616
FXUS64 KEWX 280557
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1257 AM CDT Mon Sep 28 2026

...New SHORT TERM, LONG TERM, AVIATION...

.KEY MESSAGES...
Updated at 1225 AM CDT Mon Sep 28 2026

- Above normal heat persists into mid-week, with some low rain
chances along and east of I-35 Tuesday.

- An active pattern is still expected mid to late week, with
concerns for heavy rainfall increasing.

&&

.SHORT TERM...
(Today through Tuesday)
Issued at 1225 AM CDT Mon Sep 28 2026

Northwest flow aloft and daytime heating helped to generate
isolated to scattered convection across the Hill Country, southern
Edwards Plateau and into portions of the Rio Grande plains
yesterday afternoon and evening. MRMS data along with automated
gauges showed the higher rainfall amounts across northwest
Gillespie County where amounts in the 1" - 2.5" range were
estimated. Eastern Burnet/Western Williamson Counties,
southwestern Kerr as well as western Edwards/eastern Val Verde
also managed to pick up some 1/2" to near 1.75" amounts.

Given recent radar trends, we have kept some low rain chances in the
forecast for the early morning hours across portions of the southern
Edwards Plateau and northern Hill Country. Northwest flow aloft is
expected to decrease today as the subtropical ridge axis builds in
from the south. We can`t rule out some isolated afternoon convection
near the northern Hill Country, but chances are low and will not
mention in the forecast at this time. No significant change in
temperatures are expected today, so another round of highs in the
lower 90s to near 100 degrees will be in the forecast today.

The influence of the subtropical ridge will persist into Tuesday.
However, the ridge axis will be shunted eastward as an upper level
low deepens over the southwestern U.S. In response to the
approaching upper low, lee-side surface troughing east of the
Rockies will bring an increase in southerly winds to the region.
Increased low-level moisture and daytime heating should be enough
to develop some afternoon convection from the coastal plains
region northward into the I-35 corridor near San Antonio. With
moisture levels likely remaining elevated during the afternoon
hours and daytime highs mostly in the 90s, a few spots in the
coastal plains may see brief heat index values of 106 to 108
degrees. Peak heat index values farther northwest into the I-35
corridor will peak around 105 degrees.

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 1225 AM CDT Mon Sep 28 2026

As we head into the middle of the upcoming week, a definite
pattern change is in store, resulting in an increase in rain
chances beginning mid-week and continuing through late in the
week. A strong mid and upper level low initially located in the
desert southwest early Wednesday will begin to gradually move
eastward into the southern plains states. Ahead of the upper low,
a plume of mid and upper level Pacific moisture will move into the
region, while the low-levels continue to moisten from the Gulf.
While the operational models (ECMWF, GFS, Canadian) continue to
show some differences in handling the mid and upper level low, the
ensemble members offer a little more agreement. Overall, the
ECMWF Ensemble continues to be slightly slower in handling the mid
and upper level features, while the GFS and Canadian are a little
faster. For now, it appears the chance for rain will noticeably
increase late Wednesday as daytime heating and more than adequate
moisture generate some scattered afternoon convection. An
approaching Pacific cold front will then provide another focus for
convection, likely in the form of southwest to northeast oriented
bands of showers and storms for Wednesday night into Thursday.
During this period, there will be a risk of excessive rainfall and
flash flooding. WPC continues to show levels 2 and 3 out of 4 in
place across all of south central Texas for Wednesday and
especially Thursday. Given the setup of deep moisture, a strong
upper low and frontal boundary, this seems very reasonable.

The forecast for Friday will likely remain active given an upper low
to our west, plenty of moisture and a frontal boundary lingering
somewhere near or just west of the I-35 corridor. Rain chances
remain good into Friday, with the forecast for the upcoming weekend
remaining highly uncertain. A widespread break from the heat appears
to begin Thursday through the upcoming weekend with highs currently
expected to trend downward into the mid 70s to mid 80s.


&&

.AVIATION...
(06Z TAFS)
Issued at 1247 AM CDT Mon Sep 28 2026

NW flow showers are coming to an end with the final cells on their
way to dissipating about 50 miles north of DRT. No other
convective activity is expected to impact the four TAF sites
through the period. hi-res models hint at some more pockets of
MVFR CIGs forming around San Antonio, but not much elsewhere. With
light SE winds this looks reasonable, and will only show one
4-hour window of CIGs at SAT and nothing for SSF. VFR skies and
SE winds will continue through the rest of the TAF periods with a
slight uptick in speeds expected for Monday afternoon as compared
to Sunday afternoon. With this slight upward trend, the MOS
depiction of 09Z MVFR cigs forming over I-35 again looks
reasonable.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              99  74  96  75 /   0   0  20  20
Austin Bergstrom Intl Airport  99  73  96  75 /   0   0  20  20
New Braunfels Muni Airport     97  72  94  74 /   0   0  30  20
Burnet Muni Airport            95  72  92  73 /  10   0  10  10
Del Rio Intl Airport           99  76  97  77 /   0   0   0  30
Georgetown Muni Airport        97  73  95  74 /   0   0  10  20
Hondo Muni Airport             96  73  94  74 /   0   0  20  20
San Marcos Muni Airport        98  72  95  74 /   0   0  30  20
La Grange - Fayette Regional   98  73  97  75 /  10  10  20  10
San Antonio Intl Airport       96  76  93  77 /   0   0  20  20
Stinson Muni Airport           97  75  94  77 /   0  10  20  20

&&

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

$$

SHORT TERM...Platt
LONG TERM....Platt
AVIATION...18