textproduct: Austin/San Antonio

UPDATE

Issued at 449 AM CST Thu Dec 26 2024

Expanded the Dense Fog Advisory to include Atascosa, Wilson, Karnes, Gonzales, and DeWitt counties. The advisory is good still 9 AM CST.

SHORT TERM

(Today through Friday) Issued at 220 AM CST Thu Dec 26 2024

Key Messages...

- Areas of fog to widespread dense fog is forecast to affect areas along the I-35 corridor and parts of Hill Country and southern Edwards Plateau this morning.

- Chances for showers and storms are in the forecast mainly late morning into the afternoon as another cold front pushes across the local area.

- Some storms could be strong to severe mainly along and east of a Burnet to New Braunfels to Yorktown line. Primary threats are large hail and damaging winds. Can't rule out isolated tornadoes.

Visibilities continue to drop early this morning across the Hill Country, I-35 corridor, and parts of the coastal plains. This trend is forecast to persist through the overnight hours into the middle of the morning. We are monitoring closely surface observations and webcams in case of needing a Dense Fog Advisory within the next few hours. A Special Weather Statement was issued earlier to address the development of areas of fog to patchy dense fog along the I-35 corridor and the expectation of it spreading over a larger area overnight.

As the morning progresses, an upper level short wave over New Mexico pushes to the southeast and over central Texas mid to late morning and afternoon. At the surface, a cold front is forecast to move across South Central Texas during the same time period. Light showers and a thunderstorm or two are possible ahead of the boundary as it approaches the I-35 corridor. Convection begins to increase as the cold front moves across the I-35 corridor and then into east Texas. We can start seeing strong to severe thunderstorms developing as early as 11 AM across the Hill Country and nearby locations. Instability continues to grow as the frontal boundary pushes to the east in the afternoon. A broken line of strong to severe thunderstorms is forecast to push along and east of Highway 77 in the afternoon with forecast soundings supporting the potential for large hail, damaging winds, and even an isolated tornado or two. Pwats are around 1.3 inches which could help thunderstorms to produce localized heavy downpours, but it won't be a concern for localized flooding due to the fast moving front.

By sunset, the activity should be ending over the far eastern counties with dry and cooler airmass spreading across South Central Texas. Overnight lows are forecast to range from the lower 40s across the Hill Country to upper 40s across the coastal plains.

Another upper level short wave trough moves across South Central Texas on Friday. At the surface, a back door front makes it to the southern Edwards Plateau and Hill Country and that's it. Dry weather conditions persist. Partly cloudy skies are forecast with highs in the 70s.

LONG TERM

(Friday night through Wednesday) Issued at 220 AM CST Thu Dec 26 2024

Key Messages...

- Very pleasant temperatures with cool nights and unseasonably warm days Saturday through Monday.

- Cold front early New Year's Eve/Tuesday with near to below seasonable temperatures into the New Year/Wednesday.

The last of the ongoing series of upper level troughs and Pacific style fronts is expected on Saturday with no impacts other than a dry airmass out west where locally breezy winds may bring elevated fire weather conditions. In its wake, southwesterly boundary layer flow develops on Sunday leading to the warmest temperatures of the long term on Monday. High temperature records for December 30th will be approached and possibly broken or tied. Current record highs are 83 at KAUS, KATT, KSAT and 86 at KDRT. There is a possibility of an isolated 90 degree high in Dimmit or southern Maverick counties. Then, a cold front of Canadian origin moves across our area Monday night into early Tuesday/New Year's Eve cooling off temperatures by New Year's Day. No rain is forecast due to a mainly unseasonably dry airmass through the long term.

AVIATION

(12Z TAFS) Issued at 544 AM CST Thu Dec 26 2024

IFR, LIFR and VLIFR conditions are affecting the local terminals due to low visibilities (areas to widespread dense fog). This trends is forecast to persist through 15z when fog is expected to lift above critical values. Then, a cold front is forecast to push across South Central Texas mid to late morning and the afternoon. Showers and storms are expected to develop ahead and along the boundary as it moves to the east. Clearing takes place from west to east by mid afternoon. Light and variable winds are expected this morning with the wind flow shifting to the northwest to north in the wake of the frontal passage.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 75 48 78 54 / 70 0 0 0 Austin Bergstrom Intl Airport 76 46 77 49 / 70 0 0 0 New Braunfels Muni Airport 77 48 80 54 / 50 0 0 0 Burnet Muni Airport 73 46 78 50 / 50 0 0 0 Del Rio Intl Airport 78 46 81 51 / 0 0 0 0 Georgetown Muni Airport 74 45 77 49 / 70 0 0 0 Hondo Muni Airport 77 44 79 50 / 20 0 0 0 San Marcos Muni Airport 75 45 78 51 / 60 0 0 0 La Grange - Fayette Regional 74 49 75 55 / 70 0 0 10 San Antonio Intl Airport 76 48 79 55 / 40 0 0 0 Stinson Muni Airport 77 48 79 55 / 40 0 0 0

EWX WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 9 AM CST this morning for Atascosa-Bastrop- Bexar-Blanco-Burnet-Caldwell-Comal-De Witt-Gonzales-Guadalupe-Hays- Karnes-Kendall-Travis-Williamson-Wilson.