648 
FXUS64 KFWD 041206
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
606 AM CST Tue Feb 4 2020



.SHORT TERM... /NEW/
Update:

The main changes to the forecast with the early morning update was
to adjust PoPs with latest guidance and to match the current
trends. The leading shortwave that produced rain across the area
tonight is leaving the area with only lingering light rain North
of I-20 and along/west of the I-35 corridor. Winds and temperatures
were also adjusted to reflect the current location of the cold 
front...which is currently analyzed across Cooke to Wise to 
Eastland counties and will continue moving east/southeast through 
the morning. There is a roughly 15-20 degree temperature change 
from the air directly ahead of and a few miles behind the front. 
For most of us...the warmest temperatures of the day will be this 
morning with falling temperatures expected through the day along 
with a brisk north wind.

The 06Z model suite in regards to the upcoming system tonight and
Wednesday remains largely unchanged from the 00Z guidance. The 
guidance is still indicating a vigorous shortwave moving into and 
through the area tonight and tomorrow morning. The area most likely
to receive accumulating sleet and snow remains to be west of I-35
and north of I-20 with the highest accumulations remaining north 
and west of our forecast area. Additional details regarding our 
thoughts on the system can be read below.

Bonnette

Previous Discussion... /Issued 237 AM CST Tue Feb 4 2020/ 
/Today through Wednesday Night/

A multi-faceted storm system will move through the region over 
the next few days...


 This storm will bring:
1) Much colder temperatures and gusty north winds to the region
   today 
2) The chance for a few isolated strong thunderstorms this
   afternoon and evening east of I-35 and south of I-20 
3) Wintry precipitation across Big County, NW Texas, and the 
   western parts of the Metroplex tonight and Wednesday, with 
   lingering light snow possible Wednesday night across the 
   entire forecast area.


 Impact Focus:
At this time, the area northwest of the Metroplex is forecast to 
be most impacted by accumulating sleet and snow late tonight 
through Wednesday morning. We're expecting a band of sleet to move
through in the early morning hours Wednesday, with accumulating 
sleet likely. This band is forecast to move along and just north 
of the I-20 corridor west of I-35W and along the I-35W/I-35 
corridor north of D/FW near daybreak Wednesday morning. Areas west
of this line can expect a change over to all snow with 
accumulating snow likely.

The precip intensity will gradually weaken over the course of the
day Wednesday with lingering light snow/sleet possible NW of D/FW
and light rain SE of D/FW through the day. The dividing line
between rain and wintry mix Wednesday is still very much in
question at this time, but the current trend is that the dividing
line lies near or just west of the Tarrant/Dallas and Denton/Collin
county lines.

Colder air moving into the region will allow a change over to all
snow (with little to no accumulation) across the entire forecast 
area Wednesday night with all precip coming to an end by daybreak
Thursday.


 Uncertainties:
There is still uncertainty as to how far east the band of sleet
tonight/Wednesday morning will develop and how much snow will
accumulate behind this line. The other large uncertainty is how
far east the diving line between wintry precip/rain will be
Wednesday.

Additional details regarding precip amounts and precip types will
largely come into focus over the next 12-24 hours.


 Meteorological Details: 
Today...A cold front is currently analyzed along the Red River and
will make its way south across North and Central Texas today.
Gusty south winds ahead of the front are transporting a warm/humid
airmass north with mid to upper 60 degree temperatures currently
observed across the region. Not much of a cool down tonight is
expected as widespread cloud cover and scattered precipitation
continue due to a weak leading shortwave trough moving through. As
this trough continues east today, most of the precip will come to
and end with any lingering precip remaining along the leading edge
of the cold front. Surface dew points in the mid 60s ahead of the
front should help allow MUCAPE around 1000 J/kg to develop, which
when combined with the strong forced ascent in the low levels,
should develop at least isolated showers and thunderstorms this
afternoon east of I-35 and south of I-20. A few strong
thunderstorms are possible, however, meager lapse rates aloft 
will keep the severe threat at bey.

Tonight...The cold front and shallow cold airmass will have made
its way all the way through Central Texas by sunset. A potent 
shortwave trough will eject out of the Desert SW in the early 
evening hours...developing an area of elevated precip across West
Texas and Big County. This will move into our far western counties 
before midnight. A brief period of rain is possible, but a rather 
quick change over to sleet and snow is likely for the ares west of
Highway 281. The change over will take a bit more time between 
Highway 281 and I-35, however, as previously mentioned, we expect 
a convective band of sleet to develop around/after midnight. This
band is due to steepening lapse rates aloft and increasing MUCAPE
forecast to develop overtop of the cold airmass. This will allow 
the sounding to "wet bulb" near freezing, and the thermal profiles
favor accumulating sleet to develop. To the west of this band of 
sleet, a total change over to snow is expected. Synoptically 
speaking...this band should reside between the leading edge of the
H850 front to the south and the secondary H850 thermal gradient to
the north, where frontogenesis is favored. Where these two
boundaries settle will have to be closely monitored since it 
will have large implications on the forecast.

Wednesday and Wednesday Night...The shortwave trough will continue 
east by the afternoon, and increased frontogenesis will then drive
the secondary H850 thermal gradient through the area Wednesday, 
further reinforcing the cold air aloft. While the heaviest precip 
will occur before noon Wednesday ahead of the shortwave, any
lingering precip should gradually change over to snow by the evening
hours. Recent trends have indicated yet another shortwave trough 
moving through South Central texas Wednesday night, brining an 
enhanced band of rain/snow to Central and East Texas. Little to no
accumulation is expected with this time due to the fast moving 
nature of this shortwave. This too, will have to be monitored over
the next day or so.

