Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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589 FXUS64 KEWX 091350 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 850 AM CDT Thu May 9 2024 ...New UPDATE... .UPDATE... Issued at 850 AM CDT Thu May 9 2024 We have cancelled the dense fog advisory for this morning as visibilities are 1 mile or greater in mist and haze. We have also inserted haze into the forecast through the day, south of the front and east of the dryline, given the background residual smoke in the air originating from seasonal burnings in Mexico and Central America. Minor updates were made on timing of storms later this afternoon and evening. && .SHORT TERM... (Today through Friday) Issued at 354 AM CDT Thu May 9 2024 Morning surface observations show high moisture levels across all of south central Texas with dewpoints currently in the lower to upper 70s. Fog development continues and as winds begin to ease across portions of the Hill Country and I-35 corridor, some dense fog is expected. We have issued a Dense Fog Advisory until 11 AM for the above mentioned areas. We will continue to monitor and may need to expand the Advisory pending observational trends. The dryline is still expected advance eastward beginning mid-morning and continuing through the afternoon hours. Meanwhile, a cold front will slowly work southward out of north Texas into portions of west central Texas this afternoon. Hi-res models continue to initiate convection along the intersection of the front and dryline this afternoon somewhere between Mills county southward into northern Llano and Burnet counties. The late afternoon hours appear to be the most favored time for convection initiation. However, we are noting that at least a few of the hi-res models manage to develop some convection earlier than this over portions of the southern Edwards Plateau near Junction by late morning. Convection will then likely continue to develop along the southward moving cold front across the remainder of the Hill Country and into the I-35 corridor, mainly north of San Antonio during the early evening hours. Large to very large hail and damaging winds are the main severe weather concerns. However, a tornado can not be ruled out, especially where discrete supercells interact with any boundaries. SPC has expanded the Enhanced Risk area (level 3 of 5) to cover areas generally north of a Fredericksburg to San Marcos to La Grange line. South of this line to a Rocksprings to Cuero line could still see some isolated severe storms with a Marginal to Slight (level 1 to 2 of 5) in place. It will be very warm to hot again across south central Texas with highs ranging from near 90 to near 106 degrees. Another record high may be tied or broken out west at Del Rio. We could be close to the record high at San Antonio as well. Some relief in the temperatures will arrive tonight as northerly winds behind the cold front usher cooler air into the region. Lows will ease back into the mid 60s to lower 70s. On Friday, expect highs in the lower 80s to lower 90s, with a few of the models trending upward slightly with temperatures compared to previous runs. We will keep a low chance for rain in the forecast for the Rio Grande plains into the Hill Country. && .LONG TERM... (Friday night through Wednesday) Issued at 321 AM CDT Thu May 9 2024 Our active stretch of weather looks to continue into the long term period as southwest flow aloft continues to feed mid-level Pacific moisture into the region. Saturday and Sunday will feature the best chance for rain through the extended period with an upper level low over the Four Corners finally becoming absorbed by the upper jet and sliding eastward. Early Saturday, a surface high will be in place over north Texas, with flow turning back out of the east-southeast over South Central Texas as early as Friday night, we will start to see showers and perhaps some isolated thunderstorms develop under isentropic ascent over the Rio Grande Plains. This activity should start to spread eastward with time through the early afternoon Saturday, but coverage and intensity is expected to be limited due to weak forcing aloft. The aforementioned trough will take some time to exert its influence on rain chances so we`ll mainly be working with the isentropic and terrain induced lift on Saturday. Cooler temperatures in the 70s and 80s for highs along with mostly cloudy to cloudy skies can be expected. By late Sunday, a positively tilted 500mb trough will be situated over the Texas Panhandle, resulting in a 100- 130 kt jet streak at the 300mb level to become situated in an ideal location for showers and storms to develop over South Central Texas. Within the right entrance region of this jet streak, we should see good forcing for ascent and some decent 0-6km bulk shear. However, the overall severe threat looks to be limited by a lack of heating and resultant instability. We should be able to squeeze out a good 1/2-1" of QPF out of storms on Sunday afternoon over the eastern half of the region, but once again, western zones don`t look to be so lucky, especially where long term drought has been the worst. One thing to note before moving on the the start of next week: There are some signals for some heavier rainfall over the southwestern CWA and southern Rio Grande Plains Saturday night. For now, will take this with a grain of salt, but the potential is there for some beneficial rains out west. Monday looks like the most active day next week, with lingering showers and storms as the 500mb trough exits to our east. The dryline will also start to work its way back east on Monday afternoon, resulting in a hot and dry forecast out west over the Rio Grande Plains Monday afternoon. Temperatures will climb back into the mid 90s after a bit of a break Friday-Sunday from the heat. Beyond Monday, things look to dry out and heat up considerably, with highs in the 88-101 range for South Central Texas on Tuesday, Wednesday, and Thursday. By late Wednesday, things could get active once again with a trough moving in over southwest Texas and sparking off some storms, but this is still quite a ways out and a lot can change between now and then. && .AVIATION... (12Z TAFS) Issued at 650 AM CDT Thu May 9 2024 The biggest change for the most recent aviation forecast was to increase expected vsbys and cigs along I-35 over the next few hours. In addition, we have added a mention for brief IFR at DRT this morning. Convection is still expected to develop over the Hill Country around 21Z, then move southeast into the I-35 corridor. We have adjusted the PROB30 group slightly for AUS. Confidence in convection at SAT and SSF is lower and we will not mention in the TAF at this time. A cold front moves through this evening, with MVFR cigs likely to reform at all TAF sites between 07-09Z. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 93 68 83 65 / 30 40 10 10 Austin Bergstrom Intl Airport 91 67 83 65 / 20 40 10 10 New Braunfels Muni Airport 94 69 86 67 / 10 20 10 10 Burnet Muni Airport 89 65 80 63 / 40 40 10 10 Del Rio Intl Airport 107 74 92 72 / 0 10 40 30 Georgetown Muni Airport 89 66 81 63 / 40 50 10 10 Hondo Muni Airport 100 71 88 69 / 10 10 20 10 San Marcos Muni Airport 92 68 84 65 / 20 30 10 10 La Grange - Fayette Regional 90 71 85 67 / 20 40 10 10 San Antonio Intl Airport 95 71 86 68 / 10 20 10 10 Stinson Muni Airport 96 72 87 70 / 10 10 10 10 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...76 Short-Term...Platt Long-Term...MMM Aviation...Platt