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

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FXUS64 KFWD 202006
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
306 PM CDT Thu Jul 20 2017


.SHORT TERM...
/Rest of this afternoon and Tonight/

Diurnally-driven cumulus is bubbling this afternoon across the
region as temperatures have warmed into the mid and upper 90s.
While most of this Cu is quite flat thanks to the influence of
mid-level high pressure just to our north, some slightly more
robust puffs are apparent on visible satellite imagery. As a
result, we can`t completely discount the possibility of a renegade
shower into the early evening hours, but a 10% PoP or lower will
suffice. Dewpoints will continue to slowly mix out into the mid
and upper 60s, and this will be sufficient to result in heat
index values of 105-107 degrees in spots mainly along and east of
I-35 through the rest of the afternoon. A heat advisory remains in
effect for these locations.

Another muggy (but mostly clear) night is on tap as temperatures
will generally only manage to fall into the upper 70s to near 80
degrees.

Carlaw

&&

.LONG TERM...
The upper level ridge will still be in control of our region on
Friday but be centered to our northeast where the Midwest and
Southeast regions meet. We expect the region to remain dry but an
isolated shower or two may be possible south of Interstate 20. The
heat will continue, and the Heat Advisory will remain in effect
for tomorrow, along and east of Interstate 35. Our far southeast
counties may not quite reach Advisory criteria but several
locations are calculated to near the 105 degree mark (for Heat
Index values). We may have to consider expanding the Advisory west
one column but will watch trends this afternoon and reevaluate
dewpoints with the next few model runs.

Very similar conditions are expected on Saturday, but a
disturbance moving west underneath the upper level ridge will move
into the Texas Coast. This will bring a slight chance for rain to
our southeastern counties, and heat indices may rise due to
higher dewpoints/better moisture. Elsewhere, better mixing of
dewpoints may keep heat indices just below criteria across most
of the Advisory area, but will keep the current Advisory going
through Saturday as the models may be under doing moisture
associated with the upper level disturbance.

As the upper level disturbance moves across the southern half of
the state on Sunday, this will temporarily weaken the ridge
allowing for better rain chances. Have expanded PoPs across the
region but kept them low at 20-30% due to isolated to scattered
coverage of showers/storms. On Sunday night, a weak front may slip
into Oklahoma but this front should not advance into Texas.
However, the models are split on how much impact the possible
approaching front and weaker upper level ridge will have over the
region. Have opted to keep low rain chances across most of the
region Sunday night through Tuesday night due to uncertainty about
where and how strong the upper level ridge will be. It will have
an influence over the region keeping hot temperatures in place for
several days, but weaknesses within the ridge and/or its location
may allow for some diurnally-driven convection.

By the middle of next week, where the upper level ridge will be
located is still in question, and that will impact temperatures
and (low) rain chances. For now, have kept the end of the forecast
dry and trended it towards the higher end of the temperature
guidance, but not as hot as the ECMWF which suggests temperatures
over 100 may be common because it places the ridge right over the
Southern Plains.

JLDunn

&&


.AVIATION... /Issued 1238 PM CDT Thu Jul 20 2017/
No aviation weather concerns anticipated over the next 24-30
hours. Diurnal Cu continues to percolate early this afternoon, and
bases will steadily rise to around FL055-065. Surface winds will
diurnally oscillate between about 150 and 210, but with speeds
remaining generally under 9 kts, will continue with one-line TAFs
through the forecast period.

While the potential for a rogue shower cannot be entirely
discounted, the very limited potential and minimal impacts to
operations precludes any VCSH mention in the TAFs at this time.

Carlaw

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    82  99  80  99  80 /   5   5   0  10   5
Waco                78  99  77  99  78 /   5  10   5  10   5
Paris               77  96  75  95  75 /   5   5   5  10   5
Denton              79  98  78  99  79 /   5   5   0  10   5
McKinney            77  97  78  97  77 /   5   5   0  10   5
Dallas              82  99  80  99  80 /   5   5   0  10   5
Terrell             76  96  76  97  76 /   5   5   0  10   5
Corsicana           77  96  77  96  77 /   5  10   5  10   5
Temple              76  99  76  99  76 /   5  10   5  20  10
Mineral Wells       76  98  76  99  76 /   5   5   0  10   5

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT Saturday for TXZ092>095-103>107-
118>123-133>135-145>148-158>162-174-175.

&&

$$

82/90



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