Bonnette

&&

.LONG TERM... /Issued 309 AM CST Tue Feb 4 2020/
/Thursday Through Monday/

After our first taste of winter weather in quite a while, a
moderating trend is expected as we move through the end of the
week. Thursday will remain seasonably cold after a chilly start in
the 20s Northwest (where some residual sleet/snow accums may 
still be around) to the lower 30s elsewhere. Our vigorous mid 
level trough will exit stage right with dry northwest flow aloft 
and mass subsidence give the area it's first taste of abundant 
sunshine and moderating temperatures. A broad and diffuse surface 
high will be draped across Central and East Texas. Resultant west-
southwest winds near 10 mph should help most of the area rise into
the lower 50s, though areas that saw any sleet/snow accumulation 
in the northwest will see cooler highs in the mid-upper 40s. After
another chilly start in the 20s and 30s Friday morning...light 
west winds and abundant insolation will help highs Friday afternoon
warm well into the mid 50s Red River Valley to the lower to mid 
60s elsewhere as our once amplified mid level northwest flow
dampens. 

A reinforcing surge of continental air arrives on Saturday with a
dry and much less noticeable cold front moving through the region
with support from a strong mid level shortwave moving through the
Mid Mississippi/Tennessee Valleys. Any notable moisture for any 
light rain should remain just east of our area, as will the
stronger low level cold advection, however we will still manage 
to rise into the 50s across North Texas into the 60s across
Central Texas. The reinforced dry airmass in place across the 
CWA should result in a broad diurnal ranges on Sunday, as the 
resultant surface high shifts quickly east of the area with strong
lee-side pressure falls across the Central High Plains. Despite 
an increase in mid-high clouds embedded in increasing southwest 
flow aloft in advance of our next significant system, gusty south 
winds 15-20 mph Sunday and partial sunshine should help all but 
the the immediate Red River Valley warm well into the 60s. 

With the past few cold fronts beforehand having scoured the Gulf 
shelf off the immediate Texas Coast, I only expect modified 
moisture return with surface dew points recovering back into the 
40s/50s, as widespread stratus overspreads the CWA Monday morning. 
Enough moisture depth may surge up across East Texas for a few 
showers late Sunday night into Monday morning east of I-35, but 
really nothing of significance. The stratus and gusty south winds 
will result in a warm start to your work week next week with lows
only falling into the mid 40s to mid 50s. As southwest flow 
continues amplifying in the mid levels, several impulses will 
transverse northeast across the area with a gradual increase to 
our rain chances within the warm sector. Steepening mid level 
lapse rates may offer a few rumbles of thunder by Monday
afternoon, but nothing strong or severe in nature is expected 
due to very limited instability based near the surface. A cold 
front will arrive by Monday night, however, highs on Monday in 
advance of this cold front will still manage to rise into the 60s 
for the majority of the area. 

05/

&&

.AVIATION... /NEW/
/12Z TAFs/

Concerns: MVFR/IFR ceilings, wind shift this morning, wintry
precipitation tomorrow morning

A strong cold front is making its way into the northern fringes of
D10 ATTM, and is expected to move through all D10 terminals 
between 1330-1530Z today. Ahead of the front, south winds around
10 kts will continue with MVFR ceilings prevailing. A few patches
of IFR and VFR ceilings are scattered about D10, but the front is
expected to lower all terminal to IFR after frontal passage. The 
guidance is poorly handling the ceiling trends, therefore the 
current TAFs are lower than any suggested guidance (based upon 
upstream observations). The ceilings are expected to gradually 
lift to MVFR through the afternoon with a 30% chance of going VFR 
between 00-03Z this evening. Nocturnal cooling and weak isentropic
ascent aloft after sunset will once again drop the ceilings to 
low end MVFR and/or high end IFR.

Overnight...a shortwave trough will move into the region from the
west creating scattered rain showers with wintry precip
potentially mixed in. The current TAF package does not include 
any wintry precip due to the lack of confidence of the timing and 
intensity of the precip type, but the potential for rain/sleet 
across the western half of D10 after 10Z is there. The most likely
timeframe to receive rain/sleet is between 11-14Z, with lingering
light rain/sleet mix transitioning to light (non accumulating) 
snow through the afternoon and early overnight hours. These
details will continue to be ironed out with subsequent TAF 
updates throughout the day.

Bonnette

&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    62  33  37  30  50 /  60  70  80  20   0 
Waco                65  36  40  30  54 /  20  60  60  20   0 
Paris               62  34  38  29  44 /  90  40  80  20   0 
Denton              60  32  36  28  48 /  70  70  90  20   0 
McKinney            62  33  37  27  47 /  80  60  80  20   0 
Dallas              63  34  38  31  51 /  60  60  80  20   0 
Terrell             64  34  39  30  48 /  70  50  80  20   0 
Corsicana           68  36  40  30  50 /  50  50  70  20   0 
Temple              67  37  41  30  55 /  10  60  50  20   0 
Mineral Wells       57  31  33  25  48 /  20  90  80  20   0 

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late tonight through Wednesday afternoon 
for TXZ091>093-100>103-115>118-129>131-141.

&&

$$

06/05