Area Forecast Discussion
Issued by NWS San Angelo, TX
Issued by NWS San Angelo, TX
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374 FXUS64 KSJT 221901 AFDSJT Area Forecast Discussion National Weather Service San Angelo TX 201 PM CDT Sun Sep 22 2024 ...New LONG TERM... .SHORT TERM... (Today and tonight) Issued at 342 AM CDT Sun Sep 22 2024 ...Thunderstorms expected this afternoon through tonight... Currently, an upper level low is located over CO, with southwest flow over west central Texas. This low is expected to open into a wave while slowly moving east into the central and southern plains by Monday morning. This will maintain southwesterly flow over our area. At the surface, a cold front is expected to move south into our CWA by this afternoon, making its way through the rest of the area by late tonight. Scattered to widespread thunderstorms are expected to develop along and ahead of the cold front this afternoon, and continue through most of the overnight hours. With temperatures warming well into the 80s to lower 90s this afternoon, combined with plentiful low level moisture (precipitable water values near 2 inches), low levels will destabilize ahead of the front. Mixed layer CAPE values are forecast to be in the 500 to 1500 J/kg range during peak heating hours. Deep layer shear values of 40 to 50 knots over the area, combined with the instability will allow some of the storms to become strong, with a few storms possibly severe. The main concern with the storms will be wind gusts over 60 mph, but hail up to the size of quarters will also be possible. After sunset, instability will wane, and although storms may continue, the concern for severe weather will diminish. The other concern will be heavy rain and localized flooding with precipitable water values near 2 inches. Storms are expected to develop first over the Big Country along the front, then spread southward over the rest of the area during the afternoon and overnight hours as the front moves south. Overall coverage should diminish late tonight, but isolated to scattered activity will still be possible after midnight, mainly south of Interstate 20. && .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... (18Z TAFS) Issued at 1256 PM CDT Sun Sep 22 2024 Ceilings have lifted to VFR across the terminals early this afternoon. Still expecting a cold front to move south across the terminals late this afternoon and evening, with FROPA at KABI around 22Z, KSJT around 00Z and the far southern terminals by mid to late evening. Showers and thunderstorms are expected to develop along and behind the front, and will include TEMPO groups for TS this forecast cycle. Precipitation is expected to end across the far southern terminals by mid to late morning tomorrow. Also, ceilings are expected to lower to IFR overnight, and persist through at least the mid morning hours. && .PRELIMINARY POINT TEMPS/POPS... Abilene 61 75 62 85 / 80 30 40 40 San Angelo 63 77 64 86 / 70 40 30 30 Junction 67 83 66 88 / 40 30 10 30 Brownwood 64 78 64 85 / 60 40 30 40 Sweetwater 60 75 63 85 / 70 30 30 40 Ozona 64 78 65 86 / 70 40 20 20 Brady 65 78 65 85 / 50 40 30 30 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...20 LONG TERM....50 AVIATION...24