Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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133 FXUS64 KEWX 230727 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 227 AM CDT Thu May 23 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today through Friday) Issued at 113 AM CDT Thu May 23 2024 Southeasterly flow off the Gulf of Mexico maintains a warm and humid airmass over South Central Texas early this morning. This airmass will persist across all areas today with the dryline remaining west over all of our area, except Val Verde County. Expect little change in high temperatures most areas, however better mixing of low clouds should allow for a return of high temperatures above 100 farther north up the Rio Grande to the Val Verde County area. Expect similar heat index values today most areas. The highest values of 108 to 111 will be found generally along and south of US 57 and west of I-37 where a Heat Advisory will be issued for this afternoon into early evening. On Friday, the dryline mixes to the east into the Edwards Plateau and the Rio Grande Plains. The drier airmass west of the dryline will allow for even hotter high temperatures there, however heat index values will be lower due to lower dewpoints. A strengthening thermal ridge also brings hotter high temperatures and heat index values east of the dryline. Another Heat Advisory is likely, this time for portions of the I-35 corridor, including the San Antonio area and possibly Austin area. Later forecasts will determine the areal coverage for Friday`s Heat Advisory. As far as chances of showers and thunderstorms, portions of the Hill Country into Central Texas remain favored both days. Forcing by a weak mid level impulse today and the dryline Friday afternoon along with heating should generate showers and thunderstorms. However, capping due to an encroaching Subtropical Ridge from the south should keep activity mainly isolated. Forecast soundings show MLCAPE of 2500 to 3500 J/kg and mid level lapse rates of 8.5 C/km today and MLCAPE of 4000 J/kg on Friday. All hazards of severe storms are possible with large to very large hail and damaging wind gusts the main threats. PWs around 150% of normal could bring some high rainfall rates with a threat of minor flooding. && .LONG TERM... (Friday night through Wednesday) Issued at 113 AM CDT Thu May 23 2024 * Much of South Central TX is about to experience probably the hottest Memorial Day weekend of all time * Monthly high temperature record for May likely to be tied or broken at DRT * Heat Advisories and/or Excessive Heat Warnings are likely for much of the region through Monday The negative impacts of below normal precipitation this year will help with making the southern and western two-thirds of South Central TX extraordinarily hot for this Memorial Day weekend. The driest areas near the Rio Grande has already resulted in a tie of the monthly high temperature record for May, and an even hotter weather pattern looms ahead in the next few days. The pattern itself isn`t particularly eye-catching with a somewhat flat ridge over TX and dry air mixing down from westerly flow aloft and some downsloping influences coming from the higher terrain to the west setting the table. Over our NE counties, high heat indices could still warrant a heat advisory, but a more robust wet season will make the afternoon ambient temperature more typical low to mid 90s for a stable weather patten for late May. Nevertheless, the dryline should mix the farthest east on Sunday, possibly leading to the first triple digit MaxT day of 2024 and daily high temperature record if our forecast verifies. A final day of unusually hot weather is expected Monday, but northern counties could get some relief should a cool front arrive in the afternoon. Friday`s dry-line could trigger isolated storms that could carry over into the evening over parts of the Hill Country and Central TX, and the next rain chance skips to Monday when a late day front tries to cut into the TX heat. Each of these days could see some strong wind gust potential, and perhaps a low threat for hail Friday evening. Rain chances after Monday will be accompanied by a more typical late May pattern, but a few strong storms could still develop as the afternoon air will still be quite warm. && .CLIMATE... (RECORD HIGH TEMPERATURES THURSDAY THROUGH MONDAY) THU FRI SAT SUN MON 05/23 05/24 05/25 05/26 05/27 ------------------------------------------------------------ AUS 99/2008 99/1955 100/2011 97/2018 100/2011 ATT 100/2008 104/1925 100/2011 99/2018 100/2011 SAT 99/2008* 101/1989* 103/1989 100/1989 100/2011 DRT 105/2000 109/2000 104/2011 106/2018 106/2018 * TIED RECORD WITH MOST RECENT OCCURRENCE SHOWN && .AVIATION... (06Z TAFS) Issued at 1229 AM CDT Thu May 23 2024 MVFR CIGs over the I-35 corridor into the Hill Country will spread to all areas overnight, then mix to FEW-SCT VFR by midday on Thursday. MVFR CIGs return Thursday night. HZ can be expected with occasional reductions in VSBY, however 6SM or higher should prevail at the sites. Any SHRA/TSRA will pass well north of the KAUS on Thursday. Breezy/gusty southeasterly winds prevail, though lighter at KDRT. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 94 76 96 75 / 10 0 10 10 Austin Bergstrom Intl Airport 93 76 96 74 / 10 0 10 10 New Braunfels Muni Airport 96 76 98 74 / 0 0 10 10 Burnet Muni Airport 91 74 93 73 / 20 0 10 10 Del Rio Intl Airport 105 80 108 78 / 0 0 0 0 Georgetown Muni Airport 91 75 94 73 / 20 0 10 10 Hondo Muni Airport 99 74 102 74 / 0 0 10 0 San Marcos Muni Airport 95 75 97 74 / 10 0 10 10 La Grange - Fayette Regional 92 77 94 77 / 0 0 0 10 San Antonio Intl Airport 96 76 99 75 / 0 0 10 10 Stinson Muni Airport 98 77 100 76 / 0 0 10 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...04 Long-Term...18 Aviation...04