Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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076 FXUS63 KLSX 171915 AFDLSX Area Forecast Discussion National Weather Service Saint Louis MO 215 PM CDT Mon Jun 17 2024 .KEY MESSAGES... - Isolated to scattered thunderstorms can be expected both late this afternoon and again on Tuesday afternoon over parts of the area. Brief downpours are possible with the strongest storms. - High temperatures are expected to remain mainly in the 90s through the upcoming weekend. && .SHORT TERM... (Through Late Tuesday Night) Issued at 213 PM CDT Mon Jun 17 2024 Latest radar imagery is showing a complex of showers and thunderstorms moving north across southeast Missouri ahead of a vort max moving north around the back of the subtropical high currently centered over the Carolinas. This complex will will likely affect the southeastern counties late this afternoon with some brief downpours given that PWATS are around 1.8" before it begins to diminish by early this evening. There will another chance (20-30%) for isolated showers and thunderstorms late Tuesday morning into Tuesday afternoon as another vort max moves north across Missouri and Illinois in the deep moisture feed. Temperatures so far this afternoon have climbed into the upper 80s to the mid 90s with a few locations having heat indices over 100 degrees. Highs tomorrow are expected to be a degree or two cooler with a few more clouds and slightly more coverage of showers and storms. Lows the next two nights will stay in the low to mid 70s. Britt && .LONG TERM... (Wednesday through Next Monday) Issued at 213 PM CDT Mon Jun 17 2024 The overall forecast remains on track as the global models and the LREF continue to show that the upper high over the East Coast will expand back into the central CONUS as soon as Wednesday which will push the westerlies north of the area through Saturday. This will now confine the chance of showers and thunderstorms on Wednesday to just the northwest third of the CWA and keep the CWA dry through Saturday. There continues to be some agreement that a trough and an attendant cold front will move across the Midwest late in the weekend with 30-60% of the ensemble members showing a chance of rain with the passage of this system. There remains some uncertainty with the timing of this system between the deterministic guidance, but the LREF is showing northwest flow over the area by next Monday with just slight (20%) chances for showers and thunderstorms. Temperatures are expected to climb into the middle to upper 90s late this week as the upper high builds back over the area. Dewpoints are expected to remain in the 60s which are forecast to keep maximum afternoon heat indices near 100 degrees. Temperatures will drop back down just a bit on Sunday and next Monday with the frontal passage. This matches up well with the NBM IQR which is only showing a 5 degree spread at St. Louis through Saturday under the upper high, but then increases to 8-9 degrees with the passage of the trough early next week. Britt && .AVIATION... (For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1218 PM CDT Mon Jun 17 2024 Mainly dry and VFR conditions are expected through the period. The only exception will be around the St. Louis terminals where isolated showers and thunderstorms will be possible this afternoon and Tuesday afternoon, but the potential is too low at this point to include in the TAF. Otherwise winds will remain out of the south through the period with gusts out of the south to 20 knots during the day. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX