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

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868
FXUS64 KFWD 192049
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
349 PM CDT Sat Oct 19 2019

.LONG TERM...
/Sunday night through next Saturday/

An active and trough-laden longwave upper pattern will continue
to dominate the Plains States through next weekend. Two distinct
weather systems will impact North Central Texas during the
forecast period - the first Sunday night, and the second in the
Thursday/Friday timeframe. Both rounds of weather will bring
widespread precipitation and repeated incursions of cool Canadian
air to the forecast area.

Short-term guidance is in terrific agreement concerning the
ejection of a strong shortwave trough out of the Central Rockies
into the Plains States Sunday night, with an associated cold front
diving southeastward toward North Texas after sunset. Plenty of
large-scale forcing for ascent will develop across the region
from late evening through the early morning hours, as these
features transit our area.

Two modes of convection still seem likely: 1) Discrete cells
along/east of I-35 and N of I-20 later Sunday evening, and 2)
Linear convection just ahead of the front from approximately
midnight through 5 am. The big question is how much discrete
convection will actually form prior to midnight. The latest CAMs
seem pretty conservative about breaking out widespread cellular
activity ahead of the front. However, given the good synoptic
forcing and cap strength appearing less prominent in the 12z model
soundings, believe there`s a reasonable chance for scattered
activity to break out - especially closer to the Red River.
Further south near the Metroplex and I-20 corridor, any pre-
frontal development is still very uncertain. For any storms that
do form, shear profiles and CAPE values augur well for supercells
and their associated severe threats. While large hail and strong
wind would be the primary risk, a low-end tornado threat can`t be
totally ruled out with these pre-frontal cells.

There`s still a fair amount of uncertainty regarding any discrete
convection ahead of the front. On the other hand, confidence is
quite high regarding the development of a broad linear
shower/thunderstorm band just ahead of the front itself. Have gone
with high likely to categorical PoPs in all areas along/east of a
Sherman-DFW-Lampasas line, with most of this rainfall occurring
in the 07z-11z timeframe. This line could initiate faster back to
the west, near a Bowie/Comanche line, but the forcing and moisture
make that scenario less likely. Most of the convection should be
out of our SE counties by daybreak, with the front clearing all of
the CWA by 8 am Monday morning. We can`t rule out the
possibility of some strong to marginally severe thunderstorms
with this main band, but the impacts should be confined to
isolated strong wind gusts. A good chunk of the CWA east of I-35
should see rainfall amounts of 0.50-1.00" with this system.

In the wake of this first system, dry, seasonable conditions
should prevail across all of North and Central Texas from Monday
through Wednesday. In our far western counties, some elevated fire
weather concerns may persist Tuesday and Wednesday given the low
afternoon humidities and breezy conditions that are expected.

Still a great deal of uncertainty regarding the next weather
system that`ll affect our area Thursday and Friday. A vigorous
shortwave trough will drop into the western High Plains by
Thursday afternoon/evening. While the GFS and Canadian maintain an
open, progressive wave that exits east of the Plains by Friday,
the 12z Euro sends more mid-level energy farther south into the
back of this trough, resulting in the development of a closed low
over DFW by Friday. The sensible weather implications for these
contrasting scenarios are pretty significant, but the confidence
in the Euro`s solution is not very great currently. For now, have
maintained chance PoPs across our eastern counties Thursday
afternoon (where warm advection-inspired lift and better moisture
will reside), with chance values spreading elsewhere across the
forecast area Thursday night/Friday morning. These PoPs may be
underdone, given the dynamics involved with this system, but later
forecasts will be able to fine tune the locations where rainfall
is most likely to occur.

Temps Friday should dip well down into the 60s and upper 50s,
given the amount of cloudcover and precipitation around, and post-
frontal north winds will make it feel even chillier. As of now,
going with the idea that the system will lift out of the area,
will go with clearing skies for next Saturday, with a modest
rebound in daytime temperatures. If later runs lean more toward
the Euro solution, this may be a tad optimistic. Not a lot of
confidence in the overall scenario unfolding for the end of this
week.

Bradshaw

&&

.SHORT TERM... /Issued 154 PM CDT Sat Oct 19 2019/
/Saturday afternoon through Sunday/

Another beautiful, but warmer afternoon is in shape for North and
Central TX. Some of us (mainly those north of the I-20 corridor)
were lucky early this morning and received some rain and maybe a
rumble of thunder. This activity was associated with a passing
mid-level shortwave that it is now east of our area. Dry weather
and plenty of sunshine is expected through the rest of the day.
Afternoon high temperatures will still be in the upper 70s across
the Red River, to upper 80s (maybe a few 90s) across parts of
Central TX. As of 1 PM, the associated cold front is moving across
the I-35 corridor. Most of the area will have north/northwest
winds by this afternoon through Sunday morning. Winds will
eventually shift back to the south early Sunday afternoon. No
significant chances were made to the previous forecast of
tonight`s low temperatures (expect 50s and 60s).

Most of the day on Sunday will stay dry and warmer as surface
high pressure settles over us. The not so good news is that the
high temperatures will likely reach the mid 80s in the east to
low 90s in the west. Elevated grass fire danger will occur across
the western zones as RH drops to near 25% and surface winds
increase to 10 to 15 mph. There is high confidence that most of
the area will remain rain-free throughout the day. Although we
will be in the warm sector of our next storm system, the lack of
moisture and lift will likely inhibit any development until early
Sunday evening.

Sanchez

&&

.AVIATION... /Issued 154 PM CDT Sat Oct 19 2019/
/18Z TAFs/

Northwest winds behind the cold front (currently over the I-35
corridor). North winds will prevail through Sunday morning. Then,
southerly winds (5 to 15 kts) through the end of this forecast
period.

Skies have cleared from the high clouds left over by the mid-level
shortwave that moved over our region early Saturday morning. They
will remain clear throughout this forecast period, as this
afternoon cold front reinforces the atmosphere with drier air.
Expect a quiet night for both DFW Metroplex and Waco TAF sites. We
will return to south flow late Sunday morning into early
afternoon. Although it is outside of this TAF period, it is
important to start talking about the cold front that will arrive
Sunday night. It will bring the chance for thunderstorm as early
as Sunday evening, mainly north of I-20 and east of the I-35.
Details will continue to be refined as new data become available
and we get close to this time period.

Sanchez

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    57  87  58  75  52 /   0   5  60  10   0
Waco                56  90  60  77  50 /   0  10  70  20   0
Paris               54  80  55  70  47 /   0  10  90  20   0
Denton              53  87  55  75  49 /   0  10  60   5   0
McKinney            53  86  55  74  48 /   0  10  60  10   0
Dallas              58  87  59  75  52 /   0   5  60  10   0
Terrell             57  87  58  75  49 /   0  10  80  20   0
Corsicana           56  87  60  74  50 /   0  10  80  20   0
Temple              57  90  62  77  50 /   0  10  70  20   0
Mineral Wells       52  89  53  75  47 /   0  10  50   5   0

&&

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

$$

17/25/66



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