to gradually
increase through the afternoon, although it is likely that rates
above 2 inches/hr will be needed to overcome the dry antecedent
conditions noted across the discussion area.  Slightly lower FFGs
are noted with northeastward extent (north of I-40), suggesting
slightly more susceptibility to runoff in that area as storms
approach after 18Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...LZK...OUN...SGF...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   36729475 36249357 35039383 33719494 33179830 
            33339887 33939870 35329772 36579629 

397 
AWUS01 KWNH 140606
FFGMPD
ILZ000-MOZ000-IAZ000-KSZ000-141204-

Mesoscale Precipitation Discussion 0096
NWS Weather Prediction Center College Park MD
205 AM EDT Thu Mar 14 2024

Areas affected...northern MO...southeastern IA...north-central IL

Concerning...Heavy rainfall...Flash flooding possible

Valid 140604Z - 141204Z

Summary...Additional localized totals of 2-3" may lead to isolated
instances of flash flooding.

Discussion...Intense thunderstorms are becoming more organized
across portions of the Middle MS Valley overnight, as indicated by
continued cold cloud tops via GOES-East infrared imagery. Despite
somewhat modest elevated instability (MU CAPE generally 250-1000
J/kg), convection has thrived in the vicinity of an 850 mb warm
front with significant deep layer shear (40-55 kts) in the
idealized right-exit region of a 110 kt jet streak over the
Southern Plains (promoting large scale lift via upper-level
divergence and diffluence). While total available tropospheric
moisture is somewhat low compared compared to late spring/early
summer, PWATs of 0.8-1.1 inches are between the 90th percentile
and max moving average for this time of year (per SPC sounding
climatology). Supercells in this environment have managed to
produce rainfall rates exceeding 2"/hr at times, as bunkers right
storm motion vectors support a east-northeast motion as slow as 25
kts (allowing for localized training along the paralleling
elevated warm front). This has resulted in isolated totals of
2.0-3.5 inches around Topeka and Kansas City northeastward to
Burlington.

While these localized higher rainfall rates and totals have
remained fairly isolated, continued intense convection may allow
for a few more hours of rainfall rates of 1-2"/hr in the vicinity
of already saturated areas across portions of northern MO and
southeastern IA. Isolated instances of flash flooding are possible
in this region with continued heavy rainfall, and would perhaps be
most likely in the vicinity of the MO/IA/IL border region and
eastward into north-central IL (downstream of the strongest
convection at the time of writing). Given the latest hi-res
guidance, additional localized totals of 2-3" are possible, ending
across western portions of the area by 12z.

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...DMX...DVN...EAX...ILX...LOT...LSX...

ATTN...RFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON   41839060 41698788 40898764 40028899 39089179 
            39319445 39959527 41099365 

729 
AWUS01 KWNH 132327
FFGMPD
MOZ000-IAZ000-KSZ000-NEZ000-140525-

Mesoscale Precipitation Discussion 0095
NWS Weather Prediction Center College Park MD
727 PM EDT Wed Mar 13 2024

Areas affected...northeastern KS into northern MO and adjacent MO
Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 132325Z - 140525Z

Summary...Thunderstorm coverage and flash flood potential are
expected to increase overnight across portions of the middle MO
River Valley. Repeating and training of cells with rainfall rates
of 1-2 in/hr will be possible. There is some uncertainty with
timing, but the flash flood threat is expected to be greatest
after 03Z.

Discussion...23Z surface observations and fading visible satellite
imagery placed a surface low near DDC with a warm front extending
eastward into MO, roughly 50 miles south of I-70. A bulged dryline
was analyzed across south-central KS into central OK with early
stages of convective initiation over eastern KS. 23Z SPC
mesoanalysis data showed MLCAPE of 1000 to 2000+ J/kg south of the
warm front in KS and MO, with weak to near-zero CIN, along with
PWATs ranging from 0.7 to 1.1 inches. Meanwhile, water vapor
imagery showed a mid-level shortwave over western KS, tracking
toward the northeast with an upper level jet max over the southern
High Plains, with RAP analysis estimates of 100-110 kt, on the
south side of a western trough axis.

Over the next 6 hours, as the shortwave over western KS and the
larger scale trough over the West continues to advance downstream,
upper level divergence and diffluence should increase across the
MO Valley within the left exit region of the upper level jet max.
In the lower levels, 850 mb wind speeds are forecast by the RAP to
increase into the 40-50 kt range by 03-06Z over eastern KS,
overrunning the warm front, leading to elevated convection along
the NE/KS border, eastward into northern MO and northward toward
the IA/MO border. Increased forcing in the lower and upper levels
should lead to an expansion of organized thunderstorms through 03Z
and while PWATs are modest within the pre-convective environment,
sufficient shear is in place for organized, rotating storms which
should help to boost precipitation efficiency. Bunkers-right
supercell motions and upshear Corfidi vectors are generally west
to east, or parallel to the slow moving warm front. Possible
congealing of storms would have both a northeastward and eastward
component to them, while additional upstream development may
support repeating and training from the instability pool south of
the warm front. 1-2 in/hr rates and 2+ inch totals in 2 to 3 hours
time through 05Z may support localized flash flooding across the
region, despite very dry antecedent conditions with area FFG
values showing 1.5 to 2.5 inches in 3 hours.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...DMX...EAX...GID...ICT...LSX...OAX...TOP...

ATTN...RFC...ABRFC...MBRFC...NCRFC...NWC...

LAT...LON   40889462 40049206 39119202 38939306 38919484 
            38869648 39029791 39689813 40159728 40699636 
            

779 
AWUS01 KWNH 130307
FFGMPD
MOZ000-130745-

Mesoscale Precipitation Discussion 0094
NWS Weather Prediction Center College Park MD
1107 PM EDT Tue Mar 12 2024

Areas affected...Central Missouri...

Concerning...Heavy rainfall...Flash flooding possible

Valid 130305Z - 130745Z

SUMMARY...Slow moving, possibly rotating elevated convection
overcoming dry atmospheric conditions for moderate rainfall and
hail production.  Short-term training crossing dormant soils and
therefore nearing 1-3hr FFG values suggesting isolated low-end
flash flooding conditions may be possible over the next few hours.

DISCUSSION...A compact, but well defined mid-level shortwave can
be seen in GOES-E WV suite this evening across MO. EIR 10.3um also
denotes a cluster of thunderstorms continuing to expand with small
overshooting tops continuing to percolate along the
southwest/upwind edge of the complex.   This wave remains well
defined through the mid, lower levels including at the surface
where a 1004 low sits within the the KC Metro with an slowly
advancing cold front angling SSW through the Flint Hills and a
stationary front extending through NW to north-central MO toward
SE IA.  VWP and RAP analysis suggest the the LLJ along/ahead of
the cold front has been accelerating up to 40-45kts across SW MO
before slowing/becoming convergent and isentropically ascending
along and east of the deeper cyclone in proximity to I-70. 

While surface Tds are modest in the low to mid 50s, the LLJ does
have some increased moisture through depth, but still remains even
seasonably average at best with total PWATs reaching 1".  Though
modest 30-35 kts of Effective Bulk Shear along this elevated
925-850 effective warm front/WAA axis has resulted in a few
updrafts picking up weak updraft rotation.  This further increases
isallobaric moisture flux, while concurrently reducing forward
propagation speeds.  Bunkers' right moving supercell vectors
suggest 15-20kts of east to east-southeast motions generally along
the effective warm frontal axis.  As such, this allows for cells
that have already observed 1-1.5"/hr rates and 2" totals per local
observations in proximity to I-70.  Mid-level drying and
evaporative cooling should allow for cold pool generation as well
as hail generation (which is likely contaminating MRMS
rain-rates/FLASH response); however, observational trends in KEAX
and further upstream backbuilding noted along the upstream edge of
the EIR canopy, suggests at least another round of thunderstorms
and therefore training/repeating and slowed cells motions in
proximity to I-70 over the next few hours is becoming a bit more
likely.  

While soil conditions per AHPS/NASA SPoRT are below average, they
are also dormant suggesting low FFGs of ~1.5/hr or ~2/3hrs may be
in range for one, maybe two isolated incidents of FFG exceedance,
and therefore possible low-end flash flooding conditions over the
next few hours.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EAX...LSX...SGF...

ATTN...RFC...MBRFC...NCRFC...NWC...

LAT...LON   39779335 39559256 39249172 39029139 38679114 
            38249118 37989155 37969209 38179296 38539393 
            39019414 39399433 39729417 

008 
AWUS01 KWNH 091052
FFGMPD
SCZ000-FLZ000-GAZ000-ALZ000-091630-

Mesoscale Precipitation Discussion 0093
NWS Weather Prediction Center College Park MD
551 AM EST Sat Mar 09 2024

Areas affected...Eastern FL Panhandle...Far Southeast
AL...Southern GA...Adj Southern SC...

Concerning...Heavy rainfall...Flash flooding likely

Valid 091100Z - 091630Z

SUMMARY...Continued risk for training thunderstorms and 2-4"
totals resulting in possible flash flooding.

DISCUSSION...GOES-E 10.3um IR loop depicts a mature linear
convective complex across Southern GA with the upstream edge
across the far western portion of the FL Panhandle. In concert
with regional RADAR, VWP and observations suggest another subtle
low level wave is lifting northeast out of the Panhandle along the
slowly sagging WSW to ENE oriented front resulting in another
burst of convective development along the upwind edge.  Ample deep
layer moisture remains attendant to the feature with total PWats
AoA 2" and the nose of central Gulf unstable air to feed the
linear complex with values of 1000 J/kg of MLCAPE from VPS to SW
GA.  Increasing southerly flow across the Atlantic has
lifted/connected the warm frontal feature across southern GA and
nearing the Low country of SC.  Given the favorable forcing a few
more hours of intense thunderstorms with rates of 1.5-2"/hr remain
likely. 

Southward propagation of the line has begun enough to reduced
duration at any given location, but still may result in streaks of
2-4" totals over the next 5-6 hrs with slow reduction in
intensity/coverage as the wave lifts NE through mid-morning but
will drop in latitude further into the drier/sandier soils of the
Coastal Plain. Eventually into early/mid-morning, the LLJ speed
max will shift out of the Gulf into GA/SC and reduce overall deep
layer convergence and slowly fracture the convective line. 
Clusters will likely continue to be highly efficient; however, the
coverage and duration may reduce enough for coverage of potential
areas of excessive rainfall to induce flash flooding. , However,
there is ongoing flash flooding from Walton county FL across SE AL
into south-central GA (Telfair county) where FFG values are
already being exceeded with continued hour or two of heavy
rainfall, so therefore flash flooding is considered likely.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CHS...FFC...JAX...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON   32788100 32158065 31348127 30618326 30238497 
            30378581 30818627 31518545 32248366 32778219 
            

004 
AWUS01 KWNH 090610
FFGMPD
FLZ000-GAZ000-ALZ000-091200-

Mesoscale Precipitation Discussion 0092
NWS Weather Prediction Center College Park MD
109 AM EST Sat Mar 09 2024

Areas affected...Southern AL...Southwest to Central GA...Florida
Panhandle...

Concerning...Heavy rainfall...Flash flooding possible

Valid 090610Z - 091200Z

SUMMARY...A few more hours of potential back-building and training
thunderstorms capable 2"/hr rates and isolated spots of flash
flooding or re-aggravation of ongoing flooded/saturated grounds.

DISCUSSION...06z surface analysis denotes a pair of surface waves
along a relatively stationary frontal zone from central AL back
toward southeast LA.  A very subtle low to mid-level wave is
riding northeastward along this boundary at the lead edge of a mid
to upper level speed max ahead of the positively tilted synoptic
long wave over the mid to lower Mississippi River Valley.  Spurred
by weak divergence aloft, this 925-850 wave is providing a
short-term increase in warm advective response off the high
Theta-E air mass of the central Gulf where Tds remain in the low
70s.  CIRA LPW notes that the sfc-850 layer is highly anomalous
and near 1" total across SE LA into southern AL ahead of this
front.  Combined with confluent 850-700 (.5-.66") and exiting
pocket of 700-500 (.25-.33) values combine to 1.75-2" total PWat
across Mobile Bay.   Modestly unstable MLCAPEs to 1500 J/kg will
provide ample buoyancy for the warm sector for stronger efficient
thunderstorms with rates of 2"/hr likely.

However, the overall flow continues to become increasingly
unidirectional through depth, limiting convergence for convective
initiation.  Surface convergence has been weak enough to spur
occasional cells/weak clusters that train across the warm sector
until reaching the warm front that cross SE AL into the eastern FL
Panhandle.  Afterward, isentropic ascent is strong with 50+kt of
ascent over the cooler/stable air in GA, but providing strong
moisture flux for broad shield precipitation.  While rates
decrease to .5"/hr with some embedded convective elements
occasionally up to 1" randomly scattered through GA...adding to
moderate rainfall that has already fallen over the last few hours.
  As the mid-level wave/upper-level speed max moves through,
height-falls will increase  movement of the cold front from
west-east reaching the western FL panhandle by 12z.  As such,
streaks of 2-4" totals in short 1-2hr durations remain possible
across the warm sector in S AL/FL panhandle with broad 2-3" of
shield precip across areas of GA which may still result in
flooding, but less likely flashy in nature.  In either scenario,
flooding is considered possible though 12z.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   33878368 33728300 33238250 32678235 31998275 
            31608325 31238371 30358496 30208724 30348824 
            30968820 31408750 32008652 32708559 33108518 
            33628438 

632 
AWUS01 KWNH 090030
FFGMPD
FLZ000-GAZ000-ALZ000-MSZ000-LAZ000-090629-

Mesoscale Precipitation Discussion 0091
NWS Weather Prediction Center College Park MD
730 PM EST Fri Mar 08 2024

Areas affected...portions of the northeast Gulf Coast

Concerning...Heavy rainfall...Flash flooding possible

Valid 090029Z - 090629Z

Summary...Heavy rain with embedded thunderstorms continues to
spread eastward along and inland of the northeast Gulf Coast. 
Hourly rain totals to 2.5" with local amounts to 5" could lead to
widely scattered flash flooding.

