Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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569
FXUS64 KHGX 181803
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1203 PM CST Tue Feb 18 2025

...New AVIATION...

.SYNOPSIS...
Issued at 357 AM CST Tue Feb 18 2025

It has been a very swingy winter this year, where we have
routinely found ourselves very much above normal...until we are
very much not. An advancing cold front will give us a shot at
showers and thunderstorms today, followed by a shot of air behind
the front that will remind us that it is indeed still winter.
Though wintry precip does not appear in the cards at this time,
we`ve got a cold stretch ahead of us. Here are the highlights:

- Showers and storms ahead of and along the front will generally
  be manageable, but there will be some potential for 1-2 inch
  per hour storms around and east of the Houston metro. There is a
  marginal risk (threat level 1 of 4) for excessive rain due to
  this potential.
- On the waters, strong winds behind the front tonight and
  Wednesday are prompting a gale warning on all coastal waters and
  a wind advisory on coastal peninsulas and islands. Folks right
  on the Gulf will want to get those loose items secured today
  before the front rolls through.
- Cold air surges in behind the front on gusty north winds; look
  for wind chills below 20 degrees north and west of the Houston
  metro. These areas have a cold weather advisory in place.
- Tomorrow night, even colder air has prompted an extreme cold
  watch as the coldest wind chills look to drop to the high single
  digits. In portions of the Houston metro, potential wind chills
  range from 25 degrees down to around 15 degrees. A hard freeze
  is most likely north of the Houston metro, though it could
  extend into the northern suburbs and into rural areas well west
  of the metro.

&&

.SHORT TERM...
(Today through Wednesday Night)
Issued at 357 AM CST Tue Feb 18 2025

This winter has seemed like it`s either been full out spring, or
it has been winter. A cold front currently up around the Red River
is on its way southward today is going to put us right back in a
reminder that February is still a winter month. Until then,
however, we`ll have a roughly seasonable day - perhaps a bit
colder thanks to cloud cover - along with increasing potential for
showers and an isolated thunderstorm. Expect chances for a
smattering of showers to gradually grow later this morning, with
rain showers becoming likely late this afternoon into this
evening, before the frontal passage puts an end to any rain
potential late tonight.

One thing we will want to watch out for is locally heavy rain.
Forecast soundings are...not impressive at all, and I`d expect
rain rates to be pretty manageable. That said, mean LREF
precipitable water values are around/above the 90th percentile
across Southeast Texas, and around the 97th percentile coastward
of I-10, so we do have ample moisture available. CAM guidance
does show some convective pattern to the rainfall late this
afternoon into the evening, in spite of the generally lousy
soundings. So, if we can manage one or two decently strong storms,
those particular cells could produce 1-2 inch per hour rain rates.
HREF guidance suggests a 40 percent chance of 1 inch per hour rain
around the Houston metro, and a 60-80 percent chance of 1 inch per
hour rates east of the metro, along with a 10ish percent chance
of 2 inch per hour rain rates. While not all that scary, it does
show that there is some signal that the strongest storms will be
capable of tapping into the unseasonable amounts of moisture
available to today`s rains. It seems to match up well with WPC`s
marginal risk for excessive rain (threat level 1 of 4)
today/tonight.

Deeper into the night tonight, and even more so tomorrow night,
focus turns towards incoming cold air. On the plus side, rain
doesn`t look to linger too long after the frontal passage, and
the arrival of the wintry air does look to lag a little bit
behind the front, which should keep any concerns for anything
frozen falling out of the sky at bay. Temperatures, on the other
hand, are showing a stronger potential of reminding us that yes,
it is still winter in Southeast Texas. Expect temperatures to fall
into the low 40s and 30s across the area late tonight into the
first hours of Wednesday morning. Freezing temps should be fairly
limited in area, held behind a line arcing from roughly Columbus
to Navasota to Huntsville to Crockett. Paired with the expected
strong north winds though, and we`re still looking at some cold
wind chills late tonight. Expect those to bottom out in the teens
and 20s for all but right on the immediate Gulf coast, and low
enough to require a cold weather advisory along the western edge
(where winds are strongest) and northern edge (where temperatures
are lowest) of our forecast area. This is where we can expect wind
chill to be driven below 20 degrees, and into the 10-15 degree
range at their lowest up around Caldwell.

