Extreme Cold Warning 1, NWS Austin/San Antonio, TX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1136 AM CST Tue Feb 18 2025

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 206 AM CST Tue Feb 18 2025

Key Messages:

- Strong cold front moves across South Central Texas this evening

- Slight to chances of showers and thunderstorms (20-40%) are
anticipated along and east of a Burnet to New Braunfels to Yorktown
line this afternoon and evening

- In the wake of the frontal boundary, an Arctic airmass rushes and
spreads across the local area with strong northerly winds helping
temperatures to drop the teens, 20s and lower 30s and wind chill
in the single digits and teens values

- A Cold Weather Advisory is in effect from midnight tonight through
  noon Wednesday

- Wednesday's highs are forecasted to range from the mid to upper
30s across the Hill Country and 40s to lower 50s elsewhere, however,
it is going to feel much colder because the wind chill factor

The overnight period has begun with low clouds spreading across most
areas of South Central Texas with surface observations reporting
southerly winds around 6 to 10 mph with a few locations coming in at
11 to 14 mph. According the forecast soundings, the lower levels
continue to moisten for the rest of the overnight period and for
most of the day on Tuesday. Can't rule out patchy to areas of fog
developing around dawn and lingering around through at least noon.
Also, don't be surprised if some light drizzle occur along and east
of Interstate 35 and coastal plains through the morning time frame.

Mostly cloudy to cloudy skies are in store throughout the day with
highs in the upper 60s across the Hill Country to the 70s for the
San Antonio area and locations to the south with even some 80s along
the southern portion of the Rio Grande.

As the afternoon period progresses, the lower atmosphere has the
chance to become a bit unstable for showers to occur and even a few
elevated thunderstorms are possible mainly along and east of
Interstate 35.

Moving onto the early evening, a strong cold front pushes across the
local area and rushes an Arctic airmass to quickly spread across
South Central Texas. Strong northerly winds are expected to assist
the airmass to feel even colder during the overnight period into
Wednesday. Overnight lows are forecast to drop to the teens, 20s and
lower 30s with wind chill values into the singe digits and 20s for a
good portion of the local area. A Cold Weather Advisory is in effect
midnight tonight through noon Wednesday. This cold spell is the
coldest thus far for this 2025 winter season. We recommend to pay
close attention for the 4 P's: people, pets, pipes, and plants.

During the day on Wednesday, highs are only reaching the mid to
upper 30s across the southern Edwards Plateau, Hill Country
including the Austin metro and 40s to lower 50s rest of the local
area. However, the wind chill factor is likely to make the
temperatures much colder. If you are in the Hill Country,
temperatures are going to feel in the 20s all day long. And just
wait to read below as temperatures are likely to be even colder for
Thursday morning.

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 206 AM CST Tue Feb 18 2025

Key Messages:

- An Extreme Cold Watch is in effect for much of South-Central Texas
  Wednesday night into Thursday morning with wind chills between 0 and
  10 degrees.

- Follow cold weather safety and protect the 4 P's: People, Pets, Pipes,
  and Plants.

- Another storm system may bring a brief round of wintry precip to the
  Hill Country late Friday night/Saturday morning, but at this time
  confidence is low in any impacts.

Wednesday night remains on track to be the coldest night of the
season for much of South-Central Texas. Models are in good agreement
in lows diving into the teens and 20s for most of the region. A
bitter north wind is forecast to persist throughout the night as
high pressure continues to spread southward, possibly producing
gusts topping 20 mph. This will potentially result in wind chills
reaching 0 to 10 degrees for many areas, and accordingly, an Extreme
Cold Watch remains in effect for most of our region Wednesday night
through noon Thursday. Confidence in meeting the threshold for
extreme cold is higher across the Hill Country, Edwards Plateau, the
I-35 corridor north of Bexar County, and Coastal Plains along and
north of I-10. The watch extends beyond these regions as temperatures
and winds would only need to change marginally for areas farther
south to also reach extreme cold criteria.

Temperatures Thursday afternoon may only climb into the upper 30s to
mid 40s. Some of the model guidance also suggests a low-level cloud
deck spreading across the Winter Garden, Hill Country, and I-35
corridor. If this comes in a little quicker, the daytime warmup may
be even more muted. This push of clouds will mark the onset of a
gradual shift to southerly winds aloft in response to an approaching
trough, carting moisture into South-Central Texas. Lows Friday
morning are forecast to be a few notches warmer than Thursday's
lows, but a hard freeze is still anticipated for the Edwards
Plateau, Hill Country, and I-35 corridor near Austin. Friday's highs
may be comparable if not even slightly colder than Thursday's as
cloud cover is expected to be much more prevalent by then.

