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

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FXUS64 KFWD 212357
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
657 PM CDT Mon Aug 21 2017


.AVIATION...

Afternoon cumulus clouds have started to dissipate, and are
expected to erode by/shortly after sunset. VFR will remain
through this TAF cycle with southerly winds around 10 kts. As has
been the case for the last few days, winds will slightly veer to
the southwest by Tuesday afternoon, but not enough to add another
FM group.

Hernandez

&&


.SHORT TERM... /Issued 346 PM CDT Mon Aug 21 2017/
The weather across North and Central Texas will be quiet tonight
as we remain under the influence of upper level ridging. Isolated
showers and thunderstorms that developed this afternoon in the
area of deeper moisture across East and Southeast Texas will
dissipate as sunset approaches. Cannot rule out an isolated
shower/thunderstorm in the extreme southeastern counties through
sunset, so have placed 10 percent PoPs there. South to southeast
winds 5 to 10 mph will prevail under mostly clear skies. Lows will
be in the 70s.

58

&&

.LONG TERM... /Issued 346 PM CDT Mon Aug 21 2017/
/Tuesday and Beyond/

An active second half of the week is expected with several
opportunities for rain and thunderstorms continuing even into the
upcoming weekend. There is substantial uncertainty in the extended
forecast period as it will hinge on the path of the remnants of
Tropical Storm Harvey from the Gulf of Mexico. If this system
were to track northward into the forecast area, it would bring a
chance for widespread heavy rain, especially to our Central Texas
counties. This shouldn`t eclipse our midweek chances for rain
though, as first we will have to contend with a cold front and
thunderstorm chances beginning Tuesday night and lasting into
Thursday.

Tuesday will be another hot and mostly dry day across the region.
While temperatures will climb into the mid and upper 90s,
dewpoints are expected to mix into the 60s or low 70s which will
hold heat index values to 105 or less. Later Tuesday evening, a
cold front will be advancing south through OK. This front and its
associated upper trough will set off numerous showers and
thunderstorms in Central OK, some of which could drift into our
Red River Counties Tuesday night. Low-level flow is expected to
be fairly weak, and limited shear should limit any organization of
a convective complex. However, this activity could still pose at
least a borderline severe wind threat with any more robust
convection. Scattered showers or storms could affect any area
roughly along and north of I-20, although there should be somewhat
of a lull in convection overnight as there will be limited
support for thunderstorms other than the front across North TX.
Activity should redevelop Wednesday as heating occurs and will be
primarily focused along the slow-moving frontal zone. Slightly
cooler air behind the front and increased cloud cover should keep
high temperatures several degrees cooler than Tuesday.

Substantial model disagreement sets in on Thursday as the GFS
lingers the front through the forecast area and initiates more
diurnal showers and thunderstorms both Thursday and Friday. The
ECMWF and CMC shove the front farther south and keep a majority
of the area dry during the end of the week. Have continued to
side with the slightly drier guidance and reflected a southern
frontal position in the forecast. Also during this time, the
remnants of Harvey should be re-intensifying in the western Gulf
of Mexico. This rejuvenated tropical system is expected to make
landfall and track northwestward through the Rio Grande Valley.
This solution would bring widespread heavy rain through portions
of South and Central TX.

The question remains how far north this tropical system may track
and what impacts it could potentially have within our forecast
area. The GFS moves the circulation north through the Texas Hill
Country which would bring widespread heavy rain to our Central TX
counties through next weekend. The ECMWF lingers the circulation
to the south, which would keep us drier and subsident, likely
resulting in very warm temperatures. Have continued to side with
the drier ECMWF for now until we see some better agreement/consistency
among model runs. The signal is quite clear that some location in
South/Central Texas will receive too much rainfall out of this
system if it materializes as currently suggested, but it will
likely be a couple days or more before we have a better idea of
where this rainfall maximum could occur. Even if the system itself
does not enter our forecast area, we could still see some
enhanced rainfall chances in the form of a Predecessor Rain Event
(PRE), especially if the midweek frontal zone is still draped
somewhere through North TX during this time.

-Stalley

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    79  97  76  93  74 /   0   5  20  30  40
Waco                76  98  76  96  75 /   0   5   5  40  30
Paris               75  92  73  89  70 /   0  10  30  40  30
Denton              76  97  74  92  72 /   0  10  30  30  40
McKinney            74  95  75  91  70 /   0  10  30  30  40
Dallas              80  98  78  93  75 /   0   5  20  30  40
Terrell             75  96  75  93  73 /   0   5  20  30  40
Corsicana           76  96  75  94  74 /   5   5  10  40  40
Temple              75  98  74  97  74 /   0   5   5  50  30
Mineral Wells       75  96  73  92  71 /   0  10  20  40  40

&&

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

$$

08/24



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