Discussion...Warm air advection east of a wave of low pressure
entering southernmost MS has lead to a broad area of heavy
rainfall, with showers and thunderstorms along its southern
periphery.  This is occurring north of the polar warm front (the
southern edge of the dew point gradient) and not far from a
strengthening outflow boundary/coastal front-like feature forming
inland across the Southeast, which has greater temperature
gradient.  This is occurring south of an upper level low entering
northwest IL and ahead of a southern stream shortwave moving east
into the northwest Gulf Coast, so the atmosphere is quite
diffluent/divergent aloft.  GPS data indicate precipitable water
values as high as 2.1" across southeast LA.  ML CAPE of 500-1000
J/kg continues to edge eastward through southernmost MS and AL
into the FL Panhandle.  Convergent 850 hPa inflow of 30-55 kts is
seen in area VAD wind profiles.

A combination of increasing low-level frontogenesis, sufficient
instability, and sufficient effective bulk shear is expected to
lead to heavy rain-related issues for several more hours in this
area through a combination of cell training and embedded
mesocyclones.  The mesoscale guidance continues to err northwest,
proving to be too slow and too poleward, as is their bias.  Hourly
rain totals to 2.5" with local amounts to 5" are possible past
midnight CST/1 a.m. EST.  Much of this area has been relatively
dry over the past week -- any flash flooding issues would be more
likely in urban areas, so think the issues should be widely
scattered at best.  This led to the use of the flash flooding
possible category.

Roth

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...JAN...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   32968394 31848361 30678496 30298619 30058946 
            30468994 31238922 32958533 

104 
AWUS01 KWNH 082224
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-090422-

Mesoscale Precipitation Discussion 0090
NWS Weather Prediction Center College Park MD
523 PM EST Fri Mar 08 2024

Areas affected...southern Mississippi, southern Alabama,
southeastern Louisiana

Concerning...Heavy rainfall...Flash flooding likely

Valid 082222Z - 090422Z

Summary...Flash flood potential continues as an MCS develops
southeastward across the discussion area through 04Z.

Discussion...The combination of earlier convection and light 850mb
northerly flow (per RAP analyses and high-res model guidance) has
allowed for an extensive front/outflow boundary to shift southward
across central Mississippi and portions of southwestern Alabama
and is generally located from west of Montgomery, AL to near
Hattiesburg and McComb, MS.  Earlier, convection focused along
this boundary resulted in widespread 3-5 inch rainfall totals
along the I-20 corridor in Mississippi along with several reports
of excessive runoff and flooding.  Recent radar and objective
analyses indicate general storm motions that have allowed for
training (and 1.5-2 inch/hr rain rates) in southern Mississippi
over the past hour, although the southward movement of the
front/outflow and west-southwesterly flow aloft has undercut
deeper convection especially in southern Mississippi.  This
scenario has tempered the longevity of rainfall rates at times,
although areas of 2 inch/hr rain rates continue to persist for at
least an hour near the outflow where cells can remain at or close
to surface based while maturing and becoming persistent.

The ongoing scenario for flash flooding is expected to continue
through 04Z, although a slow south and southeastward translation
is expected to continue.  This should enable training and areas of
~2 inch/hr rain rates to develop especially from southeastern
Louisiana into southern Alabama through the evening along and
ahead of the outflow boundary.  While FFGs increase into the 3
inch/hr range with southward extent, at least local impacts are
expected where heavier rainfall and/or training can impact
low-lying or urbanized areas.  Additional rainfall totals are
expected to reach 2-3.5 inches especially where training is most
pronounced.  Lastly, destabilization is expected across southern
Alabama through the evening which should continue to support areas
of deep convection and training.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...LCH...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   32538668 32008615 30898637 30378726 30048884 
            29528978 29419072 30399161 31069107 31729037 
            32078953 32478734 

731 
AWUS01 KWNH 081658
FFGMPD
ALZ000-MSZ000-LAZ000-082257-

Mesoscale Precipitation Discussion 0089
NWS Weather Prediction Center College Park MD
1157 AM EST Fri Mar 08 2024

Areas affected...central Louisiana, central/southern Mississippi,
and central/southern Alabama

Concerning...Heavy rainfall...Flash flooding likely

Valid 081657Z - 082257Z

Summary...An elongated MCS was becoming more favorably oriented
for training and flash flooding.  A few areas could experience 3-5
inch rainfall totals within this MCS through 23Z.

Discussion...In the wake of a lead bow/MCS now entering portions
of central AL (near TCL), an elongated axis of convection has
emerged from near MEI to JAN to ESF.  Additional convection was
located along a cold front from near SHV to LFK that was moving
eastward toward the ongoing axis of heavy rainfall.  In the past
30-60 minutes, areas of 1-2 inch/hr rain rates have developed
especially near and southwest of JAN.  This was occurring in
response to a couple of factors: 1) a slowly southward-moving
outflow boundary across central Mississippi, 2) fast
west-southwesterly steering flow aloft oriented parallel to
ongoing convection, and 3) very moist, unstable conditions (1000
J/kg SBCAPE, 1.8 inch PW values) that were feeding the updrafts
and contributing to efficient rainfall processes.

Through 23Z, expectations are that heavier rainfall axes will
focus along the outflow boundary, which should remain stationary
or move very slowly southward this afternoon especially across
Mississippi.  Training and cell mergers along this boundary should
allow for areas of 2 inch/hr rainfall totals to continue to
materialize, and storm totals as high as 5 inches could occur
through 23Z.  The magnitude of the rainfall should exceed FFG
thresholds and cause scattered areas of flash flooding to develop
(locally significant).  This threat may eventually spread into
southwestern Alabama after 20Z.

Farther upstream across Louisiana, training convection remains
likely along the nearly stationary boundary extending from north
of AQV to north of HEZ, although FFGs are slightly higher in these
locales compared to farther east.  Still, a few instances of flash
flooding are possible especially in low-lying areas and beneath
training cells.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...LCH...LIX...MOB...SHV...

ATTN...RFC...LMRFC...SERFC...WGRFC...NWC...

LAT...LON   33228686 32478608 31428622 30748870 30619182 
            31559339 32019282 32609136 33188857 

390 
AWUS01 KWNH 081055
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-TXZ000-081645-

Mesoscale Precipitation Discussion 0088
NWS Weather Prediction Center College Park MD
554 AM EST Fri Mar 08 2024

Areas affected...Central LA through Central MS...

Concerning...Heavy rainfall...Flash flooding possible

Valid 081055Z - 081645Z

SUMMARY...Veering upstream wind profile within broad warm
advection pattern should favor back-building development with
potential for training thunderstorms through early morning period.
 Streaks of 2-4" totals and incidents of flash flooding are
considered possible

DISCUSSION...CIRA Sfc-850mb LPW analysis depicts a broad
triangular wedge of enhanced moisture across the northwestern Gulf
angled across southeast TX and western/central LA.  VWP and RAP
analysis shows increasingly confluent/veering LLJ nosing across
northeast LA into west-central MS at this time, providing solid
40-45kts of WAA isentropic ascent across a flat frontal zone
across N LA into northeast MS at this time.  Slow increase in
higher theta-E air (and Tds into the 70s) will continue to
encroach northeastward with broad ascent along and southeast of
approaching/amplifying mid-level shortwave out of central TX.  
Analysis also suggest weakening capping across this higher Theta-E
air where MLCAPE are ticking up over 1000 J/kg across southeast
TX.

GPS total PWat values have risen to 1.7" across this area and with
strong WAA/ascent and proximity to modest instability, increasing
convective activity will continue to expand at the nose of the LLJ
over the next few hours, slowly back-building into the richer/more
unstable air after 12z.  Rates of 1.5"/hr should build to 1.75",
though cell motions of 30kts or greater should limit any one
particular cell resulting in significant totals.   However, with
the approach of the wave, low level confluence will start to
become more unidirectional through a greater depth and favor some
upstream redevelopment/convergence.  This should allow for
potential for training thunderstorms from the 12-18z time period
across central LA into central MS.

There still remain some modest uncertainty in the latitude of
convective initiation upstream, be it closer to the slowly sagging
frontal zone across E TX/NW LA or on the initial outflow
boundaries from ongoing/early developing convection across LA into
MS.  Still, the potential for a streak or two of 2-4" totals may
result in a a few incidents of localized flash flooding. 
Potential is ever so slightly higher across Carroll parish, LA to
Holmes to Lowndes county, MS where upper soil conditions are that
ever so slightly more saturated due to prior heavy rainfall over
the 7 days per AHPS and NASA SPoRT LIS products.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...SERFC...WGRFC...NWC...

LAT...LON   33698951 33438859 32598837 31998885 31528993 
            31279084 30809322 31039420 31889377 32859176 
            33249101 33599036 

174 
AWUS01 KWNH 080805
FFGMPD
TXZ000-081130-

Mesoscale Precipitation Discussion 0087
NWS Weather Prediction Center College Park MD
304 AM EST Fri Mar 08 2024

Areas affected...Southern Edwards Plateau into Western Hill
Country of Central Texas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 080805Z - 081130Z

SUMMARY...Very short window for initially stationary thunderstorms
to produce 2-3" totals in 1-2 hours before generating cold pools
for sufficient cell motions to reduce rainfall totals and
therefore flash flooding risk

DISCUSSION...Solid 15-20kt surface to boundary layer return flow
up the Rio Grande Valley intersects the dry line in proximity to
6R6 and OZA in the lower Pecos Valley.  Low to mid 60s Tds and
modestly mixed mid-level profiles support a pocket of enhanced
instability with SBCAPEs of 2000-2500 J/kg.  GOES-E and Regional
RADARs depict a solid line of development at the tail end of the
mid-level forcing/trof axis and surface dry-line - convergence
axis.  Given mid 60s Tds and CIRA LPW denoting localized PW
maxima/tight gradient through the 3 lower layers (sfc-850;
850-700; and 700-500), solid moisture loading to the profiles
should allow for solid rainfall production along with some loss to
hail.  03z HRRR 15-min rainfall totals suggest .5-.75" totals
given both updraft stregth and flux into the column.

Additionally,  the strong sfc to boundary layer moisture
convergence is aligned favorably low level to mid-level
orientation to the deep layer flow (generally parallel) supports a
line of thunderstorms that will have a short-term period of
training.  As such a few hours of very intense rainfall rates
(1.5-2"/hr) may result in a few localized spots of 2-3" totals,
potentially exceeding 1-3hr FFG values in the area.  However,
mid-level dry air will mix and aid in cold pool development in
about an additional hour or two to finally promote forward
(eastward propagation) of the delevloping line.  Still, given the
intensity of the cores and potential for training, a spot or two
of flash flooding is considered possible over the next 2-3 hours.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EWX...SJT...

ATTN...RFC...WGRFC...NWC...

LAT...LON   31109933 30949847 30579837 30199862 29879946 
            29710030 29690102 29820145 30250170 30770107 
            

061 
AWUS01 KWNH 080641
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-081245-

Mesoscale Precipitation Discussion 0086
NWS Weather Prediction Center College Park MD
140 AM EST Fri Mar 08 2024

Areas affected...Northeast TX....Northern LA...Southern
AR...Central Western MS...

Concerning...Heavy rainfall...Flash flooding possible

Valid 080645Z - 081245Z

SUMMARY...Increasing breadth of isentropic ascent across the area
of concern within fairly unidirectional cell motions suggest
prolonged duration of moderate to occasionally heavy elevated
thunderstorms capable of 1-1.5"/hr rates and possible localized
2-3.5" totals and isolated possible incidents of flash flooding.

DISCUSSION...06z surface analysis denotes a weak boundary defined
mainly as a convergence axis extending from NW AL across central
MS, northern LA into northeast TX.  Here, the boundary is
reinforced by strengthening low level ridging behind older outflow
boundary from dying convective clusters/linear that crossed
northern Texas and S Oklahoma.  GOES-E and RAP analysis suggest
the catalyst for the earlier convection continues across
along/north of the Red River as a weak inflection/shortwave along
the 500-300 mb jet streak.  Weak diffluence and DPVA has increased
LLJ off the northwest Gulf of Mexico with southeasterly return
flow across E TX/W LA.  Surface obs and Sfc-850mb CIRA LPW denote
the eastern edge of enhanced moisture through the Sabine River
Valley generally intersecting across northeast TX.  CIRA LPW in
the 850-700 layer also notes an enhanced slug of moisture along
solid veering through the layer intersecting across the area of
best DPVA/vertical ascent in proximity to the surface boundary.

As such a recent uptick in convective activity has started to
occur in across NE TX into northern LA and far southern AR,
ascending to elevated LFC.  VWP in the region has been steadily
increasing to over 40 to 45kts through the layer further
supporting moisture flux for efficient rainfall production. Lapse
rate and profiles are very weak and so instability has been
limited for updraft vigor, but the sheer magnitude of convergence
will likely continue given the strength of the LLJ and convergence
along the veering profile.  Currently, this is supporting .75"/hr
rates that will steadily increase to over 1-1.5"/hr.  Combine this
with the length of the ascent across the boundary and
unidirectional flow for steering generally parallel to the
boundary should support training profiles through the early
morning.  As such, spots of 2-3.5" totals can be expected.  While
the area has remained dry recently (with 14-day anomalies less
than 25% of normal; with exception of far NE LA into central
Western MS); NASA SPoRT LIS suggests relative soil moisture values
are near 50% and at or just above normal (70th percentile)
suggesting perhaps an isolated incident or two of flash flooding
will be possible through early morning.

Later in the time period (10-12z), there is some model
uncertainty...but appears to becoming into focus that enhanced
theta-E air will emerge from the western Gulf and reach the
boundary toward this time period increasing overall moisture depth
to 1.5-1.7 still within a highly confluent 850mb isentropic ascent
channel across northeast LA into west-central MS increasing
rainfall efficiency from 1.5" to 2"/hr. 

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LZK...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   33449141 33249053 32689004 32079031 31909164 
            31899251 31839495 32529539 32979493 33269389 
            33399256 

641 
AWUS01 KWNH 080054
FFGMPD
CAZ000-080652-

Mesoscale Precipitation Discussion 0085
NWS Weather Prediction Center College Park MD
753 PM EST Thu Mar 07 2024

Areas affected...Southern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 080052Z - 080652Z

Summary...Slow moving convective showers will continue to pose a
flash flood risk into the evening hours. Rain rates approaching
1"/hr and isolated 1-2" totals through 06Z may lead to instances
of flash flooding, particularly for the more sensitive locations.

Discussion...A weak mid-level shortwave trough, noted in the
latest water vapor imagery and 500 mb heights, is slowly moving
southeastward along the southern California coast. A favorable
environment for convective showers has developed, where the
combination of colder heights aloft and a bubble of 500 J/kg of
SBCAPE has led to convective low-topped showers and thunderstorms.
Current radar estimates put hourly rain rates above 1"/hr as they
slowly drift into the Los Angeles metro.

The latest hi-res guidance supports this activity continuing for
the next several hours as it drifts south/southeast and may impact
portions of the Los Angeles metro. Rain rates up to 1"/hr will be
possible and isolated totals through late this evening could
approach 1.5-2" based on the latest HREF and HRRR runs.

While isolated in nature, given the sensitivity in the terrain
areas and urban locations, some flash flooding will continue to be
possible until instability diminishes and the convective cores
lose their intensity later this evening.

Taylor

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34561859 34441799 34211744 33951715 33601714 
            33371734 33261767 33601825 33891902 34361899 
            

225 
AWUS01 KWNH 072129
FFGMPD
TXZ000-080328-

Mesoscale Precipitation Discussion 0084
NWS Weather Prediction Center College Park MD
428 PM EST Thu Mar 07 2024

Areas affected...portions of west-central into north Texas

Concerning...Heavy rainfall...Flash flooding likely

Valid 072128Z - 080328Z

Summary...Flash flood potential will continue across the region
through at least 03Z tonight.

Discussion...A loosely organized MCS continues along a general
axis from near ABI east-northeastward to near DFW currently.  This
MCS has resulted in development of an outflow boundary along that
same general axis, with a maturing cold pool located just north of
that boundary.  This boundary was located perpendicular to 20-40
kt southerly 850mb flow (strongest along the I-35 corridor in
northern and central Texas), and may provide a continued focus for
redevelopment of cells generally along I-20 and vicinity through
03Z.

Additionally, deep convection was increasing in intensity and
coverage along and just ahead of a dryline extending from near
Midland to near Childress.  Evolution of this convection is a bit
uncertain, although the general consensus from models and
observations is that these storms should grow into a small cluster
and/or MCS that migrates eastward and further interacts with the
ABI/DFW outflow boundary.  The end result of this evolving
convective pattern is a relatively focused corridor of higher
rainfall totals (supported by repeating cells and mergers) that
could boost rainfall totals into the 2.5-3.5 inch range (along
with hourly totals exceeding FFG/2 inch/hr) in spots through 03Z. 
The greatest likelihood of this axis developing will continue to
reside in the general vicinity of ABI to DFW.  Flash flood
potential will increase over time if the aforementioned scenario
plays out as anticipated.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...LUB...MAF...OUN...SHV...SJT...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   33699808 33639537 33019443 32289447 31819591 
            31609692 31339891 31410057 32200114 33550023 
            

171 
AWUS01 KWNH 071901
FFGMPD
TXZ000-072141-

Mesoscale Precipitation Discussion 0083
NWS Weather Prediction Center College Park MD
200 PM EST Thu Mar 07 2024

Areas affected...west-central into north-central Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 071841Z - 072141Z

Summary...A band of convection has emerged along a general axis
from roughly 35 mi WSW of Abilene to near Mineral Wells.  The
orientation of the band suggests that at least a spotty/isolated
flash flood threat should materialize through 22Z depending on
persistence of storms.

Discussion...A band of storms have recently formed across the
discussion area generally along and just north of the I-20
corridor in west Texas near ABI.  The storms are oriented
generally parallel to west-southwesterly steering flow aloft
(supporting localized training) and are also located on the
northwestern extent of better low-level moisture/instability axes
moving into the region (on low-level southerly flow).  Steeper
mid-level lapse rates to the west of the region (per SPC
Mesoanalyses) were also contributing to a gradual (and likely
elevated) destabilization across the area.  Given the robust
updrafts parallel to flow aloft, areas of 1+ inch/hr rain rates
were already beginning to show beneath the stronger cores
(estimated per MRMS), and pending convective trends, these rates
may continue or locally increase, approaching FFG thresholds (~2
inch/hr) in spots.

While longevity of the convective band is a bit in question due to
modest/weak forcing for ascent aloft, at least an isolated flash
flood risk is evident based on the recent intensification of
storms (per radar/satellite) and potential for training.  Models
(particularly the Nam 3km) support potential for persistence of
this convective band over the next 2-4 hours.  Also, maturity of
storms and subsequent cold-pool formation may also enhance the
longevity of the storms and associated flash flood risk.  The
evolution of the convection will be monitored for any possible
increase in flash flood potential, and may need to be re-addressed
per convective trends before 22Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...LUB...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON   33659708 33169609 32539596 31929625 31429696 
            31139798 31349926 31810020 32250032 32970005 
            33529889 

847 
AWUS01 KWNH 071842
FFGMPD
TXZ000-072141-

Mesoscale Precipitation Discussion 0083
NWS Weather Prediction Center College Park MD
142 PM EST Thu Mar 07 2024

Areas affected...west-central into north-central Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 071841Z - 072141Z

Summary...A band of convection has emerged along a general axis
from roughly 35 mi WSW of Abilene to near Mineral Wells.  The
orientation of the band suggests that at least a spotty/isolated
flash flood threat should materialize through 22Z depending on
persistence of storms.

Discussion...A band of storms have recently formed across the
discussion area generally along and just north of the I-20
corridor in west Texas near ABI.  The storms are oriented
generally parallel to west-southwesterly steering flow aloft
(supporting localized training) and are also located on the
northwestern extent of better low-level moisture/instability axes
moving into the region (on low-level southwesterly flow).  Steeper
mid-level lapse rates to the west of the region (per SPC
Mesoanalyses) were also contributing to a gradual (and likely
elevated) destabilization across the area.  Given the robust
updrafts parallel to flow aloft, areas of 1+ inch/hr rain rates
were already beginning to show beneath the stronger cores
(estimated per MRMS), and pending convective trends, these rates
may continue or locally increase, approaching FFG thresholds (~2
inch/hr) in spots.

While longevity of the convective band is a bit in question due to
modest/weak forcing for ascent aloft, at least an isolated flash
flood risk is evident based on the recent intensification of
storms (per radar/satellite) and potential for training.  Models
(particularly the Nam 3km) support potential for persistence of
this convective band over the next 2-4 hours.  Also, maturity of
storms and subsequent cold-pool formation may also enhance the
longevity of the storms and associated flash flood risk.  The
evolution of the convection will be monitored for any possible
increase in flash flood potential, and may need to be re-addressed
per convective trends before 22Z.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FWD...LUB...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON   33659708 33169609 32539596 31929625 31429696 
            31139798 31349926 31810020 32250032 32970005 
            33529889 

902 
AWUS01 KWNH 070116
FFGMPD
MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-070715-

Mesoscale Precipitation Discussion 0082
NWS Weather Prediction Center College Park MD
816 PM EST Wed Mar 06 2024

Areas affected...Southern New England

Concerning...Heavy rainfall...Flash flooding possible

Valid 070115Z - 070715Z

Summary...Widespread moderate to locally heavy rainfall through
tonight may produce instances of flash flooding across portions of
southern New York and southern New England. Rainfall totals of
2-3" are expected. 

Discussion...Low pressure organizing over eastern North Carolina
this evening will lift north/northeast toward southern New England
tonight, interacting with a stationary boundary currently draped
offshore New Jersey to Long Island. As it does so, a strengthening
low level jet will begin to push much higher moisture into the
region, aided by 850 mb winds exceeding 40-50 kts after 04Z. This
will result in PWs climbing to well above 1", locally 1.25-1.5"
across far southern New England. With a corridor of enhanced low
level convergence downstream of the approaching low and broad
large scale forcing for ascent provided by the height falls and
approaching mid-level shortwave, the setup will become
increasingly favorable for heavy rainfall through tonight.

The latest guidance is in good agreement for a widespread area of
moderate/heavy rainfall across far southern New York through
southern New England including much of Connecticut, Rhode Island,
western to east-central Massachusetts, and portions of southern
Vermont and New Hampshire. The latest HREF neighborhood
probabilities are high (>70 percent) for at least 2 inches in the
outlook area with a slight signal (10-20 percent) for 3 inch
amounts. Hourly rain totals are likely to top out between
0.5-0.75", limited by the lack of deep instability expected.
However, the longer duration of the rainfall event should overcome
the relative lack of intensity in rain rates to produce flooding.

Much of the area has seen above normal precipitation over the last
several days with ground conditions remaining quite wet. As a
result, this additional rainfall overnight may result in
additional flooding and flash flooding, particularly for southern
New England.

Taylor

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ALY...BOX...GYX...OKX...

ATTN...RFC...NERFC...NWC...

LAT...LON   42717217 42647142 42197106 41877092 41307116 
            40977167 40797210 40677298 41367374 42427314 
            

393 
AWUS01 KWNH 062206
FFGMPD
CAZ000-070405-

Mesoscale Precipitation Discussion 0081
NWS Weather Prediction Center College Park MD
505 PM EST Wed Mar 06 2024

Areas affected...Coastal Ranges of Central and Southern CA

Concerning...Heavy rainfall...Flash flooding possible

Valid 062205Z - 070405Z

SUMMARY...A localized threat of runoff problems and flash flooding
will exist through this evening across portions of the coastal
ranges and interior foothills of central and southern CA from
areas of heavy showers.

DISCUSSION...The latest GOES-W satellite imagery shows a rather
vigorous mid-level shortwave trough and compact area of low
pressure offshore of the coastal ranges of central and southern CA
advancing gradually off to the east. This energy coupled with the
diurnal heating cycle has been fostering the development and
expansion of heavy shower activity over the last couple of hours
for areas south of the Bay Area, and especially for areas south of
Monterey down toward San Luis Obispo and Santa Barbara counties.

Steepening mid-level lapse rates coupled with DPVA/forcing aloft
and low-level convergence out ahead of the approaching low center
and associated front should maintain concerns heading through the
late afternoon and early evening hours for locally heavy showers
and even a few thunderstorms. MUCAPE values along the coast have
risen to as high as 500 J/kg, and this in conjunction with
somewhat favorable moisture convergence aligning itself down near
the Transverse Range ahead of the surface low should help yield
locally heavy rainfall rates that will also have some assistance
with orographic ascent over the terrain.

The 12Z/18Z HREF guidance shows rather good agreement in seeing
some banded convective showers advancing inland over the
Transverse Range, and perhaps reaching the Peninsular Range by
late this evening. Furthermore, the HREF guidance does show rather
high probabilities (50% to 70%) of seeing rainfall rates exceed a
0.50"/hour over the upslope areas of the higher terrain, and
already some of the more discrete convective showers farther north
in Monterey County have been producing 1 inch totals in less than
30 minutes.

Given the current radar and satellite trends, there should be a
further increase in coverage of convective showers over the next
few hours with heavy rainfall rates. Expect some localized
rainfall totals of 1.5 to 2.5 inches to be possible by late this
evening where any of the more organized/focused bands of
convection set up. This should favor at least some localized
runoff concerns with an isolated threat for flash flooding, and
the potential for spotty debris flow/mudslide activity.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...MTR...SGX...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   37402221 37292130 36692091 35682018 34881935 
            34791879 34401806 33821743 33421716 32861690 
            32591719 32731747 33361798 33801873 34161953 
            34372042 34792081 35212092 35522130 36012172 
            36402202 36732204 37052232 

395 
AWUS01 KWNH 060842
FFGMPD
VAZ000-NCZ000-061440-

Mesoscale Precipitation Discussion 0080
NWS Weather Prediction Center College Park MD
341 AM EST Wed Mar 06 2024

Areas affected...far eastern NC into far southeastern VA

Concerning...Heavy rainfall...Flash flooding possible

Valid 060840Z - 061440Z

SUMMARY...Training of heavy rain is expected to impact far eastern
NC, including the Outer Banks, through 15Z. Flash flooding will be
possible within an axis of 3-6 inches of rain, which may fall over
a narrow stripe of land.

DISCUSSION...08Z regional radar imagery and infrared satellite
showed ongoing showers over eastern NC and offshore of the
southern NC coast. Recent cloud top cooling was noted roughly 50
miles east of Cape Fear, with occasional flashes via GOES East GLM
imagery over the past 1-2 hours. The recent uptick in convection
was located over the Gulf Stream and on the warm side of a slow
moving warm front which paralleled the coast of the Carolinas at
08Z, out ahead of an approaching low to mid-level low/trough
located over AL/GA. Estimated MLCAPE just offshore of the Outer
Banks and southeastern NC coast was 500 to 1000 J/kg via the 08Z
SPC mesoanalysis. Loops of Blended TPW showed 1 to 1.5 inch PWATs
advecting toward the coast as the warm front slowly approaches
land.

Increased forcing for ascent will continue to overspread the
central and southern Mid-Atlantic coast as the mid-level trough
advances east this morning, supporting the continued development
of showers and thunderstorms offshore of the Carolinas.
Unidirectional southerly flow seen in RAP forecast soundings and a
gradually strengthening 850 mb wind field will allow for training
of heavy rain, beneath modest diffluence aloft. The environment
will be capable of hourly rainfall of 1-2 inches, but locally
higher values cannot be ruled out within pockets of higher
instability. The forecast slow movement of the warm front, perhaps
stalling over eastern NC, will allow for repeating and training of
heavy rain from near Cape Lookout to the northern Outer Banks,
including locations on either side of Pamlico and Albemarle Sound
and perhaps as far north as southeastern VA. Recent heavy rainfall
over this region since Friday has increased susceptibility to
rapid rises of water with the potential for an additional 3-6
inches of rain by 15Z. Locally heavy rain may support flash
flooding, with the greatest risk occurring within urbanized/more
impervious locations, but the coverage of any higher end rainfall
amounts is expected to be limited in coverage.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...AKQ...MHX...

ATTN...RFC...MARFC...SERFC...NWC...

LAT...LON   36857590 36427523 35847513 35117535 34877597 
            34347685 34467706 35587677 36537652 

776 
AWUS01 KWNH 060706
FFGMPD
SCZ000-GAZ000-061215-

Mesoscale Precipitation Discussion 0079
NWS Weather Prediction Center College Park MD
206 AM EST Wed Mar 06 2024

Areas affected...north-central GA into western SC

Concerning...Heavy rainfall...Flash flooding possible

Valid 060703Z - 061215Z

SUMMARY...Isolated flash flooding will be possible across
north-central GA into western SC through 12Z from slow moving
areas of moderate to heavy rain. Hourly rainfall of 0.5 to 1.0
inches and totals of 2-3 inches may support excess runoff within
low lying and poor drainage locations.

DISCUSSION...Regional radar imagery across GA at 0630Z showed a
region of stratiform rain over northeastern GA, with peak observed
hourly rainfall totals of 0.5 to 1.0 inches from downtown Atlanta
to locations just east of the city. KFFC rainfall estimates
appeared too low but MRMS was closer to selected gauge reports
from the Wunderground.com network.

Rainfall was occurring ahead of a negatively tilted upper trough
over AL and southern GA, with diffluent flow downstream and
southeasterly low level winds (centered near 925 mb) near 30 kt
over southern GA into northern FL, converging near a strengthening
925 mb warm front over north-central GA. Convergence was being
enhanced ahead of a remnant low level circulation advancing
northeastward from the south-central AL/GA border as seen on
longer loops of IR imagery.

While PWATs were anomalous for early March (1.25 to 1.50 inches),
MUCAPE was lacking according to the 06Z SPC mesoanalysis with only
about 100 J/kg located along the south side of the moderate to
heavy precipitation shield. However, continued low level moisture
advection from the south coupled with cooling 500 mb temperatures
as the mid-level reflection of the upper trough nears should act
to increase MUCAPE values into the 250 to 500+ J/kg range through
12Z along with heavy rainfall coverage for north-central GA.

The axis of low level forcing is expected to slowly shift east
through 12Z, resulting in a prolonged period of moderate to heavy
rain with hourly totals approaching 1 inch at times. The axis of
heavy rain will translate eastward through 12Z, resulting in
localized 2-3 inch totals from north-central GA into portions of
western SC. These rainfall totals may result in areas of isolated
flash flooding, mainly across locations that are low lying and/or
of poor drainage.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CAE...FFC...GSP...

ATTN...RFC...SERFC...NWC...

LAT...LON   34728313 34488223 33988181 33538271 33288447 
            33688500 34248479 

534 
AWUS01 KWNH 052139
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-060335-

Mesoscale Precipitation Discussion 0078
NWS Weather Prediction Center College Park MD
437 PM EST Tue Mar 05 2024

Areas affected...Portions of the Lower OH Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 052135Z - 060335Z

SUMMARY...Some gradual increase the coverage and intensity of
showers and thunderstorms can be expected going through the late
afternoon and early evening hours. A localized threat for flash
flooding will exist given concerns for at some cell-training.

DISCUSSION...The latest GOES-East satellite imagery in conjunction
with radar shows some uptick in the coverage of shower and
thunderstorm activity over the last couple of hours across
portions of the Lower OH Valley with the rainfall rates tending to
increase as boundary layer instability increases.

While still modest, MLCAPE values near and just north of the OH
River have increased to as much as 500 to 1000 J/kg. Some
additional destabilization is expected over the next 1 to 2 hours
ahead of sunset, and this coupled with a relatively broad area
surface moisture convergence focusing out ahead of a cold front
should tend to favor an additional expansion of convective
activity. However, with a general lack of shear, the organization
of the convection should be limited.

Rainfall rates are expected to increase locally to as high as 1"
to 1.5"/hour with some of the stronger cells heading through the
late afternoon and early evening hours, and with the convection
overall becoming aligned more parallel to the mean steering flow
ahead of the cold front, there will be some concerns for
cell-training which will favor locally excessive rainfall totals.

Some spotty 2 to 4 inch rainfall amounts will be possible and
especially where any southwest to northeast oriented bands of
convection can set up ahead of the cold front. This may result in
some localized areas of flash flooding.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ILN...ILX...IND...LMK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC...

LAT...LON   39598664 39598520 38948491 37928634 36648776 
            36198845 36028903 36288956 36748958 38118874 
            38878800 

991 
AWUS01 KWNH 042153
FFGMPD
MSZ000-LAZ000-050351-

Mesoscale Precipitation Discussion 0077
NWS Weather Prediction Center College Park MD
452 PM EST Mon Mar 04 2024

Areas affected...portions of southeast LA & southwest MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 042151Z - 050351Z

Summary...Showers and thunderstorms are expected to continue to
cause heavy rainfall as a cold pool develops and moves somewhat as
the rain area as a whole shifts east-northeast with time.  Hourly
rain totals to 2.5" with local amounts to 4" could lead to flash
flooding.

Discussion...Heavy rains have fallen across portions of central
LA, with radar estimates of 4"+ west of Simmesport.  Showers and
thunderstorms have been forming within a region of decent 850 hPa
confluence across LA ahead of an upper level shortwave moving into
northwest LA.  Surface observations show a forming cold pool
across areas near the southwest MS/LA border, with upper 60s
temperatures in the cold pool and mid to upper 70s south of the
boundary.  CIN is developing; MU CAPE of 1000-2000 J/kg exists in
this area per SPC mesoanalyses.  Effective bulk shear is near 40
kts, which has supported occasional mesocyclones.  Precipitable
water values of ~1.5" exist here, per GPS data.  The convective
area appears to be forming on the cool side of the 5C isotherm at
700 hPa.

The mesoscale guidance has a strong signal for 3"+ through 04z
over portions of LA and southwest MS, but show a bit of dispersion
on location and on areal extent of the 3"+ area anticipated. 
Recent RAP runs give as suggestion as to the evolution expected. 
The area of 850 hPa confluence shifts east with time, which should
move the heaviest rainfall slowly eastward.  Normally the guidance
can be too poleward with convective activity, which is probably
true with the 12z Canadian Regional guidance.  However, RAP runs
show warming at 700 hPa moving in from the southwest which implies
some northeast shift with time due to a possible mid-level capping
inversion nosing in.  The movement of the 850 hPa confluence zone
eastward implies an east-northeast shift with time.  Since CIN has
already developed, convection is likely to remain elevated and if
it follows the 5C isotherm at 700 hPa northeast, the outflow
boundary/possible section of the polar warm front would follow
suit/retreat somewhat in that direction.  The 18z HREF
probabilities of 3"+ seemed to be a reasonable starting point for
future expectations; generally followed the 15% outline for the
MPD area since the guidance dispersion is likely underplaying the
potential.  Due to mesocyclone formation, short periods of cell
training, and cell mergers, hourly rain totals to 2.5" and
additional local amounts to 4" remain possible, which could lead
to widely scattered flash flooding concerns, particularly across
urban areas.

Roth

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...NWC...

LAT...LON   31749064 31368990 30888946 30468936 29848957 
            29719039 30299142 30749237 31329219 31699132 
            

988 
AWUS01 KWNH 041730
FFGMPD
MSZ000-LAZ000-042330-

Mesoscale Precipitation Discussion 0076
NWS Weather Prediction Center College Park MD
1230 PM EST Mon Mar 04 2024

Areas affected...Much of Louisiana & Adjacent SW Mississippi and E
Texas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 041730Z - 042330Z

SUMMARY...Strong, slow moving rotating cells capable of very
intense rainfall rates (2-2.5"/hr) pose short-term totals possibly
inducing localized flash flooding.

DISCUSSION...Regional RADAR and GOES-E imagery suite depicts broad
area of widely scattered thunderstorms starting to sprout through
low level cloudy conditions across Louisiana.  Solid
warm-advective regime with southeasterly surface veering quickly
to south and south-southwest into the 850-700mb layer is providing
ample theta-E advection in combination with solid low level
moisture flux convergence bisecting LA from SE to NW.  GOES-WV
suite and VWP/RAP analysis denotes solid mid to upper level
divergence/diffluence just west of apex of mid-level ridging over
south-central TX, providing excellent evacuation as well as solid
lapse rates for the upper 60s to lower 70Fs surface moisture
values into any developing updrafts.  CIRA LPW does note that
850-500mb moisture is lagged a bit further south across the
northwestern Gulf of Mexico, but will continue to advect
throughout the afternoon rising from total PWAT values of 1.3"
currently per GPS (1.5" at the coast) eventually toward 1.75" by
evening hours. 

Cell mode will be key toward rainfall efficiency and given bulk
shear values, cell rotation and therefore isallobaric moisture
influx should load the lower portion of the cells for the
potential for efficient rainfall production.  12-15z HRRR
solutions suggest discrete cells with capability  of 1.25-1.5" in
15-30 minutes are possible with the rotating thunderstorms.  Cells
across eastern Texas and northern Louisiana will have slight
faster cell motions and are probably going to be more
scattered/discrete in nature, even with Bunkers right moving
propagation vectors being a bit faster than further south from
I-10 to the Gulf, this may limit some of the overall totals
further north, but isolated 2-3" over a short-duration may still
pose localized flash flooding concerns even though soils have been
dry (as noted by NASA SPoRT LIS 10-40cm soil moisture below 50%,
in the 5-10 percentile for the season).  If hard enough,
infiltration will be difficult and almost hydrophobic given the
high rates. 

Further south, propagation vectors due to rotation may be very
slow, perhaps even support less than 10kt southeasterly
propagation with some near stationary motions anchoring along the
deeper layer moisture convergence/WAA axis in the realm of
possibility between 21-00z. While most of the guidance and
observations suggest these stronger cells are likely to be further
south into the swamps...there are ample areas at or south of I-10
with urban ground conditions that may quickly flood if the cells
stall or even potentially back-build/redevelop upstream along that
moisture convergence axis.  As such, highly focused but higher
totals in excess of 4" are possible with 12z HREF denoting some
spots of 30-50% of 5" exceedance by 06z from BTR to MSY and into
the Chandeleur Islands.  This may occur after the valid time of
this MPD, so will continue to watch trends closely for any
subsequent required updates.

All in all, the discrete nature to the cells requiring stronger
cell rotation to support moisture influx as well as slower cell
motions while also occurring across urban areas leaves the risk of
flash flooding to localized and considered possible given the
lower confidence in precision of cell track/location this
afternoon into evening.  

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   32989272 32919173 32639125 31919074 31329031 
            30888973 30238900 29588884 29028908 29008986 
            29879117 30919304 31799379 32799360 

662 
AWUS01 KWNH 011544
FFGMPD
GAZ000-ALZ000-012030-

Mesoscale Precipitation Discussion 0075
NWS Weather Prediction Center College Park MD
1043 AM EST Fri Mar 01 2024

Areas affected...North-central Alabama...

Concerning...Heavy rainfall...Flash flooding possible

Valid 011545Z - 012030Z

SUMMARY...Narrow band of training thunderstorms with up to 2"/hr
rates and localized totals nearing 4" pose localized flash
flooding over the next few hours before remaining instability
wanes.

DISCUSSION...Regional RADAR loop, along with regional lightning
network denotes a long ~125 mile, but very narrow ~10-15 mile band
of thunderstorms across north-central AL slowly translating
eastward.  While the width has been narrow, the deeper layer
steering flow as remained consistent and unidirectional while
parallel to the forcing axis.  RAP along with RAOBs, observations
suggest that strong FGEN forcing between the 850-700mb layer is
providing a sharp isentropic ascent path for this persistent
vertical ascent, overcoming the limiting instability within the
region.  Weak low level ridging between an exiting 850mb low in
the Cumberland Plateau and approaching wave in east-central MS (at
the edge of core of favorable mid-level DPVA) has supported
accelerated 35-40kts of 850mb flow per BMX VWP nearly orthogonal
to this band before rapidly veering in the 700-500mb layer.  CIRA
LPW shows sfc-850mb moisture values are a tad higher than forecast
with values of 2/3rds increasing to 3/4" to increase rainfall
effectiveness.  As such, moisture flux convergence and weak
vertical instability has resulted in efficient rainfall production
with 1.5"/hr rates increasing to near 2"/hr.

Recent observations from MRMS may be a tad higher, but a few
backyard weather observations show a solid 2-3" band across  from
Lamar/Fayette county toward Etowah county, with a spot or two of
3-4" in northern Jefferson county.  This generally aligns with the
lowest FFG values in the region and as such MRMS FLASH to FFG
ratios have exceeded 200%. Even with an overestimation in MRMS,
these spot 3-4 totals are exceeding and probably resulting in a
few instances of flash flooding across that narrow axis.   As
cells move further east into northern GA, the weak instability
should further diminish and rates should reduce in turn limiting
the highest totals toward more 1-2" totals and beneficial factors
compared to further west in north-central AL. 

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...HUN...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   34518536 34358498 34058497 33788527 33638596 
            33548683 33458788 33598822 33918800 34138715 
            34418598 

735 
AWUS01 KWNH 282212
FFGMPD
NMZ000-AZZ000-290410-

Mesoscale Precipitation Discussion 0074
NWS Weather Prediction Center College Park MD
510 PM EST Wed Feb 28 2024

Areas affected...South-Central to Southeast AZ...Southwest NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 282210Z - 290410Z

SUMMARY...Scattered bands of heavy showers and thunderstorms with
locally heavy rainfall rates may foster an isolated concern for
runoff problems and flash flooding going into the evening hours.

DISCUSSION...The latest GOES-W visible satellite imagery in
conjunction with dual-pol radar has been showing an uptick in the
coverage of convection across areas of south-central to southeast
AZ. A relatively strong and compact mid-level low center/trough is
seen gradually ejecting east-northeast out of far northwest
Mexico, and strong dynamical forcing/divergent flow aloft coupled
with the diurnal heating cycle has been favoring the expansion of
convection and increase in rainfall rates over the last couple of
hours.

MLCAPE values across southern AZ have risen to as much as 500
J/kg, and there are pockets of locally stronger moisture
convergence in place that are seen helping to facilitate some
loosely organized bands of convection around the eastern flank of
the mid-level low center. The visible satellite imagery downstream
of the current activity involving especially southeast AZ has been
reflecting an increasingly agitated CU/TCU field, and this is
reflective of the increase in diurnally enhanced boundary layer
instability.

