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268
FXUS64 KHGX 202357
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
657 PM CDT Sun Sep 20 2026

...New AVIATION...

.KEY MESSAGES...

 - Isolated showers and thunderstorms today, generally along the
   coast east of Galveston.

 - Higher chances of storms for northern areas Monday.

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

&&

.DISCUSSION...
Issued at 1227 PM CDT Sun Sep 20 2026

An upper ridge continues to encompass the forecast area, however
latest water vapor imagery indicates mid and lower level moisture
approaching the area from the west along an associated trough. This
will bring a return of the humidity albeit not to the same extent as
such that prompted the Heat Advisories last week. Heat indices are
expected to be around 103-105F today, so continue to use caution if
outdoors for extended periods. The afternoon sea breeze will help
initiate some onshore thunderstorms, although they still look to be
confined along the coast and generally east of Galveston. Per usual,
these will taper off around sunset. The aforementioned trough will
track eastward overnight. Although the timing is unfavorable, the
wave/vort max is potent enough that a few weak storms will be
possible in our northern counties overnight where the greatest
associated forcing will be present. As such, some mentionable 10%
PoPs have been added for this time period. With the moist air
returning along with the usual daytime instability, PoPs have also
been increased in this same area for the afternoon hours, before
ending in the evening.

The forecast remains on track for the rest of the week. The overall
pattern will bring hot and humid conditions during the day with
isolated-to-scattered sea breeze initiated diurnal thunderstorms.
These look to become less prevalent towards the end of the week as
an upper ridge builds over the area and subsequently brings stronger
capping. Temperatures will slightly cool by the end of the week as
well, but still remain a few degrees above average for this time of
year, generally in the low-to-mid 90s.

&&

.AVIATION...
(00Z TAF Issuance)
Issued at 657 PM CDT Sun Sep 20 2026

The isolated convection that developed earlier this afternoon has
mostly dissipated as we approach sunset. VFR conditions continue
to prevail alongside southeasterly winds around 6-12 kt with
occasional gusts near 15-20 kt. Winds will become light and
variable later this evening through Monday morning. We continue to
monitor the progression of a boundary and associated convection
moving through central TX currently. High-resolution model
guidance is still in agreement on convection dissipating before it
makes it into southeast TX. As we saw earlier this morning, the
potential for intermittent periods of patchy fog at CXO/UTS
continues. Winds will remain southeasterly on Monday but should
remain more in the 5-10 kt range.

Added in PROB30s for isolated to widely scattered thunderstorm
development in the afternoon hours. Currently have these relegated
to the northern and coastal terminals, but can`t entirely rule out
additional PROB30 groups being needed for the Houston metro
terminals depending on how the models trend.

Batiste

&&

.MARINE...
Issued at 1227 PM CDT Sun Sep 20 2026

Southeast winds peaking around 10 kts are expected today and Monday.
These will back to northeasterly Tuesday and veer due easterly
Wednesday/Thursday sustained at 15-20 kts, before slightly
diminishing thereafter. Seas of 1 to 4 ft will persist, highest on
Thursday afternoon. Isolated-to-scattered coastal and offshore
thunderstorms are expected each day, slightly tapering off towards
the end of the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  76  97  75  97 /  10  30  20  10
Houston (IAH)  78  95  78  97 /   0  10   0  10
Galveston (GLS)  83  90  82  91 /  10  20   0  20

&&

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

$$

DISCUSSION...AP
AVIATION...Batiste
MARINE...AP

NWS HGX Office Area Forecast Discussion