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National Weather Service Forecast Discussion

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148
FXUS64 KHGX 202331
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
531 PM CST Tue Jan 20 2026

...New AVIATION...

.KEY MESSAGES...

- Rain chances increase tonight into Wednesday in association
  with a weak surface trough and some upper disturbances.

- Arctic Front should sag into the region Friday and Friday night,
  bringing various winter hazards over the weekend:
- Some prolonged temperatures and potential hard freezes.
- Low Wind Chill Values, potentially between 7-20 degrees.
- Risk of Freezing Rain, Sleet/Ice Pellets
- Hazardous marine conditions.

- Residents are encouraged to winterize their home during the
  work week prior to the cold weather arrival.

&&

.DISCUSSION...
Issued at 136 PM CST Tue Jan 20 2026

Today through Thursday:

A weak front remains stalled across the area today. A few showers
have developed in the vicinity of Matagorda Bay in a low-level
confluence zone and have raised PoPs in that area for the rest of
the day. Tonight and tomorrow a couple shortwaves in the northern
stream will have a glancing influence on our northern counties,
while some weak southern stream disturbances have a glancing
influence on our southern counties with overall cyclonic flow
aloft across the forecast area. As this occurs southerly low-level
flow will strengthen and push the front northward as a warm front.
This will cause some drizzle/light showers to develop overnight
tonight with the highest chances in our far northern counties.
Scattered to numerous showers will continue across much of the
area Wednesday into Wednesday evening. Some weak instability will
be present for a small chance of a thunderstorm but HREF thunder
probabilities are only 10 percent or less. Generally warmer
temperatures are expected, though if coverage of rain ends up
being higher than high temperatures could end up lower than
forecast. The front drifts back to the southeast as a cold front
but quickly stalls. With the stalled front in the area some low
rain chances continue into Thursday.

Friday through Monday:

Attention then quickly turns to the winter storm that will impact
much of the southern CONUS as we go into the weekend. A cutoff low
will drift slowly eastward off the coast of California and the
Baja, resulting in persistent moist southwest flow
aloft/isentropic lift downstream. Meanwhile at the surface a very
strong 1050+ mb Arctic high will build southward across the
Central CONUS, with a shallow Arctic airmass moving underneath
warm air advection aloft. Rain will overspread the area
Friday/Friday night as the Arctic front moves in. Temperatures
look to drop below freezing in the far northern counties as early
as Friday night or as late as during the day on Saturday morning.
This will be the main thing to watch as we get closer, since
models often struggle with the timing of shallow Arctic air
masses. Forecast soundings indicate a large warm nose aloft that
will melt any snowflakes, with a predominant precip type of
freezing rain. In the northern counties there will also be the
potential for a changeover to sleet as the low-level cold air mass
deepens. Temperatures won`t warm up much on Saturday and will be
falling in many areas during the afternoon.

Temperatures really start to drop on Saturday night though there
starts to be quite a bit of spread in temperatures in the guidance
by this point. This will result in the potential for wintry
precipitation to expand to cover much of the rest of the forecast
area. It is interesting to note that some guidance does indicate a
dry layer at 700mb pushing in, which is why current ensemble
blends show a decrease in PoPs. However, there remains quite a bit
of moisture above and below this layer, and even light freezing
rain/freezing drizzle at these temperatures could have significant
impacts. Additionally, any remaining water on roadways from
earlier rain will have the potential to refreeze. The current
forecast shows precipitation chances tapering off from northwest
to southeast by Sunday though there remains quite a bit of spread
in the guidance. Will keep in mind that any time a cutoff low is
involved there is always the potential for systems to slow down.

The latest probabilistic WSSI shows medium to high chances
(40-70%) of at least minor winter weather impacts for areas along
and north of I-10, with at least low (20%) chances extending
southward towards the coast. Probabilities for "moderate" winter
weather impacts are 20-30% across northern portions of the
forecast area. However, it is important to note that WSSI can
under-do impacts for freezing rain since small amounts of ice
accumulation can have big travel impacts. It`s too early for any
Winter Storm Watches at this time, but those will probably
eventually be needed for at least part of the CWA in the next day
or two. Current forecast winds are sustained around 10-12 kts with
gust to 20kts, which may also aid in power outages.

While there is a understandably a lot of focus on the wintry
precipitation, it is also important to focus on the dangerously
cold temperatures also occurring with this system. Hard freeze
conditions (temperatures below 24 degrees) are expected across
portions of the area Saturday, Sunday, and Monday nights, with the
coldest temperatures/most widespread temperatures below 24 degrees
Sunday night. Forecast lows in northern portions of the area are
in the teens on those nights. Dangerously cold wind chills are
also forecast, with the lowest values Sunday morning ranging from
the single digits north to the teens south. At minimum widespread
Cold Weather Advisories (wind chills below 20 north/25 south)
will likely be needed. Additionally, some Extreme Cold Warnings
(wind chills below 10 north/15 south) will probably be needed.

Make sure to continue to check back for the latest forecasts with
system since it is still a few days away and forecasts will likely
change. Now is the time to begin to prepare.

JDavis

&&

.AVIATION...
(00Z TAF Issuance)
Issued at 531 PM CST Tue Jan 20 2026

VFR ceilings heading into the overnight hours. Strengthening low
level jet (25-30kt) will drive moisture levels higher as the
night progresses. Would anticipate some increasing shra activity
not long after sunrise in combination with this increasing
moisture, a weak developing surface trof, and some upper impulses
trekking overhead. Best coverage in the metro/coastal areas
should be in the 17-01z timeframe (a few hours earlier at
CLL/UTS), followed by more isolated coverage. Ceilings will be on
a downward trend thru the day...down into MVFR territory toward
mid-late morning then possibly IFR territory late in the afternoon
and evening. 47

&&

.MARINE...
Issued at 136 PM CST Tue Jan 20 2026

Mariners should remain mindful of negative tide levels again
today, mainly across the northern bay areas around low tide
cycles. A tightening pressure gradient will lead to some
increasing Gulf winds today. A Small Craft Caution has been issued
for the Gulf waters for winds of 15-20 kts. A weak coastal trough
is expected to develop and move eastward bringing periods of
showers on Wednesday into Thursday. Patchy fog is also possible
Wednesday night and Thursday morning, but conditions do not appear
overly favorable for prolonged stretches of the dense variety. An
Arctic cold front is expected to push into the coastal waters
late Friday or Saturday bringing hazardous marine conditions: a
much colder airmass, strong north winds and building seas through
the weekend. Periods of precipitation are anticipated through
Saturday. Advisories are likely, and Gales cannot be ruled out.
Mariners are advised to keep up with the latest forecasts.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  55  67  55  73 /  40  60  30  10
Houston (IAH)  57  69  60  74 /  20  70  40  20
Galveston (GLS)  59  68  58  68 /  20  70  50  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Low Water Advisory until 6 PM CST this evening for GMZ335.

     Small Craft Should Exercise Caution through late tonight for
     GMZ350-355-370-375.

&&

$$

DISCUSSION...JDavis
AVIATION...47
MARINE...JDavis

NWS HGX Office Area Forecast Discussion