Despite the dry boundary layer profiles, the 12Z/18Z HREF guidance
supports some localized 20 to 30 percent probabilities of seeing
1"+/hour rainfall rates with some of the stronger convective cells
going through the 00Z to 03Z timeframe. The heaviest rates should
tend gradually shift from south-central AZ into southeast AZ and
southwest NM through early this evening. Given some of the uptick
in convective organization and banded structures, some spotty
storm total amounts of 1.5 to 2.5 inches cannot be ruled out in at
little as 2 to 3 hours.

These rainfall amounts may cause some isolated concerns for runoff
problems and flash flooding, with the normally dry washes/arroyos
in this case being the more sensitive areas to closely monitor.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

ATTN...RFC...CBRFC...WGRFC...NWC...

LAT...LON   33760861 33240777 32530764 32010788 31530831 
            31310899 31190960 31201079 31441192 31771256 
            32461238 33021150 33690960 

001 
AWUS01 KWNH 280933
FFGMPD
PAZ000-MDZ000-VAZ000-WVZ000-OHZ000-KYZ000-INZ000-281500-

Mesoscale Precipitation Discussion 0073
NWS Weather Prediction Center College Park MD
433 AM EST Wed Feb 28 2024

Areas affected...portions of the upper Ohio Valley and surrounding
areas

Concerning...Heavy rainfall...Flash flooding possible

Valid 280931Z - 281500Z

Summary...Fast-moving convection across Indiana/Kentucky will
migrate through the discussion area over the next 3-6 hours.  A
modest increase in flash flood potential is expected, though the
overall threat is expected to remain isolated at best.

Discussion...Mid-level ascent across the Lower Ohio Valley has
finally interacted favorably with seasonably high warmth/moisture
located across much of the Ohio Valley to promote development of
bands of convection generally from near Dayton, OH southwestward
to near Paducah.  The storms were embedded in a warm sector
characterized by around 1000 J/kg MUCAPE (per SPC Mesoanalyses)
and 70-80 knot mean westerly flow between 850-300mb, promoting
fast storm motions (around 50 knots).  Despite the quick forward
speeds, a few structures were oriented favorably for localized
training/repeating and rain rates estimated at around 1 inch/hr
per MRMS.  The storms are currently located atop areas of mostly
1.5-2 inch/hr FFG thresholds, suggestive of a very isolated flash
flood threat in the near term (through 1030Z).

Over time, however, expanding convective coverage and movement
toward more moist soils and generally more sensitive ground
conditions (i.e., FFGs at around 1 inch/hr into Ohio and West
Virginia) suggests a gradual uptick in flash flood potential from
1030Z-1500Z.  Hillier terrain and sensitive low spots could be the
focus for this flash flood risk, especially if those spots happen
to underlie training convection that can foster better rain rates
for an hour or two.  Despite more favorable ground conditions with
eastward extent, the fast storm motions should still mitigate the
overall risk.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...CLE...CTP...ILN...JKL...LMK...LWX...PBZ...RLX...
RNK...

ATTN...RFC...MARFC...OHRFC...NWC...

LAT...LON   40788179 40748014 40287859 39567830 38567926 
            38098073 37698395 37758576 38978526 40498354 
            

686 
AWUS01 KWNH 210959
FFGMPD
CAZ000-211530-

Mesoscale Precipitation Discussion 0072
NWS Weather Prediction Center College Park MD
458 AM EST Wed Feb 21 2024

Areas affected...Transverse and Peninsular Range of Southern CA

Concerning...Heavy rainfall...Flash flooding possible

Valid 210955Z - 211530Z

SUMMARY...Heavy showers arriving across the Transverse and
Peninsular Ranges over the next several hours may result in more
concerns for runoff problems with at least a localized threat for
flash flooding.

DISCUSSION...The latest GOES-18 IR satellite imagery shows a
relatively compact shortwave trough offshore of southern CA which
is advancing gradually off to the east. There is a pool of
instability associated with this energy with MUCAPE values just
offshore of the Transverse and Peninsular Ranges of as much as 500
to 750 J/kg, and radar imagery coupled with offshore
microwave/CMORPH2 data confirms some convective elements
approaching the coast with pockets of heavier rainfall rates.

This energy will spread inland early this morning, and the more
orographically favored terrain of Santa Barbara, Ventura, and Los
Angeles County will likely tend to see the heaviest rainfall rates
with this concentration of showers that arrives. Some rainfall
rates may reach into the 0.50" to 0.75"/hour range, and especially
considering the instability parameters that are pooling along the
immediate coast. Somewhat lesser rates will tend to impact Orange
and San Diego County farther south, but even here, some localized
rates approaching a 0.50"/hour will be possible.

There has been a fair amount of spread in the 00Z HREF guidance
with the details of this energy and the additional rains that may
spread inland heading through the early morning hours, but based
on the latest radar/satellite trends and the recent HRRR guidance,
it is expected that a new round of heavy rainfall will occur.

Some of the convective showers that are offshore are also quite
slow-moving, and thus as they move inland they will have the
capability to to produce heavy totals. Additional rainfall amounts
of as much as 1 to 3 inches will be possible through early this
morning before the activity then weakens and advances off to the
east.

Given the very wet/sensitive antecedent conditions, a renewed
threat of runoff problems will exist including at least a
localized threat for flash flooding where these stronger and
slower moving showers focus.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34991861 34481818 34341785 34001696 33581665 
            33121644 32761642 32531660 32591717 33221763 
            33641832 34011916 34282000 34552054 34872051 
            34981977 

898 
AWUS01 KWNH 201720
FFGMPD
CAZ000-202315-

Mesoscale Precipitation Discussion 0071
NWS Weather Prediction Center College Park MD
1220 PM EST Tue Feb 20 2024

Areas affected...Central California...

Concerning...Heavy rainfall...Flash flooding possible

Valid 201720Z - 202315Z

SUMMARY...Scattered slow-moving but locally intense downpours pose
.5-.75"/hr rates with up to 1.5" totals pose possible localized
flash flooding concerns, especially near urban settings.

DISCUSSION...GOES-W WV denotes a subtle inflection in the broad
southwesterly flow along the Central CA coast.  This is along the
western cyclonic portion, weakly diffluent edge of the 150kt jet
currently over south-central CA, providing sufficient upper-level
divergence to further amplify the wave.  Combined with sharpening
core of the upper-level trof near 41.7N 127.3W along with broad
CAA aloft is providing a steepening lapse rates increasing
available instability for convective development in the next few
hours.  MUCAPE to 750-1000 J/kg near coast remains to 250-500 J/kg
into the southern Sacramento Valley.  GOES-W GLM and Visible loop
shows recent convective development nearing the mouth of San
Francisco Bay,  given depth of modest moisture and 15-20kts of low
level moisture convergence (within .75" total PWats) suggest rates
of .5"/hr are possible within the core of the narrow updraft
cores.  Weak bulk shear to 30kts and favorable back-building flow
regime suggest some slow cell motions and perhaps weak rotation
for increased isallobaric moisture flux to potentially reach a low
end possibility of .75"/hr rates particularly near the instability
source for the next few hours before height-falls from the main
trof press this regime eastward after 00z. A spot or two of 1-1.5"
totals are not out of the realm of possibility.  Given the
rates/short-duration, localized flash flooding is considered
possible given well above normal run-off capability given
saturated ground conditions (per NASA SPoRT LIS). 

Further east...As cells translate through the Napa Valley/Santa
Cruz range toward the Sacramento Valley, cells will weaken with
diminished instability but some filtered insolation may help some
buoyancy to maintain weaker elevated cells.  Deep layer flow will
continue to support narrow banded-like features translating
eastward allowing for some training and increased duration.  With
reducing rates but increased duration streaks  .5-1.25" are
possible and may induce some nuisance flooding especially near
urban/poor draining locations. 

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EKA...MTR...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   39602185 39462115 38982095 38442103 37842113 
            37182142 37002184 37032238 37432277 38362335 
            38892319 39432248 

661 
AWUS01 KWNH 200911
FFGMPD
CAZ000-202110-

Mesoscale Precipitation Discussion 0070
NWS Weather Prediction Center College Park MD
410 AM EST Tue Feb 20 2024

Areas affected...Portions of the Transverse and Peninsular Ranges
including the Los Angeles Basin

Concerning...Heavy rainfall...Flash flooding likely

Valid 200910Z - 202110Z

SUMMARY...The tail-end of an atmospheric river continues to impact
areas of southern CA, and some uptick in rainfall concentration
and intensity is expected going through the morning and midday
hours. Given the extremely sensitive conditions on the ground
locally, any additional heavy rain is likely to foster more runoff
problems and flash flooding.

DISCUSSION...The latest GOES-W WV suite shows a well-defined
subtropical moisture fetch associated with the tail-end of an
atmospheric river impacting southern CA along with proximity of a
stalled out frontal zone.

Shortwave energy offshore of southern CA situated near and
adjacent to 30N 130W will be advancing off to the east over the
next 12 hours and this will be interacting with the deeper layer
moisture axis and nearby front for what should be a gradual
increase in shower activity offshore of the Transverse and
Peninsular Ranges.

This activity heading through the morning hours will overspread
the coastal terrain, including the Los Angeles Basin, and with an
uptick in forcing and stronger IVT magnitudes, the rainfall rates
should also increase. IVT magnitudes by 12Z are forecast to rise
to as much as 500 kg/m/s across portions of Los Angeles and Orange
County, and adjacent areas to the south into San Diego County will
also see increasing moisture transport that will facilitate a
threat of heavier shower activity.

A combination of a generally orthogonal orientation of the IVT
axis relative to the terrain along with the subtropical origins of
the moisture transport should favor rather efficiently high
rainfall rates that should increase to occasionally over a
0.50"/hour.

The 00Z/06Z HREF guidance suggests additional rainfall totals of
as much as 2 to 4 inches with isolated heavier amounts possible
for the southwest-facing slopes of the San Gabriel and San
Bernadino mountains by midday on Tuesday. Areas farther back up
the coast involving eastern portions of the Santa Ynez mountains
which have already been hard hit by this most recent atmospheric
river event will also see locally heavy rains of 1 to 3 inches.

Given the extreme sensitivities locally on the ground, these
additional rains will favor more runoff problems and a likelihood
of additional flash flooding which will include more debris flow
and landslide activity.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34811972 34791864 34541791 34431717 34111669 
            33681664 32941668 32761704 32971732 33371768 
            33591797 33871842 33931879 34111936 34341998 
            34652003 

068 
AWUS01 KWNH 200031
FFGMPD
CAZ000-200500-

Mesoscale Precipitation Discussion 0069
NWS Weather Prediction Center College Park MD
730 PM EST Mon Feb 19 2024

Areas affected...northern and central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 200029Z - 200500Z

Summary...Isolated flash flood potential continues across northern
and central California through 05Z or so.

Discussion...Areas/bands of heavy rainfall (and occasional
embedded deep convection) continues across the discussion area -
especially along an axis from San Francisco northeastward through
Yuba City, Chico, and higher terrain near Lassen County, CA. 
Areas of 0.25-0.5 inch/hr rain rates continue to be reported
beneath stronger convection, and occasional reports of water over
roadways have also been received.  The convection continues amid
broadly cyclonic flow aloft southeast of a closed mid-level low
centered near 42N, -130W.  Difluence aloft combined with strong
low-level warm advection, orographic lift, and 250-750 J/kg SBCAPE
continue to support ongoing convection, and individual cell
motions (parallel to southwesterly steering flow aloft) have
enabled localized training/repeating along with local rainfall
totals near an inch in spots over the past 3-6 hours.

The ongoing scenario should continue to support isolated flash
flood potential for at least the next 3-5 hours.  Synoptic
features supporting the potential have changed very little through
the day and should remain nearly steady state for a few more
hours.  The loss of daytime heating could act as a catalyst for
weakening instability/updraft strength at some point this evening,
though orographic lift and ascent associated with the Pacific
upper low should act to overcome waning instability and still
result in spots of locally heavy rainfall.  Local totals exceeding
1 inch are possible through 05Z on a spotty basis.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EKA...MFR...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   41912247 41042100 38951999 37772102 37132221 
            37982278 39292383 40762436 41662417 

490 
AWUS01 KWNH 192045
FFGMPD
CAZ000-200219-

Mesoscale Precipitation Discussion 0068
NWS Weather Prediction Center College Park MD
344 PM EST Mon Feb 19 2024

Areas affected...portions of central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 192019Z - 200219Z

Summary...A few thunderstorms have developed in the southern San
Joaquin Valley in the past couple hours.  Brief heavy rainfall has
resulted in spots of 0.5 inch/hr rain rates at times.  Flash
flooding is possible in this regime.

Discussion...Abundant sunshine and ascent from weak shortwave
troughs embedded in cyclonic flow aloft has allowed for several
thunderstorms to form recently near Fresno and Hanford in the
southern San Joaquin Valley.  The storms are in a fairly unstable
environment characterized by 1000+ J/kg SBCAPE and fairly strong
shear aloft resulting from 75 kt southwesterly flow at 500mb.
Despite the strong steering flow, the presence of deep convection
and potential localized backbuilding within the axis of
instability suggests some potential for localized backbuilding and
spots of 0.5+ inch/hr rain rates could result in an isolated flash
flood risk.  This risk will likely persist through the afternoon
(perhaps through 02Z or so) as insolation and warm advection helps
to maintain sufficient instability for deep convection.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   39002030 37911934 37761927 36171841 35241879 
            35411960 36752086 37432161 37912156 38832081 
            

616 
AWUS01 KWNH 192021
FFGMPD
CAZ000-200219-

Mesoscale Precipitation Discussion 0068
NWS Weather Prediction Center College Park MD
321 PM EST Mon Feb 19 2024

Areas affected...portions of central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 192019Z - 200219Z

Summary...Areas of rainfall and isolated thunderstorms continue to
migrate northward across the discussion area.  The heavier
rainfall will help to maintain at least an isolated flash flood
risk through the next 6 hours or so.

Discussion...Northern and central California remain under the
influence of a stout mid/upper low over the northeastern Pacific
centered at around 42N, -130W.  Downstream of that low, difluent
southwesterly flow aloft continues to support updrafts and
developing convection in addition to orographic lift from strong
southerly low-level flow (exceeding 45 knots at 850mb in some
areas).  Furthermore, cooling aloft associated with the mid/upper
low and areas of sunshine have allowed for surface-based CAPE
values to increase into the 250-1000 J/kg range especially across
the central Valley and coastal areas.  All of these factors point
to a sustained heavy rainfall threat over the next 3-6 hours, with
occasional deep convection resulting in local rain rates exceeding
0.5 inch/hr at times.

