FXUS64 KFWD 190925

Area Forecast Discussion
National Weather Service Fort Worth TX
425 AM CDT Thu Sep 19 2019

/Through Friday Night/

The theme through the end of the week continues to be the remnants
of Imelda, which are currently taking residence near Lufkin, Texas
early this morning. This system is expected to continue its N-NNW
drift today across East Texas, in the vicinity of our far eastern
counties. This system should continue to slowly track toward the
I-20 corridor in East Texas through this evening. The latest CAMs
and short-term deterministic models show any closed surface
reflection of this system losing definition and morphing into an
inverted northeast-southwest surface trough across our eastern
Texas counties by tonight. However, any mid-level reflection of
Imelda's remnants look to be preserved across East Texas with the
bulk of the richer tropical moisture remaining east of our area,
over the Texas/Louisiana border region, then into the Ark-La-Tex
on Friday.

As for how this parlays into sensible weather across North and
Central Texas, the most likely areas to see beneficial rainfall
will be across our far eastern counties, well to the east of I-35.
Areas further west will not get in on much of the rain chances
until we move into Friday, at which time the mid-level forcing
will be more due to shortwave energy lifting northeast overhead in
advance of a western CONUS trough. Any of Imelda's residual mid-
level energy looks to shift quickly eastward toward the Lower
Mississippi Valley Friday night. So what does this mean with
regard to the heavy rainfall threat across our eastern counties?
There will still be localized pockets or bands of heavier rainfall
near and southeast of the aforementioned inverted surface trough.
This surface trough will act as a low-level focus beginning late
tonight and continuing on Friday. Any localized heavy rainfall
amounts in excess of 2 inches will likely occur near this feature,
well east and southeast of the DFW Metroplex. The widespread
heavier rains will remain further east over Far East Texas into
extreme western Louisiana.

Though cloud cover from this system will play a role in holding
high temperatures down in the 80s across much of the CWA, hotter
values back in the 90s may reach areas as far east as the I-45
corridor by Friday afternoon. The added partial insolation and
heating will bring higher instability values to the west of
Imelda's slow northward track across Far East Texas and allow for
some strong storms containing localized heavy downpours, increased
lightning strikes, and very gusty downburst winds. Finally, a few
CAMs do indicate slightly backed, enhanced southerly 0-1km flow
of 15-25 knots. This backed backed flow in the boundary layer
noted on model sounding hodographs indicate that discrete cells on
Friday will need to be monitored closely for at least weak low-
level mesocyclones. Thankfully, a rapid downtrend in convective
activity is expected after sunset Friday evening as stronger
ascent from Imelda's remnants continue shifting east away from
North and Central Texas. Those attending local high school
football games or enjoying other outdoor venues or activities
should see mostly rain-free conditions with little in the way of
impacts from weather Friday evening. There will even be increasing
southerly breezes of 10 to 15 mph, with temperatures in the upper
70s to lower 80s.



/This Weekend Through the First Half of Next Week/

Relatively speaking, this weekend's weather will be quiet and hot
with highs above climatological normals to end (astronomical)
summer across North and Central Texas. The area will be under the
influence of increasing southwest flow aloft and subsidence as we
remain located between a longwave trough over the Central Rockies
and the western edge of a subtropical mid-level ridge across the
central Gulf Coast and southeast CONUS. This will likely provide
an increasingly warm elevated mixed layer (or cap) in the 850mb-
500mb layer. A strong southerly fetch below 850mb will keep the
humidity in place through the weekend, along with the potential
for a few late day showers and storms across our far southeast
counties through sunset each day. Otherwise, dry, breezy, and warm
conditions are expected.

Entering the first days of fall, it won't feel fall-like, that's
for sure. The subtropical ridge does briefly weaken in response to
a strong shortwave disturbance moving across the Central and
Northern Plains. Unfortunately for our area, a weak surface cold
front will stall to the north across Northwest Texas and Oklahoma.
The bulk of the associated thunderstorm activity and cooler air
look to remain well north of the Red River though a few storms
could propagate across the Red River Valley on Monday, and I have
low rain chances for that possibility. The remainder of the area
will remain high and dry under stronger large-scale subsidence. If
you were hoping for cooler weather, you still have a bit of a
wait to endure. Highs Monday will continue to be above normal,
with many areas reaching the lower to mid 90s. Beyond Monday,
variability within the deterministic medium range models and their
ensemble brethren increases. The GEFS maintains a cut-off low
near the Great Basin, with strong mid-level ridging across our
area. The EPS shows a weaker and more progressive open mid-level
trough over the New Mexico/Arizona border and a weaker ridge aloft
over the central Gulf Coast. With these uncertainties existing,
the hot temperatures will remain, while I held close to blends on
low daily rain chances.



.AVIATION... /Issued 1136 PM CDT Wed Sep 18 2019/
/06Z TAFs/

As Tropical Depression Imelda continues its slow northwestward
movement across southeast Texas, rich tropical moisture will aid
in the development of low-end MVFR to high-end IFR ceilings across
all TAF sites after 10-11Z. Several airports east of the TAF sites
are already reporting ceilings ranging from FL007 to FL025, and
expect a westward expansion to continue in the coming hours. Opted
to push back the arrival of stratus to 10-11Z based on the latest
high res guidance.

Ceilings across the Metroplex will likely struggle to lift to VFR
and will remain closer to high-end MVFR near FL025 through the
remainder of the day. For Waco, it is possible ceilings may lift
to near or above FL035 as drier air on the western side of the low
aids in scattering the stratus by the afternoon hours.

As far as precipitation affecting the TAF sites on Thursday, the
greatest potential remains during the afternoon and evening hours
as Imelda moves inland. Similar to previous days, will maintain a
mention of VCSH from 19-01Z and will allow future issuances to
address the potential for SHRA/TSRA.

SREF guidance indicates another round of stratus early Friday
morning, with a greater potential across the Metroplex terminals
as low-level moisture edges northward. CAMs also develop scattered
showers/storms during this time period, but confidence in timing
is too low to mention in the DFW TAF.



Dallas-Ft. Worth 87 74 90 74 91 / 20 30 50 10 5
Waco 89 73 93 73 93 / 30 30 40 5 5
Paris 84 71 82 71 86 / 40 60 70 20 10
Denton 87 70 89 74 90 / 20 30 50 20 10
McKinney 86 71 88 74 89 / 30 40 60 20 10
Dallas 87 75 90 75 91 / 30 40 50 10 5
Terrell 84 73 89 74 91 / 40 50 60 10 5
Corsicana 84 72 89 73 89 / 40 50 50 5 5
Temple 91 75 92 73 91 / 30 30 30 5 20
Mineral Wells 88 70 91 71 91 / 10 10 40 10 5




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