textproduct: Austin/San Antonio

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.