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882
FXUS64 KHGX 300627
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1227 AM CST Tue Dec 30 2025

...New DISCUSSION, MARINE, FIRE WEATHER...

.KEY MESSAGES...

- A light freeze can be expected for at least a portion of the
  area tonight, with an even broader swath of the area seeing a
  light freeze Tuesday night.

- Hard freeze potential is virtually nil for most of the area.
  However, there is a low chance (30 percent of less) of a hard
  freeze in the northernmost reaches of the area - portions of
  Madison, Houston, Walker, Trinity, and Polk counties. It may be
  prudent to consider protections against that occurrence for
  locations in those areas where vulnerability to a hard freeze is
  a critical concern.

- Hazardous conditions remain on coastal waters while winds and
  seas slowly improve from the recent gale. A Small Craft Advisory
  is in place through mid-day Tuesday. Abnormally low water
  levels in Galveston Bay are also anticipated, and these may
  persist deeper into the week.

&&

.DISCUSSION...
Issued at 1227 AM CST Tue Dec 30 2025

There`s no fog, I hardly know what to do with myself this evening!
Oh right, we`ve got gusty winds, plummeting temperatures,
and...also...*checks notes*...sleet?! Yes, indeed. In an setup that
we seem to manage roughly a time or two each winter, we had just
enough lingering mid-level moisture to fall out of clouds several
thousand feet up - use evaporative cooling falling through the
very dry air beneath it to freeze itself, and result in a handful
of pellets making it to the ground to ping off of hard surfaces.
Fortunately, this happens in amounts far too meager to accomplish
anything but light up social media, but it is still frustrating to
conclude that the column will be too dry for this potential...only
to have it happen anyway. Going forward, cloud bases have now
risen to 10-12k feet, and while this SHOULD be high enough to stop
any more sleet from reaching the ground, we do still have some
radar echoes over the Brazos Valley, so I can`t completely rule
that out over the next few hours.

Ultimately, though, the main focus of the forecast - and
especially the short term portion - is the incoming cold
temperatures. Gusty north winds continue, and colder air from the
north will keep on getting pumped in tonight. However, the winds
will also make the boundary layer more turbulent, which tends to
act against cooling, so we`ve got a bit of cross purposes there.
Additionally, while not a pure overcast, we have plenty of clouds
overhead to help reduce overnight cooling as well. But with
afternoon temps only starting us off from something in the range
of 43 to 55 degrees, it won`t take much to fall below the freezing
mark, especially up in the chillier north.

In my explicit forecast, I have freezing temps focused north of
the Houston metro, but that freezing line should be encroaching on
the far northern fringes of the metro towards dawn - I`m thinking
roughly Caldwell to Conroe to Cleveland northward. But a little
bit south of there, we could see localized cold spots as far south
as extreme northern and northwest Harris County briefly dip to the
freezing mark. This scenario in my head (and my grids) puts the
freezing line in roughly the same spot as the line for a 40
percent NBM probability or greater of freezing temps. As I am
opting to hedge slightly under NBM, this seems like a reasonable
place to draw the line. But for locations south of this line -
spots like Brenham, Columbus, Cypress, The Woodlands, etc. NBM has
a 20-25 percent chance of a brief, light freeze tonight.
Considering chances will be even higher Tuesday night, it probably
wouldn`t hurt to just be prepped for a light freeze tonight, as
well.

Speaking of Tuesday night, it seems like each crack I take at
these lows, I`m nudging those numbers down a little more. With
high pressure dropping right in, we really are looking to grab a
great radiational cooling setup and one chilly night. The urban
core of Houston should have a chilly, but above freezing night,
though it`s definitely worth mentioning that the NBM has freeze
probabilities inside the loop as high as 20 percent now. And the
less of a concrete jungle you get, the more likely a light freeze
will be. Those same NBM probs rise to around 70 percent for Katy,
Cypress, and Tomball. And while the highest odds of a freeze stay
north of I-10 (roughly over 80 percent), the rural area southwest
of the Houston metro is now seeing odds of a freeze as more likely
than not all the way down to Lake Jackson! At this point, only
the immediate coast and the core of Houston appear safe from that
32 degree temperature between the hours of 3am and 8am Tues
night/Wed morning.

For now...I`m opting to hold off on any sort of freeze watch. For
most of the area, we`ve already had our "season ending" freeze
warning of the year, and those few locations left are right on the
coast, where I`d like to see a little more run-to-run confidence
in temps getting this cold before going with a warning there. I
will give the day shift one more crack at it tomorrow morning. The
one other way we use freeze warnings is for hard freezes. And
though a light freeze is virtually certain for the northern part
of the area, confidence is also quite high that we won`t see a
hard freeze. The one area to watch for will be generally north of
Huntsville, in portions of Madison, Houston, Walker, Trinity, and
Polk counties. There, NBM probabilities for a hard freeze do get
into the 20-30 percent range. Probably not high enough for most
people to be concerned, but if you have something where protecting
against a hard freeze is vitally important, it may be prudent to
be prepared anyway, even if the odds favor it not happening.

