378
FXUS63 KLOT 120532
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1232 AM CDT Sat Sep 12 2026

.KEY MESSAGES...

- Dry and mild through Saturday before rain chances begin to
  increase later Sunday.

- Waves of heavy rain producing thunderstorms possible in the
  general region early to mid next week.

&&

.DISCUSSION...
Issued at 209 PM CDT Fri Sep 11 2026

A slow-moving compact wave along an elongated trough from
Arkansas to southern Indiana will drift northeastward across
Indiana through tonight. Upper-level clouds associated with the
trough will continue to filter northward over the area through
tonight. Meanwhile, a cold will track across the area late
Saturday morning through the afternoon under notable surface-
based capping. Given a rather dry antecedent airmass north of
the trough and ahead of the cold front and a lack of organized
large-scale forcing, precip-free conditions are expected through
Saturday. The only exception is for the potential for a few
showers nearing/brushing the extreme southeast CWA (i.e. Benton
County) late tonight.

A mid-level trough crossing the western Great Lakes will
interact with the stalling cold front across central Illinois
Sunday before ridging quickly builds northeastward Sunday night
into Monday. Optimal mid-level jet placement over and to the
northeast of the area in conjunction with broad low-level
isentropic ascent over the frontal surface should yield several
bands of rain and/or scattered showers with perhaps some
embedded thunderstorms Sunday afternoon into Monday morning.
Sufficient moisture will be a limiting factor for precip
coverage and intensity, so at least some of the area will likely
remain dry during this period.

An aforementioned cold front will lift back northward as a warm
front Monday afternoon and night in response to a strong
surface low crossing far south-central Canada. An associated
occlusion with the system`s cold front and existing warm front
will ultimately lead to a stalled front near or over the
forecast area Tuesday into Wednesday. Persistent low-level
moisture advection within an airmass characterized by PWATS of
1.7 to as high as 2 inches will likely lead to several rounds of
heavy rain/showers and convection in this corridor, with an
increased flooding potential if multiple rounds of precip align
over the same area. Continue to monitor for updates as the
forecast location of any persistent rain corridor becomes more
refined.

The front will attempt to shift south late in the week as high
pressure builds southward across the Great Lakes region. Have
maintained chance PoPs Thursday and Friday as the showers would
likely continue over the area if the front struggles remains
stalled or only drifts southward with time.

Kluber

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1232 AM CDT Sat Sep 12 2026

VFR with no significant concerns through the period.

The only item of note is changing wind directions. Light south-
southwest winds early this morning will become west-southwest
(occasional 15-20 kt gusts) by the mid to late morning ahead of
an approaching cold front. Winds will shift to northwest behind
the frontal passage in the late afternoon/early evening, and
then vary to northerly at times overnight/early Sunday.

Castro

&&

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

&&

$$

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