Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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816 FXUS64 KEWX 051957 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX Issued by National Weather Service Brownsville TX 257 PM CDT Wed Jun 5 2024 ...New SHORT TERM, LONG TERM, CLIMATE... .SHORT TERM... (Tonight through Thursday night) Issued at 257 PM CDT Wed Jun 5 2024 The main issue will be this evening, as we watch for potential development/re-development along the Sierra Madre, the edge of the old outflow boundary, and other locations where prior outflows can potentially hook up with a weak...though north-south diving short wave...which scoots through south-central and south Texas on the backside of the general trough across the Lower Mississippi Valley. This is a difficult call, as model consensus is bearish...including the hourly updated convective-allowing models (CAMs). Still...any energy running into the oppressive air mass has the potential to create something...and this matches well with the Storm Prediction Center`s marginal (level 1 of 5) risk. So...have expanded the coverage of slight chances to include locations south and west of the Austin-San Antonio corridor (which should stay just stable enough). All the activity should be over between 10 and 1 AM as the wave moves into the Lower Rio Grande Valley and beyond. Otherwise...will hold onto the current single county (Frio) Heat Warning and Heat Advisory for part of the Edwards Plateau and Rio Grande Plains/Big Bend region as temperatures are generally matching up nicely. Frio may fall short (advisory vs. warning) since the earlier outflow pushed dewpoints down a hair...but not enough confidence to remove at this point. Sunshine and heat returns everywhere Thursday...though the potential for Heat Advisory is held to portions of the Rio Grande Plains/Big Bend region based on slightly lower temperatures in the low levels. Will defer to later shifts for hoisting another advisory. A mostly clear, mainly calm, but plenty warm and humid night follows Thursday night as east side of expansing 500 mb ridge noses in. && .LONG TERM... (Friday through Wednesday) Issued at 257 PM CDT Wed Jun 5 2024 The aforementioned 500 mb ridge builds across most of Texas Friday and Saturday, locking in more heat and modest humidity. Dewpoints may be a touch lower with some drier air mix-down, so situation may fall just short of a Heat Advisory (108+ east and 110+ near the Rio Grande). Plenty of sunshine and light winds will make it feel pretty hot by early June standards. See Climate section for records...which should hold but not by much. By Sunday, the ridge begins shifting southward as a fairly deep (for early June) 500 mb trough develops across the eastern U.S. Northerly flow on the backside of this trough...along with southwest extent of short wave energy into east Texas...may help form up a band of moisture along/ahead of a wind shift (early summer "front"). After another hot and dry Sunday, this moisture should be sufficient to provide at least scattered thunderstorms across the region late Sunday night through Monday night...perhaps continuing into Tuesday before potentially pushing south of the area Tuesday night/Wednesday. Uncertainty is high as to how far south the wind shift makes it...with the deterministic ECMWF taking it through the entire area and the GFS washing it out closer to Austin. Regardless...the combination of increased cloud cover and/or a wind shift to the north will bring high temperatures closer to seasonal averages (90 to lower 90s) for Monday through Wednesday and elminate the need for additional Heat hazards. && .AVIATION... (18Z TAFS) Issued at 106 PM CDT Wed Jun 5 2024 Outflow that created gusty northeast winds across the Austin/San Antonio metro has petered out and winds have veered to the east/southeast at the terminals in this corridor. With atmosphere stabilized not expecting any mentionable convection through the afternoon...but do expect to see few-scattered cumulus to redevelop by mid afternoon with mainly scattered cirrus above. For this evening...some models (mainly GFS) hinting at possible quick convection in the corridor but others are very limited...so despite the remining 15-20 percent overall storm probabilities have left out of the overnight TAF. That said...500 mb north/northwest flow with embedded weak short waves is conducive...if atmosphere can recover by late afternoon/early evening. Did not include any light haze/fog for the 08Z-13Z window but something to consider, and did leave a period of low VFR/high MVFR ceilings during this time as well. As for Del Rio...the GFS hints at a potential interaction of the outflow with possible Sierra Madre activity during the early to mid evening but confidence is low in whether this can develop/move into the area. For now, have left out but will need to keep an eye on as well by late afternoon and early this evening. && .CLIMATE... Issued at 253 AM CDT Wed Jun 5 2024 THU FRI SAT 06/06 06/07 06/08 ------------------------------------------------ AUS 103/2011 100/2022 99/2022 ATT 103/2022* 103/2022 102/1925 SAT 104/2022 104/2022 101/2022 DRT 110/2022 108/1974 107/2020 * TIED RECORD WITH MOST RECENT OCCURRENCE SHOWN && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 76 98 75 98 / 10 0 0 0 Austin Bergstrom Intl Airport 74 97 73 97 / 10 0 0 0 New Braunfels Muni Airport 75 99 72 99 / 10 0 0 0 Burnet Muni Airport 73 96 73 96 / 10 0 0 0 Del Rio Intl Airport 80 106 82 107 / 10 10 0 0 Georgetown Muni Airport 73 95 72 96 / 10 0 0 0 Hondo Muni Airport 75 100 74 100 / 10 0 0 0 San Marcos Muni Airport 73 97 72 98 / 10 0 0 0 La Grange - Fayette Regional 75 95 73 96 / 10 0 0 0 San Antonio Intl Airport 76 99 75 99 / 10 0 0 0 Stinson Muni Airport 76 100 76 99 / 10 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM CDT this evening for Dimmit-Kinney- Maverick-Medina-Uvalde-Val Verde-Zavala. Excessive Heat Warning until 8 PM CDT this evening for Frio. && $$ 52/BSG