Beyond a freeze warning, I also gave some consideration to a cold
weather advisory. In the northern half of our area, that is when
temps or wind chills are expected to get below 20, and below 25 in
the southern half of our area. With the gusty winds continuing
tonight, wind chills get pretty close to those thresholds, and in
the 20s across Southeast Texas. However, temperatures should stay
just high enough to keep things above the advisory thresholds,
even despite the gusty winds. The reverse is true Tuesday night -
yes, it will be the coldest night of the week, but as that is
facilitated by the winds dropping off dramatically, neither temps
nor wind chills still look to get low enough for a cold weather
advisory.

Once we bottom out with the cold, the general trend of the
forecast will be for gradual warming and fair weather under the
reign of generally high pressure and zonal flow or weak ridging
aloft. A passing upper shortwave trough that could probably be
well described as a "ripple" should bring no more than some
increased cloudiness Thursday into Friday. Winds should remain
fairly light, but will turn to be onshore, and jump start the
warming trend, such that we are looking for highs to return back
to the 70s late in the week. Finally, I had been keen on Saturday
as an unexpectedly warm day, with sunny conditions following a
weak Pacific front that brings little to no cold air with it.
Well...the models have decided - what if that front, but in phase
with a trough in the polar jet stream? As those link up, we more
solidly get northwest flow aloft instead of westerly flow, so I am
begrudgingly holding off on this idea for now, and falling in line
with the NBM cooling things down a bit (but still remaining on the
warm side of average) going into the weekend.

Now, cross-jet phasing can be a fragile thing, as it can be broken
by subtle shifts in either or both troughs. I went to the LREF
clustering analysis to see if this was just a passing model fancy,
only to be abandoned with the next run. And...it doesn`t really
seem like it. With the caveat that this type of resolution and
ensembling can wipe out subtle features, all four 500 mb clusters
in this analysis show a setup that doesn`t deviate much from the
grand ensemble, and would generally support a slightly cooler day
Saturday after the front. Now, because of this setup`s fragility,
I reserve the right to bring a hot Saturday back to the forecast!
But...right now, the data seems to quite clearly favor the model
consensus, and so I will follow it for now.

&&

.AVIATION...
(00Z TAF Issuance)
Issued at 526 PM CST Mon Dec 29 2025

Gusty northerly winds should gradually decline this evening into
the tonight. The lone exception will be near the coast, where
winds may remain gusty until tomorrow morning. Isolated shower
activity should subside this evening, as the high VFR cloud deck
gradually breaks, yielding to clearer skies tomorrow. Winds
tomorrow remain northerly, but will be much lighter than today,
averaging around 10 knots.

&&

.MARINE...
Issued at 1227 AM CST Tue Dec 30 2025

Winds and seas are very slowly diminishing from earlier gale
conditions, but this improvement is indeed quite gradual. As a
result, winds and seas will stay elevated through Tuesday
morning, so a small craft advisory continues for the hazardous
conditions lingering on coastal waters.

On the bays, in addition to the high winds and rough waters, currents
may become strong near the interface of the rivers and the bays
during times of low water, which may particularly be an issue on
Galveston Bay. Low water will likely persist through at least
Tuesday`s low tide cycle and potentially deeper into the week.

Deeper into the week, light northwest winds on Wednesday will
become southwesterly by Wednesday night. This light to moderate
onshore flow will continue through Friday. The onshore flow will
also boost humidity. While we are beyond any model guidance at
this point, the expected environment should make patchy fog
possible during the overnight hours Thursday night and Friday
night. Winds, though, may ultimately create a situation where fog
formation is disrupted. This potential will continue to be
evaluated through the week.

&&

.FIRE WEATHER...
Issued at 1227 AM CST Tue Dec 30 2025

Breezy north winds will persist through the night, but more
substantially decrease on Tuesday as high pressure settles into
the region. While winds may be on their way down, dry conditions
will be going nowhere. Very low humidity is virtually certain to
persist through Wednesday with minimum relative humidity values
dropping into the 20s during the afternoon hours for most of the
region. Locations west of the Brazos River will be capable of
dropping into the upper teens on Wednesday, boosted by slowly
increasing temperatures without a corresponding boost in humidity.
The lower winds will mitigate fire weather threats, but it will
still be important to consider these dry conditions for fire
planning purposes. This will be particularly prudent in areas of
dense, fine fuels. Texas A&M Forest Service data shows that in
general, near to above normal fuel moisture continues, but grassy
areas and other fine fuel beds will be the first to show the
influence of a prolonged low humidity stretch.

Later in the week, southwesterly winds will finally lead to
increasing humidity Thursday and Friday. This will be interrupted
by a weak cold front at the end of the week, roughly around Saturday
morning. In the wake of this front, drier conditions will filter
back in over the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  31  54  30  66 /   0   0   0   0
Houston (IAH)  35  54  33  64 /   0   0   0   0
Galveston (GLS)  39  52  41  60 /   0   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until noon CST Tuesday for GMZ330-335-350-
     355-370-375.

     Low Water Advisory until 6 PM CST Tuesday for GMZ335.

&&

$$

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

NWS HGX Office Area Forecast Discussion