Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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629 FXUS64 KEWX 060849 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 349 AM CDT Mon May 6 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today through Tuesday) Issued at 312 AM CDT Mon May 6 2024 Light streamer showers are seen near and south of San Antonio early this morning. This activity should spread north into Central TX later this morning with a small chance of one or two breaking the cap this afternoon. PWat values should hover near or above 1.5 inches and there should be plenty of low level wind to support the roll cloud pattern in the lower portion of the conveyor belt of the upper low moving into the central/northern Plains states. The mostly cloudy day should help hold temperatures close to seasonal values, but above normal temperatures are expected near the Rio Grande where some downsloping plateau air mixes into the area. The transition to more stable air is more complete by this evening as a more dry zonal pattern develops over TX. The surface pressure gradient should weaken tonight and this could allow for a more stable fog pattern which could become dense in areas where good rains fell. Tuesday, the weaker pressure gradient and an eastward mixing of the dry-line will bring much more sunshine into the area and a significant uptick in daytime heating. The San Antonio area should get the first taste of mid 90s heat so far this year, but lower maxes are still expected over the rain-soaked soils around Austin. High RH values Tuesday could send the Heat Index soaring, and a few areas could see near advisory level values. && .LONG TERM... (Tuesday night through Sunday) Issued at 312 AM CDT Mon May 6 2024 Mid and upper level high pressure off the coast of the western U.S. along with low pressure over the Intermountain West will yield a Rex block pattern as we head into the middle portion of this week. Across our region, west-southwesterly flow aloft will persist in the mid and upper levels of the atmosphere. In the lower levels, the thermal ridge remains strong and this combined with warm air off the Mexican plateau will result in continued above normal temperatures on Wednesday. Most areas will see highs in the 90s along with humid conditions. Temperatures will be hotter (100-105) across the Rio Grande plains as the dryline mixes eastward during the afternoon hours. We will need to monitor areas along and east of I-35 for a few spots briefly approaching Heat Advisory levels with the heat index near 108 degrees. Some convergence along the dryline and perhaps some weak upper support may allow for some afternoon convection to develop over the Hill Country into north Texas. For now, rain chances appear favored to our north, so we will keep the forecast dry. On Thursday, a cold front will move southward through the region, with the GFS trending a little stronger with the cooler air behind this front. The most notable cooling will occur across the Hill Country and I-35 corridor from San Antonio northward. Farther west into the Rio Grande plains, another round of hot temperatures in the 100-105 degree range will remain in the forecast. We could see a few showers or storms develop behind along and behind the front and will keep a low chance for precipitation in the forecast for the Hill Country and nearby I-35 corridor. The cooling trend continues for Friday and Saturday along with a low chance for showers and storms initially confined to the Rio Grande on Friday. An upper level jet moves across north Texas on Saturday into Sunday and this may help spread low rain chances farther east into the Hill Country, I-35 corridor and coastal plains. Highs for Friday through the upcoming weekend will generally range from the upper 70s to upper 80s along with lows in the upper 50s to mid 60s. && .AVIATION... (06Z TAFS) Issued at 1253 AM CDT Mon May 6 2024 Short-term model trends seem to favor some streamer showers or drizzle on either side of daybreak, with maybe some sprinkles continuing into the early afternoon. Will focus on the daybreak period for lowest CIGs and VSBYS, with VCSH to show a hint. When we get closer to daybreak, we`ll make a commitment to either a tempo or prevailing group depending on the character of the radar returns we expect to see. A decent LLJ is depicted on VAD wind profiles and in the mid cloud layers on satellite imagery, so will hold with mainly IFR CIGs close to daybreak and expect any dips into LIFR or worse categories to be short-lived and localized. Much of the day we`ll see the conveyor belt of focused low level moisture over Central TX as a large upper low ejects NE out of the Central Rockies into the plains. Thus will hang onto the MVFR daytime cigs for an hour or two longer than what was indicated in earlier TAFs. The low level moist layer never really gets a chance to mix out today, so a return to MVFR skies should occur over I-35 sometime in the evening. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 85 73 91 72 / 30 20 10 0 Austin Bergstrom Intl Airport 85 72 92 72 / 30 10 10 0 New Braunfels Muni Airport 87 72 93 73 / 30 10 0 0 Burnet Muni Airport 83 70 89 71 / 30 10 10 0 Del Rio Intl Airport 96 74 100 76 / 10 0 0 0 Georgetown Muni Airport 84 71 90 71 / 30 20 10 0 Hondo Muni Airport 88 71 94 71 / 20 0 10 0 San Marcos Muni Airport 85 71 92 71 / 30 10 10 0 La Grange - Fayette Regional 85 74 90 73 / 20 10 10 0 San Antonio Intl Airport 85 73 93 73 / 30 10 10 0 Stinson Muni Airport 87 73 94 73 / 20 10 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...18 Long-Term...Platt Aviation...18