Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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165 FXUS63 KLSX 032324 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 624 PM CDT Mon Jun 3 2024 .KEY MESSAGES... - Several rounds of showers and thunderstorms are expected through early Wednesday. Isolated severe storms are possible through this evening and again on Tuesday, capable of producing large hail and damaging winds. Locally heavy rainfall is also possible. - Dry weather is expected mid-late week followed by a chance (20- 40%) of showers and thunderstorms this weekend. - Temperatures are expected to be at or just below normal through early next week. && .SHORT TERM... (Through Late Tuesday Night) Issued at 346 PM CDT Mon Jun 3 2024 Scattered showers and thunderstorms have developed across central and southeast Missouri along outflow boundaries that moved into the area. The atmosphere is very unstable over the CWA right now with MLCAPES between 1000-2000 J/kg with no CIN which the RAP shows holding on through sunset. The latest water vapor imagery is showing a trough over the eastern Plains that will move slowly east into Missouri tonight. This trough is far enough west that there is little ascent or low layer or deep layer shear for organized thunderstorms tonight. As such, should only see isolated instances of strong-severe hail and wind through mid evening. There may also be some locally heavy rainfall with any training thunderstorms given the high PWATS and warm cloud depths. I have lowered PoPs late this evening into the overnight hours as CAMS have backed off on the coverage of showers and thunderstorms overnight. Still expect an uptick in scattered showers and thunderstorms again on Tuesday as the HREF is bringing the aforementioned trough across the area. It is possible that a MCV from overnight Plains activity will move across the area sparking additional convection. The CAPE/shear parameter space tomorrow afternoon into tomorrow evening will once again support isolated severe storms with locally heavy rainfall. The coverage of showers and thunderstorms will become more widespread later in the evening and overnight as the NAM/GFS is showing a upper trough dropping southeast into Missouri and Illinois with an attendant cold front. Britt && .LONG TERM... (Wednesday through Next Monday) Issued at 346 PM CDT Mon Jun 3 2024 There is general agreement between the deterministic models and the LREF that the upper flow will stay northwesterly late week through the upcoming weekend. Wednesday through Friday still looks dry as a large surface high will move southeast across the Midwest with very few of the ensemble members producing precipitation over the area during this timeframe. There is more uncertainty as we go into the weekend as each of the models are showing slight differences in the timing and strength of two shortwaves on Saturday and Sunday which will determine the placement and amount of the QPF. There is an increase in LREF ensemble members producing rain (20-40%) with these two shortwaves over the weekend. There are lower chances as we go into next Monday with the model consensus showing a surface high moving back into the area. Temperatures will not stray too far from early-mid June normals as 850mb temperatures will stay in the 10-15C range. The NBM IQR is around 5 degrees, though it does increase by early next week behind a cold front. Britt && .AVIATION... (For the 00z TAFs through 00z Tuesday Evening) Issued at 611 PM CDT Mon Jun 3 2024 Scattered and thunderstorms will affect the terminals in the first 1-2 hours, then mainly dry and VFR conditions are expected tonight. Another round of scattered showers and thunderstorms is expected late Tuesday morning and afternoon. Any thunderstorm has the potential to reduce ceilings and visibilities to MVFR (possible IFR) conditions in brief downpours with gusty winds. Winds will remain out of the south around 10 knots outside of thunderstorms. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX