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National Weather Service Forecast Discussion

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174
FXUS64 KHGX 280441
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1141 PM CDT Sun Sep 27 2026

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

.KEY MESSAGES...

-  Hot and slightly more humid today 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 through most of the forecast period.


&&

.DISCUSSION...
Issued at 1134 PM CDT Sun Sep 27 2026

A wet pattern is expected this week, with periods of showers and
thunderstorms and a risk of locally heavy rainfall through the
upcoming weekend.

Hot weather continues today with a gradual increase in humidity
throughout the day. Although the mid to upper level ridge continues
to weaken and move out of the region, sufficient subsidence remains
to inhibit widespread convection today. However, isolated, diurnally
driven showers/storms remain possible. Rain and storm chances
increase slightly Tuesday as weak vorticity maxima aloft move over
the region. WIll continue with 15% to 25% chance, mainly for the
afternoon.

We will continue to monitor the next rainmaker system. A slow-moving
mid to upper level longwave trough will continue to move over the
western CONUS today, merging with the remnants of what is now
Hurricane Polo near Baja California late tonight into Tuesday.
Deep Pacific and tropical moisture will be enhanced at the mid to
upper levels as the trough moves over the southern Rockies/West
Texas. Additionally, a strong southerly influx of humid Gulf
airmass will filter across the region, resulting in PWATs in the
2.0 - 2.4 inch range across Southeast Texas through the weekend.
These values are in the 90th to 97th percentile of climatology per
NAEFS, GEFS and ENS. In terms of standard deviation, these PWAT
values are 2 sigma above normal (2-3 near the Brazos Valley),
suggesting heavy rainfall that could result in localized flooding.
Therefore, showers and thunderstorms will continue to increase on
Wednesday, particularly during peak daytime heating due to the
combination of deep moisture and mesoscale boundaries such as
seabreezes or outflow boundaries from convection developing across
central TX.

PWs peak on Thursday and Friday as the main trough digs across the
Plains/north-central TX. Global guidance shows a general consensus
on timing, but there are still discrepancies regarding the evolution
of the system once it approaches our region. Most models suggest a
swath of heavy rainfall extending across central Texas, potentially
reaching our western counties by Thursday. Confidence in the final
location of this axis of convergence and heavy rain is low to
moderate. So, it will need to be monitored closely in the coming
days, especially for our western zones, including the Brazos Valley.
While the general consensus at the moment brings the heaviest band
of precipitation west of I-45, we will continue to monitor impacts
for higher totals east of I-45 and across the coastal zones through
the weekend as PWs remain elevated. Specific details on rainfall
amounts remain uncertain. Will continue to monitor trends for any
upward or downward adjustments in the coming days. In the meantime,
remain weather aware and keep in mind that periods of showers and
storms are expected, mainly from Wednesday into the weekend with a
risk of heavy rainfall leading to localized flooding.

This system will drag a weak cold front through sometime late Friday
or Saturday with rain chances gradually diminishing through the
weekend. While the front itself won`t have a significant impact on
temperatures, precipitation chances and increased cloud cover will
keep temperatures near seasonal levels through most of the forecast
period.

JM

&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1134 PM CDT Sun Sep 27 2026

VFR conditions to persist throughout this forecast cycle. Winds
calm with MVFR VSBYs possible (10-30% chance) around sunrise
primarily north of I-10. Confidence/coverage of this reduced VSBY is
too low to include in TAFs at this time except at CXO. Afterwards,
daytime winds on Monday pick up again out of the SE between 5-10
kts. Along and south of I-10, expect stronger winds with gusts
between 15-20 kts possible in the late afternoon. Otherwise, PoPs
are low between 10-20% and oriented along the coast, mostly south of
I-10 and west of I-45. Winds become light and variable again between
02Z-05Z Tuesday.

BSM

&&

.MARINE...
Issued at 1134 PM CDT Sun Sep 27 2026

Light onshore winds and low seas will persist through at least
Tuesday along with isolated showers and storms. Rain and storm
chances will increase after Tuesday as a disturbance moves over the
Plains and pushes a frontal boundary off the coast sometime upcoming
weekend. Therefore, a daily risk of showers and storms can be
expected during the second half of the week, peaking Thursday and
Friday. Elevated winds and building seas (up to 7-8ft) are also
anticipated. A Small Craft Advisory will likely be needed late
Tuesday or Wednesday.

JM

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  73  96  72  96 /   0  10   0  10
Houston (IAH)  76  94  75  93 /   0   0   0  20
Galveston (GLS)  82  89  82  88 /  10  20   0  30

&&

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

$$

DISCUSSION...JM
AVIATION...BSM
MARINE...JM

NWS HGX Office Area Forecast Discussion