San Antonio, Texas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

414
FXUS64 KEWX 220452
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1052 PM CST Sat Dec 21 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Sunday night)
Issued at 122 PM CST Sat Dec 21 2024

Key Messages...

- Quiet weather this weekend with increasing cloud cover on Sunday.

Surface high pressure continues to influence the area with cool and
quiet weather seen this afternoon. Skies have remained mostly clear
except for a pocket of low clouds that has lingered near the
escarpment west of San Antonio. Easterly wind will shift to the
southeast late this afternoon bringing increasing moisture towards
South Central Texas overnight. Low clouds will first form in the
west, expanding over the Hill Country and I-35 corridor after
sunrise. Even with clouds, Sunday will trend a few degrees warmer
for most as southerly flow continues. Highs range from the low 60s
north to the low 70s south. Overcast skies are expected across the
area late Sunday night into Monday leading to warmer low
temperatures in the 50s.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 122 PM CST Sat Dec 21 2024

Key Messages:

- First of 3 storm systems this week arrives late Tuesday. Low end
  chance for some strong storms Tuesday evening.
- Second system arrives Thursday, bringing a better chance for rain
  to eastern areas (Hill Country and eastward).
- Third storm system arrives next weekend, bringing yet another
  chance at rain and storms.

An active pattern is expected through the final week of 2024. The
Polar jet remains rather progressive, and with that being said, we
will get what looks to be a "train" of storm systems this week.

Monday will start off milder with temperatures in the 50s and some
low stratus. Clouds should thin by the late morning hours as south to
southwesterly surface flow ramps up ahead of the first mid-level
trough approaching late Monday. Temperatures should easily climb
into the 70s for most, with perhaps a few southern spots touching the
lower 80s. On Tuesday, the first trough starts to push eastward,
aided in its progression by a powerful 120kt jet moving inland over
the west coast. This will keep the pattern rather progressive. With
regard to Tuesday`s rain chance, the trend is unfortunately not our
friend. Each successive run of the deterministic GFS keeps nudging
the mid-level trough further north, limiting our rain and storm
potential. Ensembles of both the GFS and ECMWF have also been
trending northward. It is not uncommon for this to occur, with models
often starting a bit further south and trending northward as we get
closer to an event. Have trimmed PoPs somewhat and limited to 30-40%
at best over extreme eastern and northern zones on Christmas Eve. The
threat for a strong storm or two is still there, but with mid-level
dynamics a bit further north, think that the severe threat is very
limited.

Our attention turns to the next mid-level trough, which may actually
remain as a closed off low. Medium range guidance starts to differ
significantly at this distance, with the GFS well north over Kansas
with the mid-level low and the ECMWF over southern Oklahoma. If the
southern solution were to verify, locally heavy rainfall may develop
along a slow moving frontal boundary Thursday afternoon. Model trends
will need to be monitored. Immediately following this storm, a third
system will quickly eject out over the Texas Panhandle Friday
morning. With southeasterly surface flow remaining in play and
surface moisture to work with, showers and storms may develop late
Friday morning or early afternoon and continue through late evening.
Beyond Friday, things look to quiet down a bit with zonal flow and
pleasant, albeit mild days, heading into the new year.

&&

.AVIATION...
(06Z TAFS)
Issued at 1042 PM CST Sat Dec 21 2024

The new run of models that have started to come in have not changed
the forecast much. A batch of mid clouds have formed near DRT over
the past hour or two...but the expected low decks have yet to form
along or near the Rio Grande. Still plenty of time for that to
happen. NAM is showing the most bullish numbers for ceilings over
DRT/SAT/SSF....but the SREF and HRRR still show the Rio Grande area
and Rio Grande Plains getting most of the low clouds by the early AM
hours. Am keeping some IFR mentioned in DRT but only in a TEMPO
group as the lasted NAM has backed off a bit on the very low cigs
from earlier. Will keep AUS in VFR and SAT/SSF in MVFR with a tempo
as confidence is still low. All the RH time sections do show plenty
of clouds in the 850MB range mid day tomorrow lasting through early
Monday. Cloud cover should be much more widespread Sunday night into
Monday in response to strengthening low level wind fields. Still in
question is how low will the ceilings go tomorrow night. GFS is
mainly VFR cigs on Monday...NAM is lower into the MVFR range.


&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              41  66  55  76 /   0   0   0   0
Austin Bergstrom Intl Airport  39  67  54  76 /   0   0   0   0
New Braunfels Muni Airport     41  68  56  78 /   0   0   0   0
Burnet Muni Airport            41  64  54  73 /   0   0   0   0
Del Rio Intl Airport           50  68  58  77 /   0   0   0   0
Georgetown Muni Airport        40  65  54  74 /   0   0   0   0
Hondo Muni Airport             44  68  57  76 /   0   0   0   0
San Marcos Muni Airport        39  67  55  76 /   0   0   0   0
La Grange - Fayette Regional   38  68  52  76 /   0   0   0   0
San Antonio Intl Airport       44  67  58  76 /   0   0   0   0
Stinson Muni Airport           45  69  59  79 /   0   0   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Short-Term...09
Long-Term...CJM
Aviation...09