420 FXUS63 KLSX 251136 AFDLSXArea Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 636 AM CDT Thu Sep 25 2025
.KEY MESSAGES...
- A prolonged stretch of dry weather is expected beginning today and continuing into next week. Temperatures will warm from the mid and upper 70s today into the 80s for the remainder of the period.
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.SHORT TERM... (Through Late Friday Afternoon) Issued at 300 AM CDT Thu Sep 25 2025
A long wave trough stretching from southeast Canada, through the Mississippi Valley, into southern Texas will drift east today and tonight, leaving a closed low over the southeastern U.S. on Friday. Meanwhile, the surface ridge currently over the Great Plains will drift east over the Mississippi Valley, as upper level ridging builds over the Midwest behind the trough. Another cut off low moves into the Desert Southwest behind the upper ridge forming an omega block which locks the ridge in place over the Midwest. This will result in dry weather today and Friday as the ridge builds across the region. Should see plenty of sunshine behind the trough, and temperatures will warm back to near normal in the mid to upper 70s today. Above normal temperatures in the low 80s are expected Friday as the airmass modifies.
Carney
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.LONG TERM... (Friday Night through Wednesday) Issued at 300 AM CDT Thu Sep 25 2025
Guidance shows the blocky pattern remaining in place at least through the middle of next week. Ridging over the Midwest/Mississippi Valley will keep our weather dry, with a mostly clear sky. The mostly clear sky will result in good insolation each day pushing high temperatures 5 to 10 degrees above normal into the mid 80s. That same clear sky along with light winds at night will produce excellent radiational cooling conditions. This will allow temperatures to fall 25 to 30 degrees overnight into the 50s in most locations to the low 60s in the St. Louis Metro Area.
Carney
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.AVIATION... (For the 12z TAFs through 12z Friday Morning) Issued at 630 AM CDT Thu Sep 25 2025
Patchy low IFR ceilings/visibilities will hang on over river valleys and other low lying sheltered areas in central Missouri until 13-14Z this morning. Otherwise VFR flight conditions and light north winds are expected to prevail. River fog is possible again late tonight.
Carney
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.LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. &&
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NWS LSX Office Area Forecast Discussion