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National Weather Service Forecast Discussion

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329
FXUS64 KHGX 211942
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
242 PM CDT Tue Jul 21 2026

...New DISCUSSION, MARINE, TROPICAL...

.KEY MESSAGES...


- A Heat Advisory remains in effect through 8 PM this evening.

- Even hotter conditions are expected on Wednesday with
  dangerously heat indices across all of southeast Texas. An
  Extreme Heat Warning has been issued from 11 AM - 8 PM
  Wednesday.

- Tropical Storm Bertha is forecast to weaken as it approaches
  southeast Texas late in the week. While forecast uncertainty
  remains fairly high, residents should monitor the latest
  forecasts and evolution of this system.

- Corresponding rain and temperature forecasts for the local area
  are subject to changes later in the week and highly dependent on
  the tropics.

&&

.DISCUSSION...
Issued at 217 PM CDT Tue Jul 21 2026

No major changes to the forecast... The main weather concerns are
dangerously hot conditions as we continue to monitor the westward
progress of Tropical Storm Bertha over the northern Gulf.

Now through Wednesday: A mid to upper level ridge centered over
the Rockies continues to dominate weather conditions across the
region by providing strong subsidence and dry air across the area.
As Bertha moves into the northwestern Gulf, even hotter
conditions will be in place by Wednesday, with highs mostly in the
triple digits. The first 100-degree day may occur on Wednesday in
some locations. With increasing Gulf moisture, expect dangerous
heat index values in the 108 to 115F range. A Heat Advisory
remains in effect for all of Southeast TX through 8 PM this
evening. An Extreme Heat Warning has been issued for all of
Southeast Texas on Wednesday from 11 AM through 8 PM. Remember,
heat-related illnesses increase significantly during extreme heat
and high humidity events. Please, stay cool, hydrated and
informed.

Wednesday night into Friday... Weather conditions will be mainly
influenced by the eventual track and intensity of Tropical Storm
Bertha. Dry air entrainment and increased wind shear will continue
to play a big role in its development once it moves near the
Louisiana coast and heads westward toward the TX coast. Current
observations and forecasts show the heaviest precipitation and
strongest winds for this system are located on the south side of
this asymmetrical storm. Therefore, no significant impacts are
anticipated for Southeast TX at this time. Isolated to scattered
showers and thunderstorms are possible, with the best chances over
the coastal counties and coastal waters. Please continue to
monitor for forecast updates as Bertha evolves over the northern
Gulf. See the TROPICAL section below for more details on Bertha.

Saturday through early next week... Depending on the
track/intensity of Bertha, a few showers/storms will be possible
on Saturday. Otherwise, the mid to upper level ridge re-
establishes over the central CONUS through the weekend, leading
again to drier and hotter conditions. Heat headlines may be needed
late this weekend into early next week as heat indices rise into
the 105-108 degF range.

JM

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 623 AM CDT Tue Jul 21 2026

MVFR and localized IFR conditions due to patchy fog being observed
this morning, especially at KCXO and KLBX, similar to what has
occurred the past few nights. By 14Z all terminals are anticipated
to return to VFR. Winds are expected to vary between west and
southwesterly flow throughout the day. Overnight we may have another
round of patchy fog; however, an increasing dewpoint depression may
inhibit dense fog. A few of the usual fog prone sites may drop to
MVFR during the 10Z-14Z timeframe, otherwise expect VFR conditions
to continue overnight. Light and variable winds are likely across
all regions tomorrow night.

Davis/Wingo/Bailey

&&

.MARINE...
Issued at 217 PM CDT Tue Jul 21 2026

Light to occasionally moderate west to southwest winds and low
seas will continue across the Upper TX coast through at least late
Wednesday. Mariners should continue to monitor weather
conditions, especially Thursday and Friday as Tropical Storm
Bertha moves westward along the northern Gulf. There still remains
high uncertainty in the forecast track and intensity of Bertha.
However, Bertha is expected to weaken back to a depression before
it reaches our coastal waters. While forecast confidence remains
low given this uncertainty, significant impacts are not
anticipated across our coastal waters. However, Small Craft
Advisories could potentially be issued for elevated winds and seas
up to 6 ft.

JM

&&

.TROPICAL...
Issued at 217 PM CDT Tue Jul 21 2026

The National Hurricane Center continues to track Tropical Storm
Bertha, currently centered off the Florida Panhandle coast. It is
slowly moved NNW to NW today at around 3-5mph, but a building high
pressure to the north is expected to force Bertha on a more westward
track later today into Wednesday morning. Bertha has strengthened
through the day today with maximum sustained winds of 60 mph as
of the 1pm CDT Update. However, strong northerly shear has
displaced most of the thunderstorms and winds to be located on the
south side of the storm. Environmental conditions continue to
look unfavorable for future strengthening/organization as Bertha
deals with the high wind shear, increasing subsidence from the
building high pressure, and deals with land interaction along the
central Gulf Coast over the next few days. The current forecast
has Bertha approaching the Upper Texas coast as a weak tropical
depression late Thursday into Friday morning - if it survives.

We are not anticipating significant impacts to Southeast Texas from
Tropical Storm Bertha. The lop-sided nature of the showers and
thunderstorms is expected to keep the bulk of the rainfall offshore.
Some shower and thunderstorms could be possible along the coast
Thursday into Friday as the system approaches from the east, but not
anticipating any significant rainfall totals. NBM shows about a 10%
chance of rainfall greater than 1" near the barrier islands, but
otherwise is

NWS HGX Office Area Forecast Discussion