Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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827 FXUS64 KEWX 190512 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 1212 AM CDT Wed Jun 19 2024 ...New AVIATION... .SHORT TERM... (Tonight through Wednesday night) Issued at 225 PM CDT Tue Jun 18 2024 Key Messages: *Bands of moderate to heavy rains expected to begin early Wednesday and continue into Thursday. *Confidence increasing for greatest rainfall amounts to focus across southern half of the region; Flood Watch has been expanded to include Maverick, Zavala, and Dimmitt Counties. *Isolated tornado possible across our southeastern-most counties on Wednesday into Wednesday night. Discussion: Isolated to widely scattered showers have developed this afternoon across the region, especially along and east of the I-35 corridor, in combination with a weak upper level disturbance earlier this morning located to our west-northwest and with activity coming off the middle to upper Texas coast as higher moisture levels start to inch westward. These should remain brief with a few locations picking up a quick quarter inch or so. While lightning is not expected to be common, a few strikes could be possible later this afternoon with peak daytime heating. Partly cloudy skies otherwise trend into this evening with highs into the low to mid 90s for most except for the Rio Grande communities which may approach or reach the 100 degree mark. Deeper tropical moisture that is in association with Potential Tropical Cyclone One over the southwestern Gulf with PWATs as high as 2.7 inches and warm cloud layer depths that exceed 14,500 feet should arrive into the Coastal Plains by early Wednesday morning then gradually expand westward into the I-35 corridor and portions of the Hill Country by mid to late morning and towards the Rio Grande through Wednesday afternoon. Bands of moderate to locally heavy rainfall will pivot across the region with this deeper tropical moisture. Some embedded thunderstorms may be possible as well but widespread thunderstorm activity will not be expected. As stated within the previous forecast discussion, model solutions have continued the trend of shifting the highest rainfall totals farther to the south. This leads to the greatest confidence for heaviest rainfall to commence across our southern counties with a fairly tight gradient centered in our CWA. Not going to make any major configuration changes to the issued Flood Watch except for expansion across the remainder of the Rio Grande Plains. Amounts will also be lowered within the product into the 1 to 4 inch range with isolated totals up to or in excess of 6 inches across our southern most counties. This is in step with most recent QPF forecast from WPC. The newest released Day 2 Excessive Rainfall Outlook from WPC has been adjusted as well to where the Moderate (level 3 of 4) risk of excessive rainfall and flooding has been shifted southward to include mainly our southern tier of counties and points southward. Majority of the rest of the CWA will stay within the slight (level 2 of 4) risk. Those locations where the heaviest rainfall does occur could see some rises in the river levels as well. Gusty winds will be expected within some of the bands of rain as well where gusts into the 25 to 35 mph range will be possible. However, direct wind impacts associated with Potential Tropical Cyclone One are to remain well south of our area. There will be enough ingredients and vorticity for the potential of a brief isolated tornado or two. Greatest focus would be across our southeastern most regions, where SPC has highlighted a marginal (level 1 of 5) risk for severe thunderstorms. Otherwise, high temperatures on Wednesday will be well below normal due to the thick clouds and fairly widespread rains, mainly ranging from upper 70s into the 80s across most locations. && .LONG TERM... (Thursday through Tuesday) Issued at 225 PM CDT Tue Jun 18 2024 Rain and storms will be ongoing over the Rio Grande Plains Thursday morning. Locally heavy rainfall remains a possibility through late morning before the heaviest stuff moves off to the west. Continued showers and storms appear likely Thursday afternoon as tropical moisture remains in place with PWATs in excess of 2-2.5". WPC still has a Slight risk ERO (level 2 of 4) for the western and southwestern zones on Thursday, with the threat for flooding rains remaining in play through the day Thursday. On the back side of the inverted troughing over the region, continued showers and storms are expected over the southern and western half of the region on Friday. As we move into the weekend, we`ll be watching yet another area of disturbed weather over the southwestern Gulf of Mexico for development. As of right now, NHC gives it a low chance of developing into a tropical storm over the next 7 days (1 in 5 odds). Easterly flow aloft will continue through the weekend as well, allowing showers and storms to be a possibility most days in the long term forecast period. Temperatures should remain acceptable by late June standards, but the humidity will continue due to recent rains. While the Subtropical Ridge may attempt to build over northeast Texas early next week, continued easterly flow on its southern periphery will result in a slightly cooler than normal and more active pattern than is typical for late June. && .AVIATION... (06Z TAFS) Issued at 1211 AM CDT Wed Jun 19 2024 VFR conditions at sites will be short lived with MVFR ceilings developing between the start of the period and 09Z, and then IFR ceilings near sunrise over the Hill Country and areas east. RA and SHRA activity associated with the tropical disturbance in the Gulf will move into the Coastal Plains near sunrise, impacting I-35 sites around 15Z. Activity will continue west during the day reaching the Rio Grande late afternoon or evening. DRT may see VFR conditions again during the afternoon, but overall MVFR/IFR ceilings will be the normal today. East to northeast wind will strengthen through the morning with gusts from 20-30 knots forecast through the period. Late tonight into Thursday morning, LIFR ceilings will be possible. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 83 75 90 75 / 70 60 40 10 Austin Bergstrom Intl Airport 82 75 90 73 / 70 60 40 10 New Braunfels Muni Airport 82 75 87 74 / 80 70 50 10 Burnet Muni Airport 82 72 87 73 / 60 60 30 10 Del Rio Intl Airport 91 75 88 77 / 40 80 80 60 Georgetown Muni Airport 82 73 88 72 / 60 50 30 10 Hondo Muni Airport 83 74 85 73 / 80 80 60 20 San Marcos Muni Airport 81 74 87 72 / 80 70 50 10 La Grange - Fayette Regional 82 76 88 74 / 80 50 40 0 San Antonio Intl Airport 82 74 86 75 / 90 80 60 20 Stinson Muni Airport 83 76 87 76 / 90 80 60 20 && .EWX WATCHES/WARNINGS/ADVISORIES... Flood Watch from 7 AM CDT this morning through Thursday afternoon for Atascosa-Bexar-Caldwell-Comal-De Witt-Dimmit-Fayette-Frio- Gonzales-Guadalupe-Karnes-Lavaca-Maverick-Medina-Wilson-Zavala. && $$ Short-Term...Brady Long-Term...MMM Aviation...27