FXUS64 KFWD 210444 AAB

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1144 PM CDT Thu Jul 20 2017

/06Z TAFs/

VFR conditions will prevail as ridging aloft persists across the
Southern Plains. Daytime CU will continue to develop by midday
around FL040, bases rising to near FL070 before dissipating around
sunset. Isolated showers and storms may impact routes to/from the
south, but no issues are expected at any TAF sites.



.SHORT TERM... /Issued 306 PM CDT Thu Jul 20 2017/
/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



.LONG TERM... /Issued 306 PM CDT Thu Jul 20 2017/
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.



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


Heat Advisory until 8 PM CDT Saturday for TXZ092>095-103>107-



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