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National Weather Service Forecast Discussion

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590
FXUS64 KHGX 210504
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1204 AM CDT Mon Sep 21 2026

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

.KEY MESSAGES...

 - Isolated to widely scattered showers and thunderstorms on
   Monday. Highest risk of a shower/storm will be in our northern
   counties and along the sea breeze boundary in our southern
   counties.


 - Hot temperatures with daily isolated to scattered diurnal
   thunderstorms for much of the upcoming week.

 - Less humid later in the week.

&&

.DISCUSSION...
Issued at 1200 AM CDT Mon Sep 21 2026

Mid/upper WV imagery coupled with 500 MB RAP analysis indicate that
ridging overhead has broken down somewhat, with a modest
troughing feature setting up across northern and central Texas.
This system should supply a little extra lift to the SE TX
atmosphere, which will at least give a slight boost to diurnal
PoPs on Monday. Already we have had showers and thunderstorms in
central Texas Sunday evening and couldn`t rule out a few showers
managing to make into our northwestern-most areas overnight. For
Monday, the best chance of receiving isolated to scattered showers
and thunderstorms will be across our northern counties and in
areas that experience the sea breeze boundary (southern / coastal
counties). Tuesday and Wednesday will also feature a chance of
isolated showers/storms, albeit lower and more associated with the
sea breeze. However, a plurality of ensembles suggest Wednesday
may have better chance of showers/storms due to an approaching
boundary (spoken about in the next paragraph). Afternoon
temperatures should be well into the 90s with high humidity and
triple digit heat indicies.

Mid/upper ridging becomes more stout over central CONUS as a trough
digs south over E CONUS during the second half of the week. This
will keep things toasty while our friends back east experience a
good cool down. However, it still appears a backdoor boundary of
sorts may drop humidity levels by Thursday, with temperatures
possibly dropping a few degrees as well. That being said, late-
week temperatures are likely to skew a little warmer than normal.
There`s some ensemble support for a more meaningful front around
the 1st of October. But it`s much too early to get excited about
that.

Self


&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1200 AM CDT Mon Sep 21 2026

VFR conditions continue as winds become light and variable
through late Monday morning. Showers/storms associated with a
boundary pushing through central TX continues to gradually
fall apart. As we saw on Sunday morning, the
potential for intermittent periods of patchy fog at CXO/UTS
continues in the early morning hours. Winds will remain
southeasterly on Monday but should remain more in the 5-10 kt
range outside of any convection.

PROB30s have been added to account for isolated to widely scattered
thunderstorm development in the afternoon hours. High-resolution
model guidance is in agreement on convection developing along a
lingering boundary near the northern terminals and along the
seabreeze near the coastal and southern terminals. Current timing
is generally in the 20Z-01Z timeframe. Convection subsides after
sunset with winds becoming light and variable in the evening.

Batiste

&&

.MARINE...
Issued at 1200 AM CDT Mon Sep 21 2026

Light to occasionally moderate east to southeast winds (7-15 KT) Monday,
are expected to become northeasterly by Tuesday. These winds
should become more consistently moderate to occasionally fresh
(10-20 KT) by Wednesday and Thursday. There will be a daily risk
of isolated showers and thunderstorms through mid week. Gulf seas
of 1 to 3 feet may increase to the 2 to 4 foot range by week`s
end.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  97  76  97  75 /   0   0  30  20
Houston (IAH)  96  78  95  77 /  10   0  20   0
Galveston (GLS)  90  83  90  82 /  10   0  20  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

DISCUSSION...Self
AVIATION...Batiste
MARINE...Self

NWS HGX Office Area Forecast Discussion