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National Weather Service Forecast Discussion

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889
FXUS64 KHGX 171753
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1253 PM CDT Mon Aug 17 2026

...New AVIATION...

.KEY MESSAGES...

- Hot and dry conditions to prevail, with temperatures skewing a
  little hotter than normal this week.

- We will be near Heat Advisory criteria through the week. Heat
  will be dangerous even if we remain a little below advisory
  criteria.

- Rain chances remain near zero through the forecast period.

&&

.DISCUSSION...
Issued at 1133 AM CDT Mon Aug 17 2026

Very hot and dry conditions will prevail thanks to the dominance
of a strong mid/upper ridge over our area. Temperatures this
afternoon are expected to reach near 100 degrees for most inland
areas (low/mid 90s near the coast). The one saving grace will be
the efficient mixing that will bring down afternoon dew points. I
utilized drier guidance in our dew point grids, showing values
dropping well down into the 60s north of I-10, with sub-70 dew
points reaching inland-most areas of coastal counties. But with
today`s atmosphere similar to today, I`m not going to be surprised
if dew points drop a little lower than what I have in the grids.
These lower dew points should help keep heat index values in the
102-106F range. Still plenty hot to cause heat related illness but
technically below advisory criteria.

Tuesday and Wednesday appear very similar to today. However,
LL onshore flow is looking deeper (especially Tuesday). This may
help to provide a little more cumulus and overall marine
influence, which would tend to drop actual temperatures down a
degree or two or three. However, deep onshore flow suggests a more
moisture rich LL profile. Thus, dew points may not mix down as
much. Therefore, Tuesday and Wednesday may actually feel hotter.
Current predicted heat indices are generally 104-107F. WBGT values
suggest the heat stress on the human body could be nearing
extreme levels (~90) during the noon to 3 PM time frame. Couldn`t
rule out a rogue isolated shower on the sea breeze boundary. But
PoPs are close to zero areawide.

The flow pattern across CONUS is expected to transition into a
more amplified regime as we head into the second half of the week.
The zonally elongated ridge centered over Texas is expected to
retrograde westward as it amplifies, while a trough digs southward
into E CONUS. I wish Texas could experience more influence from
the trough. Alas, it`s August and cooler temperatures are not
allowed. If anything, deterministic and ensemble data all suggest
slightly hotter temperatures during the later portion of the
week. Heat indices and heat stress on the body (WBGT) will be in
part dependent on how much dry air we can mix to the surface.
Current data that is utilized in the long term grids (Thursday -
Sunday) suggest widespread extreme heat stress in the early
afternoon, with heat index values high enough (107-112F) to
warrant advisories. However, if we can add a tad more mixing to
the equation, then we could shave off a few degrees, or more, from
those indices. Regardless, practicing heat safety will be a must.
We can`t expect it to be comfortable in August here in Southeast
Texas.

Rain chances remain low through the weekend. However, disturbances
embedded in the flow aloft between the W CONUS ridge and the E
CONUS trough will be worth watching for possible
shower/thunderstorm producers this weekend. For now, weekend PoPs
are very low.

Self

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1234 PM CDT Mon Aug 17 2026

Light south to south-southeast flow is expected to develop this
afternoon, before becoming light and variable overnight. VFR
conditions should prevail. However, locally MVFR to IFR conditions
are expected tomorrow morning in locations prone to fog and low
cigs (CXO / LBX).

&&

.MARINE...
Issued at 1133 AM CDT Mon Aug 17 2026

A very typical summer-like pattern is expected through this week,
featuring light SW winds in the morning hours that back south and
increase during the afternoon and evening hours. Winds should be
highest in the evening (up to 15 knots) before decreasing again by
morning. Winds could become SSE to SE at times in the late
afternoon and early evening. Seas should remain relatively low,
averaging 1-3 feet over the Gulf.

&&

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

&&

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

$$

DISCUSSION...Self
AVIATION...Self
MARINE...Self

NWS HGX Office Area Forecast Discussion