587
FXUS64 KEWX 191845
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
145 PM CDT Tue May 19 2026

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

.KEY MESSAGES...

- Line of strong to severe storms with locally heavy rain possible
  this evening into tonight.

- Active weather pattern continues through the upcoming Memorial
  Holiday weekend. Rounds of storms with heavy rain could lead to
  localized flooding.

&&

.SHORT TERM...
(Tonight through Wednesday night)
Issued at 138 PM CDT Tue May 19 2026

At approximately 1 PM noon CDT, satellite and observations indicated
a cold front to our north slowly pushing towards the Edwards
Plateau. Subsidence from an MCS over South Texas last night helped
to produce clearer skies than anticipated over our area this morning
and has also modified the mid-level flow relative to previous model
forecasts, making today`s forecast less confident than usual.
Namely, subsidence has allowed an area of drier and warmer near-
surface air to take root around the Hill Country, but as moist Gulf
air returns this afternoon this may restore more conducive
conditions for storm development.

The clearer skies should allow daytime warming to promote large
amounts of conditional instability over South-Central Texas, to the
tune of 3000-4000 J/kg of SBCAPE, and as the front to our north and
a dry line to our west encounters this air with the aid of broad
southwesterly flow aloft, we do expect that the overhead cap sampled
in aircraft observations from near AUS and SAT will eventually be
overcome in part by developing thunderstorms along the
aforementioned features.

The afternoon should remain mostly dry, but storms may begin
developing in earnest around the periphery of South-Central Texas
mainly after 5 PM CDT. The broader environment continues to favor a
line of storms pushing south or southeast across our area, though
given the wrinkles to the mid-troposphere there`s some disagreement
over where storms will form first, largely due to uncertainties with
the current bubble of drier air over the Hill Country. The weak
front enabling many of these storms will be sluggish, so whatever
portion gets active first will have the best shot of becoming the
dominant driver of storms this evening/tonight.

There are going to be a few areas to initially monitor for storms as
we head to the late afternoon into the evening: the front to our
north, the dry line near the Rio Grande which extends into the
Edwards Plateau, and a lower potential for some isolated activity
with some moisture convergence ahead of these features on the I-35
corridor. The primary severe potential today arises from the storms
on the front and dry line. The SPC continues to highlight up to a
Level 2 of 5 (Slight) risk for severe weather over most of our area
this evening. Some of the initial development over the Edwards
Plateau could produce isolated large hail, but as storms start to
congeal, the risk should lean more towards a potential damaging wind
threat if bowing segments begin to materialize from the storm
clusters. The heavy rain threat and the potential for isolated flash
flooding will also need to be monitored as any slow-moving storm
ahead of the front/dry line and higher rates within the lines of
storms could drive up rain totals. Areas that catch the main storm
complexes could see totals generally above 1" with isolated pockets
above 3" within the moist environment with PWATs above the 90th
percentile. Uncertainty in the overall timing of this event is
somewhat high, but we expect most activity will tend to be
concentrated in the evening and first half of the night, clearing
out early Wednesday morning.

Slightly cooler conditions should prevail in the wake of these
storms Wednesday morning. A moist airmass should still remain in
place aloft, though the atmosphere will take some time to reload.
Temperatures will be a bit more moderated with forecast highs in the
80s. Most of the Wednesday will thus be on the drier side, but as we
head later in the day sufficient destabilization and an approaching
shortwave trough over West Texas could spark another round of
activity along the Rio Grande late afternoon / evening on Wednesday,
preferentially along the dry line. Instability should be somewhat
lower for these storms compared to today`s action, resulting in a
lower severe threat. However, these storms could produce locally
heavy rain if they advance east Wednesday night into areas saturated
by earlier storms. The moist environment could allow these storms to
maintain strength with sufficient energy aloft, leading to good rain
chances extending from the Rio Grande eastward to the Hill Country,
I-35 corridor, and Coastal Plains Wednesday night into Thursday
morning.

&&

.LONG TERM...
(Thursday through next Tuesday)
Issued at 138 PM CDT Tue May 19 2026

The wet pattern that kicks off today should continue through the
week as persistent upper-level southwesterly flow continues to carve
out a favorable pathway for multiple disturbances over our area
overlapping atop moist Gulf air.

Each round of storms will influence the following day`s storm
potential, so confidence on precise timing and placement for any
activity is low in the long-term forecast. However, based on the
broader synoptic environment, a shortwave impulse Thursday could
produce another round of activity late Thursday into early Friday. A
more pronounced upper-level disturbance may push into the area over
the weekend, indicating another favorable time window for
potentially widespread rains. The rather stagnant upper-air pattern
keeps moisture in our area through early next week, with a lack of
clear indicators for a definitive ending to this wet pattern into
early next week.

Repeated rounds of rainfall will further moisten soils, increasing
the broader potential for more surface runoff from rain as grounds
saturate. The pattern may lead to widespread beneficial rain for
most areas, but the most impacted portions with higher totals and
rain rates may see an increasing likelihood for flash flooding or
river flooding. Due to the dependence of each round of storms on the
previous salvo of activity, it is impractical at this forecast range
to pinpoint the areas that will be receiving the most rain, and in
general, model precipitation forecasts spread substantial totals
across virtually all of the South-Central Texas. Continue to check
the forecast as the week progresses for those with plans this
weekend for the Memorial Day holiday.

&&

.AVIATION...
(18Z TAFS)
Issued at 138 PM CDT Tue May 19 2026

Moisture and daytime heating will lead to a developing cu field
across the region this afternoon. Some isolated convection remains
possible, but given low coverage, we will not mention any SHRA or
TSRA for the next few hours. However, we will keep the TSRA in the
forecast for the evening hours at all TAF sites as a cold front
drops southward with showers and storms developing along and behind
the front. Also included a TEMPO group between 01-05Z for the I-35
sites for an increased likelihood of gusty winds, heavy rain and
lightning. For DRT, timing is a little less certain, but did focus
convection mainly during the 03-06Z period. Low cloud will move in
behind the front, with widespread MVFR after 06Z, with some IFR
after 10Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              71  84  71  82 /  80  40  60  90
Austin Bergstrom Intl Airport  72  84  71  82 /  80  40  60  90
New Braunfels Muni Airport     71  84  70  83 /  80  40  60  80
Burnet Muni Airport            68  81  68  79 /  70  40  70  80
Del Rio Intl Airport           70  86  68  86 /  70  40  80  20
Georgetown Muni Airport        70  82  69  80 /  80  40  60  90
Hondo Muni Airport             70  84  69  82 /  80  30  80  70
San Marcos Muni Airport        71  84  71  82 /  80  40  60  90
La Grange - Fayette Regional   72  84  72  82 /  80  50  50  90
San Antonio Intl Airport       72  85  72  83 /  80  30  70  80
Stinson Muni Airport           72  85  72  84 /  80  30  70  80

&&

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

$$

SHORT TERM...Tran
LONG TERM....Tran
AVIATION...Platt