410 
FXUS62 KJAX 010823
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
423 AM EDT Wed Apr 1 2020

...DRY WITH SEASONABLY COOL NIGHTS FOR THE REST OF THE WEEK... 
...ROUGH SURF AND A HIGH RISK OF RIP CURRENTS AT AREA BEACHES THIS
WEEKEND...

.CURRENTLY...
Early morning surface analysis depicts strengthening low pressure
(996 millibars) near North Carolina's Outer Banks accelerating 
northeastward, with a trailing strong cold front moving southward
through the Florida peninsula. Meanwhile, weak high pressure (1017
millibars) was building into the lower Mississippi Valley from
eastern Texas. Aloft...a potent shortwave trough pivoting through
the Mid-Atlantic states was being absorbed into a larger cutoff
trough positioned over eastern Canada and New England. Following
the passage of a squall line that produced at least two tornadoes
in the Suwannee Valley and coastal northeast Florida on Tuesday
afternoon and early evening, cold air advection is finally taking
hold of our weather pattern on the heels of gusty northwesterly
winds. Wrap-around moisture from ongoing bombogenesis off the
Carolina coast in the form of stratocumulus cloud decks are
dissolving as the low and mid levels quickly dry out, with
cloudiness now mostly relegated to the Savannah River Valley.
Temperatures at 08Z range from near 50 along the Altamaha/Ocmulgee
Rivers to near 60 in north central and coastal northeast Florida.
Dewpoints have been rapidly falling overnight and ranged from the
upper 30s in our northern counties to the lower 50s at the coast 
and in our southern counties. 

.NEAR TERM [Through Thursday]...

A blocked weather pattern is becoming established over the western
Atlantic waters that will trap the strengthening storm system off
the New England and Mid-Atlantic coasts for the rest of this week.
This will keep a dry west-northwesterly flow pattern aloft in
place over our region as weak surface ridging gradually builds
into the southeastern states. Breezy northwesterly winds this
morning will shift to northerly with gradually diminishing speeds
at inland locations this afternoon, while breezy conditions
prevail at the coast through sunset. Full sunshine will offset
cold air advection today, with highs mostly reaching the 70-75
degree range. These values are about 3-6 degrees below early
April climatology. 

Some very thin cirrus may begin to invade our skies toward sunrise
on Thursday, with fair skies otherwise prevailing and winds
decoupling early this evening inland. Lows will fall to the low to
mid 40s inland, while northerly winds of 5-10 mph overnight will
keep coastal lows mostly in the lower 50s. 

Heights aloft will rise slightly on Thursday and a loose local
pressure gradient will prevail, which will allow for prevailing
northeasterly winds at coastal locations. A 110-knot jet streak
migrating through the southeastern states may spread some slightly
thicker cirrus over our region, but filtered sunshine, light winds
and a very dry air mass will allow highs to reach the mid to upper
70s at most inland locations, while coastal highs stay in the
upper 60s to near 70 due to onshore winds.

.SHORT TERM [Thursday Night Through Saturday Night]...

Zonal west-northwesterly flow will prevail, and surface ridging
will begin to strengthen early this weekend along the Carolina
coast. Cirrus will continue to occasionally move through our
skies, but a dry air mass and slowly rising heights should allow
for a gradual warm-up, with seasonably cool overnight lows
persisting as winds continue to decouple early each evening. A 
weak shortwave trough migrating across the northern Gulf of Mexico
may begin to spread some thicker cloud cover into our region by
late Saturday night. Lows Thursday night will again fall into the
40s inland and near 50 at the coast. Highs Friday will approach 80
inland, with light onshore winds keeping coastal highs in the low
to mid 70s. Temperatures will continue to slowly moderate into the
weekend, with highs on Saturday reaching the low to mid 80s
inland, while 70s prevail at the coast as light onshore flow
prevails. Increasing cloud cover should keep lows in the mid to
upper 50s inland on Saturday night.

.LONG TERM [Sunday Through Wednesday]...

