445
FXUS63 KILX 240503
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1203 AM CDT Mon Aug 24 2026

.KEY MESSAGES...

- Seasonal and mostly dry weather is expected through at least
  Tuesday evening over central and southeast IL.

- The next chance for showers and thunderstorms arrives on
  Wednesday afternoon and Wednesday evening. Some of these
  thunderstorms could be strong to marginally severe.

&&

.DISCUSSION...
Issued at 230 PM CDT Sun Aug 23 2026

Nice late summer weather pattern expected through Tuesday across
central and southeast IL after a very active weather pattern 1st
3 weeks of the month. Weak 1021 mb surface high pressure over nw
MO into central Iowa and upper MS river valley to settle over IL
during tonight and into the mid Ohio river valley on Mon and Mon
night while ridging back into central/ne IL. This will continue
fair wx across the prairie state into Tuesday with dry conditions
and more comfortable humidity levels. NW winds 5-15 mph and
scattered diurnally driven cumulus clouds over central and ne
IL to dissipate after sunset while veil of high clouds over MO
and central/se Iowa is clipping west central and sw IL. A
disturbance over the central plains to keep chances of
convection well sw of IL over central and sw MO tonight into
early Monday as it tracks se across the MO valley/Ozarks. Patchy
shallow ground fog may develop during overnight into early Mon
morning mainly near river valleys and low lying rural ares. HREF
only has 15-30% chance of vsbys getting to 5 miles or less over
portions of CWA later tonight. HRRR and RAP show very little
fog formation with drier air in place while NAM and GFSLamp show
some patchy fog development mainly near river valleys.
Comfortable night ahead with lows in the mid to upper 50s. Highs
Monday around 80F with lower 80s southeast IL and sw CWA, with
scattered cumulus clouds developing by midday giving partly to
mostly sunny skies. Lows 55-60F Monday night and highs in the
low to mid 80s Tuesday. Winds to stay fairly light generally
under 10 mph tonight through Tue.

A northern stream upper level shortwave moving over the southern
Canadian Prairie Provinces next few days, will track se through
the northern Great Lakes Region, sending a cold front se through
IL during Wed afternoon and Wed night. This will likely bring
our next chance for showers and thunderstorms. Increasing south
to SW flow ahead of the cold front to bring in warmer and more
humid air into central/se IL on Wed. Highs in the mid to upper
80s Wed and possibly approaching 90F from Springfield sw with
dewpoints climbing into the upper 60s/lower 70s. A cap
initially in place on Wed could break later in the afternoon and
Wed evening allowing thunderstorms to develop in a moderate
instability with wind shear environment. Although the better
upper forcing will be displaced to our north, a few strong to
marginally severe storms could develop later Wednesday
afternoon and evening, posing a threat for damaging wind gusts.

Could see lingering low chances of showers/thunderstorms in se
IL early Thu, otherwise fair weather with seasonable
temperatures to return Thu through at least Friday night as high
pressure settles into the region. Strong mid/upper level ridge
over the Southwest States through this work week begins to break
down/flatten this weekend, and may see disturbance tracking
into the midwest during this weekend especially by Sunday. A few
model members shows some convection chances as early as
Saturday over the IL river valley, while more members wait until
Sunday for convection chances, though GEM and Ecmwf are dry
thru the weekend. NBM keeps pops low this weekend with 20% pops
over IL river valley Sat and Sat evening and 20-40% pops
overnight Sat night and Sunday.

The Climate Prediction Center (CPC) 8-14 Day outlook for Aug
31-Sep 6th has a 35-45% chance of above normal temperatures
over central/se IL and 33-40% below normal precipitation from
Quincy to Danville north and trending near normal south.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1202 AM CDT Mon Aug 24 2026

High pressure will be in place over central Illinois most of
the period resulting in light and variable winds. Fog is the
primary concern overnight into Monday morning and may be
possible again after the current TAF period Monday night into
Tuesday morning. Outside of fog, VFR conditions will prevail the
remainder of the period with some high based diurnal cumulus
developing Monday afternoon and increasing mid level clouds late
in the period.


&&

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

&&

$$

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