textproduct: Austin/San Antonio

KEY MESSAGES

- Unseasonably hot and humid in the short term with heat indices from 100 to 107 degrees for much of the area.

- A pair of cold fronts brings increasing rain chances Wednesday through through Friday. Locally heavy rains possible each day.

- Cooler than normal weekend behind the second cold front.

SHORT TERM

(Today through Tuesday) Issued at 1255 PM CDT Mon Apr 27 2026

A slightly thinner batch of low clouds over South Central TX is allowing the temperature trends to keep better pace with model forecasts than it did yesterday. This means the high heat indices and dew points in the low 70s will make the next couple days dangerous to those not accustomed to the outdoor heat. Some of the gridded data values may push into borderline heat advisory criteria, but we think the mixing out in the afternoon will probably not match up well to get the max heat index values that high. It's probably safe to say that most areas should see values at or above 100 degrees.

The dry-line today looks more distinguished on radar and has pushed farther SE than on the previous days. This might normally be a cause for concern, but the ALPW depicts a pretty dry mid layer of air and the overlay of 850 hPa winds would suggest the 5000 foot level air is dry with a southwest wind. So while the boundary looks sharp on radar, there will probably be a challenge to get enough moisture depth to break through the capping inversion unless a weak MCV were able to suddenly appear off the higher terrain of Mexico. Some of the latest deterministic GFS runs do show a little vorticity leaking out, but the majority of models are coming in drier. Most likely, we'll see another old faithful puff or two over the Burro Mountains and not much more both today and late Tuesday.

LONG TERM

(Tuesday night through Sunday) Issued at 123 PM CDT Mon Apr 27 2026 Late Tuesday is where we break of to call the forecast long term, and there is a subtle change in the pattern that makes this break convenient. Lowering mid-level height fields and increasing mid- level vorticity begins to take shape over our area and that might get the dry-line over the area active for a break of the cap in a couple places. The consensus among models favor somewhere in Central TX, so we'll maintain some isolated evening storms mainly for Burnet and Williamson Counties. As we've seen over the past few days, the storm strength should be over the marginally severe variety, mainly large hail, damaging winds.

Height fields aloft continue to drop into Wednesday and more shortwave energy is forecast for when a cold front arrives back door style or in from the NE. That will leave a midday gradient of hot and humid over SW counties contrasting to cooler and cloudy conditions over NE counties. There could be an opportunity for some severe storms that go beyond the scope of a Marginal Risk day should the frontal timing hold off over our southern counties. Later in the afternoon into the early evening, the storm motion vectors could slow down as mid level shear weakens some. Thus a cluster or small complex is possible and could bring a heavy rain threat not seen since 4/21-2. We should learn a little more about this scenario after more of the higher res models reach out to within the 48 hour window. Elevated rain chances continue post- frontal for Thursday, and then perhaps the highest rainfall coverage and intensity period of the week is expected for Friday. With multiple rounds of rain in the late week forecast, there's a potential that a localized FF watch may be needed by that time.

Another cool weekend is in store as the Friday front makes a more thorough push into South TX than will the Wednesday front. The drier air brought by the front will not show signs of eroding until Sunday night, so a somewhat dry and stable pattern should carry over into early next week.

AVIATION

(00Z TAFS) Issued at 614 PM CDT Mon Apr 27 2026

Still some haze restricting visibility at AUS. Conditions should improve over the next couple of hours then all terminals will be VFR for the rest of the evening. Low ceilings will develop later tonight in the Austin and San Antonio areas and then around sunrise at DRT. The Austin and San Antonio airports will drop to IFR overnight. All sites will be back to VFR ceilings by around noon Tuesday. Not sure what to do with haze during the day Tuesday. For now will keep visibility unlimited, but reductions are possible with little change in the overall pattern.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 75 93 72 88 / 10 10 10 30 Austin Bergstrom Intl Airport 75 93 72 89 / 10 10 10 30 New Braunfels Muni Airport 74 94 72 90 / 10 0 10 20 Burnet Muni Airport 73 90 69 83 / 10 10 20 20 Del Rio Intl Airport 76 96 76 96 / 10 0 10 20 Georgetown Muni Airport 75 92 70 86 / 10 10 20 20 Hondo Muni Airport 75 94 71 94 / 10 0 10 20 San Marcos Muni Airport 75 93 72 90 / 10 10 10 30 La Grange - Fayette Regional 76 93 73 89 / 10 10 10 20 San Antonio Intl Airport 75 94 73 91 / 10 0 10 20 Stinson Muni Airport 75 95 74 93 / 10 0 10 20

EWX WATCHES/WARNINGS/ADVISORIES

None.