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Area forecast discussion
National Weather Service Fort Worth Texas
1218 PM CDT Wed Oct 23 2019



Aviation...
/18z tafs/
no major aviation weather concerns through this evening
with a mostly clear sky and a breezy south wind between 12 and 17
knots along with some gusts near 27 knots.

The cold front will move across the Red River in the pre-dawn
hours Thursday with storms likely moving into the the Bowie
cornerpost between 11z and 13z. The storms should become more
organized along the cold front as they approach the metroplex
airports late Thursday morning. For now we will include thunderstorms in the vicinity in
the extended portion of the dfw taf beginning at 19z, but a
prevailing group for thunder will most likely be introduced in the
00z taf issuance. MVFR ceilings will arrive ahead of the front
just after sunrise at all taf sites and remain in place through
the afternoon. Some brief IFR ceilings and visibility restrictions
will be likely in any thunderstorms.

The northerly wind shift associated with the frontal passage will
likely occur between 18z and 19z Thursday at the metroplex taf
sites and a few hours later in Waco.

79

&&



Short term... /issued 354 am CDT Wed Oct 23 2019/
/today and tonight/

Low level winds are on the increase due to a tightening pressure
gradient ahead of the next upper level storm system and cold
front. South winds around 45 miles per hour are already occurring at 925 mb
based on VAD wind data from The Fort Worth radar. Boundary layer
mixing will bring a component of these winds to the surface,
resulting in sustained winds of 15-20 miles per hour along with gusts at or
above 30 miles per hour by midday. Plentiful sunshine and warm air advection
will push temperatures into the 70s and lower 80s this afternoon.
The warmer temperatures will be collocated with the driest air
and driest soils across the west. For that reason we will be
issuing a grass fire danger statement for this afternoon generally
along and west of Highway 281. Fire danger will abate around
sunset as temperatures drop and winds decrease.

The cold front will be nudged southward this evening by a lead
shortwave, and should bisect Oklahoma from northeast to southwest
by midnight. Meanwhile, strengthening ascent will occur across
the Southern Plains late evening and overnight as the main upper
trough digs south across Colorado. A broken band of convection
will be the end result in the vicinity of the front, with activity
initializing just to the north of the Red River. Showers and
storms will spread southward with the front, warranting chance
pops across the northern-most zones for the overnight period. A
strong storm or two cannot be ruled out, but the lack of
instability will mitigate severe weather potential. Otherwise,
the pre-frontal environment will be warmer than the past few
nights with low temperatures ranging from the upper 50s to lower
60s.

30

&&

Long term... /issued 354 am CDT Wed Oct 23 2019/
/Thursday through Tuesday/

Big changes are on the way Thursday and for the end of the week,
as our brief reprieve of calm and nice weather comes to end. A
vigorous mid level impulse is forecast to dig southward over the
Southern Plains and rockies thanks to a strong upper jet maximum
of 130-150 knots on the backside across The Four Corners area.
Meanwhile, a strong surface cold front, being briefly held up by
strong mid level height falls across the OK/Texas panhandles and
central OK the previous night begins getting supported southward
into the area. Scattered showers and tstorms along the front will
begin to progress southeast with the surging cold front as the
vigorous mid level energy lifts east across the Texas/OK panhandles.
Showers and thunderstorms will become more numerous; especially
along and north of the I-20 corridor as large-scale ascent with
the approaching strong upper jet Max takes hold across the region.
It is very difficult to ascertain how fast the shallow, but
colder airmass undercuts this activity through the morning hours.
Even in advance of the strong cold front, surface dew points will
be only in the mid-upper 50s, with lower 60 values arriving into
central Texas for the afternoon hours.

