093
FXUS64 KEWX 181140
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
540 AM CST Sat Jan 18 2025

...New AVIATION...

.SHORT TERM...
(Today through Sunday)
Issued at 247 AM CST Sat Jan 18 2025

- Cold Weather Advisory for Sunday morning.

- Wind chill values 10 degrees or lower Hill Country and Edwards
  Plateau. Wind chill values 10-20 degrees I-35 Corridor and Coastal
  Plains. Wind chills above 20 southern Rio Grande Plains.

A cold front is currently moving into central Texas and will move
through South-Central Texas this morning. The front will usher in
northerly winds and a cooling trend for the rest of the weekend. High
temperatures Saturday will start to be affected with 50s across the
Hill Country and northern I-35 Corridor. The cooler air will not make
it farther south and west with highs in the 60s from the Edwards
Plateau to the Coastal Plains and 70s over the Rio Grande Plains.
Much colder air will move in tonight with temperatures plummeting
into the 20s and 30s. Brisk northerly winds or 15-20 mph will send
wind chill values to advisory levels. The wind chills will be 10
degrees or lower over the Hill Country and Edwards Plateau and 10-20
degrees over the I-35 Corridor and Coastal Plains. We have issued a
Cold Weather Advisory for these areas for midnight tonight until 9 am
Sunday. Northerly winds will continue during the day Sunday, but
will weaken through the afternoon. High temperatures Sunday will be
from the upper 30s in the Hill Country to near 50 in the southern Rio
Grande Plains with most of the CWA in the 40s.

&&

.LONG TERM...
(Sunday night through Friday)
Issued at 247 AM CST Sat Jan 18 2025

Key Messages:

- There is very high confidence (near 100%) that hard freezes will
  occur Sunday night through Tuesday night. Protect People, Pets,
  Plants, and Pipes from the cold weather.
- There is a high chance (60-70%) of winter precipitation occurring
  Monday night into Tuesday morning across the eastern Hill Country,
  I-35 corridor, and Coastal Plains, with increasing confidence of
  minor to moderate travel impacts.
- There is a low to medium chance (20-50%) of winter precipitation
  occurring across the western Hill Country, southern Edwards
  Plateau and Rio Grande.

A widespread hard freeze is expected Sunday night through Monday
morning, with lows in the teens across the Hill Country and low to
mid 20s for most other locations. While wind speeds will weaken
slightly Sunday night into Monday morning, Cold Weather Advisories
are expected to be extended into Sunday night and Monday morning
across much of the region, as wind chill values around 10-15 degrees
will be common for many locations.

Conditions start very cold and mostly sunny for MLK JR Day. We do
expect an increase in cloud cover from south to north through the
afternoon, which will likely put a cap on high temperatures only in
the mid to upper 30s across the Hill Country, I-35 corridor, and
Coastal Plains, and low to mid 40s along the Rio Grande.

Global ensembles continue to converge on the speed and sharpness of
the mid and upper level trough approaching from the northwest Monday
night, which leads to increasing confidence in winter precipitation
developing across the area Monday night. However, there are some
differences in GEFS and ECMWF ensemble members with how quickly the
coastal low pulls away and H85 front moves south through the area
early Tuesday morning, leading to lower confidence on how quickly
precipitation ends and winter precipitation accumulation amounts.

As far as precipitation type, most trends have been towards
increased odds of a mixed bag of freezing rain and sleet for most of
the night near and south of U.S. 90/I-10 and snow/sleet north of
this. A deeper dive into forecast soundings indicate a warm nose
aloft initially across southern areas in addition to a dry layer, at
least initially, within the more favorable dendrite growth zone
region. This has all led to increasing probabilities for light
freezing rain accumulations across the Coastal Plains and into the
San Antonio metro area. A changeover to light snow on the back side
of the precipitation across southern areas is still possible Tuesday
morning, albeit it low to medium confidence (20-40%).

Farther north, ensemble members have trended northeast with heavier
snow amounts. Probabilities above 40% for 1 inch or more of snow are
mainly confined north of I-10 and east of I-35, with probabilities
of 1/2 to 1 inch of snow in the 20-40% range through the I-35
corridor and eastern Hill Country. The Winter Storm Severity Index
continues to show increases in probabilities for minor to moderate
travel impacts across the eastern Hill Country, I-35 corridor, and
Coastal Plains. Additional fluctuations in favored locations for the
ice vs snow, as well as accumulations, are likely.

Highs on Tuesday remain very chilly, only in the low to mid 30s for
the Hill Country, I-35 corridor, and Coastal Plains, upper 30s to
low 40s along the Rio Grande. There is a potential that some bridges
and overpasses across portions of the Hill Country, I-35 corridor,
and Coastal Plains could remain impacted well after precipitation
ends, possibly into Tuesday night, where highs struggle to make it
out of the low 30s or where any re-freezing occurs Tuesday night.

Clearing and light winds will lead to the coldest night Tuesday
night. Lows Wednesday morning are forecast in teens to low 20s for
most areas.

Southerly flow finally resumes during the day on Wednesday, with
highs rebounding into the mid 40s to near 50 degrees along the Rio
Grande. There is very low confidence in Thursday and Friday`s
forecast, as there remains considerable timing differences on the
next upper level trough, associated cold front, and a possible coastal
low. We`ll have to again monitor the surface temperatures closely
but we`ll get to those details as we get closer in time.

&&

.AVIATION...
(12Z TAFS)
Issued at 532 AM CST Sat Jan 18 2025

A cold front is approaching our terminals and should reach AUS within
the next hour or two and then proceed southward to San Antonio and
Del Rio. This will bring northerly winds. Initially wind speeds will
be 5-10 kts, but then will increase to 10-15 kts with gusts to 25 kts
by late morning. Strong, gusty winds will continue through the end of
the TAF period.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              59  28  44  23 /   0   0   0   0
Austin Bergstrom Intl Airport  60  28  44  21 /   0   0   0   0
New Braunfels Muni Airport     65  30  46  23 /   0   0   0   0
Burnet Muni Airport            55  25  39  21 /   0   0   0   0
Del Rio Intl Airport           72  32  50  26 /   0   0   0   0
Georgetown Muni Airport        56  25  42  21 /   0   0   0   0
Hondo Muni Airport             69  29  47  23 /   0   0   0   0
San Marcos Muni Airport        62  28  44  21 /   0   0   0   0
La Grange - Fayette Regional   60  29  44  23 /   0   0   0   0
San Antonio Intl Airport       65  30  45  25 /   0   0   0   0
Stinson Muni Airport           67  32  47  26 /   0   0   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory from midnight tonight to 9 AM CST Sunday 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...05
Long-Term...76
Aviation...05