Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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254 FXUS64 KEWX 200803 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 303 AM CDT Fri Sep 20 2024 ...New SHORT TERM, LONG TERM... .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... (06Z TAFS) Issued at 1215 AM CDT Fri Sep 20 2024 VFR conditions are forecast for the next couple of hours (to about 07z) before MVFR cigs begin to affect the I-35 corridor sites. The RGB nighttime microphysics imagery is showing pockets of low cigs pushing from the Coastal Plains into the I-35 corridor as well over the southern part of the Rio Grande. These low cigs are forecast to affect the area terminals overnight through mid Friday morning. There are some hints of IFR cigs affecting the KAUS, KSAT and KSSF between 12z and 13z and therefore mentioned. VFR cigs return to area terminals along the I-35 by 16z and shortly after across KDRT. Southeast winds of 6 knots or less are forecast for the overnight into mid Friday morning time frame, then 6 to 9 knots in the afternoon and evening with occasional gusts up to 15 knots for the I-35 sites and up to 20 knots for KDRT. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 99 75 97 73 / 0 0 0 0 Austin Bergstrom Intl Airport 99 74 97 71 / 0 0 0 0 New Braunfels Muni Airport 100 74 98 73 / 0 0 0 0 Burnet Muni Airport 97 73 94 71 / 0 0 0 0 Del Rio Intl Airport 98 79 96 78 / 10 10 10 10 Georgetown Muni Airport 98 73 96 71 / 0 0 0 0 Hondo Muni Airport 96 74 94 72 / 20 10 10 0 San Marcos Muni Airport 98 73 96 70 / 0 0 0 0 La Grange - Fayette Regional 97 74 95 72 / 0 0 0 0 San Antonio Intl Airport 97 76 95 74 / 10 0 10 0 Stinson Muni Airport 98 76 97 75 / 10 10 10 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...17 Long-Term...Platt Aviation...17