828 FXUS63 KLOT 291717 AFDLOTArea Forecast Discussion National Weather Service Chicago/Romeoville, IL 1217 PM CDT Mon Sep 29 2025
.KEY MESSAGES...
- Dry and unseasonably warm daytime conditions through next weekend will lead to worsening drought.
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.DISCUSSION... Issued at 154 AM CDT Mon Sep 29 2025
A stretch of quiet weather will continue through the week as persistent ridging remains in place overhead with 500 mb heights forecast to hang out right around 590 dam.
925-850 mb temperatures today will be similar to Sunday`s which will yield highs in the upper 80s/near 90 degrees for all but our immediate lakeside locales where a midday and afternoon lake breeze will hold temperatures in the mid to upper 70s. Deeper east to northeast flow off the lake on Tuesday and Wednesday, combined with a touch of column cooling will result in highs moderating back a few degrees each day. Increased high-level moisture will also likely result in a bit more of a cirrus canopy Wednesday into Thursday.
By Friday and into the upcoming weekend, the sprawling surface high will shift east across the Mid Atlantic (and eventually offshore). A tightening pressure gradient will result in the return of southerly breezes, particularly on Saturday and Sunday. While the mid and upper-level flow will become more active over the weekend, latest indications are that any upper waves of note will remain displaced well to our north and west. Combined with developing drought conditions, this should yield little in the way of meaningful precipitation chances. Latest guidance does suggest a low potential for decaying convection to make a run at northern Illinois Saturday evening/overnight, but chances appear no higher than 15-20 percent at this point.
Carlaw
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.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 1217 PM CDT Mon Sep 29 2025
No major forecast concerns are expected for the terminals as high pressure remains overhead. Therefore, expect light and variable winds to become easterly this afternoon as a lake breeze moves inland resulting in 6-8 kt winds at the Chicago terminals. While directions should become more north-northeast at the Chicago terminals tonight, east-northeast winds (040-060) will prevail through the period with speeds generally in the 5-10 kt range. Otherwise expect VFR conditions through the TAF period.
However, there is a low chance (10-15%) for some shallow ground fog to develop again tonight mainly across far northeast IL. Given uncertainty as to fog coverage have opted to forego a TAF mention at this time, but will keep an eye on trends.
Yack
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.LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None.
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