000
FXUS64 KFWD 201551
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1051 AM CDT Fri Jul 20 2018


.UPDATE...

Only minor changes were made to today`s forecast, mainly to
account for the temperature trends and slightly more dense cirrus
deck moving in from the north.

High temperatures are once again expected to break records today
at both Waco and DFW. An Excessive Heat Warning continues through
the weekend, with highs expected to reach and exceed 105 degrees
across the region. Precautions should be taken to avoid heat
related illnesses.

Hernandez

&&


.AVIATION... /Issued 644 AM CDT Fri Jul 20 2018/
/12Z TAFs/

VFR is expected at all terminals through Saturday morning, with
the only cloud cover expected to be occasional CI/CS anvil debris
left over from weakening convection across Oklahoma and Arkansas.

Minor challenges will occur with wind direction diurnally and
nocturnally, as early morning southwest winds 10-13 knots, back
around southerly, or even south-southeasterly to around 10 knots
in the late afternoon and evening hours.

No VSBY restrictions or potential for showers or storms expected
the next 24 hours, as the strengthening upper high over the area
that`s producing the record heat keeps strong subsidence across
North and Central Texas.

05/

&&

.SHORT TERM... /Issued 330 AM CDT Fri Jul 20 2018/
/Today and Tonight/

Early this morning continued to show the eastern extent of a 595
decameter upper high extending over North and Central Texas this
morning. Dissipating showers and thunderstorms were noted within
northwest flow aloft across Oklahoma/Arkansas and extending into
the Lower Mississippi Valley. Anvil debris from this activity was
already arriving across areas along and north of I-20/30 and
will likely result in periods of broken cirrus across the
northeast half of the region today. Though this may likely keep
high temperatures from getting a degree or two higher than
Thursday by diminishing insolation somewhat, deep mixing through
850mb at temperatures 25 to 30 degrees Celsius will likely result
in another record-breaking day temperature-wise across the area.
Veered low level flow from the southwest may also add a degree or
two from compressional warming coming from higher terrain to the
southwest of the DFW and Waco. Records today at both locales
should be easily broken (DFW: 105 degrees in 2000/2012 and Waco:
104 degrees in 1969/2000), especially the latter where any cirrus
decks will have less of an impact on this afternoon`s
temperatures. All said, we will obviously be keeping the Excessive
Heat Warning for the entire CWA in effect through tonight.

More late day showers and storms will form along a stationary
front north of I-40 in the Texas Panhandle/Northern Oklahoma later
today and this evening, as northwest flow aloft continues near or
over this area. This front will sink slowly south across the I-40
corridor well north of the Red River tonight, but don`t expect any
of that activity to reach North-Central Texas due to drier air and
strong subsidence related to the eastern part of the strong upper
high across the CWA. Outside of sporadic high cloudiness, continue
south or southwest winds and a stout inversion above the surface
will result in lows of 75-85 degrees.

05/

&&

.FIRE WEATHER... /Issued 330 AM CDT Fri Jul 20 2018/
/This afternoon/

Energy Release Component(ERC) percentiles continue to increase
across the western half of the area and over 90 percent in many
areas. This is a sign of combustive and very dry vegetation and
grasses. Combined with the record-breaking, very hot temperatures,
low humidity values below 20 percent, and south-southwest winds 10
mph or slightly higher, an elevated risk for grass fires like the
Harman Road fire(30% contained currently) near Fort Hood will
continue to be a concern both today and continuing into this
weekend. A Grassland Fire Danger Statement has been issued for all
but our far eastern counties today. The threat should diminish
somewhat after nightfall when humidity values rise above critical
levels.

05/

&&

.LONG TERM... /Issued 330 AM CDT Fri Jul 20 2018/
/Saturday Onward/

The main stories through the extended forecast are the continued
oppressive heat, followed by a "cool down" where high
temperatures in the upper 90s or low 100s will return along with
some low rain chances.

We`ll reach the apex of the ongoing heat wave on Saturday with
some exceptional high temperatures possible. There are a few
factors that will contribute to Saturday being the warmest day in
this stretch. First, the upper ridge will become centered
overhead Saturday afternoon with with 500mb heights climbing to
598dam. Also, 850mb temperatures will be some of the warmest on
record based on our local sounding climatology, with readings of
28-30C possible across parts of North Texas. The main difference
on Saturday from the previous days however, will be persistent
west/southwest winds throughout the entire day. The wind`s
increased downsloping component will add adiabatic warming in
addition to the previously mentioned factors. The reason for these
veered winds will be the presence of a weak surface trough/front
which will be moving into North Texas from the north/northeast
late Saturday afternoon and evening. Additional warming due to
compression along this boundary is also possible. All of these
factors combined will mean the potential for some temperatures to
reach or exceed 110F, or possibly even approach all-time record
highs. Daily records at both DFW and Waco are likely to fall. The
only caveat may be if any dense cirrus moves into the area from
Oklahoma which could slightly inhibit warming. Regardless, the
entire forecast area should easily meet Excessive Heat Warning
criteria, either through raw temperatures exceeding 105 or heat
index values exceeding 110. The heat will continue on Sunday with
the Excessive Heat Warning remaining in effect area-wide. However,
the subtle boundary should continue moving slowly southward, and
areas north of it should be a couple degrees cooler than Saturday
with a light northeast wind. Most areas should still climb into
the 103-108F range.

A gradual cooling trend will begin on Monday as the upper ridge
retreats westward while deep troughing develops across the
eastern US. This pattern will leave us in deep northerly flow
through the first half of the week, inviting a backdoor cold
front to move into the area late Monday and Tuesday. This weak
but noticeable front should mark the end of the most oppressive
heat, and possibly the streak of 100+ degree weather for some
locations. This would put DFW at a total of 10 consecutive days
with temperature of 100 or higher, which is fairly uncommon (only
29 10+ day streaks since records began in 1898). Even though
temperatures will be cooler, some areas may still meet Heat
Advisory criteria on Monday and possibly even Tuesday across
Central Texas. Along with the slightly less hot temperatures,
there will also be a chance for a few showers or storms to develop
in the vicinity of this boundary, although coverage would likely
only be isolated to scattered at most and maximized during the
peak heating hours Tuesday afternoon. If any storms do mange to
develop, stronger storms would be capable of a downburst wind
threat given temperatures will still be in the upper 90s or low
100s.

The second half of the week should feature temperatures around the
century mark with little opportunity for rain. The ridge will
build back eastward a bit while the upper trough across the
eastern US deamplifies, leaving us with a more "typical"
summertime heat heading into next weekend.

-Stalley

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth   107  84 109  83 107 /   0   0   0   0   0
Waco               106  78 108  81 109 /   0   0   0   0   0
Paris              105  79 105  77 100 /   0   0   0   0   5
Denton             108  80 109  79 107 /   0   0   0   0   0
McKinney           106  80 108  79 104 /   0   0   0   0   0
Dallas             108  85 110  85 108 /   0   0   0   0   0
Terrell            106  78 109  81 106 /   0   0   0   0   0
Corsicana          105  78 107  79 106 /   0   0   0   0   0
Temple             105  75 107  78 108 /   0   0   0   0   0
Mineral Wells      108  77 108  78 108 /   0   0   0   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 7 PM CDT Sunday for TXZ091>095-
100>107-115>123-129>135-141>146-156>161.

Excessive Heat Warning until 7 PM CDT Sunday for TXZ147-148-162-
174-175.

&&

$$

08

NWS FWD Office Area Forecast Discussion