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National Weather Service Forecast Discussion

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555
FXUS64 KHGX 022025
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
325 PM CDT Thu Jul 2 2026

...New DISCUSSION, MARINE...

.KEY MESSAGES...

- Closely monitoring weather for the 250th Independence Day with
  increased heat stress expected.

- Hot Weather continues with peak heat index values reaching 100-
  110F (38-43C).

- Daily rain chances. Light streamer showers possible in the
  morning, then scatters/isolated storms during the afternoon.

&&

.DISCUSSION...
Issued at 315 PM CDT Thu Jul 2 2026

The broader synoptic pattern has not changed significantly across SE
Texas. A robust ridge is still situated across the Tennessee-Ohio
Valley/Mid Atlantic region today, with midlevel heights upwards of
596-597 dam (around the 99th-100th climate percentile). On Friday,
this ridge will shift eastward and weaken, with heights decreasing
and slowly meshing into the broader tropical high to the south on
Saturday, which amplifies to around 591-592 dam this weekend.
Though, southeast Texas is still expected to remain on the
peripheral of both these ridges, with midlevel heights remaining
around 590-593 dam (~70-90th climate percentile) and 850mb
temperatures around 18-21C (~70-80th climate percentile). With this
persistent onshore flow and WAA we`ll continue to see hot weather
across SE Texas for the foreseeable future. Rain chances will vary
from day to day, though, with some weak impulses passing aloft, no
strong capping and onshore theta e advection, there can certainly be
some occasional showers and thunderstorms. This is most likely to
manifest as spotty streamer showers over the Gulf early in the
morning, then as some scattered/isolated showers and thunderstorms
in afternoon near the coast along the sea breeze. As noted
yesterday, low level lapse rates are also very steep, nearly dry
adiabatic at 8-9 DegC/km, so any pop up storms could produce some
modest downbursts at least, though not particularly strong.

In general, hot weather continues with highs in the 90s and triple
digit heat indices ranging from 100-110F (38-43C). WBGT values
indicate that heat stress on the human body will be high, possibly
reaching extreme in spots during the afternoon. There will be daily
chances of rain, possibly as light streamer showers over the
Gulf/Coast in the morning and maybe some pop-up showers/storms in
the afternoon, especially along the sea breeze.

Independence Day is this Saturday, and as many of you have likely
heard, it will be the Semiquincentennial (250th anniversary) of the
founding of the United States of America. Outdoor events and
celebrations for this milestone will likely draw in massive crowds,
thus extra care was put into the July 4th forecast, specifically
with regards to heat stress.

Heat index values these last few days have generally remained under
108, mainly as a result of modest afternoon mixing lowering
humidity. The NBM generally struggles with this mixing, so I`ve
adjusted dewpoints down slightly in the afternoon, generally keeping
to the higher-end observed values from our ASOS stations (as to not
mix out too much). Model guidance has been pinging temps to be
generally higher on Saturday. Yesterday NBM was a tad too cool in
spots, so I`ve increase highs slightly to compensate, closer to
around the 75th percentile in the NBM. The pressure gradient does
weaken on Saturday, and thus winds become very calm in the morning
through the early afternoon. Timing/intensity of the sea breeze can
be tricky to pin down on day 3 (since it falls beyond the cams),
thus to error on the side of caution, I mixed in some NBM 10th
percentile to simulate a slower & weaker afternoon sea breeze. Cloud
cover is another parameter that can be difficult to narrow down
beyond the 48 hour high-res window, though this current synoptic
pattern has tended to produce few-scattered q-fields in the
afternoon. Model vorticity and UVV are both especially weak on
Saturday, in addition to NBM guidance trending lower on PoPs for the
4th as well. With this in mind, I`ve opted to lower cloud cover
slightly (in addition to capping PoPs around 10%).

The culmination of all these changes still produces highs in the 90s
and heat indices around 101-109F for the 250th Independence Day. The
resulting Wet Bulb Globe Temperature values are forecasted around 86-
91 between 12PM-6PM. Resulting heat stress on the human body is
forecasted to be high (level 3/4), reaching extreme (level 4/4) in a
few isolated spots. Extra emphasis on the *isolated spots* portion,
as the spatial & temporal scale of those extreme values is small
(mostly within the Houston metro between 2-4PM). In laymens terms,
it`ll feel a warmer than the typical summer days as of recent,
though not dramatically different.

Despite more conservative heat projections, the current forecast
doesn`t suggest a need for heat headlines at this moment, though
that could change with the next forecast cycle. Regardless of
whether or not a heat advisory is issued, it would still be wise to
practice heat safety. If you plan to spend the day outdoors, make
sure you wear light cloths, apply sunscreen and stay hydrated by
drinking plenty of water. Heat is the #1 weather-related killer in
the U.S. each year, and often people greatly underestimate it`s
danger. Even if the heat isn`t advisory-strength, more people
outside means that more cases of heat illnesses will likely emerge
as a result.

03

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 622 AM CDT Thu Jul 2 2026

VFR conditions and light winds are currently in place across all
terminals. Streamer shower activity this morning may result in
brief MVFR ceilings for the coastal locations. Isolated to
scattered showers and thunderstorms are likely to develop late
this morning along the coast and move inland through the day. Any
convection that does develop should wane around 00Z. Will maintain
the current PROB30 groups for TSRA with this TAF cycle. Have
introduced a TEMPO group Friday morning to account for a medium
chance (per the latest HREF probs) for MVFR ceilings from 09-12Z.

&&

.MARINE...
Issued at 315 PM CDT Thu Jul 2 2026

Light S/SE winds around 10 knots and calm seas of 1 to 3 feet are
expected throughout the next several days. Light streamer showers
could develop over the Gulf waters each morning. Isolated to
scattered thunderstorms could develop along the sea breeze in the
afternoon near the coastline and bays.

03

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  76  95  77  96 /  10   0   0   0
Houston (IAH)  77  95  78  96 /  20  10  10  10
Galveston (GLS)  83  90  82  90 /  20  20  10  10

&&

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

$$

DISCUSSION...03
AVIATION...Castillo
MARINE...03

NWS HGX Office Area Forecast Discussion