372
FXUS64 KHGX 291100
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
600 AM CDT Tue Sep 29 2026

...New AVIATION...

.KEY MESSAGES...

-  Hot and slightly more humid conditions continue Tuesday with
   isolated coastal showers/storms.

-  Periods of showers and storms are expected each day, peaking
   from Wednesday to Saturday. Locally heavy rain will be
   possible.

-  Rain chances and increased cloud cover will keep temperatures
   near seasonal levels after midweek.

&&

.DISCUSSION...
Issued at 1128 PM CDT Mon Sep 28 2026

There`s quite a bit to talk about beyond midweek, so we`ll split the
discussion into two pieces...kind of a throwback to days of short
term and long term. If you`re mostly interested in reading about the
heavy rainfall potential, you`ll want to read the long term
discussion. I`d suggest reading the short term one too though
because that`ll cover a couple of things that are important in the
lead-up to the heavy rain...and I spent quite a bit of time on it
too. Let`s begin!

Short Term {Thru Wednesday}:

Palacios tied a daily record high temperature on Monday with hot
conditions continuing going into midweek. There will be an ever so
slight downward trend in temperatures over the next few days though
as moisture gradually increases. Heat and increasing moisture is
probably setting off some bells to check heat indices, but we`re all
good in that department. Lingering dry air east of I-45 will keep
peak heat indices in the upper 90s in that region. West of I-45 is
where the moisture initially increases, so heat indices over there
will peak in the low to mid 100s...still low enough to not even
think of a Heat Advisory. High temperatures area-wide will be in the
low to mid 90s over the next few days. By Wednesday, low-level
moisture will be elevated enough for widespread heat indices in the
100s and may flirt with the advisory threshold west of I-45.

Moisture is already on the rise well west of I-45/south of I-10 near
Matagorda Bay. Some of you in this region received some rain earlier
this afternoon, and you`ll see some more again overnight and
Tuesday. The latest CAMs (including me) still point towards this
region seeing isolated showers early Tuesday morning then expanding
in coverage going into the late morning and afternoon. Remember that
drier air remains in place on Tuesday east of I-45...it wouldn`t be
impossible to see an isolated shower or two, but definitely way less
plausible. Factoring in the tilted ridge axis overhead Tuesday
doesn`t make it any better either. Increased low-level moisture on
Wednesday will lead to more widespread chances of scattered
showers/storms.

Tuesday night into Wednesday will also feature breezy southeasterly
winds as the pressure gradient tightens as surface low pressure
develops near west TX/east NM. Wouldn`t be too surprised to see a
Wind Advisory along the barrier islands at some point on Wednesday
(most likely Wednesday night). To segue into the long term, the
development of the surface low pressure comes in response to an
upper level trough and an embedded upper low transitions through the
southwestern CONUS. The remnants of what is currently Hurricane Polo
(making landfall in Baja California overnight) will become embedded
with this upper level disturbance. Most notably, the moisture from
Polo`s remnants will become embedded with this trough and move
eastward into TX.

-----------

Long Term {Wednesday Night and Beyond}:

By Wednesday night, a slow-moving upper level low will begin to move
into the TX panhandle. An axis of climatologically high moisture (PW
values well above the 90th percentile [~1.95"]) will begin gradually
nudging into portions of the Brazos Valley as moisture converges
along and ahead of a slow-moving frontal boundary. Northern areas
may catch the tail-end of a few embedded shortwaves late Wednesday
into early Thursday, but the main timeframe of concern for heavy
rainfall in Southeast TX remains late Thursday into Friday. This is
when we have the combination of PW values well above 2.0", embedded
shortwaves, and potentially frontogenetic forcing lining up over
portions of the Brazos Valley. The best potential for heavy rainfall
remains to our northwest, but there`s enough uncertainty remaining
in exactly where the band of heavy rain sets up that it`ll be worth
your time staying up to date on the forecast as confidence
increases...especially for those of you in the Brazos Valley.

