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National Weather Service Forecast Discussion

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295
FXUS64 KHGX 182328
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
628 PM CDT Thu Jun 18 2026

...New AVIATION...

.KEY MESSAGES...

- Dangerous heat will continue through the weekend, with heat
  indices in the 108 to 110 range. Limited cooling overnight will
  exacerbate the heat.

- Scattered showers and thunderstorms are possible on Friday and
  Saturday, with the potential for locally heavy rainfall. There
  is a Slight Risk (Level 2 out of 4) of Excessive Rainfall Friday
  and Friday night.

- High risk of strong rip currents is expected through the
  weekend.

&&

.DISCUSSION...
Issued at 107 PM CDT Thu Jun 18 2026

Broad upper troughing will persist over much of the CONUS, with
ridging building over the Gulf. Strong southerly flow over the
local area continues to filter an abundance of moisture across the
area. Meanwhile, mostly clear skies have allowed temps to soar
into the lower 90s. Temps may climb another degree or two this
afternoon. Combined with dewpoints in the upper 70s, RH values are
quite moist. Heat indices are already in the Heat Advisory range
(108-113) and these should max out around 115 this afternoon.
Given this, an Extreme Heat Warning is in effect for the entire
area through this evening.

Heat concerns will continue into the weekend, as the moist airmass
remains over the area. There will be enough heating each day for
temps to rise into the lower 90s. One caveat will be Friday into
Saturday, when a southern stream trough tries to move through the
area. That said, given the warmer dewpoints, overnight lows will
remain in the upper 70s to lower 80s through Saturday night. This
will provide little in the way of cooling and the risk for heat
illnesses may compound each day. Due to the lower confidence with
the trough building in, a Heat Advisory is in effect through
Saturday night. If the clouds/rain don`t pan out, we may have to
explore more Extreme Heat products this weekend.

Turning our attention to the potential rain Friday afternoon into
Saturday, guidance is in a bit of a disagreement on where the
trough will move and, therefore, where the heavier rain will set
up. The moist airmass persists, with PWs well above normal, so
there is a potential for locally heavy rainfall. The area remains
wet from previous days rain, so any additional heavy rain will
quickly become a flooding concern. Low confidence on timing and
location, but it`s a concern to monitor over the next 24 hours.

Beyond Sunday, we will likely be in a more typical summer pattern,
with high pressure building in and little to no rain chances. The
deep layer moisture transport may be more limited and reduce the
risk of heat.

&&

.AVIATION...
(00Z TAF Issuance)
Issued at 609 PM CDT Thu Jun 18 2026

The hot and humid conditions today has led to the development of
some haze, especially south of I-10. LVJ, LBX, and GLS have all
been reporting visibility around 4-6mi this afternoon due to this
haze, and this will likely continue into this evening. Otherwise
VFR conditions this evening will transition to MVFR conditions
across much of the region between 3-5z with CIGs dropping to
around 1500ft with scattered clouds around 500-700ft. Patchy fog
is also possible late tonight into early Friday morning bringing
visibility reductions to around 4-6mi. UTS and CXO may see IFR
conditions beginning around 08-13z with CIGs down to around 700ft.
VFR conditions return to the region by 14-16z with SSE winds
around 8-12kt prevailing through the day.

There will be a chance of showers and thunderstorms to develop and
move across the region from west to east Friday afternoon into
the evening hours. Exact timing and location of the storms is
still a bit uncertain, but for now have included a PROB30 for all
inland terminals Friday afternoon. These thunderstorms will have
the capability of producing gusty winds and heavy rainfall
reducing visibility.

Another night of MVFR (to occasionally IFR) conditions is expected
Friday night into Saturday morning.

Fowler

&&

.MARINE...
Issued at 124 PM CDT Wed Jun 17 2026

Light to moderate southerly winds and sea up to 6ft are expected
today and persist into the weekend. Caution flags could be
warranted at times over the next few days as the pressure gradient
tightens.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  79  93  78  91 /   0  30  50  50
Houston (IAH)  81  93  80  92 /   0  20  30  30
Galveston (GLS)  84  90  83  89 /   0   0  30  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Extreme Heat Warning until 8 PM CDT this evening for TXZ163-164-
     176>179-195>200-210>214-226-227-235>238-300-313-335>338-436-
     438-439.

     Heat Advisory until 10 PM CDT Saturday for TXZ163-164-176>179-
     195>200-210>214-226-227-235>238-300-313-335>338-436>439.

     High Rip Current Risk through Friday evening for TXZ436>439.

GM...Small Craft Should Exercise Caution through Friday morning for
     GMZ330-335.

     Small Craft Advisory until 7 AM CDT Friday for GMZ350-355-370-
     375.

&&

$$

DISCUSSION...JTC
AVIATION...Fowler
MARINE...JTC

NWS HGX Office Area Forecast Discussion