Area Forecast Discussion
Issued by NWS San Angelo, TX
Issued by NWS San Angelo, TX
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517 FXUS64 KSJT 230531 AFDSJT Area Forecast Discussion National Weather Service San Angelo TX 1231 AM CDT Mon Sep 23 2024 ...New AVIATION... .SHORT TERM... (This evening through Monday) Issued at 240 PM CDT Sun Sep 22 2024 ...Thunderstorms and cooler temperatures on the way... Early this afternoon, a cold front was moving south across northwest Texas and the Texas High Plains. The front will push south into the Big Country by mid afternoon and continue south across the remainder of the area late this afternoon and evening. Aloft, an upper low was located over eastern Colorado, with an associated trough axis extending southwest across New Mexico. Convection is already developing along and north of the front near Lubbock and this trend will continue, with showers and thunderstorms expected to increase in coverage across the Big Country by mid to late afternoon as the front continues south. An expansion southward is expected this evening and overnight with the bulk of precipitation ending across southern sections by mid to late morning tomorrow. A very moist airmass remains in place across the region, with PW values near 2 inches. As temperatures warm into the upper 80s and lower 90s this afternoon, the airmass will continue to destabilize, with MLCAPEs ranging between 1500 and 2000 J/kg. This combined with deep layer shear between 30 and 40 knots will support some strong to locally severe storms into the early evening hours before the low levels stabilize. The main severe hazard will be strong winds gusts over 60 mph and hail up to i inch in diameter. In addition to the severe threat, heavy rainfall and a threat for localized flooding will also be a concern. Precipitation will gradually diminish late tonight, with some lingering showers/isolated storms south of I-20 during the morning hours. A cooler airmass, coupled with mostly cloudy skies, will result in below normal temperatures tomorrow. Afternoon highs will be mainly in the mid and upper 70s, although a few lower 80s are possible along the I-10 corridor. && .LONG TERM... (Monday night through next Sunday) Issued at 159 PM CDT Sun Sep 22 2024 ...Cool and wet pattern through Wednesday with drier and warmer conditions expected by the end of the work week... Overnight Monday into Tuesday, the upper level shortwave trough associated with the primary cold front will exit off to our northeast, leaving our area in brief zonal flow. Some HREF members are picking up on convection forming across our central counties as an embedded shortwave impulse tracks across the area. Have capped PoPs during this timeframe in the chance category as certainty with this development is limited but still possible as the earlier cold front is not expected to scour out any moisture (as shown by forecasted PWats in the 1.4+ inches range). The better chances for showers and storms look to come later in the day on Tuesday into early Wednesday. An upper low is expected to drop south out of the Northern Great Plains and into the Central Plains/Mid Mississippi Valley. This will send another upper level trough axis through the region. An attendant cold front is also expected to swing south through the area during this Tuesday/early Wednesday timeframe. The NAM and many of the European ensemble members seem set on a potentially wet frontal passage with the GFS ensemble members painting a much drier picture. Will keep with the blended solution for now, showing chance PoPs mainly through 12Z Wednesday. Any convective activity looks to wane through the day on Wednesday as the front continues to push well south and east of our area. With the rain chances and continued high amounts of moisture across the area, temperatures will remain fairly consistent Tuesday and Wednesday with highs in the upper 70s to mid 80s and lows in the upper 50s to mid 60s. Models seem to be in good agreement that much drier air will begin to filter in at the surface behind the cold front Wednesday, leading to a dry pattern for the end of the work week and weekend. Surface flow will generally stay out of the north through this timeframe, limiting moisture return. The aforementioned upper low is expected to become cut-off from the main flow during this timeframe and will stay in the general vicinity of the Southern Plains. How the track of the potential tropical system across the gulf impacts this remains to be seen but consensus for now is that we will stay to the west of the low in an area of weak subsidence. High temperatures for the late week/weekend timeframe will be on a steady upward trend as the 850 mb thermal ridge begins to slowly work its way back into the area. Daytime highs will approach 90 degrees again by the weekend. Overnight lows are expected to be on the cool side in the mid 50s to low 60s. && .AVIATION... (06Z TAFS) Issued at 1231 AM CDT Mon Sep 23 2024 SHRA and TSRA continue to affect the KABI area. Farther south, much less coverage of SHRA with no TSRA currently. Will continue at least VCSH for southern terminals, but confidence is lower in better coverage of TSRA farther south given the current trends. Still expect CIGs to deteriorate into MVFR, and likely IFR between now and 12Z at all sites. Expect these ceilings to then improve gradually throughout the day tomorrow, with most sites back in the VFR category by 00Z or a couple hours earlier. Winds will be out of the north at all sites within the next hour or so, and should remain northerly at 10 knots or less through 00Z Monday. && .PRELIMINARY POINT TEMPS/POPS... Abilene 75 62 86 64 / 30 40 40 40 San Angelo 77 64 87 66 / 40 30 40 30 Junction 83 66 88 65 / 30 10 40 30 Brownwood 78 64 86 63 / 40 30 50 40 Sweetwater 75 63 86 65 / 30 30 30 30 Ozona 78 65 86 65 / 40 20 20 20 Brady 78 65 86 65 / 40 30 40 30 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...24 LONG TERM....50 AVIATION...20