The extent of the heaviest rain rates are in question, however. 
Most areas will experience periods of 0.25 inch/hr rain rates at
times as areas of heavier rainfall quickly drift northward.  The
latest thinking is that at least an isolated flash flood risk will
exist in this regime, with perhaps the greatest threat residing in
1) northern coastal ranges from San Francisco northward and 2)
along windward slopes of the Sierra below the freezing level. 
Models generally focus the greatest rainfall rates along these
areas through 03Z, where another 1-2 inches of rainfall could
occur through 0330Z.  Localized training of cells should also
occur across the central Valley, prompting at least isolated flash
flood potential there through the afternoon.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   39002030 37911934 37761927 36171841 35241879 
            35411960 36752086 37432161 37912156 38832081 
            

600 
AWUS01 KWNH 191832
FFGMPD
NVZ000-CAZ000-200031-

Mesoscale Precipitation Discussion 0067
NWS Weather Prediction Center College Park MD
132 PM EST Mon Feb 19 2024

Areas affected...portions of northern and central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 191831Z - 200031Z

Summary...Areas of rainfall and isolated thunderstorms continue to
migrate northward across the discussion area.  The heavier
rainfall will help to maintain at least an isolated flash flood
risk through the next 6 hours or so.

Discussion...Northern and central California remain under the
influence of a stout mid/upper low over the northeastern Pacific
centered at around 42N, -130W.  Downstream of that low, difluent
southwesterly flow aloft continues to support updrafts and
developing convection in addition to orographic lift from strong
southerly low-level flow (exceeding 45 knots at 850mb in some
areas).  Furthermore, cooling aloft associated with the mid/upper
low and areas of sunshine have allowed for surface-based CAPE
values to increase into the 250-1000 J/kg range especially across
the central Valley and coastal areas.  All of these factors point
to a sustained heavy rainfall threat over the next 3-6 hours, with
occasional deep convection resulting in local rain rates exceeding
0.5 inch/hr at times.

The extent of the heaviest rain rates are in question, however. 
Most areas will experience periods of 0.25 inch/hr rain rates at
times as areas of heavier rainfall quickly drift northward.  The
latest thinking is that at least an isolated flash flood risk will
exist in this regime, with perhaps the greatest threat residing in
1) northern coastal ranges from San Francisco northward and 2)
along windward slopes of the Sierra below the freezing level. 
Models generally focus the greatest rainfall rates along these
areas through 03Z, where another 1-2 inches of rainfall could
occur through 0330Z.  Localized training of cells should also
occur across the central Valley, prompting at least isolated flash
flood potential there through the afternoon.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EKA...MFR...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   41772347 41482183 40212041 38731981 37902029 
            37542249 38682403 40522476 41402439 

099 
AWUS01 KWNH 191605
FFGMPD
CAZ000-200404-

Mesoscale Precipitation Discussion 0066
NWS Weather Prediction Center College Park MD
1105 AM EST Mon Feb 19 2024

Areas affected...portions of southern California

Concerning...Heavy rainfall...Flash flooding likely

Valid 191604Z - 200404Z

Summary...A landfalling atmospheric river will continue to impact
portions of the discussion area with moderate to heavy rainfall
(and attendant flash flooding) through at least 04Z Tuesday.

Discussion...Areas of moderate to heavy rainfall continue across
southern California currently - especially in portions of Santa
Barbara and Ventura Counties.  Numerous areas of 0.25-0.6 inch/hr
rain rates have been observed along with reports of flash flooding
and mud/debris flows.  The rainfall continues as a result of a
landfalling atmospheric river located on the southeastern
periphery of a slow-moving mid/upper low centered near 40.4N,
-130W.  Strong southwesterly flow within the atmospheric river,
orographic lift against coastal ranges, and 1+ inch PW values will
continue to support the ongoing heavy rain/flash flood risk in the
short term.

Models/observations support a very slow, southeastward translation
of this atmospheric river over the next 6-12 hours, with heavier
rainfall eventually impacting more of the Los Angeles Basin and
adjacent areas of the Transverse and Peninsular Ranges across
southern California.  As this occurs, a lengthy duration of 0.25+
inch/hr rain rates is expected in the aforementioned areas,
continuing to support flash flood/debris flow potential.  The
greatest threat for heavy rainfall (and overall 2-4 inch rainfall
totals) should exist from the 10Z-00Z timeframe.  Thereafter, most
models lessen rainfall rates although at least an isolated flash
flood risk should continue given the preceding rainfall and wet
soils.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   35431912 34631735 33491663 33011692 33071761 
            33901937 34492054 35022059 35342000 

100 
AWUS01 KWNH 190847
FFGMPD
CAZ000-191830-

Mesoscale Precipitation Discussion 0065
NWS Weather Prediction Center College Park MD
345 AM EST Mon Feb 19 2024

Areas affected...Much of Central and Northern CA

Concerning...Heavy rainfall...Flash flooding possible

Valid 190845Z - 191830Z

SUMMARY...A threat of heavy rainfall will continue for the
remainder of the night and into the morning hours as a strong low
center persists offshore of the West Coast. This will maintain a
threat of flooding given the locally saturated ground conditions.

DISCUSSION...A deep low center offshore of the West Coast
associated with an upper-level trough will continue to advance
gradually off to the east over the next 6 to 12 hours which will
allow a cold front to advance inland across central and northern
CA. A rather well-defined atmospheric river of Pacific moisture
continues to advance north around the eastern flank of the deep
layer trough/low and this will maintain a threat of heavy rainfall
going through the remainder of the night and into the morning
hours for much of the region.

The axis of strongest warm air advection/isentropic ascent and
deep layer moisture transport will be across the San Joaquin and
Sacramento Valleys as well the west-facing slopes of the Sierra
Nevada. Locally enhanced low-level jet energy of 40 to 50+ kts
continues to lift northward up through the Central Valley, and the
latest RAP analysis continues to show a modest axis of instability
with MUCAPE values of as much as 100 to 250 J/kg. This coupled
with some locally strong low-level moisture convergence over the
Central Valley and near the foothills of the Sierra Nevada
continue to support some occasionally stronger convective elements
with heavier rainfall rates.

Rainfall rates within the main warm conveyor belt along and ahead
of the cold front will have the capability to occasionally reach
into the 0.50" to 0.75"/hour range with some spotty heavier rates
possible where any stronger convective cells materialize. Behind
the cold front, there should tend to be a break in the coverage of
moderate to heavy rainfall, but eventually there will be the
arrival of additional shortwave energy from offshore along with
the arrival of steeper mid-level lapse rates. This coupled with
orographics is likely to result in some redeveloping yet broken
lines of showers and thunderstorms. The 00Z HREF and especially
the HRRR tend to favor the Bay Area, northern CA coastal ranges,
and the northern Sacramento Valley as having the best potential of
seeing these semi-organized bands of convection this morning.

Along and ahead of the cold front, additional rainfall totals of
as much as 2 to 4 inches with isolated heavier amounts can be
expected for the upslope areas of the Sierra Nevada below the snow
line, with eastern portions of the Central Valley seeing as much
as 1 to 2 inches. The areas that do see more discrete convection
redeveloping early this morning closer back to the Bay Area and up
north across the coastal terrain and northern Sacramento Valley
may also see some additional 1 to 2 inch amounts.

Given the heavy rainfall that has already occurred, and with
locally saturated ground conditions, these additional rains should
maintain a flooding threat going into the morning hours.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EKA...HNX...MFR...MTR...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   41252339 41012207 39862093 38451992 38271982 
            37531929 37111884 36621857 36161873 35791923 
            35801978 36182012 36682048 36972100 36922139 
            36822173 36922208 37242251 38202304 38632349 
            39262391 39832397 40372439 40982413 

815 
AWUS01 KWNH 190519
FFGMPD
CAZ000-191600-

Mesoscale Precipitation Discussion 0064
NWS Weather Prediction Center College Park MD
1218 AM EST Mon Feb 19 2024

Areas affected...Central and Southern California

Concerning...Heavy rainfall...Flash flooding likely

Valid 190515Z - 191600Z

SUMMARY...Heavy rainfall arriving across the coastal ranges of
central to southern CA, including portions of the Transverse
Range, will couple with wet antecedent conditions to result in
areas of flooding and flash flooding.

DISCUSSION...An atmospheric river of Pacific moisture focused
around the southeast flank of an upper-level trough offshore of
the West Coast will be focusing a heavy to excessive rainfall
threat overnight and into Monday morning across the coastal ranges
of central to southern CA.

The latest CIRA-ALPW data products in conjunction with GOES-W WV
satellite imagery show a relatively concentrated axis of mid-level
moisture already streaming inland across the terrain with the axis
of deeper layer moisture transport extending well southwest and
offshore of southern CA. IVT magnitudes nosing toward the Santa
Lucia Range and extending south down toward the Santa Ynez Range
are already approaching 500 kg/m/s, and localized rainfall rates
across these areas have been approaching a 0.50"/hour over the
last couple of hours.

The latest GOES-W IR satellite imagery shows some cloud top
cooling noted offshore of Monterey, San Luis Obispo, and Santa
Barbara County with a more focused batch of heavier showers
quickly approaching and this was confirmed by a 0253Z GPM/GMI
overpass which showed multiple bands of broken convection and
heavier rainfall rates. This activity is being aided by a
combination of some offshore instability and also the nose of an
increasing southwest low-level jet which is yielding an axis of
stronger low-level speed convergence.

A cold front offshore of the West Coast will be gradually settling
southeast overnight and will be crossing over the coastal ranges.
However, the front will also be slowing down as it becomes more
aligned with the deeper layer steering flow. This coupled with
strengthening IVT magnitudes approaching 750 kg/m/s in the 06Z to
09Z time frame in association with the low-level jet should focus
enhanced rainfall rates into the orographically favored terrain
along the coast. Given the orthogonal orientation of the deeper
layer IVT axis, the rates should be maximized and occasionally
capable of reaching 0.75" to 1.0"/hour, and especially with any
more organized convective elements that advance inland.

Rainfall amounts overnight and through Monday morning are expected
to be on the order of 3 to 6 inches, with isolated heavier amounts
possible. The heaviest rains should gradually focus over the
Transverse Range in particular, with Santa Barbara County and
eventually Ventura County likely to see enhanced rainfall rates
and corresponding totals with this event.

Given the sensitive/wet antecedent conditions on the ground
already, these rains with this latest atmospheric river event are
likely to cause areas of flooding, including a threat for flash
flooding. Debris flow and landslide activity will also be a
notable concern at least locally as these heavier rains arrive.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HNX...LOX...MTR...

ATTN...RFC...CNRFC...NWC...

LAT...LON   36942093 36072004 35261962 34751858 34381845 
            34011895 34201973 34282032 34552069 35322112 
            35582139 36172184 36632192 36822169 

098 
AWUS01 KWNH 190348
FFGMPD
CAZ000-190945-

Mesoscale Precipitation Discussion 0063
NWS Weather Prediction Center College Park MD
1045 PM EST Sun Feb 18 2024

Areas affected...Northern and Central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 190345Z - 190945Z

SUMMARY...Heavy rainfall is expected overnight from bands of
showers and thunderstorms with locally enhanced rainfall rates.
Areas of flooding will be a concern, especially around the Bay
Area tonight, and there may be at least a localized flash flooding
threat in portions of the Sacramento Valley where any bands of
convection train over the same area.

DISCUSSION...A deep upper trough offshore of the West Coast
continues to gradually shift off to the east which will be
bringing a front inland across areas of central and northern CA
overnight. Bands of heavy showers and a few thunderstorms are
already impacting many coastal ranges of northern CA and also
portions of the northern Sacramento Valley where recent dual-pol
radar imagery is showing some localized concentration of stronger
convection. Cloud top temperatures in the GOES-W IR satellite
imagery are also cooling across the region, including areas just
offshore, and thus suggestive of an uptick in convective
organization and rainfall rate trends.

In fact, the latest RAP analysis is showing a well-defined nose of
instability ahead of the cold front, with MUCAPE values of 250+
J/kg, nosing across the Bay Area and into the Sacramento Valley.
This coupled with the arrival of rather strong left-exit region
jet dynamics with the aforementioned upper trough, and stronger
low-level convergence/forcing with the cold front should maintain
and expand the convective threat heading well into the overnight
hours. The 12Z/18Z GFS solutions support a well-defined nose of
stronger 850/700mb flow arriving across the Bay Area and through
the Sacramento Valley by 06Z, with a southerly low-level jet
forecast to peak at 50+ kts. This is expected to drive moisture
flux anomalies of 3 to 4 standard deviations above normal which
coupled with the available instability should drive locally
enhanced rainfall rates.

Already some of the more organized convective cells in the
northern Sacramento Valley are focusing 1.0" to 1.5"/hour rainfall
rates, and this should continue locally over the next several
hours as the heavier rainfall threat gradually shifts off to the
south and east with the arrival of the approaching front. The
18Z/00Z HREF guidance does support this along with recent runs of
the HRRR guidance as well. Some of these heavier rains are likely
to also spread into at least the windward slopes/foothills of the
northern Sierra Nevada.

Areas closer to the coast and near the Bay Area with the enhanced
Pacific fetch of moisture will see occasionally heavy rain as
well, and especially with the aid of orographic forcing.

Going through the overnight hours, generally as much as 1 to 3
inches of rain will be possible for the coastal ranges, with
potentially heavier amounts of 2 to 4 inches where any convection
sets up and locally trains over the same area farther inland.
Given the wet antecedent conditions, the additional rains heading
into the overnight hours will result in a regional threat of
flooding, especially around the Bay Area, and this will include a
more discrete flash flood threat for portions of the northern
Sacramento Valley.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EKA...MFR...MTR...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   41162223 40072090 38982061 37612091 37022162 
            37002208 37222247 37942307 38512344 39272386 
            40022408 40992380 

827 
AWUS01 KWNH 182130
FFGMPD
CAZ000-190328-

Mesoscale Precipitation Discussion 0062
NWS Weather Prediction Center College Park MD
429 PM EST Sun Feb 18 2024

Areas affected...northwestern and portions of central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 182128Z - 190328Z

Summary...Increasing coverage of moderate to heavy rainfall is
expected across the discussion area through the afternoon and
early evening.  Areas of 0.5 inch/hr rain rates are expected,
potentially causing a few areas of excessive runoff.

