991
FXUS63 KILX 212258
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
558 PM CDT Mon Sep 21 2026

.KEY MESSAGES...

- Cooler weather will prevail this week as high temperatures
  range from the 60s to 70s.

&&

.DISCUSSION...
Issued at 144 PM CDT Mon Sep 21 2026

Water vapor imagery early this afternoon shows an upper low spinning
over eastern Nebraska/western Iowa with ridging on both sides of it.
At the surface, a cold/stationary front is draped from the Mid-
Atlantic states westward into Arkansas with high pressure centered
over Ontario. Widespread cloud cover will remain in place through at
least Tuesday morning as low-level moisture remains trapped beneath
a temperature inversion, holding temperatures several degrees cooler
than normal.

Spotty showers/drizzle are noted on regional radar within the
vicinity of the aforementioned upper low from central Iowa into
northwest Illinois, and also downwind of Lake Michigan where steady
northeast winds are spreading moisture inland. Similar conditions
are expected to expand east through Tuesday morning as the upper low
positions itself over eastern Iowa/northwest Illinois by daybreak.
These should be very light in nature and amount to little
accumulation. Temperatures on Tuesday will be similar to today due
to widespread cloud cover/precipitation with overnight lows
dropping into the low to middle 50s. Subsidence on the backside
of the upper low should result in some pockets of clearing
across west- central Illinois Tuesday night, potentially opening
the door for a few spots to dip down into the upper 40s (20-40%
chance).

By midweek, the upper low meanders into the Mid-Atlantic states with
subtle ridging building in its wake. Temperatures will remain cool
through the end of the week, then gradually warm back into the 70s
to low 80s by the latter half of the weekend. Precipitation chances
look minimal midweek through the weekend, though a developing low
over the Plains states may begin to encroach on the Midwest states
later this weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 558 PM CDT Mon Sep 21 2026

The central IL terminals will be dominated by MVFR ceilings over
the next 24 hours. There will be periods of breaks for MVFR this
evening, particularly at KPIA-KBMI-KCMI as drier air
temporarily works in from the northeast. Then again late Tuesday
afternoon will be another period that is likely to see ceilings
rise above the MVFR threshold area-wide. Northeast winds will
be persistent through the forecast around 10 kt.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

KEY MESSAGES...NMA
DISCUSSION...NMA
AVIATION...25