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National Weather Service Forecast Discussion

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546
FXUS64 KHGX 210521
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1221 AM CDT Fri Aug 21 2026

...New DISCUSSION, AVIATION, MARINE...

.KEY MESSAGES...

- Heat Advisory in effect through Saturday. Could be extended into
  Sunday.

- Isolated thunderstorms are possible later today and this
  evening, and again Saturday afternoon and evening.

- Hot weather expected to continue through next week.

&&

.DISCUSSION...
Issued at 1202 AM CDT Fri Aug 21 2026

It`s hard to not sound like a broken record when we`re in the
middle of a very hot and generally dry pattern. A strong ridge
centered over the Four Corners region will be the dominant player
in our forecast through much of the next week. Afternoon
temperatures are expected to range from the low/mid 90s at the
beaches to 100-103F in most inland locations through at least
Tuesday, and perhaps through the end of next week. Over the
weekend, I couldn`t rule out a few inland hot spots making a run
for the 105 degree mark. Mixing should bring dew points down
somewhat during the afternoon. But dew points are unlikely to fall
enough to keep heat index values below advisory criteria. In
fact, some locations in our eastern counties could be close to
Excessive Heat Warning thresholds (Heat Index at or above 113),
especially on Saturday. For now, we have an areawide Heat Advisory
through Saturday. This may need to be extended into Sunday. The
only thing that could potentially knock these temperatures down is
the potential for isolated afternoon / evening thunderstorms.

Weak disturbances embedded in the flow aloft, along with
convective outflow boundaries may suffice to initiate isolated
to widely scattered convection late Friday afternoon and evening,
and again Saturday afternoon and evening. Confidence is quite low
regarding whether or not these disturbances coupled with the
extreme heat and moisture will be enough to foment convection. But
if they do, then we could not rule out a locally strong
thunderstorm. Any convective activity is expected to approach from
the northeast. Those who have followed SE Texas weather know that
southwest moving convection on a hot 100-degree day can be a signal
for underestimated thunderstorms. So a robust mesoanalysis and a
watchful eye on the radar will be warranted on Friday and
Saturday.



Self

&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1202 AM CDT Fri Aug 21 2026

Winds have begun to decreased across the area as evening progresses.
The will continue to light and VRB through the morning. A chance for
brief BR continues for KLBX during the sunrise hours. begins to
peak over the horizon around KLBX does remain possible. Tomorrow a
frontal boundary well N of the area has the chance to bring the
development of ISO TS/SH. Confidence remains low, but will be
monitored. The persistent forecast continues.

CMW

&&

.MARINE...
Issued at 1202 AM CDT Fri Aug 21 2026

Generally 10-15 knot southwest winds and 2-3 foot seas are
expected through at least the middle of next week. Winds could
gust to 20 knots in the bays during the afternoon, and over the
Gulf during the overnight hours. Isolated thunderstorms are
expected north of the region Friday afternoon and evening, and
again Saturday afternoon and evening. We believe these storms will
remain north, but they will be worth watching.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 102  78 103  79 /  10  20  20  10
Houston (IAH) 102  81 102  81 /  10  20  20  10
Galveston (GLS)  92  82  92  82 /  10  10  10   0

&&

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

GM...None.
&&

$$

DISCUSSION...Self
AVIATION...CMW
MARINE...Self

NWS HGX Office Area Forecast Discussion