814 FXUS63 KLOT 151725 AFDLOTArea Forecast Discussion National Weather Service Chicago/Romeoville, IL 1225 PM CDT Mon Sep 15 2025
.KEY MESSAGES...
- Warm and dry conditions are expected through the work week.
- Periodic shower and thunderstorm chances return toward the end of the week (20-30%).
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.DISCUSSION... Issued at 245 AM CDT Mon Sep 15 2025
An overall quiescent pattern is in place across the region with amplified upper ridging across the western Great Lakes region atop a closed upper low in the Southeast (a pseudo-Rex Block pattern). This will allow unseasonably warm temperatures to prevail through the rest of the work week with high temperatures in the 80s to near 90 (warmest toward western and central Illinois). Relatively weak surface flow amidst expansive surface high pressure should allow daily lake breezes to push inland holding temperatures mainly in the 70s near the lakeshore. This should also help keep any shower/storm activity west of the local area for the majority of the work week.
Ensemble guidance has also trended a bit slower with the break down of the upper ridge/blocking pattern later in the week with most of the area remaining dry through the day on Friday and further slowing could occur with later updates. Eventually the western trough (and/or potential cut-off low) will shift east toward and over the area leading to periodic shower and thunderstorm chances over the weekend into early next week. This will be paired with cooler more seasonable temperatures in the 70s.
Petr
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.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 1221 PM CDT Mon Sep 15 2025
No significant weather concerns through the period as high pressure remains in control. East to northeast winds of less than 10 kt will continue through the afternoon then diminish to a few kts this evening. Expect that the wind direction will become somewhat variable from north to east or east-southeast tonight. Steadier east to east-southeast winds will return toward midday Tuesday.
MDB
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.LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None.
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