textproduct: Austin/San Antonio

KEY MESSAGES

- Mostly dry this weekend, then stormy with heavy rainfall possible for much of next week.

- Increasing humidity and heat indices through Tuesday, with some spots feeling like 100-105+ Sunday, Monday, and Tuesday.

SHORT TERM

(Today through Sunday) Issued at 129 AM CDT Sat May 16 2026

Mostly quiet weather is expected for the weekend, but with some strong south breezes with gusts up to 35 mph and muggy and hot conditions sending the heat index soaring. Todays heat indices may still get a small amount of relief from the dry air layer mainly in the 850-700 mb layer helping to mix down some lower surface dew points this afternoon. This layer should also ensure a strong cap, but even today, a few small showers were picked up in the streamers of cumulus blowing inland. Perhaps it appears alarmist in the forecasts, but with increased moisture above the 700 mb layer for today, will expect a less than 10 percent coverage of showers, but noting if one develops, the chance of it becoming a brief thunderstorm might only be a few percent lower. But with no mentionable weather grids shown for today, we'll turn our attention toward Sunday after models show the marine low level layer deepening beyond 850 mbs. With strong southerly low level winds continuing and Pwat values surging up to 1.85 inches Sunday afternoon, the potential for the cap breaking for deeper convection potential should exist for our central and NE counties. Coverage should remain low, and the heat index as noted before, was expected to escalate further. By this day we should see a potential that most areas could get 100 degree values with isolated values over 105 degrees. With the increase in dew points, high temperatures may end up looking the same as those for today.

LONG TERM

(Sunday night through Friday) Issued at 129 AM CDT Sat May 16 2026

By Sunday evening, an unstable SW flow aloft pattern becomes Texas- wide, meaning there would only need to be a weak ripple in the flow to generate elevated convection that could work its was down to become deeper, surface-based convection. Semi strong capping should continue to limit good coverage, so we're only expecting something of an area of 15 percent type coverage in a couple locations. Monday the moisture loading is still deeper, with the 00Z 5/16 GFS depicting a Pwat range of 1.8 to 2 inches over the central and eastern counties. Drier air to the NW over West Central TX could create enough contrast to trigger some eastern Hill Country and Central TX storms as the winds in the low levels remain strong. No significant disturbance activity is in the flow aloft, at least according to model consensus. Thus the best coverage to anticipate for late Monday might only be 30-40 percent. Going into the overnight into Tuesday, there could be enough disturbance activity embedded in the flow aloft to account for some isolated overnight activity. None of this activity appears agreeable enough to warrant covering the threat for any types of severe or heavy rain concerns thus far, but it would also not be out of the question. By daytime Tuesday, the prospect of more organized convection should come into play, as most of the global model runs show a cold front progress into the Red River Valley and some with a potential upscaled storm clusters propagating a southward boundary into Central TX. This may regress over time as Monday and Tuesday were early targets for upscaled convection in the model guidances from a few days ago. Looking at numerous cycles of the MEX and ECX MOS guidances both confirm this trend, and would probably signal the best rain potential days being Wed-Thu, and still shifting later. So by Tuesday, it wouldn't surprise me to see we were messaging the best rain chance day being Friday. That's the struggle we all face with broad late springtime patterns in Central TX. If a storm cluster begins in the earlier stages to the point a remnant boundary is left behind, the crawfishing trend of higher PoPs should end.

As it stands, the low coverage through Tuesday would suggest low chances for severity and coverage, and that means increased confidence in those further escalating heat index values. We might even have a concern for a Heat Advisory need Monday or Tuesday, but we also have to acknowledge the amount of moisture could lock in a late low cloud layer and hold ambient temperatures to below what we are showing in today's forecast package.

With only a single showing of a marginal threat of excessive rainfall for Tuesday, we think there will be some time before we get back into the routine of daily messaging for severe weather and heavy rains. Right now, the forecast seems most primed for Wednesday at the earliest, with the need for messaging perhaps not until around Monday.

AVIATION

(12Z TAFS) Issued at 539 AM CDT Sat May 16 2026

MVFR ceilings have settled over the region this morning. These clouds will last until later this morning when VFR conditions will return. Winds will become stronger and gusty before noon and continue through the afternoon and evening. MVFR ceilings will return late tonight and last until Sunday morning.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 92 76 91 78 / 0 10 20 20 Austin Bergstrom Intl Airport 92 77 92 79 / 0 10 10 20 New Braunfels Muni Airport 92 75 92 78 / 0 0 10 20 Burnet Muni Airport 87 73 86 75 / 0 0 20 10 Del Rio Intl Airport 94 76 97 78 / 0 0 0 0 Georgetown Muni Airport 90 75 90 77 / 0 10 10 20 Hondo Muni Airport 91 75 91 78 / 0 0 20 10 San Marcos Muni Airport 92 76 92 78 / 0 10 10 20 La Grange - Fayette Regional 90 77 91 79 / 0 10 10 20 San Antonio Intl Airport 92 76 92 78 / 0 0 10 20 Stinson Muni Airport 93 76 93 79 / 0 10 10 10

EWX WATCHES/WARNINGS/ADVISORIES

None.