Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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156 FXUS64 KEWX 211123 AAA AFDEWX Area Forecast Discussion...UPDATED National Weather Service Austin/San Antonio TX 623 AM CDT Sat Sep 21 2024 ...New AVIATION... .SHORT TERM... (Today through Sunday) Issued at 300 AM CDT Sat Sep 21 2024 Low clouds are increasing across the eastern part of South Central Texas as of 230 AM CDT. Also, there is a deck of mid level clouds covering the western part of Bexar County that has been around for several hours. Latest nighttime microphysics images are showing some low clouds developing underneath with San Antonio International Airport reporting broken ceiling at 1800 feet. The low level cloud coverage is forecast to remain and expand across most areas through at least 10am - 11am time frame. Overnight lows are forecast to range from the lower 70s across the Hill Country to upper 70s across the Rio Grande and Coastal Plains areas. One more thing, patchy to areas of fog are possible around dawn to about 8-9 am over the Coastal Plains especially over portions of Wilson, Karnes, Gonzales, DeWitt, Lavaca and Fayette Counties. Clouds begin to break late this morning giving way to partly cloudy and mostly sunny skies this afternoon. Highs are forecast to be a few degrees cooler than those on Friday, however, above climate normal values ranging from the upper 80s across the Hill Country to upper 90s along the I-35 corridor and the Coastal Plains. A dry airmass is forecast to push across the eastern part of South Central Texas throughout the day as pwats values come around 1.2 to 1.3 inches and 1000mb - 500mb RH layer at 36 to 38 percent based on the GFS solution. Hires models such as HRRR,NAM 3KM and RRFS also concur. Therefore, the local area should see very limited shower activity if any with 5 to 10 percent chance between U.S. Highway 83 and U.S. HIghway 281 mainly mid to late afternoon. Clouds return during the evening hours and continue developing and spreading through Sunday. An upper level low pressure system is forecast to move across the four corners region today and into the Central Plains by Sunday. A southwest flow aloft is forecast to stay in control over the Rio Grande while a moist southerly wind flow is forecast to prevail late tonight into Sunday morning. This setup could send a few showers across the Rio Grande and parts of the southern Edwards Plateau overnight and Sunday morning. As the day progresses and we enter into the Sunday afternoon period, slight chances for showers are in place for the Coastal Plains and even a shower or two with an isolated thunderstorm is possible over Val Verde County and vicinity as the upper level low pushes to the northeast over the Central Plains while sending a cold front that extends from northeast Texas southwestward to the western part of the state. Sunday`s highs still above climate normal ranging from the upper 80s to mid 90s. && .LONG TERM... (Sunday night through Friday) Issued at 300 AM CDT Sat Sep 21 2024 The upper level low currently over the desert southwest will eventually weaken into an upper trough axis and move east into the central plains states early next week. As the trough axis moves east, a cold front is expected to move southward early Monday and should be near a Rocksprings to Llano line around sunrise Monday. With some weak lift and low-level forcing along the front, rain chances will be in the forecast late Sunday into Monday across the southern Edwards and Hill Country. The latest guidance has trended a little stronger with the frontal boundary and rain chances have trended upward across the southern Edwards Plateau. The front is expected to gradually slide southward during the daytime hours on Monday. The models are fairly reluctant to develop much in the way of convection during the afternoon hours along the front and rain chances still look to remain favored over the Hill Country. In addition, some isolated afternoon convection may develop over the coastal plains as the sea breeze moves inland. Temperatures will trend downward slightly for most of the region, with the most notable drop in the Hill Country and southern Edwards Plateau. On Tuesday, a reinforcing shot of upper level energy is expected to drop southward out of the southern Rockies and help reinforce the upper level trough. The models differ with the speed and strength of this upper level energy, so there will be some uncertainty in the forecast. For now, we will keep rain chances in the forecast for most of south central Texas, with the focus for better rain chances still favored for areas generally west of I-35. We will also need to maintain an eye on the northwestern Caribbean or southern Gulf of Mexico as the last few NHC outlooks maintain an increasing probability for tropical development in the mentioned region. Uncertainty continues through the remainder of the forecast as much will depend on the development of an upper level trough or perhaps a closed low over the southern U.S. plains and the expected tropical system in the Gulf of Mexico. For now, we will keep some low rain chances in the forecast for most of the region along with near to slightly above normal temperatures. && .AVIATION... (12Z TAFS) Issued at 617 AM CDT Sat Sep 21 2024 MVFR cigs are dominating the local area terminals and forecast to remain through 16z. Afterward, VFR conditions are forecast through late tonight when low clouds once again develop across South Central Texas. Southeast to south winds of 10 knots or less are forecast for the most of this morning and increasing late this morning into the afternoon and continuing through this evening from 8 to 14 knots with occasional gusts up to 21 knots across KDRT. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 98 74 96 73 / 0 0 0 10 Austin Bergstrom Intl Airport 97 73 95 72 / 0 0 0 0 New Braunfels Muni Airport 98 74 97 73 / 0 0 10 0 Burnet Muni Airport 95 72 93 70 / 0 0 0 10 Del Rio Intl Airport 96 78 94 76 / 10 0 10 30 Georgetown Muni Airport 95 72 93 72 / 0 0 0 10 Hondo Muni Airport 95 74 93 72 / 0 0 0 10 San Marcos Muni Airport 96 72 95 70 / 0 0 10 0 La Grange - Fayette Regional 95 72 94 72 / 0 0 10 0 San Antonio Intl Airport 96 75 94 74 / 0 0 10 10 Stinson Muni Airport 97 76 96 75 / 0 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...17 Long-Term...Platt Aviation...17