As the cold front and intensive large-scale ascent overspread the
entire region through the afternoon hours, just about entire forward
County Warning Area will be mostly in the colder air outside of eastern parts of
central Texas with temperatures rapidly falling across the
northwest half of the area in wake of the cold front. In a
nutshell, a stormy, raw, and windy day will unfold throughout the
day. I cannot argue spc's marginal risk, even if those western
north and central Texas get undercut by the cold front. 50 knots
westerly bulk shear with lapse rates readily steepening from the
increasing ascent for at least a marginally severe hail threat. I
do have concerns for a brief 2-4 hour window Thursday afternoon
southwest of a Stephenville, Hillsboro, Hearne line where brief
warm sector MUCAPES 500-1000 j/kg could combine with the strong
winds aloft for a damaging wind and brief, enhanced hail threat. I
will stress this is not a similar set up to our extreme and
tornadic event we experienced this past Sunday night. This set up
is not anything close to that event in terms of set up, moisture,
warmth, and resultant instability. Still, the main and brief
strong- severe weather window from late morning Thursday to early
evening Friday will be marginally severe hail to quarter size or
slightly larger with elevated storms that rotate aloft. In
addition, widespread convective and at times, training heavy to
torrential downpours will likely lead to pockets of flooding.

The strong cold front will easily clear the County Warning Area by Thursday
evening, as an inverted and strengthening surface trough develops
across south Texas the Lower Texas coastal water in response to
very strong mid level height falls. Widespread showers and
isolated-scattered tstorms will continue through the evening hours
across the entire County Warning Area as the the deep mid level trough/low
remains west of the area. The forecast with regard to showery,
windy, and raw weather looks certain on Friday as lift and modest
instability continue at least for the first half of the day with
the mid level system remaining to the west. Where some uncertainty
creeps in for later Friday, Friday night(for outdoor events and
Friday night lights football games), and Saturday for outdoor
venues/games is how quickly our vigorous mid level system
progresses east across the Southern Plains. The NAM/GFS
deterministic members are much more progressive with bringing the
cyclonic curved jet maximum through the base of the system Friday
than the European/Canadian models. The cool, brisk, and raw
conditions are a certainty on Friday and have went toward colder
guidance. How long to hold onto rain and elevated convection
chances is a much more problematic scenario and could have
hydrologic impacts across the area with regard to rainfall amounts
and subsequent flooding issues. Using ensemble forecasts, I have
decided "to play the middle" on the speed and east progress of our
mid level impulse.

A gradual improvement west of I-35 with lessening rain chances
appears realistic on Friday, before I just hang onto mostly
chance pops across the much of the area Friday night with the cold
core mid level temperatures moving across the area. By Saturday,
gradually increasing subsidence should gradually shut down rain
chances after midday Saturday for the entire area. Rainfall totals
between 1-3" for the event looks likely. The eastern half of the
area that saw 1-2" amounts from our past event will see a higher
potential for run off and the potential for isolated instances of
flash flooding Thursday into friday; along mainstem rivers
possibly seeing minor flood stage at a few points. Otherwise,
surface high pressure settling across the region will provide
light west winds on Saturday, becoming southerly on Sunday under
sunny skies. This should make for more pleasant outdoor
conditions, especially on Sunday. Lows each night will be
primarily in the upper 30s out west to the 40s elsewhere. Highs in
the mid-upper 60s will warm well back into the 70s on Sunday.

Another shortwave impulse dropping southeast with the broader
longwave trough over the eastern two-thirds of the country will
help drive a reinforcing cold front into the area Monday with
highs cooling back into the 60s...before warming back to between
65 and 75 degrees next Tuesday. Another system looks to organize
across The Rockies and plains moving into mid week next week, but
as expected, models are all over the map on how this system
evolves and our environment. Right now, it appears low levels
remain dry and cool with mainly a return to elevated showers and
storms across the area.

05/

&&

Preliminary point temps/pops...
Dallas-ft. Worth 79 60 72 47 57 / 0 10 80 80 40
Waco 81 59 78 48 60 / 0 0 60 80 40
Paris 74 52 68 48 54 / 0 20 50 80 60
Denton 78 61 68 45 57 / 0 20 80 80 40
McKinney 78 58 70 47 56 / 0 10 70 80 40
Dallas 79 61 73 48 58 / 0 5 70 80 40
Terrell 77 57 74 49 57 / 0 0 50 80 50
Corsicana 79 57 77 49 56 / 0 0 40 80 50
Temple 81 61 80 47 60 / 0 0 60 80 40
Mineral Wells 80 60 67 42 58 / 0 10 80 70 30

&&

Forward watches/warnings/advisories...
none.
&&

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