148
FXUS63 KLOT 291836
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
136 PM CDT Mon Sep 29 2025

.KEY MESSAGES...

- Dry and unseasonably warm daytime conditions through next
weekend

&&

.DISCUSSION...
Issued at 136 PM CDT Mon Sep 29 2025

Blue skies abound across much of the forecast area this
afternoon. The exception is southeast of I-57 where weak
instability has allowed for some mid level cumulus to
develop. With an upper level ridge remaining firmly in place
through much of the week, unseasonably warm and dry conditions
are expected to prevail. Temperatures can be expected in the 80s
inland, but persistent east-northeast flow will help keep the
lake shoreline in the mid to upper 70s tomorrow through
Thursday. As winds turn back to the south-southwest on Friday,
temperatures will once again rise into the upper 80s, with low
to mid 80s near the lake setting up a warm and dry weekend.

Returning momentarily to tonight: clear skies, light onshore
winds and a stout inversion are expected overnight. Localized
patchy shallow fog may crop up in traditional low-lying areas.
For now, the best chances look to be to the north in Wisconsin,
so the only formal mention patchy fog in the forecast is in Lake
(IL) and McHenry Counties.

The upper level ridge is projected to slowly move east this
weekend with an upper level trough moving toward the western
Great Lakes Saturday night into Sunday. There is still some
discrepancies between models in the exact track of the trough
into early next week, but many are showing a more northward
track through Canada. There was already low confidence in the
chances for precipitation early next week in the last forecast
package, and it seems that models are trending lower with PoPs
more focused north of Illinois. Any chances for meaningful
precipitation seems low which could further exacerbate drought
conditions, at least in the foreseeable future.

DK

&&

.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

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

Visit us at weather.gov/chicago