445
FXUS64 KEWX 271838
AFDEWX
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
138 PM CDT Sun Sep 27 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 133 PM CDT Sun Sep 27 2026
- Isolated storms this afternoon and evening over the Hill Country
and southern Edwards Plateau.
- A Pacific cold front may bring widespread rain during the second
half of the week. Heavy rain is possible.
&&
.SHORT TERM...
(Tonight through Monday night)
Issued at 133 PM CDT Sun Sep 27 2026
Upper level winds this morning and afternoon have shifted to
northwesterlies, signaling that the upper level ridge that has
dominated our weather for the past week has reoriented itself over
Mexico. This afternoon, the lessened influence of the ridge, weak
thermally induced convergence, and the presence of a strip of higher
instability is forecast to spark a isolated showers and storms over
the Hill Country and southern Edwards Plateau. Most of the hi-res
models have the first signs of development by about 3-4 PM, with
storms continuing through the afternoon and early evening before
petering out after sunset. These storms are not expected to be well-
organized due to a lack of effective wind shear, but the combination
of decently moist PWATs in the 1.6"-1.8" range, lackadaisical storm
motion, and DCAPEs above 1000 J/kg indicate the stronger cells may
drop a few heavier downpours with strong gusts. The main focus will
likely remain in the Hill Country and southern Edwards Plateau, but
given the northwesterly flow aloft, a few residual showers and
storms could approach the I-35 corridor around 6-9 PM. Those who do
see rains today are mostly expected to record amounts ranging from a
few hundredths to a few tenths of an inch, with a few localized
spots seeing potential for 1-2" under the stronger cells.
Hot weather continues Monday with highs in the 90s for most, to
around 100F over the Rio Grande Plains. The nearby ridge over Mexico
is forecast to bulge northward and eventually eastward, so rain
chances should be lower Monday. Onshore flow will be more pronounced
Monday, so there could be a lone shower or two over the Coastal
Plains.
&&
.LONG TERM...
(Tuesday through next Sunday)
Issued at 133 PM CDT Sun Sep 27 2026
The strong trough now moving ashore the West Coast will start to
shape the weather over our area as we head further into the week.
Its approach will impinge on the ridging near our area and
eventually shove the ridge eastward. On Tuesday, the trough is
forecast to push into the southwestern US. There will still be
enough ridging over Texas to keep conditions dry and hot for much of
the day, but increasing onshore flow in response to jet divergence
caused by the trough raises chances for isolated streamer showers
over the Coastal Plains.
Along the leading flanks of the incoming trough, a substantial plume
of tropical Pacific moisture will begin flowing across Mexico up
into South-Central Texas beginning about late Tuesday, and should
continue to do so through at least Thursday with additional
contributions from onshore flow off the Gulf. This pattern sets the
stage for potential widespread rain during the latter half of the
week. There is still some variation in timing with the EPS ensembles
generally favoring a slower progression and the GEFS and CMCE
ensembles being faster, but the overall depiction of at least the
start and midpoint of the rainy period is coming into better
agreement. Rain chances start to increase Wednesday areawide as
the southerly low-level jet establishes over the region, making
for an especially humid and breezy day. However, at this range it
does appear that Wednesday`s activity will be more in the form of
scattered showers embedded in the moist flow off the Gulf. A
Pacific cold front acting to concentrate the rain and storm
potential will then slowly enter our area from the northwest. The
current consensus among the more skillful models suggests heavy
frontal rains could commence as early as Wednesday night, slowly
advancing east during the night and throughout the day Thursday.
Risks of excessive rainfall capable of causing flash flooding
applies to all of South-Central Texas during this period. While
it`s still early to give more specific rain amounts and ranges,
models have been consistent in showing a band of heavier amounts
on a roughly NNE- to-SSW swath, paralleling the orientation of the
slow- moving front. These rains will have access to ample amounts
of atmospheric moisture, to the tune of widespread PWATs in
excess of 2" as depicted on the latest ensemble means (at or above
the 95th percentile). These signals are supportive of a heavy
rain event, and we will continue to closely monitor the
development of the trough and its front for trends as we enter the
workweek.
The greatest overlap in rain chances in the latest models is around
Thursday, though that is subject to change depending on how the
trough evolves. While there are some deterministic models that clear
the front and its rains out of our area at a steady pace, more
models have trended towards showing the parent trough slowing down
and even stalling over the central and southern Plains. This may
keep the front and rain potential in our area into Friday, an
outcome best exemplified by the EPS and ML versions of the ECMWF
and GFS. We do generally expect that the mid- and upper-level flow
will become more zonal over the weekend, breaking up the moisture
plume and allowing drier air to finally make its way into the
area. The rain forecast for the weekend is uncertain and heavily
dependent on how quickly the trough leaves the area, but for now,
a gradual decrease in rain chances is depicted.
Temperatures to start the week will be unseasonably warm. The
combination of humid air and hot temperatures Wednesday afternoon
could may that day especially sultry if clouds from the approaching
front are delayed. Higher heat indices near and over 105F are
possible over the Rio Grande Plains and portions of the I-35
corridor and Coastal Plains. The Pacific cold front and widespread
rain and cloud cover should bring daytime temperatures down Thursday
into the weekend, with highs in the 80s becoming more widespread. In
the longer term, there have been some indications that a cold front
could bring cooler weather next week. I wouldn`t count too heavily
on that, but it does appear that more opportunities for fall-like
temperatures may be on tap through early October.
&&
.AVIATION...
(18Z TAFS)
Issued at 1205 PM CDT Sun Sep 27 2026
VFR conditions are expected through the period. Some mid and high
clouds will stream over the area today with a relatively light
onshore flow at the surface. A few showers and thunderstorms may
develop and move into the southern Edwards Plateau and Hill Country
this afternoon/evening, but are not expected to reach area
terminals.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 75 99 74 97 / 10 10 0 10
Austin Bergstrom Intl Airport 74 99 73 97 / 10 0 0 20
New Braunfels Muni Airport 73 97 73 95 / 10 0 0 20
Burnet Muni Airport 72 95 71 92 / 20 10 0 10
Del Rio Intl Airport 77 99 75 97 / 10 0 0 0
Georgetown Muni Airport 74 97 73 96 / 20 10 0 10
Hondo Muni Airport 74 96 73 94 / 10 0 0 20
San Marcos Muni Airport 73 98 72 96 / 10 0 0 20
La Grange - Fayette Regional 73 98 73 97 / 0 0 0 20
San Antonio Intl Airport 75 96 76 94 / 10 0 10 20
Stinson Muni Airport 76 97 75 95 / 10 0 10 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Tran
LONG TERM....Tran
AVIATION...27
No recent Short Term Forecast (NOW) has been issued for NWS Austin/San Antonio CWA (EWX).
Special Weather Statement Issued: 09/24/2026 04:40:00 AM UTC
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