A coastal low developing in the western Gulf Friday into Saturday is
expected to provide much of this moisture. The combination of the
approaching trough and the coastal low nearing the Texas coast will
increase moisture transport Friday night through Saturday, mainly
over the I-35 corridor and Coastal Plains. As this moisture glides
up and over our cold airmass, precipitation is possible. The amount
and coverage of precip will depend largely on the intensity and
broadness of the low-level jet developing over our area ahead of the
trough. The GFS has been more muted, leading to less coverage, while
the ECMWF and CMC show broader jets and consequently more
precipitation. The latest ensemble cluster analyses have thus far
favored the broader/stronger camp, so we continue to depict overall
probabilities of precipitation of 20-40 percent progressing up the
Coastal Plains, I-35 corridor, and possibly eastern Hill Country
Saturday morning then sliding eastward through the day. As
temperatures Saturday morning are forecast to dip below freezing
over the Hill Country and along the Balcones Escarpment, we continue
to monitor for the possibility of freezing rain from this
overrunning weather pattern, though amounts and likelihood remain
low at this time as the corridor of moisture is generally weighted
east of the coldest surface temperatures. For the Coastal Plains,
cold showers are the far likelier outcome. Clouds may put a damper
on daytime highs, but most areas should be able to get into at least
the mid-40s.

After Saturday's trough passes our area, northwesterly flow returns
aloft. This will push away the Arctic airmass and set up a period of
dry weather, clear skies, and warming temperatures as we head into
next week. After a cool morning in the 30s Sunday, highs are
forecast be in the 60s and 70s. Monday, highs in the 80s look to
spread across the Rio Grande Plains and parts of the Hill Country
with mid- to upper-70s elsewhere. The warmth may continue into
Tuesday as the broader upper-air pattern remains steady.

&&

.AVIATION...
(18Z TAFS)
Issued at 1130 AM CST Tue Feb 18 2025

A cold front is approaching the region. Ahead of this boundary
southerly winds are bringing low clouds and some lower visibility.
Ceilings have risen to MVFR in Austin and San Antonio and to VFR at
DRT. Ceilings in Austin and San Antonio may drop to IFR briefly over
the next couple of hours and there is a slight chance for showers at
AUS. The cold front will move through late this afternoon or early
evening turning the winds to the north. Wind speeds will increase to
15-20 kts with gusts up to 35 kts. Ceilings will remain MVFR until
Wednesday morning. Winds will remain strong through the end of the
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              65  26  39  21 /  30  10   0   0
Austin Bergstrom Intl Airport  66  26  41  20 /  30  20   0   0
New Braunfels Muni Airport     70  29  43  22 /  20  20   0   0
Burnet Muni Airport            64  21  35  17 /  10   0   0   0
Del Rio Intl Airport           78  31  51  27 /   0   0   0   0
Georgetown Muni Airport        63  23  38  18 /  30  10   0   0
Hondo Muni Airport             71  29  47  22 /   0   0   0   0
San Marcos Muni Airport        68  27  42  20 /  30  20   0   0
La Grange - Fayette Regional   68  29  41  22 /  50  50   0   0
San Antonio Intl Airport       69  29  44  23 /  10  10   0   0
Stinson Muni Airport           72  31  46  25 /   0  10   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory from midnight tonight to noon CST Wednesday
for Atascosa-Bandera-Bastrop-Bexar-Blanco-Burnet-Caldwell-Comal-De
Witt-Edwards-Fayette-Gillespie-Gonzales-Guadalupe-Hays-Karnes-
Kendall-Kerr-Kinney-Lavaca-Lee-Llano-Medina-Real-Travis-Uvalde-Val
Verde-Williamson-Wilson.

Extreme Cold Watch from late Wednesday night through Thursday
morning for Atascosa-Bandera-Bastrop-Bexar-Blanco-Burnet-Caldwell-
Comal-De Witt-Edwards-Fayette-Gillespie-Gonzales-Guadalupe-Hays-
Karnes-Kendall-Kerr-Kinney-Lavaca-Lee-Llano-Medina-Real-Travis-
Uvalde-Val Verde-Williamson-Wilson.

&&

Short-Term...17
Long-Term...Tran
Aviation...05