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National Weather Service Forecast Discussion

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251
FXUS64 KHGX 201054
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
554 AM CDT Thu Aug 20 2026

...New AVIATION...

.KEY MESSAGES...

- Heat Advisory is in effect Thursday and Friday for heat index
  values peaking between 106-110F. The advisory may need to be
  extended into the weekend.

- Rain chances will be very low through Friday, but might need to
  keep an eye out for some isolated-scattered thunderstorm activity
  near the Piney Woods Friday evening.

- Hot weather expected to continue through next week.

&&

.DISCUSSION...
Issued at 1039 PM CDT Wed Aug 19 2026

The synoptic pattern through most, perhaps all, of the forecast
period will feature a strong central / west CONUS ridge and an
east CONUS trough. Our weather will be heavily influenced by the
ridge, keeping conditions very hot and generally dry (key word
"generally"...more on that below). Inland afternoon temperatures
are expected to average around 100 degrees, with higher heat
indices. The heat will be dangerous, especially for sensitive
groups and for those doing outdoor work and activities. A Heat
Advisory is in effect through Friday, and could be extended
into the weekend in future updates.

But there continues to be a wild card in this forecast. Embedded
in the northerly-ish mid/upper flow between the ridge and the trough
will be little disturbances / vort maxes. These will occasionally
add lift to the SE Texas atmosphere and could potentially spark
off a few thunderstorms. The HRRR is under the impression that a
disturbance over Kansas could hold together enough to bring a few
showers/storms conspicuously close to our northern Piney Woods
zones Thursday evening. But the most suspicious time period is
late Friday afternoon and evening, when about half of the
guidance throws a mid/upper disturbance in our direction, opening
the door to convection that enters the CWA from the northeast.
Southwest moving convection on a hot 100-degree day can be a
signal for underestimated thunderstorms. I kept 20-30 PoPs in our
northern and northeastern zones for late Friday afternoon and
evening. I also decided to keep some low PoPs for Saturday as
well.

This theme is expected to continue deep into next week. The
signal for hot and dry weather remains strong. But we won`t be
able to totally write off the chance of an afternoon / evening
thunderstorms due to the potential for additional mid/upper level
disturbances.

Self

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 530 AM CDT Thu Aug 20 2026

There is still a chance for some MVFR cigs to develop from 12-14Z
this morning over isolated spots. Otherwise, mainly VFR conditions
expected throughout the day. Winds will be S-SW at 5-10 kts
during the morning hours, then become S-SE at 08-12 kts with
occasional gusts of 16-20 kts during the afternoon to evening
hours. Winds relax to 5 kts or less late tonight into early
Friday. There`s a chance for MVFR cigs develop once again, mainly
between the 10-14Z timeframe.

Cotto

&&

.MARINE...
Issued at 1039 PM CDT Wed Aug 19 2026

Light to moderate south to southwesterly flow and 2 to 3 foot seas
should continue through at least early next week. Occasionally
higher gusts to 20 knots are possible in the bays during the late
afternoon, and over the Gulf during the overnight hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 102  77 102  78 /   0   0  10  20
Houston (IAH) 100  80 101  80 /   0   0  10  20
Galveston (GLS)  91  83  92  82 /   0   0  10   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory from noon today to 7 PM CDT Friday for TXZ163-164-
     176>179-195>200-210>214-226-227-235>238-300-313-335>338-
     436>439.

GM...None.
&&

$$

DISCUSSION...Self
AVIATION...Cotto
MARINE...Self

NWS HGX Office Area Forecast Discussion