Discussion...Water vapor and radar mosaic imagery indicates the
presence of a few areas of rainfall beginning to approach coastal
areas near/just south of Eureka as of 2110Z.  A separate area of
lighter rainfall was located near/west of San Francisco and
vicinity.  The rainfall was increasing in coverage and being
forced by difluence aloft and the slow approach of a larger upper
wave over the Pacific centered near 38, -134.  Additionally,
low-level wind fields were beginning to increase dramatically
along coastal areas in tandem with the approach/eastward
translation of a 50-kt 850 mb jet.  Rainfall rates were generally
light over the past hour (0.1-0.15 inch/hr), although the eastward
translation of the aforementioned synoptic features, increased
orographic ascent, and slow cooling aloft/mid-level
destabilization should result in rain rates increasing into the
0.25-0.5 inch/hr range - especially during the 00Z-03Z timeframe.

As rain rates increase in tandem with a more active convective
pattern, areas of excess runoff will become more likely.  The
greatest concern for flash flooding will reside generally from the
northern coastal ranges (from San Francisco Metro northward) and
windward slopes of the Klamath Mountains below the freezing level.
 Orientation of southeasterly 850mb flow relative to terrain in
these areas will likely support local enhancement of rain rates
and excessive runoff potential especially in low/sensitive spots. 
The risk will likely extend beyond 0330Z, and an updated MPD may
be needed pending rainfall and convective trends around that time.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EKA...MFR...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   41942291 41292112 39972087 38532119 37392211 
            37832294 39932419 41402422 

078 
AWUS01 KWNH 180300
FFGMPD
CAZ000-180758-

Mesoscale Precipitation Discussion 0061
NWS Weather Prediction Center College Park MD
959 PM EST Sat Feb 17 2024

Areas affected...Bay Area into the Sacramento Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 180258Z - 180758Z

SUMMARY...Heavy rainfall rates are expected with bands of locally
stronger convection over the next few hours. Areas of flooding
will be possible over the next few hours.

DISCUSSION...The latest GOES-W IR satellite imagery in conjunction
with dual-pol radars from the Bay Area and the Central Valley have
been showing some uptick in small-scale bands of convection with
some some cooling cloud top activity noted as a cold front arrives
in off the Pacific Ocean.

Strong forcing aloft associated with the arrival of an upper-level
trough working in conjunction with a ribbon of modest instability
and localized orographics have been allowing for rainfall rates to
increase over the last few hours, and over the last hour, some
rates have been reaching as high as 0.5" to 1.0"/hour with the
stronger semi-organized convective cells.

Over the next few hours, some semi-organized linear bands of
convection will continue to impact areas near and a bit south of
the Bay Area, but also farther east into the Sacramento Valley
where even some brief training of convection will be likely given
the orientation of the activity with the deeper layer southwest
flow aloft ahead of the upper-level trough.

Expect rainfall rates to reach easily into the 0.5" to 1.0"/hour
range with the convection over the next 2 to 3 hours, which will
foster some additional rainfall totals of as much as 1.5 to 2.5
inches.

Already there have been some areas of flooding around the Bay
Area, and additional areas of flooding will be possible as these
additional rounds of heavy rainfall advance inland. Gradually the
passage of the cold front will allow for the deeper moisture axis
to advance well off to the east, along with the better forcing
aloft, and thus the rainfall rates should gradually wane later
this evening and overnight.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...MTR...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   40472215 40372146 39562094 38392081 37262113 
            36982183 37012220 37542259 38672234 39422234 
            40202255 

800 
AWUS01 KWNH 121245
FFGMPD
SCZ000-FLZ000-GAZ000-ALZ000-121845-

Mesoscale Precipitation Discussion 0060
NWS Weather Prediction Center College Park MD
744 AM EST Mon Feb 12 2024

Areas affected...Southeast Alabama into southwest to central
Georgia

Concerning...Heavy rainfall...Flash flooding possible

Valid 121245Z - 121845Z

Summary...Heavy rainfall likely to continue into this morning
along the west to east oriented front across portions of Alabama
and Georgia.  Training or repeat cells likely in the vicinity of
this front, leading to hourly rain of 2"+ and  totals of 4". 
Isolated to  widely scattered flash flooding possible.

Discussion...Surface analysis this morning is showing two well
defined west to east oriented frontal boundaries across the
Southeast.  The southern most front stretching from southeast
Alabama into southwest Georgia is the primary overrunning boundary
with a broad region of warm advection rains along and to the north
of this boundary across the Southeast.  Concerns will be in the
immediate vicinity of the southern most front where the latest
simulated hi res radar suggest cells will potentially train in a
west southwest to east northeasterly direction into this morning. 
Overall very favorable conditions remain in place this morning for
widespread heavy rains/embedded thunderstorms ahead of strong
closed low moving east from the Lower Mississippi Valley into the
Southeast.  Models continue to show strong boundary layer
convergence into the southern front this morning as moist, PW
anomalies 2.5 to 3+ standard deviations above the mean,
southwesterly h85 flow of 40-50+ knots continues into the front,
which is not expected to move appreciably. 

Hi res radars this morning are a bit too far to the north with the
observed radar precip axis, but all suggest that there will be a
continued threat of cells to focus in the vicinity of the west to
east front from southeast Alabama into southwest Georgia. HREF
neighborhood probabilities are high in the metwatch area for 1 and
2"+ amount this morning, 70-90 and 60-90% respectively. For 3"+
totals probabilities are in the 40-60%, but confined to a smaller
area over southeast Alabama into southwest Georgia. 

Oravec

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...CAE...CHS...FFC...JAX...MOB...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON   33688223 33388144 32748108 32308154 31808301 
            31808323 31408466 30458632 31108730 31618791 
            32498684 33358526 33648371 33558347 

937 
AWUS01 KWNH 120705
FFGMPD
SCZ000-FLZ000-GAZ000-ALZ000-MSZ000-LAZ000-121303-

Mesoscale Precipitation Discussion 0059
NWS Weather Prediction Center College Park MD
204 AM EST Mon Feb 12 2024

Areas affected...central Gulf Coast into the Southeast

Concerning...Heavy rainfall...Flash flooding possible

Valid 120703Z - 121303Z

Summary...Heavy rainfall related to thunderstorms increasing in
coverage across portions of the central Gulf Coast into the
Southeast could lead to hourly rain totals to 2" with local
amounts to 4".  This would lead to isolated to widely scattered
flash flooding.

Discussion...Widespread rain with embedded scattered showers and
thunderstorms cover portions of LA, MS, AL, and GA within a broad
baroclinic leaf pattern noted on recent water vapor imagery.  This
is occurring near and ahead of a surface low and its attendant
frontal boundaries, with instability noted on either side of the
slow-moving cold front in LA on SPC mesoanalyses.  Inflow at 850
hPa is out of the southwest at 30-40 kts, importing 500-2000 J/kg
of MU CAPE into the region.  Precipitable water values of 1.4-1.7"
lie here per recent GPS data.  Cell coverage has been most
numerous generally poleward of the 4C isotherm at 700 hPa, while
activity has been more widely scattered/isolated in warmer areas
closer to the Gulf Coast thus far.  Across portions of
south-central LA, there has been enough convective coverage for
short bouts of cell training overnight.

With the main upper low near the eastern OK/TX border moving
eastward, temperatures aloft (700 hPa) will cool which should
allow cell coverage to increase closer to the Gulf Coast across
southeast LA, southern MS, and portions of southern AL.  The
entire heavy rain area is expected to settle slowly southeast with
time.  The main heavy rain threats appear to be due to short bouts
of cell training as well as near and ahead of embedded
mesocyclones.  As the cold front isn't expected to pick up the
pace to the east until sunrise, this could allow for increased
bouts of cell training in more southern areas across LA, MS, and
AL beyond 10z.  Broad warm advection will continue east of the
surface low, with heavy rainfall falling across increasingly
saturated ground across south-central MS, central AL, and central
GA.  Hourly rain totals to 2" with local amounts to 4" are
possible, which is explicitly forecast in the mesoscale guidance
across portions of AL and GA and theoretically possible farther
southwest, given the ingredients available.  This is expected to
lead to isolated to widely scattered instances of flash flooding. 

Roth

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...CAE...FFC...GSP...HUN...JAN...LCH...LIX...
MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   34248628 34148271 33648148 31998448 30738680 
            28988913 28839084 29379166 31559054 33488842 
            

184 
AWUS01 KWNH 120251
FFGMPD
GAZ000-ALZ000-MSZ000-120849-

Mesoscale Precipitation Discussion 0058
NWS Weather Prediction Center College Park MD
949 PM EST Sun Feb 11 2024

Areas affected...Central MS, AL, GA

Concerning...Heavy rainfall...Flash flooding possible

Valid 120249Z - 120849Z

Summary...Isolated flash flooding is expected to continue this
evening across portions of central Mississippi, Alabama and
Georgia. As the night progresses the flash flood risk should
increase as convective intensity and organization increases across
the region.

Discussion...Convection continues to move east northeast across
portions of central MS, AL and GA this evening. This activity is
focusing near a low level boundary, with 30-40 kts of flow at
850mb resulting in ample moisture transport and convergence into
this boundary. This boundary is not expected to move much tonight,
and should act as a focus for periodic convective training with
cell motions generally parallel to this front. Large scale forcing
will increase overnight as the mid level closed low approaches
from the west. This increase in forcing and attendant uptick in
low level moisture transport should result in a gradual uptick in
convective coverage and intensity. Plenty of upstream instability
advecting in from the south (over 1000 J/KG) to support pockets of
heavy rainfall rates of 1-2"/hr at times.

Rainfall totals as high as 2-4" are expected through 09z within
swaths in the MPD area from central MS into central GA. Recent
HRRR runs seem to reasonably depict the expected convective
evolution tonight. Although will say that the HRRR appears to be
under doing the ongoing activity over MS and AL...so the coverage
of 2"+ amounts through 09z may be even a bit larger than depicted
by the HRRR. Flash flooding will initially be pretty localized in
nature...with the greatest risk over central MS where soil
conditions are more saturated. However with time tonight the risk
is expected to increase over AL and GA as training convection
increases in coverage and organization. The flash flood risk
likely continues beyond the 09z expiration time of this MPD across
portions of central AL and GA.

Chenard

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...CAE...CHS...FFC...JAN...MOB...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   33808344 33528244 33318205 32918195 32548212 
            32378276 32338363 32288499 32108605 31958716 
            31768856 31608944 31519026 31459069 31589102 
            31949091 32399052 32639026 33008959 33278880 
            33528755 33648661 33768549 33798527 

420 
AWUS01 KWNH 112058
FFGMPD
GAZ000-ALZ000-MSZ000-LAZ000-120256-

Mesoscale Precipitation Discussion 0057
NWS Weather Prediction Center College Park MD
357 PM EST Sun Feb 11 2024

Areas affected...central Louisiana, central Mississipppi, central
Alabama

Concerning...Heavy rainfall...Flash flooding possible

Valid 112056Z - 120256Z

Summary...An isolated flash flood threat continues across much of
the Deep South through 03Z.  Local convective training and cell
mergers could result in areas of excessive runoff - especially in
sensitive and/or urbanized areas.

Discussion...A mostly elevated MCS has held together across
central/northern Mississippi through the afternoon while finally
interacting with surface-based instability on its southern flank
over the past hour near/just northeast of Jackson.  Southwest of
this MCS, a trailing outflow extends from near Vicksburg, MS to
near Fort Polk, LA where it merges with a synoptic cold front. 
These boundaries have been a focus for renewed convective
development from near Jackson southwestward to far southeast
Texas, and localized training and cell mergers have allowed for
spots of 1-1.5 inch/hr rain rates to materialize espeically along
the Sabine River Valley.  Additional convection has materialized
over the open warm sector into central and southern Alabama, where
weak confluence and moderate surface-based instability has enabled
robust updrafts and spots of 1 inch/hr rain rates per MRMS.

With time, models and observations continue to indicate that both
warm-sector initiation and deep convection along aforementioned
boundaries will continue to support occasional mergers and/or
training of storms - especially from central Louisiana toward the
I-20 (and perhaps US 84) corridors in central Mississippi. 
Occasional 1-1.5 inch/hr rain rates are expected to continue,
which may exceeded FFGs on occasion especially in central MS where
1-2 inch/hr thresholds were noted.  These trends will continue to
support an isolated flash flood threat through 03Z, with perhaps
the highest threat existing along and a few counties north/south
of I-20 and portions of central Mississippi.  A separate, but more
isolated flash flood threat should exist farther away from the
outflow/cold front across Alabama, where isolated cells have now
begun to right-move and train very near Montgomery.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...JAN...LCH...LIX...MEG...MOB...SHV...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   33798776 33558531 32588519 31938568 31198792 
            30559085 30379284 30759321 31729274 32449158 
            33468995 

583 
AWUS01 KWNH 111511
FFGMPD
MSZ000-LAZ000-ARZ000-112110-

Mesoscale Precipitation Discussion 0056
NWS Weather Prediction Center College Park MD
1011 AM EST Sun Feb 11 2024

Areas affected...northern Louisiana, southeastern Arkansas,
portions of northern and central Mississippi

Concerning...Heavy rainfall...Flash flooding possible

Valid 111510Z - 112110Z

Summary...A conditional, isolated flash flood threat is evolving
across the discussion area as an organized convective complex
enters northwestern Louisiana.  Wet soils from prior runoff and
brief, heavy downpours could promote excessive runoff in a few
areas.

Discussion...Much of the outlined discussion area has experienced
2-4 inches of rainfall over the past 24 hours, resulting in wet
soils and very low FFG thresholds generally along an axis from
near Lake Providence, LA to Columbus, MS.  Meanwhile, an organized
MCS was approaching the Texas/Louisiana border near Shreveport,
and additional showers were persisting within a warm-advection
regime from central Louisiana to near Jackson, MS. The ongoing
precipitation was located just south of the axes of wettest
soils/lowest FFGs, although with showers/storms gradually moving
northeastward toward the areas of wet soils, current thinking is
that an isolated flash flood threat should begin to emerge in the
next couple of hours.

