Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
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611 FXUS64 KEWX 091730 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 1230 PM CDT Sun Jun 9 2024 ...New AVIATION... .SHORT TERM... (Today through Monday) Issued at 250 AM CDT Sun Jun 9 2024 Upper ridge amplification over the SW CONUS has become locally weakened over TX over the weekend as the H7-H5 ridge center drifted east to the coast of Louisiana while an upper low has been funneling Pacific Moisture into much of Mexico and parts of West TX. To the north a light NW flow continues to promote high plains convection with a few clusters drifting as far south as the lower TX Panhandle. Still the high pressure grasp is tight enough to maintain stability over Central and South TX for today, but some weakening in stability could begin as early as 00Z Monday with moisture levels expected to increase at mid levels from the west and north and low level moisture improving from a pool of deeper moisture feeding from Deep South TX. Temperatures may not respond as much to this moisture influx, and we are not expecting much better cloud cover in the periods prior to 21Z. However, the late day RH values leveling off could take a toll on high temps and hold the heat index below advisory levels at the same time. Needless to say, it will still be muggy. At 00Z, the PWat values take a jump towards values that might be able to take advantage of the slightly above normal heat. Instability and a weak tropical tap from the west is depicted to fire off some isolated convection from the Edwards Plateau into Mexico for this evening. This convection doesn`t progress much as the steering flow should be light. However, while this is occurring, northerly mid level flow and a cold front advances south into NW TX and promotes scattered convection of NW and North Central TX overnight. We think there will be still low coverage of convection to impact our forecast area late tonight, but the daytime setup should be a lot better for diurnal instability for Monday. Outflow boundaries and competing influences from upper support features will make this a low confidence forecast for timing and location for rain chances, but most areas should at least see an uptick, and the extra clouds, moisture, and outflows should translate to further moderations to the daytime Max T for Monday. As with most storm activity that can occur in early to mid June, there`s always a low end chance a storm could become severe, and a level 1 of 5 risk for severe weather will cover various parts of our northern and western counties today through Monday. && .LONG TERM... (Monday night through Saturday) Issued at 250 AM CDT Sun Jun 9 2024 The latest round of medium range model guidance has trended slower and a little stronger with regards to an upper system dropping southward out of the Texas Panhandle late Monday. As this system slows and continues to drop southeastward into central and east Texas through Wednesday, some precipitation chances can be expected given active northwest flow aloft. Northwest flow aloft patterns tend to favor the Hill Country westward into the southern Edwards Plateau and the latest models do tend to place the higher rain chances in these areas through mid-week. Timing of shortwave activity that will help trigger convection will be tricky. For now, we may need to monitor the late Tuesday into early Wednesday period as the operational GFS and NAM show some higher precipitation totals across the region. For now, we will keep chances capped around 30%, but could need to go higher pending later model runs. Temperatures are still expected to slowly trend upward through mid- week, with highs in the 90s to near 103 degrees along with lows mainly in the 70s. The remnants of the above mentioned upper low drop into the northwestern Gulf of Mexico on Thursday as the mid and upper level subtropical ridge builds over northern Mexico into the desert southwest. With this pattern, temperatures will remain steady or slowly rise through next week along with most areas remaining dry. A few spots mainly south of I-10/Highway 90 will need to be monitored for a possible Heat Advisory on Thursday and possibly Friday. && .AVIATION... (18Z TAFS) Issued at 1229 PM CDT Sun Jun 9 2024 VFR conditions have returned for all sites, although a cloud deck just above 3kft lingers near DRT for the next hour or two. Southeasterly flow may be breezy at times this afternoon and evening with gusts to around 20 knots, with light winds returning across South Central Texas overnight. There is a signal for patchy MVFR ceilings to return mainly to SAT/SSF, but recent trends suggest it may stay northwest of terminals. Brief MVFR conditions may also be seen at DRT around sunrise. Chances for showers or thunderstorms is mainly limited to the western half of the area overnight into Monday morning as a complex forms in northwest Texas before moving towards the south/southeast into the area. Used a PROB30 group at DRT to highlight this potential. While it is possible SAT/SSF could see some activity, confidence is too low to add any mention at this time. Better chances for thunderstorms at I-35 sites may be seen Monday afternoon with isolated to scattered thunderstorm development as a front moves south towards South Central Texas. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 75 94 74 94 / 10 20 10 10 Austin Bergstrom Intl Airport 75 94 74 94 / 10 20 10 10 New Braunfels Muni Airport 75 95 74 96 / 10 20 10 10 Burnet Muni Airport 74 91 72 91 / 10 30 10 10 Del Rio Intl Airport 80 99 80 101 / 20 30 20 10 Georgetown Muni Airport 74 91 73 92 / 10 20 10 10 Hondo Muni Airport 76 95 74 97 / 20 20 10 10 San Marcos Muni Airport 74 94 73 94 / 10 20 10 10 La Grange - Fayette Regional 75 93 74 92 / 10 20 10 10 San Antonio Intl Airport 77 95 76 96 / 10 20 10 10 Stinson Muni Airport 78 96 76 98 / 10 20 10 10 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...18 Long-Term...Platt Aviation...27