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National Weather Service Forecast Discussion

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411
FXUS64 KHGX 281813
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
113 PM CDT Tue Jul 28 2026

...New DISCUSSION, MARINE...

.KEY MESSAGES...

- A Heat Advisory is in effect for all of Southeast Texas this
  afternoon.

- Hot weather with temperatures in the upper 90s to near 100 and
  heat index values between 105-110 will continue for the rest of
  the week into the weekend.

- Notable rain chances look to return over the weekend.

&&

.DISCUSSION...
Issued at 110 PM CDT Tue Jul 28 2026

A stagnant ridging pattern has developed and will remain planted
over the region for the rest of the work week. A surface high
pressure center is observed to our southeast in the Gulf, with a
strong and expansive mid- and upper-level high to our northwest.
The combination of these two will keep the weather tranquil (for
the most part) for the next several days. One exception to this is
if we are able to get a seabreeze circulation develop off the Gulf
and Galveston Bay, it would provide enough low-level convergence
to trigger an isolated shower or two this afternoon from about 4-8
pm. The chance of a shower developing are generally less than 20%
(with even lower thunder potential), so we did not include any
mention of this in our forecast at this time.

The main storyline of this forecast is the temperature and heat
index. A Heat Advisory remains in effect for the remainder of
the afternoon today, but we do not plan to extend the advisory
into tomorrow at this time. An advisory my ultimately be needed,
but we are not confident enough at this point to extend/issue a
new advisory for tomorrow. We realize this is a change from the
messaging we have been sharing, and a large reason for this is
that we are seeing signs of deeper/more efficient mixing and
therefore a lower afternoon dew point. This is resulting in heat
index values a little lower than the medium-range guidance was
indicating, even as recently as yesterday. As a result, our heat
index forecast for the next few days is expected to peak around
105-108. Our Heat Advisory criteria is a heat index of 108, so our
forecast is currently sitting within a degree of advisory criteria
for a few hours Wednesday, Thursday, and Friday afternoon. Each
day we will likely hold off to issue an advisory until we get a
better read on that day`s diurnal trend. A trade-off of the deeper
mixing will be higher ambient temperatures, particularly Thursday,
Friday, and Saturday as the ridge to our northwest flattens and
sends increased subsidence our way. This opens the door for
100-degree days for at least parts of the region each of those
afternoons. How likely depends on the exact location, but by-in-
large, the chance of the high temp reaching 100 is around 20-30%
today and tomorrow, 40% on Thursday and Friday, closer to 50% on
Saturday, then back down to 20-30% Sunday onward.

It`s worth noting that we`re still forecasting heat index values
between 105-108 each afternoon. At the end of the day, the human
body and animal`s response to heat does not vary much between 107
and 108...therefore proper heat safety messaging and precautions
should continue to be taken regardless of the presence of an
advisory or not.

We briefly alluded to the ridge flattening and lower 100-degree
probabilities late in the weekend into early next week. An upper
trough is forecast to develop over the Eastern CONUS late this
weekend into early next week, with a backdoor "cold" front
forecast to inch closer to our forecast area. It`s too soon to
know exactly how far southwest the front will get, but either way,
slightly increased PoPs (20-30%) and more seasonal temperatures
are forecast next week.

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 548 AM CDT Tue Jul 28 2026

After some isolated patches of higher end MVFR cigs/fog north and
west of the metro area burn off early this morning, VFR
conditions will prevail area-wide. HRRR has been showing an
isolated shra popping up near the Houston area heading into
evening, but overall chances of it moving over any individual
terminal are currently low enough to not mention in the 12z TAFs
attm. Otherwise, a forecast of persistence overnight. 47

&&

.MARINE...
Issued at 110 PM CDT Tue Jul 28 2026

Light to moderate onshore flow and 2 to 4 foot seas will continue
for most of the week. With surface and upper-level high pressure
dominating, rain chances will be minimal through the work week.
Southwesterly winds increase and seas build somewhat over the
weekend, which may prompt the issuance of caution flags.

Bonnette

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  97  76  97  77 /   0   0   0   0
Houston (IAH)  99  79 100  80 /   0   0  10   0
Galveston (GLS)  91  83  92  83 /   0   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening for TXZ163-164-176>179-
     195>200-210>214-226-227-235>238-300-313-335>338.

GM...None.
&&

$$

DISCUSSION...Bonnette
AVIATION...47
MARINE...Bonnette

NWS HGX Office Area Forecast Discussion