Area Forecast Discussion
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
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252 FXUS63 KLSX 261127 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 627 AM CDT Wed Jun 26 2024 .KEY MESSAGES... - Thunderstorms this morning will exit off to the southeast early in the day, giving way to a much nicer day with cooler temperatures than we`ve seen in a while. - The heat returns this weekend, but not as intense. Heat index values around 100 are expected on Saturday. We`ll also have more opportunities for thunderstorms Friday and Saturday ahead of the next front. && .SHORT TERM... (Through Late Thursday Afternoon) Issued at 245 AM CDT Wed Jun 26 2024 Multiple convective complexes pushing south this morning have made it pretty hard to identify where the surface cold front is, but we will be seeing a change in air mass today as cooler and drier air moves in. The morning thunderstorms should exit to the southeast fairly early in the day, although some of the CAMS do keep some showers lingering into the afternoon. This just reinforces the idea that it will be significantly cooler today, especially if the clouds and showers linger into the afternoon. Temperatures tonight drop well into the 60s as the surface high pressure axis approaches. We`ll see the temperature warm a few degrees on Thursday with more sun, but still at or a little below normal for this time of year, mostly in the mid 80s. Kimble && .LONG TERM... (Thursday Night through Tuesday) Issued at 245 AM CDT Wed Jun 26 2024 Ridging over the western US moves east and flattens as it does so. So while we will see another warm up, it shouldn`t be as intense as our last heat episode. Friday and Saturday warm back into the 90s with increasing humidity as well. Heat index values over 100 are most likely on Saturday. Troughing moving onshore in the Pacific Northwest today will continue to push slowly eastward near the US/Canada border through the weekend. We`ll see a surface front developing out in the Plains and pushing southeast through our area as the upper trough axis moves into the Great Lakes on Saturday. Ahead of the front, multiple rounds of thunderstorms are possible beginning on Friday. Much of the lift stays north of our area on Friday, but the northern part of Missouri into western Illinois may be close enough to get in on some thunderstorms. The better lift moves through on Saturday ahead of the cold front with more widespread thunderstorms possible. With a southerly low level flow and a modest westerly flow aloft, there`s just enough shear available for some storm organization, so we`ll have to keep an eye on the potential for strong to severe storms both days, especially as heat and humidity peak leading to a peak in instability as well. A progressive upper pattern continues with a shift toward cooler temperatures behind Saturday`s trough, but warming back up again next week as ridging moves in to replace it. How hot we get will depend on how well established the ridge becomes over our area and whether we are affected by daily thunderstorms on the northern periphery of the ridge. Kimble && .AVIATION... (For the 12z TAFs through 12z Thursday Morning) Issued at 624 AM CDT Wed Jun 26 2024 Primary impact for the terminals is thunderstorms ongoing in the area. These are moving southeast and away from the terminals, but lingering stratiform rain may contain embedded thunder for a little while longer. Winds are variable due to all the rain, but they will be becoming northerly today. It`s possible some MVFR ceilings develop in the wake of the rain this morning, but it is unlikely. Expect a clearing sky through the day with winds becoming light tonight. Kimble && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX