349
FXUS64 KEWX 200518
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1218 AM CDT Sun Sep 20 2026

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

.KEY MESSAGES...
Updated at 1212 AM CDT Sun Sep 20 2026

- Low chances (15-30%) for showers or storms across the Hill Country
  and Southern Edwards Plateau from Sunday night into Tuesday.

- Low chances (10-30%) for spotty rain across South Central Texas
  through next week with most staying dry.

- Above average temperatures continue into next weekend.

&&

.SHORT TERM...
(Today through Monday)
Issued at 1212 AM CDT Sun Sep 20 2026

Another warm day is in the cards for Sunday. Southwesterly flow
aloft should continue to push cirrus across the area, which will
blunt insolation some during the afternoon. High temperatures are
still forecast to reach the 90s across South Central Texas with a
few isolated spots briefly nudging above 100F. A shortwave trough
embedded within the southwesterly flow will track across the Edwards
Plateau late afternoon into the evening. This is expected to trigger
showers and thunderstorms, beginning primarily northwest of the area
closer to the dry line. While this area has better kinematic support
for development, the zone of storm development could be sensitive to
where the cirrus is thinnest, which may shift storm formation closer
to the Hill Country as depicted in some of the REFS members. In
either case, weak steering flow indicates a few storms could slowly
push into the Hill Country and southern Edwards Plateau in the
evening hours before instability wears off around midnight and the
potential fizzles out. Rain chances range from 15 to 30 percent over
those areas Sunday night. While severe weather is unlikely given the
lack of noteworthy wind shear, gusty winds are possible with high
1200+ J/kg DCAPE depicted in the HREF means. Slow storm movement may
also support locally heavier rains.

The passage of the shortwave trough should weaken the overhead ridge
some on Monday, though emerging anticyclonic flow at Z250 over
Mexico and a lack of additional upstream impulses of energy means
the ridge will have some time to recuperate. Temperatures will stay
unseasonably hot with highs remaining in the 90s to around 100F and
lows not varying much from the consistent 70s. Despite the lack of
vorticity aloft, a weak front is forecast to move into North Texas
and then slow to a stall beneath the ridge over West Central Texas,
possibly interacting with any leftover boundaries deposited by
Sunday night`s convective activity. This provides a window for
spotty showers and thunderstorms Monday afternoon/evening, again for
the southern Edwards Plateau and Hill Country, and possibly into the
Austin metro area as well. Given the lack of strong forcing,
confidence is low and rain chances range from 15 to 30 percent.

&&

.LONG TERM...
(Monday night through Saturday)
Issued at 1212 AM CDT Sun Sep 20 2026

Zonal flow aloft through the midweek over South Central Texas means
the weak front is unlikely to advance much farther south into our
area. Nonetheless, its accompanying band of higher theta-e and
moisture stuck beneath mid-level ridging, as well as areally lower
convective inhibition, will support low chances for isolated rain
(with chances ranging up to 30 percent) through Wednesday.
Temperatures are expected to stay unseasonably warm, the
opportunities for slight relief from spotty rains and associated
puffs of cloudiness allow the distribution of forecast temperatures
from ensembles to gradually trend slightly cooler towards the end of
the upcoming week. The overall model blend is not optimistic,
budging only a few degrees downwards, though the statistical
guidance is slightly more optimistic and suggests increased coverage
of highs in the low to mid 90s by the week`s end. Lows are likely to
remain unseasonably mild, but there are hints in the ensemble
guidance that drier continental air could penetrate into East Texas
in the latter half of the week and help reduce low-level moisture
enough to lower overnight temperatures.

Ridging remains over the area into the weekend, keeping rain chances
low. To the west, a strong plume of moisture is expected to kick
into gear as deep southerly flow intensifies on the western
periphery of the ridge. While the bulk of the moisture will be well
west of the area, a bolstered easterly flow from the Gulf running up
the Rio Grande in response to the jet streak aloft keeps the low
possibility of isolated rains over the Rio Grande Plains in the
forecast through the week. &&

.AVIATION...
(06Z TAFS)
Issued at 1212 AM CDT Sun Sep 20 2026

VFR ceilings are expected, however there is a non-zero chance for
some MVFR ceilings at AUS. Winds remain east-southeasterly around
5-10 kts, but will likely be calm to less than 5 kts through mid-
morning. High clouds from decaying convection out west will result
in BKN clouds at 25k feet through the night.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              99  76  98  76 /   0  10  20  20
Austin Bergstrom Intl Airport  99  76  98  75 /   0  10  20  10
New Braunfels Muni Airport     98  74  99  73 /   0  10  10  10
Burnet Muni Airport            95  73  94  72 /  10  20  30  20
Del Rio Intl Airport           99  76 100  75 /  10  10   0  10
Georgetown Muni Airport        97  75  96  75 /   0  10  20  20
Hondo Muni Airport             96  73  97  73 /   0  10   0  10
San Marcos Muni Airport        98  74  98  74 /   0  10  10  20
La Grange - Fayette Regional   99  75 100  75 /   0  10  10  10
San Antonio Intl Airport       97  76  98  76 /   0  10  10  10
Stinson Muni Airport           99  75 100  75 /   0   0  10  10

&&

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

$$

SHORT TERM...Tran
LONG TERM....Tran
AVIATION...MMM