Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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FXUS64 KFWD 190449
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1149 PM CDT Fri Oct 18 2019

.AVIATION...
/6Z TAFS/

No major changes to the aviation forecast through Saturday.
Scattered thunderstorms are ongoing to the west right now, but
these will encounter increasingly drier air the farther east they
push. We`ll continue with a VCSH in the Metroplex from 8-11Z
although there is certainly a possibility that a few rumbles of
thunder persist through the overnight. Outside of this quick shot
of convection, winds will gradually become more westerly during
the early morning hours then shift to the north around midday and
VFR conditions will prevail.

At Waco, most of the precipitation should remain to the north
overnight. Similar to the Metroplex, winds will gradually become
westerly then northerly during the day Saturday.

Dunn

&&

.UPDATE... /Issued 842 PM CDT Fri Oct 18 2019/

Current short term forecast is in good shape with only minor
tweaks needed through the next several hours. Water vapor imagery
shows a mid level shortwave spreading across West Texas this
evening. Strong mid level isentropic ascent associated with this
disturbance is occurring in the presence of ample moisture and has
resulted in widely scattered showers and a few thunderstorms.
Lapse rates will remain sufficiently steep to continue at least a
low threat for a few rumbles of thunder through tonight. The
strongest forcing for ascent is still a couple of hours away for
North Texas but we should start to see an increase in cloud cover
through midnight. Timing of any showers/storms would be between 11
pm and 4 am as the system moves through. The current forecast has
20% PoPs mainly north of I-20 to the Red River which seems
adequate at this time.

Dunn

&&

.LONG TERM... /Issued 312 PM CDT Fri Oct 18 2019/
/Saturday Night through Friday/

A filling surface low over the ArkLaTex and its attendant
frontolysizing cold front should be draped across Central and
Southeast Texas Saturday evening. A weak surface high center
should also be moving into the area from the west, allowing for
light surface winds and mostly clear skies to prevail Saturday
night. These conditions will promote strong radiational cooling
making way for a cool morning as you head outside Sunday. Also by
Sunday morning, both the low and cold front should be washed out
and overtaken by southerly flow across the region.

The increased southerly flow across the area Sunday will be a
result of a rather potent upper level system ejecting out of the
Rockies Saturday night into Sunday. This will deepen a low across
the Central Plains with an attendant cold front dipping south into
the OK/TX panhandles. An active southern branch of the PFJ overtop
of the boundary will help to promote cyclogenesis along the trailing
edge of the frontal boundary over the course of the day Sunday.
Southerly flow ahead of this low will will help draw the warmer
and moisture rich airmass pooled along south Texas northward into
Central and North Texas -- effectively acting as a warm front and
inducing a triple point across the area with a dry line extending
south across Big Country. Most areas across North and Central
Texas will experience a 15-20 degree increase in Dew Points and
~0.5" increase of PWAT values between Sunday morning and Sunday
evening. ATTM, the theta-e ridge axis looks to be aligned along
the I-35 corridor, but this could shift east/west as the synoptic
picture comes into clearer focus (more on the significance of this
below).

All of this to say that as the cold front begins making its way
through North Texas, we expect showers and thunderstorms along
the boundary Sunday night with some strong to severe storms
possible. There is small potential for a few isolated storms to
develop in the open warm sector south of the effective warm front
Sunday afternoon, however the potential of this is low ATTM since
deep layer moisture and forced ascent will likely be collocated
with the frontal boundary Sunday night. As the stronger cold front
starts pushing into North Texas, strong forced ascent will tap
into the newly advected moist airmass and develop widespread
showers and thunderstorms along the boundary, especially along and
east of the theta-e ridge axis. Deep layer shear vectors look to
be generally aligned along the boundary, therefore upscale growth
seems likely to take over soon after convective initiation forming
a linear convective system across the area. A relatively quick
moving line of showers and thunderstorms should move through North
and Central Texas, clearing the area entirely by mid to late
morning Monday.

This will usher in a much drier airmass across the area with
generally pleasant temperatures remaining in place through the
early to middle parts of next week. NAEFS and ECMWF ensemble
guidance has been indicating a progressive series of troughs
digging into the Central and Eastern CONUS mid to late next week.
Confidence continues to grow of another late-week cold front
moving through the area bringing another cool down late next week
into next weekend.

Bonnette

&&

.SHORT TERM... /Issued 147 PM CDT Fri Oct 18 2019/
/Today, Tonight, and Saturday/

Our postfrontal air mass continues to modify with steady southeast
winds. Despite the unseasonally cool start to the day, dry air and
abundant sunshine will help temperatures reach near normal highs
this afternoon, generally in the 70s.

The warm exception will be in our far western zones, where a
westerly component will push temperatures into the mid 80s. Severe
to extreme drought conditions have stressed vegetation in the
areas that will see these above normal temperatures, and with
relative humidity values dipping below 30 percent, some fire
starts may occur this afternoon. Although the winds won`t be
particularly strong, the southerly breeze and dry fuels may
enhance fire spread.

An upper trough will swing through North Texas overnight, well
ahead of an approaching cold front. While moisture will be
limited, the intensity of the lift and the available instability
may allow for a few showers and thunderstorms in areas along and
north of the I-20 corridor. This activity will shift east of the
area before the cold front arrives.

The wind shift will enter our northwest zones before daybreak
Saturday morning. With the parent trough to our east and little
cold advection behind the boundary, the front will make only slow
progress through the CWA over the course of the day. With abundant
sunshine, dry air, and a downslope component to the postfrontal
wind, Saturday afternoon`s temperatures will likely exceed
Friday`s. Despite northwest winds, much of North and Central Texas
will top 80F.

25

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    61  82  58  88  60 /  20   0   0  10  60
Waco                60  87  56  90  63 /   0   0   0  10  70
Paris               54  77  53  82  58 /  20  10   0  10  80
Denton              58  82  53  88  54 /  20   0   0  10  60
McKinney            58  81  54  87  57 /  20   0   0  10  70
Dallas              62  82  58  88  60 /  10   0   0  10  70
Terrell             58  84  55  88  61 /  10   0   0  10  70
Corsicana           60  84  57  87  63 /   0   0   0  10  70
Temple              60  87  57  89  64 /   0   0   0  20  70
Mineral Wells       58  82  52  91  53 /  20   0   0   0  50

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

91



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