Don`t look for things to get much better tomorrow, as continued
cold air and lingering cloud cover to hold daytime highs down well
below average. Even our warmest spots right on the Gulf will
struggle to reach 50 degrees, while folks up in that
Caldwell-B/CS-Madisonville-Crockett stretch may not even do better
than the upper 30s! This, of course, sets us up for an even colder
night tomorrow night. Cloud cover will be diminished, allowing for
more efficient cooling. And while winds shouldn`t get too calm,
that will be a double-edged sword. Sure, it may mitigate just how
cold the temperatures fall, but it will also drive wind chills
down even lower. For now, I`ve got an extreme cold watch issued
for points at and northwestward of Palacios to Houston to
Livingston for the potential to see wind chills below 15 degrees.
Ultimately, I expect the potential to meet the extreme cold
threshold (10 degrees north, 15 degrees south) will be more
limited to the north and west, with some only reaching the
threshold for wind chills justifying a cold weather advisory (20
north/25 south) elsewhere. But here at the watch phase, I don`t
have the confidence to place precisely where that line is going to
be. For now, I will roll with placing a watch roughly in line with
the 50 percent probability contour for reaching the warning
threshold.

&&

.LONG TERM...
(Thursday through Monday)
Issued at 357 AM CST Tue Feb 18 2025

1045mb surface high centered over the Central Plains starts to
slowly tack east on Thursday. While CAA slowly weakens, this cold-
dry airmass is progged to remain in place just a tad bit longer.
Lofted moisture with building cloud cover should limit overnight
cooling, keeping lows for Friday morning in the 20s to 30s. These
overcast conditions will also limit heating on Friday, keeping highs
a tad cooler that afternoon compared to Thursday, but still
generally in the upper 30s/upper 40s.

Our next bout of active weather comes from a mid/upper level trough,
which will be passing through the Four Corners on Friday. As it
draws closers to SE Texas, a coastal trough/Gulf low will set up
over the Western Gulf coast. The influx of moisture from this
feature with forcing aloft from the trough should bring increasing
rain chances, resulting in cold and dreary conditions on Saturday.
PWs remain tame, generally around 1.0-1.3" and with a shallower warm
cloud layer and lacking instability, the threat of heavy rainfall
with this system remains low for the time being. The upper trough
and associated surface features should push off to the east
overnight, with rain chances tapering down Sunday Morning.

Thinning sky cover should bring a brief warm-up on Sunday, even
moreso on Monday as surface high pressure is pushed into
north/northeast Gulf, thus establishing onshore flow an WAA.
Uncertainty grows high by this point in the forecast, though signs
point towards more active weather in store for later next week.

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1158 AM CST Tue Feb 18 2025

A mix of MVFR to high-end IFR ceilings can be expected this
afternoon, along with periods of light showers. A cold front is
expected to move through Southeast TX late this afternoon/early
evening. At the moment, the time of arrival of the front is around
00Z Wed near CLL, between 02-03Z Wed near IAH/HOU and after 05Z at
GLS. Showers with isolated thunderstorms are expected ahead of the
boundary, with showers tapering off from west to east late this
evening. Behind the front, gusty northwest to north winds are
expected. Gusts in excess of 30 knots are possible at times.
Ceilings should gradually improve to MVFR and VFR by Wednesday
morning.

JM

&&

.MARINE...
Issued at 357 AM CST Tue Feb 18 2025

Onshore flow strengthens today ahead of an approaching strong cold
front, warranting the need for caution flags at times while showers
and thunderstorms develop across the region. Patchy sea fog could
form ahead of this cold front as winds ease up, especially over the
southwestern waters near Matagorda bay. The cold front will push off
the coast late Tuesday night, bringing strong offshore winds,
frequent gusts to Gale force and seas of 6 to 9 feet in it`s wake.
Lower water levels could develop in the bays, especially at low
tide. Gale warnings will be in effect from midnight through
Wednesday afternoon for these rough conditions. Small Craft
Advisories will likely be needed across the Gulf waters and bays
afterwards into the weekend, especially on Friday and Saturday as a
coastal trough forms offshore. This feature should bring another
round of showers and thunderstorms across the waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  62  29  40  22 /  70  60   0   0
Houston (IAH)  63  38  46  28 /  60  80   0   0
Galveston (GLS)  65  43  50  33 /  70  80   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Cold Weather Advisory from 3 AM to 10 AM CST Wednesday for
     TXZ163-164-176-177-195>198-210-211-226-235.

     Extreme Cold Watch from late Wednesday night through Thursday
     morning for TXZ163-164-176>179-195>199-210>213-226-227-235-
     236-335.

     Wind Advisory from midnight tonight to 3 PM CST Wednesday for
     TXZ436>439.

GM...Gale Warning from midnight tonight to 3 PM CST Wednesday for
     GMZ330-335-350-355-370-375.

     Small Craft Advisory until 9 PM CST this evening for GMZ335-355-
     375.

&&

$$

SHORT TERM...Luchs
LONG TERM....03
AVIATION...JM
MARINE...03