234
FXUS64 KHGX 211804
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
104 PM CDT Mon Sep 21 2026

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

.KEY MESSAGES...

- Isolated to widely scattered showers and thunderstorms today.
  Highest potential of a shower/storm will be in our northern
  counties and along the seabreeze in our southern counties.

- Hot temperatures with daily isolated to scattered diurnal
  thunderstorms through midweek.

- Less humid after midweek following a backdoor frontal boundary.

&&

.DISCUSSION...
Issued at 104 PM CDT Mon Sep 21 2026

Today is the final full day of astronomical summer and Mother Nature
is going to make sure we get our money`s worth as temperatures
remain well above normal. Our normal high temperature this time of
the year is actually in the low 90s...but most of us will see
temperatures top out in the mid to upper 90s this afternoon. Some of
you will hit the weather lottery though and get a brief reprieve
from the heat in the form of isolated showers/storms this afternoon.
The CAMs (including me) still insist on popcorn convection beginning
around 2pm along the sea breeze and a few hours later along a
lingering boundary over portions of the Brazos Valley/Piney Woods.
PW values are generally peaking around or just over the 75th
percentile (~1.80"), so it wouldn`t surprise me to see a few pockets
of 1-2" rainfall occuring in a relatively short period of time.
Showers/storms will gradually dissipate after sunset with the loss
of daytime heating.

Do you remember...the 21st night of September? We actually will be
chasing the clouds away as the overnight hours will feature mostly
clear skies...but still fairly humid with lows in the mid to upper
70s. There may be a few nights to remember later in the week though!
The above normal temperatures and daily rain chances continue
through midweek, and this is probably as good of a time as any to
mention that the autumnal equinox is tomorrow (Tuesday) at 7:04 PM
CDT. Astronomical fall begins with *checks notes* temperatures in
the mid to upper 90s...yeah that`s about right. Ridge axis and a
developing mid-level high dominate the forecast Tuesday and beyond,
which means hot and humid conditions will continue through the rest
of the week...right...RIGHT?! Not so fast, my friend!

A trough sweeping through the eastern half of the country will push
in a backdoor frontal boundary (a front moving in from the
northeast) late Wednesday/early Thursday. Drier air filters in
behind this front that lasts going into the early part of the
weekend, so low temperatures for some of you (mainly northern areas)
will feature the upper 60s/low 70s once again. High temperatures
will also be slightly "cooler" as we trade out the upper 90s for the
low to mid 90s. Of course we can throw in the cliche "bUt iT`S a DrY
hEaT", but 90s are still 90s. We`re in the realm of this being
better than nothing, but it leaves us longing for that first true
front...which we`ll briefly talk about at the end of this
discussion. Moisture/humidity returns on Sunday leading to the
return of rain chances into the forecast.

Before we get into our brief beyond the forecast period outlook on a
potential real cold front, let`s start with the usual disclaimer:
it`s too early to lock in anything...remember that we are looking at
trends this far out, so it`s not an official forecast. Looking at
both the GFS and Euro ensembles, there is still a statistically
notable number of members that reflect below normal temperatures
around the first weekend of October. Now again this doesn`t mean
that this WILL happen, but it is within the realistic realm of
possibilities for once. This is a lot better than the 0% potential
we`ve had over the past five-ish months!

Batiste

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 104 PM CDT Mon Sep 21 2026

Winds are variable throughout our region as a weak boundary to the
northwest and afternoon sea breeze to the southeast interact. These
two boundaries slightly elevate TS/SH chances, particularly south of
I-10 this afternoon and then north of CXO early this evening. Upper
level ridging and PWATs less than 2 inches suggest any
storms/showers that do develop will be isolated in coverage,
resulting in PROB30s throughout most TAF sites. More northern sites
around CLL could see elevated coverage (isolated-scattered) with
that northern boundary drifting deeper into our region this evening.
Current trends suggest that neither boundary will advance close
enough to IAH to include them in our PROB30 for the time being.
Winds become light and variable by 01-03Z before increasing to 5-10
kts generally out of the northeast by 16Z Tuesday. Patchy fog is
possible around sunrise for typical sites (LBX, CXO). Late morning
MVFR ceilings possible with a typical summertime cumulus field
developing before lifting early Tuesday afternoon. Another round of
TS/SH possible Tuesday after 18Z with the sea breeze, which pulls
winds back out of the SE by the end of this forecast period.

BSM

&&

.MARINE...
Issued at 104 PM CDT Mon Sep 21 2026

Light to occasionally moderate east to southeast winds today will
become more northeasterly to easterly beginning on Tuesday. Winds
may be consistently moderate enough to warrant periods of caution
flags at times, especially around midweek. Seas will remain mainly
in the 1-3 ft range through the end of the work week, then
increasing to 2-4 ft over the weekend. Daily chances for isolated to
scattered showers/storms persist through midweek.

Batiste

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  75  98  76  98 /  30  20  10   0
Houston (IAH)  78  97  79  96 /   0  20  10   0
Galveston (GLS)  82  92  83  91 /   0  20  20  10

&&

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

$$

DISCUSSION...Batiste
AVIATION...BSM
MARINE...Batiste