469
FXUS63 KILX 021841
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
141 PM CDT Tue Sep 2 2025

.KEY MESSAGES...

- A cold front will bring (80% chance) showers and thunderstorms
  to central Illinois Wednesday afternoon and evening. Severe
  weather and widespread heavy rain are not expected, but some
  localized pockets of 1-2 inches of rain is possible.

- Seasonable temperatures with highs in the low to mid 80s
  continue Wednesday, but well below normal temps with highs in
  the upper 60s to mid 70s will be in place Thursday through the
  weekend.

&&

.DISCUSSION...
Issued at 133 PM CDT Tue Sep 2 2025

This afternoon, upper pattern is characterized by a strong west
coast ridge and a deep trough over the Great Lakes. A series of
disturbances will move across the Midwest within the northwest
flow bringing cooler temps and a couple chances for rain through
the weekend.

A weak surface ridge is analyzed from the Mid Missouri Valley into
the Great Lakes this afternoon while a cold front is pushing
south across Minnesota and the Dakotas. Fair weather will continue
across central Illinois under the influence of the ridge and
ahead of the approaching front. The cold front is expected to
reach the Illinois River Valley mid to late Wednesday morning and
eventually push southeast across the I-70 corridor by late
evening. For areas with the earlier frontal timing, temps are
expected to top out in the upper 70s to lower 80s, while further
south, temps should warm into the mid 80s.

A broken line of showers and thunderstorms will accompany frontal
passage Wednesday. Dew points pooling in the low to mid 60s along
the front will contribute to weak/modest MLCAPE values up to
around 500 J/kg while deep layer shear peaks around 25-30kt. The
weak instability is in part due to poor mid level lapse rates, and
the parameter space does not appear to support an organized
severe threat. Still an isolated strong or severe storm cannot be
ruled out. HREF max wind gust show some pockets of marginally
severe winds (up to around 60 mph) as storms move across the area
Wednesday, though sub-severe peak gusts of 40-50 mph are more
common and widespread. Precip amounts look to stay on the light
side with HREF mean QPF advertising around 0.1 to 0.5 inches
through Wednesday night. HREF LPMM hints a few localized swaths of
over an inch will be possible.

Thursday through the weekend appears to be primarily dry with
temperatures returning back below normal behind our departing cold
front. Another strong vort max is progged to dig across the Upper
Midwest to the Great Lakes Thursday night with a surface
reflection and attendant cold front pushing across central
Illinois Thursday night into Friday morning. Unfavorable diurnal
timing and little moisture return ahead of this second cold front
will keep PoPs quite low (10-20%), but this might be the one
period to keep an eye on for some additional rain. Otherwise temps
will be the main focus as an expansive surface ridge builds from
the Canadian Rockies Thursday and eventually spreads across the
Midwest over the weekend. Highs will generally run in the low to
mid 70s during this time frame while overnight lows dip into the
40s to mid 50s.

Deubelbeiss

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1143 AM CDT Tue Sep 2 2025

VFR conditions will persist through this TAF period as skies stay
mostly clear beneath a ridge of high pressure. Surface winds will
remain light and somewhat variable today, increasing and veering
southwest Wednesday morning ahead of an impending cold front.

MJA

&&

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

$$