The blocked weather pattern over the western Atlantic will break
down late this weekend as a large trough impacts the U.S. west
coast, which should promote a gradually strengthening ridge over
the Gulf of Mexico that will build over the Florida peninsula
early next week. A weak shortwave trough could promote just enough
isentropic lift for a few showers over inland portions of
northeast and north central Florida on Sunday, but long-term
models are trending drier and blended POPs are now only isolated
on Sunday. A few showers may be possible by Monday night or
Tuesday in southeast Georgia on the northern periphery of the 
building ridge to our south as weak shortwave energy migrates
through the southeastern states. Weak shortwave energy may also
move out of the Gulf of Mexico by Tuesday or Wednesday, which
could develop isolated to widely scattered diurnal convection over
our area. Temperatures will slowly warm through the 80s each day,
with highs possibly approaching 90 degrees at inland locations
towards midweek. Lows will also warm into the 60s through midweek. 

&&

.AVIATION...
[Through 06Z Thursday]

Mainly VFR conds expected behind the frontal passage as band of
BKN 3500ft strato-cu clouds pushes through the TAF sites over the
next 3-5 hours with TEMPO gusts to 15G25 knots from the NW at
times. Otherwise becoming SKC by this afternoon with light north
winds developing after sunset.

&&

.MARINE...

Strengthening low pressure moving off the southeast U.S. coast
will decelerate off the New England coast on Thursday and will
then meander off the Mid-Atlantic coast through Friday night.
Strong northwesterly winds in the wake of this storm system will
continue this morning, with Small Craft Advisory conditions
continuing offshore through mid-afternoon, while wind speeds fall
back to Caution levels near shore this afternoon. High pressure 
will gradually weaken as it builds over the southeastern states 
Thursday and Friday. Caution level seas will continue offshore on
Thursday and Friday. Low pressure over the western Atlantic will 
then weaken and move east of Bermuda this weekend as high pressure
slowly strengthens along the southeastern seaboard. Large swells 
and rough surf from the meandering ocean storm system will impact 
our waters this weekend and early next week. Small Craft Advisory
level seas should develop offshore by Saturday evening, with
Caution level seas developing near shore. Atlantic ridging will 
then shift south of the northeast Florida waters by late Monday, 
resulting in prevailing offshore winds by Tuesday.

&&

.FIRE WEATHER...

Breezy north-northwesterly surface and transport winds will
continue to usher in a cooler and drier air mass over our region
today. Sustained surface winds around 15 mph will slowly diminish
inland this afternoon, with breezy conditions continuing through 
late afternoon at coastal locations, where surface winds will 
shift to northerly. Minimum relative humidity values will approach
critical thresholds for inland portions of northeast and north 
central Florida this afternoon, but wind speeds will fall below 15
mph this afternoon at these locations, and Red Flag Conditions 
are not anticipated. Minimum relative humidity values will again 
approach critical thresholds at most inland locations on Thursday 
afternoon and will then fall below critical thresholds at most 
inland locations on Friday afternoon. 

&&

.HYDROLOGY...

Minor flooding is expected to resume along the Altamaha River near
the Baxley gauge by Thursday as runoff from rainfall well upstream
continues to be routed downstream. Other locations along the
Altamaha will likely remain at Action levels.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  69  43  73  46  79 /   0   0   0   0   0 
SSI  69  53  68  50  73 /   0   0   0   0   0 
JAX  72  45  75  47  78 /   0   0   0   0   0 
SGJ  71  54  69  51  74 /   0   0   0   0   0 
GNV  74  42  78  48  81 /   0   0   0   0   0 
OCF  75  45  79  49  82 /   0   0   0   0   0 

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...Small Craft Advisory until 4 PM EDT this afternoon for Waters 
     from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 
     NM-Waters from Fernandina Beach to St. Augustine FL from 20 
     to 60 NM-Waters from St. Augustine to Flagler Beach FL from 
     20 to 60 NM.

     Small Craft Advisory until 11 AM EDT this morning for Coastal 
     waters from Altamaha Sound to Fernandina Beach FL out 20 NM-
     Coastal waters from Fernandina Beach to St. Augustine FL 
     out 20 NM-Coastal waters from St. Augustine to Flagler 
     Beach FL out 20 NM.

&&