Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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605 FXUS64 KEWX 201709 AAA AFDEWX Area Forecast Discussion...UPDATED National Weather Service Austin/San Antonio TX 1209 PM CDT Fri Sep 20 2024 ...New AVIATION (18Z TAFS)... .SHORT TERM... (Today through Saturday) Issued at 242 AM CDT Fri Sep 20 2024 The typical overnight clouds are developing across the Coastal Plains and then moving toward the north into the I-35 corridor, the escarpment and over areas to the southwest of San Antonio. This trend is forecast to continue through mid Friday morning. Otherwise, lows are forecast to range from the lower 70s across the Hill Country to upper 70s along the Rio Grande. Dewpoint temperatures are elevated across the Coastal Plains and areas to the east and southeast of Interstate 35, where patchy to areas of fog can`t be ruled out between dawn and the early morning commute. The low clouds are forecast to lift and dissipate for the most part of South Central Texas mid to late morning with the exception of the Rio Grande, where low clouds linger for several more hours. Today`s highs are likely to reach the lower to mid 90s across the Hill Country and upper 90 along the I-35 and portions of the Coastal Plains. Heat index values are likely to be elevated ranging from 103 to 107 this afternoon. A few places could get into the 108 to 109 for an hour or two especially across the far southeast counties of the local area (Karnes, Gonzales, DeWitt and Lavaca). Overall weather conditions are expected to be hot and dry with slight chances for showers and even a thunderstorm or two over areas to the south, southwest and west of San Antonio mid to late afternoon. The reason of these chances of precipitation is the position of a mid level low pressure system to the southwest of the Rio Grande. The influence of this feature over the local area is enough for isolated showers and maybe a storm. Any activity that develops should come to an end early evening. Clouds start to build across the local area on Friday night through Saturday morning with overnight lows in the 70s. Clouds linger through late Saturday morning before partly cloudy skies dominate the region. As far as high temperatures on Saturday, there are forecast to be above normal climate values but a few degrees cooler than Friday. The reason for this is that the upper level ridge over the local area weakens a bit and flatten as an upper level short wave moves from the four corners region into the Central Plains. Going with a rain-free forecast for Saturday but can`t rule out an isolated shower or two across the southern Edwards Plateau mid to late afternoon. && .LONG TERM... (Saturday night through Thursday) Issued at 242 AM CDT Fri Sep 20 2024 Late this weekend into early next week, the subtropical ridge axis begins to weaken as an upper level low moves out of the Rockies into the central plains states. A trough axis associated with this upper low will gradually move across the northern half of Texas and may aid in some isolated convection across portions of south central Texas on Sunday and Monday. For Sunday, we will keep rain chances limited to a small portion of northwestern Val Verde county. In addition, we could see an isolated shower or storm develop over the coastal plains as the sea breeze moves inland. Rain chances may slide a little farther southward into the southern Edwards Plateau and western Hill Country on Monday. A weak cold front is expected to gradually push into the region on Monday, with only a slight cooling trend in store for the southern Edwards Plateau and Hill Country. The front may gradually work southward to near the Highway 90 corridor late in the day. The medium range models are reluctant to show much in the way of rain chances for the I-35 corridor on Monday as most of the mid and upper level support remains to our north. The forecast for Tuesday through Thursday remains uncertain as the operational GFS and ECMWF both show differing solutions with regard to the mid and upper level flow pattern across the CONUS. For now, we will keep some low rain chances in the forecast on Tuesday and Wednesday for areas mainly along and west of the I-35 corridor. Much of the forecast will also depend on possible tropical activity in the Northwestern Caribbean Sea and Southeastern Gulf of Mexico. For now, we will show a slight cooling trend as we could see continued north winds in the lower levels. However, temperatures are still expected to remain a little above climatological normals for this time of year. && .AVIATION... (18Z TAFS) Issued at 1203 PM CDT Fri Sep 20 2024 Wash, rinse, repeat. Basically a carbon copy of the past couple of mornings with MVFR ceilings developing around 09Z at SAT and SSF and around 12Z at DRT. We should see rapid improvement after 15-17Z at all sites, with AUS looking to remain VFR at this time. Winds will generally be out of the ESE at 5-10 kts but could be a bit stronger at DRT, upwards of 10-15 kts after 17Z Saturday. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 75 97 73 96 / 0 0 0 0 Austin Bergstrom Intl Airport 74 97 71 95 / 0 0 0 0 New Braunfels Muni Airport 74 98 73 97 / 0 0 0 0 Burnet Muni Airport 73 94 71 92 / 0 0 0 0 Del Rio Intl Airport 79 96 78 95 / 10 10 10 10 Georgetown Muni Airport 73 96 71 94 / 0 0 0 0 Hondo Muni Airport 74 94 72 94 / 10 10 0 0 San Marcos Muni Airport 73 96 70 95 / 0 0 0 10 La Grange - Fayette Regional 74 95 72 94 / 0 0 0 10 San Antonio Intl Airport 76 95 74 94 / 0 10 0 0 Stinson Muni Airport 76 97 75 96 / 10 10 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...17 Long-Term...Platt Aviation...MMM