921
FXUS63 KILX 210759
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
259 AM CDT Tue Jul 21 2026

.KEY MESSAGES...

- Severe Weather Threat: A low risk (20% to 30% chance) for
 strong to severe thunderstorms exists early this afternoon
 across east-central and southeast Illinois. High-intensity
 updrafts could generate localized damaging wind gusts, along
 with locally heavy rainfall.

- Air Quality: Air quality and visibility are expected to
 improve significantly today across the area as a cold front
 moves through and pushes wildfire smoke out of the region.

- Drier & Cooler midweek: Drier and slightly cooler conditions
 arrive Wednesday through Friday, with high temperatures in the
 mid to upper 70s and minimal rain chances.


&&

.DISCUSSION...
Issued at 258 AM CDT Tue Jul 21 2026

Synoptic Overview and Severe Convective Potential...

The warm front has advanced east of Illinois putting our CWA solidly
in the warm sector. Last evenings storms have dissipated with a
lingering cluster of storms in N MO sliding southeast toward St
Louis. A prefrontal line of showers has developed from Chicago
to the Quad Cities as of 230 am CDT this morning, which signals
the synoptic lift has commenced well ahead of the cold front.
Parameter space in todays warm sector looks to destabilize to
2800 MLCAPE values along with bulk shear values up to 35 kt.
There are differing solutions among the CAMs as to timing and
location of convective initiation in our eastern and
southeastern counties, but the consensus shows early afternoon
storms should develop east of Illinois and possibly backbuild to
impact areas east of I-57. SPC has a corridor of Marginal risk
with a small section of Slight Risk for our far 3 SE counties.
At this point, confidence is low that storms will have much
impact in Illinois. However, with DCAPE values up to 1400 J/kg,
any updraft that intensifies will be able to tap into PWATs of
1.8 g/kg to increase precip loading and subsequent downdrafts.
Have 30-50 PoPs in SE IL this morning into early afternoon, with
chances dropping off quickly after 2 pm in SE IL.

Smoky conditions are projected to improve significantly today, as
the cold front pushes across IL. An eventual transition back to
high pressure later this week could set the stage for another
round of smoke to be blown into the Midwest, but for now we
should be able to enjoy improved air quality today.

Extended Outlook...

For the remainder of the work week, beginning Wednesday,
conditions will trend drier and slightly cooler. Sprawling
Canadian high-pressure will spread southeast across the Midwest,
keeping high temperatures in the mid to upper 70s Wednesday
through Friday, with no measurable precipitation through
Thursday. By Thursday night, a signal for warm advection-driven
convection develops to our west, resulting in a 20-30% chance of
storms on Friday west of Fulton Co to Shelby Co. A warming
trend will commence next weekend as the surface ridge axis
shifts to our east, allowing for a return of warmer southerly
flow.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1229 AM CDT Tue Jul 21 2026

VFR conditions will prevail at all TAF sites next 24hrs. No
precip expected through the period either. Mid and high clouds
are expected most of the night, but as the front drops south
through the area, scattered CU is expected at all sites.
Additional CU is expected behind the front during the morning
and afternoon hours with high cirrus continuing. Clear skies are
then expected during the evening hours. Winds will be southwest
to start and then become more westerly through the overnight
hours as the front moves south. Winds become west to northwest
from morning through the end of the period once the front moves
through. Speeds will be 10mph or less until after the front
moves through and then all sites will see gusts of 20-25kts.
Speeds lighten again during the evening hours.

&&

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

&&

$$

KEY MESSAGES...Shimon
DISCUSSION...Shimon
AVIATION...Auten