Swiss Alp, Texas Weather Forecast Discussion

172
FXUS64 KEWX 231111
AFDEWX
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
611 AM CDT Tue Sep 23 2025
.KEY MESSAGES...
- Unseasonably hot conditions continue today across all of South
  Central Texas.
- A cold front brings temperature relief to some areas Wednesday
  along with rain chances into Thursday.
&&
.SHORT TERM (THROUGH WEDNESDAY)...
High pressure remains entrenched over South Texas, and an
approaching front and increasing polar westerlies aloft will
only sharpen the subsident pattern over the forecast area today.
We should see one of the hottest days of the month of September
and possibly the last chance to see triple digit heat more most
of the area. Heat indices are likely to reach triple digits over
most areas this afternoon. Only a few showers are suggested in
the higher resolution models mainly in the Hallettsville area of
the Coastal Prairies. The approaching polar system from the
north could pick up the evening winds to take a little edge off
the hot late afternoon temps. Toward the end of the tonight
period, a cold front arrives with some convective potential
along it, reach mainly into the Fredericksburg to Georgetown
areas before 12Z. Overnight lows could show extra areas dipping
into the 60s but mainly for northern counties and in many cases
after daybreak Wednesday.
The front is expected to make some good progress across Central
TX in the late morning hours, but is slower to make progress
through the San Antonio and Del Rio areas until mid to late
afternoon. During this period there area expected to be
scattered showers and a few storms but generally a low amount of
deep convection according to most of the models. Late in the
afternoon, the finer resolution solutions have deeper convection
becoming more robust after the front moves through San Antonio
in the late afternoon and early evening. This means the first
wave of rain chances for daytime Wednesday into Wednesday
evening could be overstated in terms of PoP and QPF, where the
higher rain totals of 1/2 inch to 1.5 inches might be mainly
located north of Fredericksburg and Georgetown and then south of
Highway 90.
&&
.LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...
Late Wednesday evening the flow aloft becomes a bit more
northwesterly and some weak shortwave activity could help with
promoting more deep convection. So in the evening hours, this
mainly southern half of South Central TX may see a few strong
storms take shape with marginally severe hail and winds
possible. Some residual southerly wind direction areas at the
850 mb level could promote some back-filling of elevated
convection back slightly northward, but most solutions show
little or no activity spreading back as far north as the
Kerrville and Austin areas after midnight. Thus we expect to see
most of the populated areas of our forecast area to be
disappointed in the rainfall amounts for the Wednesday and
early Thursday periods despite some promising PoP values.
Temperatures will be assumed as fully post-frontal by Thursday
morning, but the post frontal winds south of Highway 90 are only
light to moderate at best, meaning the higher dewpoints will
probably keep some southern areas at 70 or above. As mixing
kicks up for daytime Thursday, there should be a more uniform
cooling across the area, with the cool air advection plus
scattered to broken cloudiness and low rain chances holding max
temperatures to near or perhaps even just below late September
normals. Then as the air becomes more stable Thursday
night/Friday morning, we should see our most pleasant
temperatures of the week. Friday into the weekend sees a
resurgence of the subtropical ridge into TX, but not as robust
as the one over us now. Temperatures will trend slowly warmer,
but we will also see some increasing elevated clouds and
moisture, as the Pacific tropics remain a bit more active than
usual. An upper low to the west is not expected to advance
eastward enough to bring enough mid level moisture and
instability past West Texas, as least through Monday. However
another mid-week opportunity for rains could come just beyond
the horizon.
&&
.AVIATION (12Z TUESDAY THROUGH WEDNESDAY)...
MVFR to local IFR ceilings have developed from the Hill Country
eastward including over I-35 terminals this morning. These low
clouds will scatter out mid to late morning with VFR conditions
expected the rest of the day. South to southeast wind will
generally be less than 12 knots with occasional gusts up to 20
knots in the afternoon and early evening hours. Besides a few
isolated showers or thunderstorms in the coastal plains, dry
conditions are forecast today. MVFR ceilings are expected to
develop early Wednesday morning ahead of a cold front moving
into the area from the north. Additionally, some showers or
storms may make it to AUS before 18Z but have not included this
in the TAF as there is low confidence in timing.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              76  92  68  89 /  10  70  40  20
Austin Bergstrom Intl Airport  75  92  68  88 /  10  70  40  30
New Braunfels Muni Airport     75  94  69  89 /   0  60  60  30
Burnet Muni Airport            73  86  66  85 /  30  70  30  20
Del Rio Intl Airport           77  93  72  88 /   0  50  50  30
Georgetown Muni Airport        74  88  66  88 /  20  70  40  20
Hondo Muni Airport             74  94  69  88 /   0  50  70  40
San Marcos Muni Airport        74  93  68  89 /   0  70  50  30
La Grange - Fayette Regional   75  93  70  87 /   0  80  60  40
San Antonio Intl Airport       77  94  71  88 /   0  60  60  40
Stinson Muni Airport           77  96  73  89 /   0  50  70  40
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...18
LONG TERM...17/18
AVIATION...27

NWS EWX Office Area Forecast Discussion