This is a pattern that favors locally heavy rainfall which can lead
to instances of flash flooding especially in urban areas and low-
lying areas. Rainfall rates could easily peak above 3-4"/hr in the
heaviest downpours. The main question that remains to be answered
(will become more clear with high-res guidance) is will we see
prolonged periods of high rainfall rates in our area. As of right
now, the "best" chance for this in Southeast TX is in the Brazos
Valley, but again a lot of uncertainty remains. It all depends on
where the frontal boundary is and if it stalls. The greatest
potential remains to our northwest closer to the Hill Country and
DFW metroplex. With that in mind, WPC has maintained the marginal to
slight risk of excessive rainfall Thursday and Friday for all of
Southeast TX with the slight risk generally for western/northwestern
areas. See the graphics on our webpage www.weather.gov/hgx for
specifics for your particular location.

In terms of rainfall totals, generally looking in the 2-4" range
with higher totals the further north and west you go. Can`t entirely
rule out locally higher totals especially if the front sags further
south Thursday night/Friday. The aforementioned frontal boundary
pushes through some time on Friday, but elevated moisture persists
through the weekend. That combined with embedded shortwaves also
persisting means that chances for showers/storms remain in the
forecast. On the plus side, this does translate to high temperatures
only topping out in the 80s and some lows in the 60s toward the end
of the forecast period.

-----------

Even Longer Term {Cold Front Hunting}:

If y`all know me, then y`all know I`m always on the hunt for the
first "real" cold front this time of the year. There looks to be
some potential out there...but first there`s the caveat that this is
in no way an official forecast. There is a lil dash of wishcasting
though. Deterministic long range guidance reflects an upper level
trough dipping down into the northern/northeastern CONUS late next
week. Now the northern/eastern CONUS has the greatest potential for
seeing cooler temperatures behind the associated cold front, but
there are quite a few members of the GEFS and Euro ensembles showing
cooler than normal temperatures towards the end of next week.

Again, it`s not a guarantee, but it is something that I`m sure a lot
of us would like to see come to fruition. The current normal low
temperature is 67 degrees...don`t start meme-ing on me just yet. The
last time the City of Houston was below 67 degrees was in mid
May...so here`s to hoping!

Batiste

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 600 AM CDT Tue Sep 29 2026

Look for a gradual increase in southeast winds today...with some
gusts to or slightly above 20kt a possibility this afternoon. VFR
conditions will mostly prevail, though we wouldn`t be overly
surprised to see some brief/intermittent cigs ~2500ft in the mid
morning hours. There`s also a non-zero chance of an isolated shra
or two, but chances should be low enough to exclude from the TAFs
attm. 47

&&

.MARINE...
Issued at 1128 PM CDT Mon Sep 28 2026

Light to occasionally moderate onshore flow and 1-3 ft seas will
persist through Tuesday afternoon before winds persist closer to the
20-25 kt range late Tuesday into Wednesday. Small Craft Advisories
will likely be needed during this time period due to the elevated
winds and subsequently increasing seas (into the 5-8 ft range in the
Gulf). Water levels during the latter half of the week will peak
around or just above 3.0 ft MLLW, not enough for coastal flooding
hazards but high enough to take note. Daily chances of
showers/storms continue especially during the overnight to early
morning hours over the Gulf. Expect rain chances to increase after
midweek as an upper level disturbance pushes into TX along with a
slow-moving frontal boundary.

Batiste

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  96  74  97  75 /  20   0  40  30
Houston (IAH)  93  78  93  79 /  20  10  40  10
Galveston (GLS)  89  83  89  83 /  20  20  40  40

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Should Exercise Caution from 4 PM CDT this afternoon
     through Wednesday evening for GMZ330-335-350-355-370-375.

&&

$$

DISCUSSION...Batiste
AVIATION...47
MARINE...Batiste