Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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000 FXUS64 KEWX 202309 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 609 PM CDT Tue Apr 20 2021 .AVIATION (00Z Aviation)... VFR conditions through the TAF period. At 23Z the cold front was just about to move through SAT/SSF and DRT. We will begin the 00Z TAFs with gusty N to NE winds, with some gusts between 20-30KT occurring through the evening. Wind gusts may settle after midnight, before briefly increasing again 15Z-18Z as mixing occurs. Winds are foreast to turn E and SE at DRT 12Z-18Z, and E at SAT/AUS 21Z-00Z. && .PREV DISCUSSION... /ISSUED 219 PM CDT Tue Apr 20 2021/ SHORT TERM (Tonight through Wednesday Night)... The cold front is moving across the northern portion of the Hill Country with northerly winds being observed at Burnet and Llano sites as 2 pm. A strong cold air advection is in place with temperatures going down to the mid 60s right behind the wind shift out of the north. Also, breezy to gusty wind conditions are affecting areas over central Texas and shortly the Hill Country and then southward late this afternoon and evening. Wind speeds are expected to range from 10 to 20 mph with gusts as high as 30 to 35 mph. No rain is forecast with the passage of this front, however, the much cooler air mass will linger around at least through Thursday. Overnight lows will be well below climate normal values with upper 30s across the Hill Country to mid 40s and lower 50s elsewhere. Skies will be sunny over most areas with partly cloudy skies along the Rio Grande and Edwards Plateau if enough moisture stays. Wednesday`s high will be in the mid 60s across the Hill Country to low to mid 70s over the rest of the region. It will be breezy on Wednesday as well with wind speeds around 10 to 15 mph and higher gusts as a surface high pressure system over central Texas slowly moves to the east. Southerly flow returns on Wednesday evening into Thursday. Some models pick up isolated light shower activity along the Rio Grande overnight/early Thursday morning. Therefore, went ahead and added less than 20 percent chance for rain for that period. Otherwise, cloudy and much warmer than the previous morning with lows in the upper 40s to lower 60s. LONG TERM (Thursday through Tuesday)... One last day with below normal temperatures expected for Thursday with highs only the mid 60s to mid 70s for most locations. Mid to upper level analysis for the start of the long-term shows a broad troughing over the eastern CONUS with shortwave ridging extending into the Northern Plains and mostly zonal flow over South-Central Texas. South to southeasterly flow will have since returned to the area and should prompt streamer shower development beginning along the Rio Grande and our southwestern zones, then expanding northeastward across the region throughout Thursday. Not much in the way of QPF for this activity but slight chances to chances are in the forecast. The next upper level low approaches the region from the west late Thursday and into Friday. Models have come into much better agreement with the handling of this feature and depict the trough axis extending well into Mexico. This will put South-Central Texas in a favorable position for large scale ascent and a veering wind profile with height. Instability on forecast soundings for Friday afternoon show MUCAPE values around 2500 J/kg and sufficient deep layer sheer for organized convection. SPC has expanded the highlighted 15% area for severe storms on Friday, with the eastern two thirds now encompassed in this 15% area. Exact timeframe for strong to possibly severe storms is still unclear but it seems the Friday 18Z to Saturday 03Z period looks most favorable with storms moving east of the area during the overnight hours of Friday into Saturday. Frontal boundary associated with this late week system will just house a pacific airmass behind it with a brief north to northeasterly wind shift. Shouldn`t fluctuate temperatures much with a gradual warming trend taking place from Friday into early next week. Quiet weather expected over the weekend with shortwave ridging building in behind this system. Temperatures by early next week look to be back above normal with highs in the mid 80s to low 90s. Next upper level trough approaches the area by Tuesday with the same presentation as the last. Details will need to be worked out with this next system given that it is on Day 7 of the forecast period but global models aren`t as keen with rainfall chances as of now. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 43 68 50 68 62 / 0 0 0 20 50 Austin Bergstrom Intl Airport 42 68 48 70 62 / 0 0 0 20 50 New Braunfels Muni Airport 45 72 51 72 64 / 0 0 0 30 50 Burnet Muni Airport 39 64 47 66 60 / 0 0 0 20 40 Del Rio Intl Airport 52 74 58 74 66 / 0 0 - 30 30 Georgetown Muni Airport 41 66 47 68 60 / 0 0 0 20 40 Hondo Muni Airport 47 76 54 71 64 / 0 0 0 40 50 San Marcos Muni Airport 43 71 48 70 62 / 0 0 0 20 50 La Grange - Fayette Regional 45 71 51 72 65 / 0 0 0 20 50 San Antonio Intl Airport 46 72 53 69 64 / 0 0 0 30 50 Stinson Muni Airport 47 73 54 71 66 / 0 0 0 30 50 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Runyen Long-Term...Oaks

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