928
FXUS63 KILX 281953
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
253 PM CDT Mon Sep 28 2026

.KEY MESSAGES...

 - Quiet and nice early fall weather is expected to continue
   across central and southeast IL through Tuesday night as
   temperatures continue to modify.

 - A chance of showers and isolated thunderstorms will occur
   over the IL river valley Wednesday and Wednesday night, with
   more widespread rain over the area on Thursday into Friday:

 - NBM has 50-70% chance of rainfall totals over 1.5 inches over
   central and southeast IL from Wednesday night through Friday
   night, with southeast IL seeing their heavier rains late
   this week.

&&

.DISCUSSION...
Issued at 250 PM CDT Mon Sep 28 2026

A delightful afternoon across central and southeast IL with
ample sunshine (some tufts of high clouds east of I-55 and north
of I-70) and light winds and comfortable humidity levels.
Temperatures were in the mid to upper 70s, with Olney and Mt
Carmel airport at 80F. Canadian high pressure over Ontario and
Quebec provinces continued to ridge across the western Great
Lakes and into IL and toward the Ozarks providing the nice wx.

High pressure to start shifting east of IL during overnight
tonight and will continue fair skies with light winds again
tonight. Latest CAM runs show the fog forming further ne
later tonight and early Tue morning but did add patchy fog to
Vermilion county. A few CAM members like NAM3 km and GFSLAMP
show some fog forming further sw over east central IL late
tonight so will need to watch for this. But RAP and HRRR keep
the fog mostly ne of central IL similar to Saturday night/Sunday
morning. Lows overnight in the upper 40s and lower 50s.

Surface high pressure continues eastward journey into mid
Atlantic States and New England by sunset Tue while upper level
ridge builds over IL Tue and Wed. The 500 mb height of 588
decameters approaches southeast IL by Wed evening and will see
summerlike temperatures by Wed over se half of CWA. Highs Tue
mostly in the lower 80s climb into the 80s on Wed (ranging from
upper 70s by Galesburg to 90F over Lawrence county).

Dry conditions should continue over CWA through Tue night. A
cutoff upper level low over southern CA to move over NM on Wed
and to pick up remnants of hurricane Polo (lifting ne across the
southern Baja peninsula and Gulf of California tonight)
combined with a frontal boundary approaching nw IL by dawn Thu.
We have 20-40% chance of showers and isolated thunderstorms from
IL river nw on Wed and Wed evening with pops increasing to
40-60% overnight Wed night nw of the IL river and 20-30% pops as
far se as I-55. The front to push se into nw CWA on Thu
afternoon and through se IL overnight Thu night and see our best
chances of showers and possible thunderstorms Thu into Friday,
WPC has slight chance of excessive rainfall Thu and Thu night
over central IL with marginal risk in southeast IL. Areas se of
the IL river have a marginal risk of excessive rainfall on
Fri/Fri night with best qpf shifting into southeast IL. NBM has
a 50-70% chance of over 1.5 inches of rainfall over CWA from Wed
night thru Friday night. Highs Thu to range from lower to mid
70s nw of the IL river to very warm 85-90F in southeast IL.

High pressure building into the Great Lakes region Friday night
and Saturday could shift the rain chances further south of
central IL though NBM still continues chance pops on Fri night
and Saturday with chance pops se half of CWA Sat night. The
ECMWF, GFS and GEM models show better agreement with high
pressure influencing central IL during this weekend with best
chances of showers south of the Ohio river. Cooler more fall
like temps arrive this this week into early next week with highs
in the mid 60s to lower 70s Fri thru Monday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1245 PM CDT Mon Sep 28 2026

VFR conditions are likely to persist through 18Z/1 pm Tue.
Surface high pressure over Ontario and Quebec provinces ridging
over the western Great Lakes into IL, will shift into the mid
Atlantic States and New England by sunset Tue with NE winds
around 5 kts today being light tonight and shifting south to SSE
4-8 kts after 14-15Z Tue. Just scattered high clouds prevail
into midday Tue. Shallow ground fog developing later tonight
into mid Tue morning appears to be more ne of central IL
airports, though getting closest to CMI. Have tempo period of
MVFR Visibility conditions at CMI from 10-13Z Tue.

&&

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

&&

$$

KEY MESSAGES...07
DISCUSSION...07
AVIATION...07