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Area forecast discussion
National Weather Service Fort Worth Texas
306 am CDT sun Aug 25 2019

Short term...
/today and tonight/

Morning water vapor imagery shows a mid level shortwave moving
through the Central Plains with regional radar imagery showing two
clusters of thunderstorms ongoing in response. The larger of the
two clusters of storms is in south-central Kansas and will remain
well removed from our area. The second, smaller cluster is diving
south through western Oklahoma. We'll continue to monitor these
storms as they move southward, but they will encounter an
increasingly hostile environment (strong inhibition and weakening
deep layer shear) the farther south they travel. This should
result in a rapid diminishment in intensity and coverage through
the early morning hours. Nonetheless, we'll have some low pops
primarily along the Red River this morning for any lingering
elevated convection that survives.

Otherwise, the mid level ridge that had been squashed somewhat and
pushed westward over the last couple of days will begin to expand
back to the east today. Mid level height rises will help keep
additional showers and thunderstorms from developing this
afternoon across North Texas. The only exception may be across our
far eastern and southeastern counties where some sea breeze
activity may sneak in before sunset. We'll keep some low pops in
those areas through the early evening. Less overall cloud cover
and little chance for rain today should allow temperatures to
climb back to near 100 degrees in most locations. The only
exception may be our far northeast counties where a little more
cloud cover may keep highs in the lower/mid 90s. A mostly clear
but warm night is expected with lows in the upper 70s to near 80
degrees.

Dunn

&&

Long term...
/Monday through Saturday/

Several storylines for this week, beginning with the oppressive
heat expected on Monday...lingering into Tuesday across central
Texas. In wake of our mid level disturbance grazing US to the
northeast and east today, the strong mid level anticyclone
currently over the Great Basin area of socal/NV/and Arizona expands
east toward the region the early part of the workweek. Mid level
heights will push 592 decameters, which isn't overly intense.
However, 850mb temperatures ranging from 24 deg c east to near 30
deg c west and 925mb temps between 30 deg c east to 35 deg c west
will likely be the drivers of the very hot weather as there's a
good likelihood this air gets easily mixed down to the surface
nearly dry adiabatically. Resultant ambient high temperatures
from the upper 90s to around 105 degrees are expected across the
entire County Warning Area Monday afternoon. We do expect stronger mixing of
surface dewpoint temperatures versus the notoriously too moist nbm
values, so I used a superblend/NAM blend. Regardless, heat index
values will likely range between 106-111 degrees across much of
the area. Isolated areas across our East Texas counties may see heat
index values("feel like" temperatures) of 110-115 degrees...so
this could be our hottest day of the season in that regard. We
have withheld any issuance of a heat advisory per coordinations
with surrounding offices and wanting to let the day forecasters
get another run of data just in case a small excessive heat
warning is possibly needed across our far eastern counties on
Monday.

Thankfully, it appears some changes are on the way as we move
into the middle of the week, though some across central Texas may
disagree. Another mid level disturbance will be moving from the
Kansas/OK border toward the Ozarks Monday night into Tuesday --
drawing a surface cold front southward quickly through the Texas
Panhandle and OK into the immediate Red River valley on Tuesday.
The strong mid level anticyclone will not immediately dampen,
thus we expect strong heating/mixing in advance of this front to
slow it down and even possibly stall it just north or south of the
immediate Red River Tuesday afternoon into the evening hours.
This front will act as a low level focus as our aforementioned
shortwave adds additional ascent aloft for the development of
isolated-scattered thunderstorms north of the I-20 corridor.
Unfortunately for central Texans, the upper ridge holds strong, so
there will be a discernible difference in weather from a
continued steamy and hot central Texas to a potentially very wet
area along and north of Highway 280 from Decatur to Sulphur
Springs. Highs will range in the lower-mid 90s just south of the
cold front where a few strong to potentially severe storms will
occur to near 100 degrees in central Texas.

Another item of concern is the copious moisture expected to pool
along the surface cold front and northward toward the elevated
850mb front north of I-20. Models are are advertising near maximum
precipitable water values between 2-2.5 inches. Combine this moisture with
relatively weak steering currents aloft in a diffluent mid level
pattern and we could see a stripe of excessive rainfall of 2-3" in
spots with isolated higher amounts between the Red River and I-20
late Monday night through Wednesday night, with mid level
impulses ripping across the Red River valley. Some challenges
include mesoscale impacts and potential for some Stout storms to a
decent potential for rounds of storms to create cold pools and
push this front toward the I-20 corridor by Wednesday. So impacts
from heavy rainfall will need to be including with the downburst
wind, lightning, and even a threat for hail -- mostly of the sub-
severe variety due to high freezing levels this time of year
Tuesday and Wednesday. Stay tuned to forthcoming forecasts early
this week with regards to our mid week storms across the northern
tier counties and subsequent hazards, including flooding.

The latter part of the extended forecast does trend drier and
warmer, but not as hot as the early part of this week. There are
some details regarding the strength of the mid level ridge and
strength/amplification of the mid level flow just north-northeast
to shed some uncertainty to the late week/early week forecast. The
GFS and gefs members are the most aggressive on bringing yet
another strong northwest flow mid level impulse across the area,
with the European model (ecmwf) and Canadian models showing this, but to a lesser
degree Thursday and Thursday night. For now, remained conservative
on both pop/temps and stayed relatively close to the wpc and
National blends. These medium range models also show another
disturbance rounding the strong mid level anticyclone anchored
over the southwest US and dragging yet another cold front into at
least North Texas. Confidence beyond mid week is not very high
and we'll continue to work out the details heading into next
weekend as the upper-air network and modeling gets a better handle
regarding any systems and surface fronts next weekend.

05/

&&

Aviation... /issued 1123 PM CDT Sat Aug 24 2019/
/06z tafs/

VFR through Sunday evening with scattered high clouds
overnight and scattered cu during the day Sunday.

Thunderstorms will be less numerous on Sunday than they were the
past couple of days due to increasing subsidence under a building
upper ridge. If storms do develop Sunday afternoon they will most
likely be east of all taf sites.

A light and variable wind tonight will become southeast between 5
and 10 knots on Sunday.

79

&&

Preliminary point temps/pops...
Dallas-ft. Worth 97 80 102 81 98 / 0 0 0 20 30
Waco 99 80 103 80 102 / 0 0 0 0 5
Paris 91 74 98 75 91 / 30 0 5 30 50
Denton 96 79 102 79 97 / 5 0 0 20 30
McKinney 95 78 101 78 95 / 10 0 0 20 30
Dallas 97 81 103 81 99 / 0 0 0 20 30
Terrell 96 79 103 80 99 / 5 0 0 10 20
Corsicana 97 78 101 78 100 / 5 0 0 0 10
Temple 98 79 102 78 101 / 5 0 0 0 5
Mineral Wells 98 76 103 77 100 / 0 0 0 5 20

&&

Forward watches/warnings/advisories...
none.

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