Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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355 FXUS64 KEWX 250733 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 233 AM CDT Wed Sep 25 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today through Thursday) Issued at 205 AM CDT Wed Sep 25 2024 A few pop-up showers are forming across Central TX overnight, but with well below 10 percent coverage and no remaining surface focus. A more concentrated focus of convection over West Central/North Central TX is located along the next front to arrive, and a distinct frontal boundary can be seen on radar early this morning. Tracking the movement on radar, this front is moving about 15 mph due southward and should still be arriving into our northern CWA just after sunrise. However, the boundary will probably be less traceable once arriving into South Central TX as winds above the boundary layer out of the north ahead of the front will mix down and reduce surface convergence. There will still be some speed convergence in the mixed layer late in the morning, so isolated convection will still be possible, but will be quickly shifting southeast of the escarpment by midday and out of the forecast area by 00Z. The breezy north midday winds will be sufficient enough to trend high temperatures down but mainly just over the northern counties today. More noticeable changes will be expected in the evening with a pleasant north breeze and the dew points falling into the 50s to low 60s. As winds decouple some by Thursday morning, lows should drop to the 60s or lower area-wide, with mainly the Hill Country seeing the lows in the mid/upper 50s. The persistence of north winds at the surface and aloft should be good for a drop of high temperatures back to seasonal values for late September, or mainly in the mid 80s to low 90s. && .LONG TERM... (Thursday night through Tuesday) Issued at 205 AM CDT Wed Sep 25 2024 A mid and upper level low combined with the remnants of `Helene` will remain anchored over the southeastern U.S. into the middle Mississippi River valley through the end of the week. On the backside of this low, north to northwest flow remains intact on Friday with the medium range models showing a weak upper disturbance dropping southward into the region into the upcoming weekend. While these disturbances would normally be monitored for rain chances, with a dry air mass in place, we do not expect any chance for rain through the upcoming weekend. As these disturbances roll through, a reinforcing shot of northerly winds in the lower levels is anticipated Friday, with perhaps another weak surge late Saturday into early Sunday. With dry air in the low-levels and clear skies, overnight lows will dip into the mid to upper 50s over the Hill Country, with lower to mid 60s elsewhere. Daytime highs will range from the mid 80s to mid 90s, with the warmest temperatures out west along the Rio Grande. For the early portion of next week, the mid and upper level ridge axis begins to build eastward into the southern U.S. plains. Temperatures may warm slightly on Monday, with models showing a surge of cooler air possibly moving into the region on Tuesday. && .AVIATION... (06Z TAFS) Issued at 1241 AM CDT Wed Sep 25 2024 Based on the downward PoP trends, there is probably a 5 percent chance of overnight convection near a TAF VCNTY and no more than a 15 percent chance during the daytime. While the overnight boundary layer shows a south wind and some decent surface dew points in the upper 60s to low 70s, model initialized winds at 850 mb are north to northwest, meaning dry air advection is already occurring over the area. There is still some mid level moisture pooled over North and Central TX, but the MOS guidance trends suggest isolated impacts if any. Thus with no convection mentioned, the attention shifts to prefrontal clouds and/or possible fog. While this is not out of the question for the I-35 sites, the MOS signals suggest only some lower Coastal Prairies areas to see this pre-frontal moisture pooling. So with VFR skies expected through the period, the only focus for the TAFs going forward is the gusty winds. North winds will begin to escalate gradually with mixing, so there isn`t much need to track a FROPA. All sites should shift to northerlies within a couple hours of each other in the late morning. Some afternoon gusts to 25 KTs are possible. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 92 66 90 63 / 10 0 0 0 Austin Bergstrom Intl Airport 93 66 88 60 / 20 0 0 0 New Braunfels Muni Airport 97 66 92 61 / 20 0 0 0 Burnet Muni Airport 86 62 86 59 / 10 0 0 0 Del Rio Intl Airport 98 67 93 66 / 10 0 0 0 Georgetown Muni Airport 87 63 86 60 / 10 0 0 0 Hondo Muni Airport 96 65 90 59 / 10 0 0 0 San Marcos Muni Airport 94 65 89 60 / 20 0 0 0 La Grange - Fayette Regional 92 66 88 61 / 20 0 0 0 San Antonio Intl Airport 95 69 90 64 / 10 0 0 0 Stinson Muni Airport 97 69 92 64 / 10 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...18 Long-Term...Platt Aviation...18