The overall magnitude of flash flood risk is in question, however.
 The convective complex near the Shreveport area is already
outperforming several high-res models -- likely due to the well
organized nature of the MCS and associated cold pool dynamics. 
With the surface warm front across central LA (and attendant
SB/MUCAPE axis) expected to lift northward, some concern exists
that at least isolated heavier rainfall (exceeding 0.5 inch/hr
rates) will spread northward into the wetter areas containing
lowered FFGs.  Areas of 0.5-2 inch rainfall totals are expected
with this activity for as long as convection holds together -
especially near and north of the I-20 corridor.  Flash flood
potential is expected to increase over time.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...LMRFC...SERFC...WGRFC...NWC...

LAT...LON   34488923 34138830 32968839 31919051 31679325 
            32239399 32899354 33339302 33819171 

185 
AWUS01 KWNH 101042
FFGMPD
LAZ000-TXZ000-101641-

Mesoscale Precipitation Discussion 0055
NWS Weather Prediction Center College Park MD
542 AM EST Sat Feb 10 2024

Areas affected...portions of southeast TX & western LA

Concerning...Heavy rainfall...Flash flooding possible

Valid 101041Z - 101641Z

Summary...A low-level convergence zone is expected to gather an
increasing amount of thunderstorm activity through the morning
hours.  Hourly rain totals to 2" with local amounts to 4" are
possible.

Discussion...A shortwave moving near El Paso has been enhancing
outflow aloft across much of central and eastern TX and slowly
eroding CIN.  Precipitable water values near the TX coast have
risen into the 1.5-1.75" range per GPS data.  MU/ML CAPE has been
more or less stable near 250 J/kg on SPC mesoanalyses.  A
low-level convergence zone, occasionally showing up in the surface
pattern but more evident at 925 hPa and 850 hPa, has been moving
little near the Middle and Upper TX coasts and across western LA
within the warm sector of a low over TX, which helped focus a band
of showers hours ahead of what was suggested by the 00z HREF. 
Around 3 a.m. CST, there was a spike in hourly rain totals up to
1.5", also earlier/more than anticipated by the guidance, from the
Galveston/Harris County border into southeast Liberty County.

Various model fields suggest that instability will be stable or
slowly increase initially, before going upward faster later this
morning near the southern end of the low-level convergence zone
either due to daytime heating or the approaching shortwave.  A
boundary itself may shift slightly northward.  The past few HREF
runs have been slowly trending to a wetter signal across this
region, focusing more on this convergence zone and less on the
front to the north.  As the shortwave near westernmost TX
approaches, the expectation is for convective coverage to increase
near the convergence zone, particularly after 13z per the 00z/06z
HREF guidance is to be believed.  The 00z ARW appears best placed
with what's expected, based on what's occurred thus far, though
its amounts could be a little light.  Hourly rain totals are
expected to peak in the 2" range, with local amounts to 4" being
possible, which would exceed the three hour flash flood guidance. 
Any heavy rain-related issues would be isolated to widely
scattered, with urban areas most sensitive.

Roth/Asherman

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...HGX...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   31799320 31209252 30029415 28999604 29509646 
            30789509 

420 
AWUS01 KWNH 062201
FFGMPD
CAZ000-070600-

Mesoscale Precipitation Discussion 0054
NWS Weather Prediction Center College Park MD
501 PM EST Tue Feb 06 2024

Areas affected...Southern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 062200Z - 070600Z

SUMMARY...Localized flash flooding will remain over southern CA
over the next several hours. Peak rainfall rates near 0.5 in/hr
are expected but should remain very localized across the region.
However, saturated grounds will continue a threat for additional
flooding and debris flows.

DISCUSSION...GOES West water vapor imagery and KSOX reflectivity
at 2120Z showed a low level vorticity max spiraling into the Los
Angeles metro, out ahead of the base of a large scale mid to upper
level trough advancing eastward across CA. Water vapor imagery
also showed a pair of mid to upper level vorticity maxima offshore
of southern CA with locally moderate to heavy rain ongoing across
eastern Ventura County into Los Angeles County in association with
lift ahead of the vorticity maxima. Cold mid-levels, 500 mb
temperatures near -26 C, were supporting weak instability near 500
J/kg along the coast as seen on the latest SPC mesoanalysis.
Earlier rainfall rates peaking near 1 in/hr were observed in the
Los Angeles metro, but precipitable water values are beginning to
lower and better large scale forcing has shifted to the east.

Across Santa Barbara, Ventura and Los Angeles counties, slow
movement of moderate to heavy rain is expected ahead of the
offshore vorticity maxima with 0-6 km mean winds of less than 10
kt across the region and only slow translation of forcing. Farther
south down the coast, onshore 850-700 mb winds of 20-30 kt into
Orange and San Diego counties should maintain over the next
several hours. Scattered showers and perhaps a thunderstorm are
expected to impact the region through early overnight and while
wetter antecedent conditions were located farther north up the
coast, localized potential for flash flooding from hourly rainfall
up to about 0.5 inches will still remain.

The entire southern CA coast to roughly 6000 ft in elevation along
the Transverse and Peninsular Ranges will continue to have a
localized threat for flash flooding and debris flows from heavy
rainfall. Additional rainfall totals through 06Z of 1 to 1.5
inches are expected.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34801981 34581917 34281807 34261713 33991683 
            33451658 32811648 32581641 32391643 32341697 
            32411720 32811747 33261777 33441800 33621851 
            33791878 33961917 34171968 34432014 34722010 
            

766 
AWUS01 KWNH 062109
FFGMPD
AZZ000-CAZ000-070300-

Mesoscale Precipitation Discussion 0053
NWS Weather Prediction Center College Park MD
408 PM EST Tue Feb 06 2024

Areas affected...lower CO River Valley into western AZ

Concerning...Heavy rainfall...Flash flooding possible

Valid 062106Z - 070300Z

Summary...Areas of flash flooding may develop across western AZ
back to far southeastern CA through 03Z. Shallow convective cells
are expected to develop later this afternoon with areas of
training after 00Z. Rainfall rates of 0.5 to 1.0 in/hr will be
possible within areas of training but may locally exceed 1 in/hr.

Discussion...2030Z GOES West water vapor imagery showed a
neutrally oriented and elongated mid to upper level trough
extending from northern CA into the eastern Pacific, just west of
120W. The trough was moving east with a dry slot noted from
northern Baja California into eastern CA/western AZ and southern
NV. Low level moisture advection was occurring just ahead of the
dry slot a seen on layered PW imagery from the lower CO River
Valley into western AZ. However, an 18Z sounding from Yuma showed
zero instability despite a precipitable water value just over 1
inch, due to a relatively warm 700-500 mb layer.

Forcing for ascent will increase as the upper trough axis to the
west continues to push eastward over the next 6 hours. Cooling of
the 700-500 mb layer should allow instability to increase with
recent forecasts from the RAP/HRRR showing up to ~500 J/kg MLCAPE
developing through 00Z over western AZ. Aloft, the left exit
region of a strong upper level jet max (~150 kt at 250 mb) is
forecast to maintain favorable lift over western AZ. An increase
in shallow convective cells is anticipated to occur near 00Z in
the vicinity of the lower CO River Valley, with expansion into
western AZ through 03Z. While steering flow should keep individual
elements moving along at 3o to 40+ kt toward the NNE, this
orientation is expected to align with a slow moving axis of
similarly oriented convergence in the 850-700 mb layer over
western AZ, allowing for training. In addition, roughly 30 kt of
700 mb flow will focus an upslope component to the flow into the
Mogollon Rim, supporting enhancement of rainfall below ~7000 ft.
While precipitable water values are forecast to decrease beyond
00Z with the eastward translation of the low level moisture axis,
a brief window of overlap with higher instability/moisture could
allow for 0.5 to 1.0 in/hr rates (perhaps locally higher) to
support some 1 to 2+ inch totals through 03Z and possible flash
flooding from the lower CO River Valley into western AZ.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FGZ...PSR...TWC...VEF...

ATTN...RFC...CBRFC...CNRFC...NWC...

LAT...LON   35861385 35721317 35331278 35021227 34941182 
            34511177 33831221 32771288 32031353 32101427 
            32531504 33491513 34091493 34901458 35701453 
            35851419 

710 
AWUS01 KWNH 061603
FFGMPD
CAZ000-062130-

Mesoscale Precipitation Discussion 0052
NWS Weather Prediction Center College Park MD
1102 AM EST Tue Feb 06 2024

Areas affected...Southern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 061600Z - 062130Z

SUMMARY...A flash flood threat will continue for southern CA
through the early afternoon. While the coverage and magnitude of
heavy rain will be reduced compared to the previous couple of
days, sensitive grounds will maintain the risk for runoff from an
additional 1 to 2 inches of rain.

DISCUSSION...GOES West water vapor imagery showed an elongated mid
to upper level low/trough centered west of the central CA coast
with a number of smaller scale vorticity maxima embedded within
the base of the trough off of southern CA. Two of the vorticity
maxima were located ~125 miles SSW of Point Conception and along
120W at 1530Z, tracking toward the east. 12Z soundings from VBG
and NKX indicated PWATs of 0.6 to 0.9 inches, as the core of the
moisture plume has shifted east into the lower CO River Valley but
700-500 mb lapse rates of 7.4 C/km at NKX were an indicator of the
upstream environment, closer to the core of the mid-level low.
Radar and infrared imagery showers ongoing showers into Ventura
and Orange counties with moderate to heavy rain.

As the mid-level low/trough axis continues to translate
southeastward through the afternoon, 850-700 mb winds are expected
to vary in magnitude (<10 kt for the Transverse Ranges up to ~30
kt for San Diego County) but veer from their present S and SW
orientation. PWATs are expected to remain similar to their 12Z
values with only slight lowering through 21Z but the steeper
upstream lapse rates will be shifting southeastward with time and
supporting up to 250-750 J/kg MUCAPE across southern CA. Forcing
ahead of the vorticity maxima off of the southern CA coast should
continue to shift east through 21Z with an increase in showers and
shallow convective cells beneath the cold core aloft. Brief
training should support isolated 0.5 to 0.75 in/hr rates but the
majority of rain rates should remain in the 0.1 to 0.3 in/hr
range. Given the extreme rainfall observed over the past 48 hours
and areas of ongoing flooding throughout southern CA, the addition
of 1 to perhaps 2 more inches of rain will continue the threat for
flash flooding and debris flows.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   34361830 34291782 34231757 34171708 33931676 
            33291656 32791636 32471639 32341697 32321728 
            32571758 33051779 33411812 33831916 34071937 
            34321904 

953 
AWUS01 KWNH 060430
FFGMPD
CAZ000-061500-

Mesoscale Precipitation Discussion 0051
NWS Weather Prediction Center College Park MD
1130 PM EST Mon Feb 05 2024

Areas affected...Southern California...

Concerning...Heavy rainfall...Flash flooding possible

Valid 060430Z - 061500Z

SUMMARY...Warm conveyor belt finally pushes through San Diego
county and the Peninsular Ranges with occasionally moderate
rainfall rates up to .33"/hr & additional 1-1.5" totals
maintaining any ongoing flooding.   Additional, scattered to
widely scattered narrow core convection may occur with rates up to
.5" and totals of .75-1.25" across saturated areas may result in
localized possible flash flooding through early morning.

DISCUSSION...CIRA LPW denotes the core of the remaining AR/Warm
conveyor belt along the cold front is currently directed at
eastern Orange county into San Diego county and points south into
Baja California.  A narrow ribbon of 1" total PWATs (generally
below 500mb) continues to be advected by southwesterly 25-40kts of
LLJ from 850-700mb, though that axis is obliquely oriented to the
Peninsular range, the depth of moisture and winds still supports
400-500 kg/ms of IVT this will support a few hours remaining of
.25-.33"/hr rates across the Peninsular Range with additional
totals reaching 1" and maybe near 1.25" at best oriented peaks
within the range.  While this area has not seen the dramatic
rainfall totals, prior bout earlier this week still depicts a
fairly well saturated upper soil ratio (55-70%) which keeps the
0-40cm layer in the 75th to 85th percentile, suggesting above
normal run-off is probable, with rapid onset/flash flooding
condition possible along some already above normal creeks/streams.

Further West...
GOES-W WV suite depicts the remaining upper-level closed low has
opened into a more SSW to NNE oriented trough axis from NW CA to
just northeast of the 30N130W benchmark.  This trof continues to
advance eastward providing modest height-falls but more
importantly, increasing cold air aloft.  This supports steepening
lapse rates.  While the low levels have been scoured a bit,
sufficient lingering moisture and some localized higher
temperatures in the mid to upper 50s through the Channel Islands
and coastal regions of Santa Barbara toward Ventura county are
starting to see an uptick in instability for some widely scattered
to scattered convective cold air showers to develop within the
weak DPVA and divergent flow along the left exit of the 150kt jet
core nosing into northern Baja California.  Given the favorable
large scale ascent, a few of areas of remaining moisture and low
level convergence within the California Bight may enhanced for
shallow convective cores capable of modest but sufficient moisture
flux to support up to .75"/hr rain rates.  Low level flow has
weakened and so, steering flow for the shallow cells may be a bit
more chaotic and slow moving especially along the Santa Barbara to
Los Angeles County coastal area including some convergence near
some of the Channel Islands, so duration is likely to be less than
an hour, but some may linger enough for localized totals of
.75-1.25" through early morning.  Given the area has hydrophobic
soil or still ongoing flooding...even these narrow core convective
cells will have the potential to induce localized flash flooding.

While there is already ongoing/remaining flooding across the Los
Angeles Basin, the Flash Flooding tag for this MPD is considered
Possible for potential for new incidents through 15z on Tuesday
morning, both with the AR/Warm Conveyor Belt as well as the
shallow scattered convective cores nearer the approaching
mid-level trough axis. 

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...LOX...SGX...

ATTN...RFC...CNRFC...NWC...

LAT...LON   35022040 34721991 34551914 34331832 34251747 
            34001702 33471658 32681650 32511716 32761783 
            32741853 32961908 33291966 33992046 34602074 
            34902070