Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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233 FXUS63 KLSX 090343 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1043 PM CDT Wed May 8 2024 .KEY MESSAGES... - Scattered strong to severe thunderstorms will persist through early this evening. All hazards are expected: large hail, damaging winds, isolated tornadoes, as well as flash flooding. - A period of much needed calmer weather and cooler temperatures is expected to end the week and continue through the weekend. && .SHORT TERM... (Through Late Thursday Night) Issued at 344 PM CDT Wed May 8 2024 (Late This Afternoon Through Tonight) As of 3 pm, outflow from the activity continues to sink south and extends from just north of Springfield, MO to just south of Carbondale, IL. The warm sector along and south of the boundary remains quite unstable with MU CAPEs in excess of 3000 J/kg, ML lapse rates of 7-8C/km and 0-6km bulk shear 50-60kts. Also, the ongoing activity, over far southeastern sections of CWA, has congealed into a line with embedded supercells, while further west, in NWS Springfield`s area, discrete supercells are forming along the outflow boundary. These storms will slide east northeast moving into the southern portions of the CWA by 21z. Therefore, there remains a tornado threat as well as large hail possible. North of the outflow boundary, could see scattered strong to severe storms with the main threat being large hail. Otherwise, as the surface low over NE OK lifts northeastward it will drag a cold front eastward through the forecast area, with the precipitation tapering off from west to east. The front will exit the region by 05z Thursday. Still some concern for isolated flash flooding as some storms may train over the area, especially south of I-70. So will not make any adjustments to the Flash Flood watch at this time. Lows tonight will be in the low 50s to low 60s. (Thursday through Thursday Night) On Thursday, a secondary shortwave/cold front on the backside of the system will slide southeast through the region. So expect increasing clouds, especially north of I-70. Otherwise, there will be enough moisture and weak instability to generate scattered showers and a few thunderstorms over portions of northeast Missouri and west central Illinois late morning through early evening. Otherwise, highs on Thursday will be near normal in the upper 60s to upper 70s. Lows Thursday night will be in the upper 40s to low 50s. Byrd && .LONG TERM... (Friday through Next Wednesday) Issued at 344 PM CDT Wed May 8 2024 Cooler and drier weather through the rest of the work week and into the weekend. Beyond that, upper level trough over the western CONUS will begin to lift out towards the region with chances of showers and storms late on Sunday through mid week. Still a lot of timing, strength and location differences among the ensembles and deterministic models, so stuck with the latest NBM solution. Temperatures will moderate through the period with highs in the mid 70s to low 80s. Byrd && .AVIATION... (For the 06z TAFs through 06z Thursday Night) Issued at 1035 PM CDT Wed May 8 2024 While an isolated shower/thunderstorm cannot be totally ruled out, the best threat has shifted well off to the southeast of the terminals with dry weather likely the remainder of the night into Thursday morning. Scattered showers may impact KUIN in the afternoon hours, but they should stay north of the other terminals. A cold front is near KCOU/KJEF and should approach KUIN over the next 1-2 hours. Metro terminals will be closer to 0600-0800 UTC. Near the front, winds are light and variable. Upstream observations (including at KCOU/KJEF) have shown some patchy (and at times dense) fog development in areas of clearing. The recent rainfall is also helping. Therefore, would not be surprised to see a brief period (~1 hour or so) of some fog at the metro and KUIN terminals over the next few hours. However, any fog should be short lived as winds behind the front pick up enough out of the west/northwest to improve visibilites back to VFR. The threat overnight into Thursday morning should be more on low stratus. Model guidance is all over the place, but I could see some high IFR/low MVFR ceilings late tonight into early Thursday morning. Best chances appear to be at the metro and KUIN terminals. Conditions should improve from west to east late tonight through Thursday morning. Gosselin && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX