Champaign, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

523
FXUS63 KILX 070717
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
117 AM CST Sat Mar 7 2026

.KEY MESSAGES...

- Scattered storms progress from west to east this morning,
  exiting eastern Illinois by midday. Isolated damaging wind
  gusts and small hail can`t be ruled out.

- Temperatures start off in the 60s early this morning, but will
  cool during the day as a cold front moves through. Above normal
  temperatures are likely Sunday (60s) into early next week (70s).

- Another system arrives mid-week, bringing more beneficial
  rainfall Tuesday into Wednesday. There is a 60-80% chance of at
  least 1" of rain. Some of the storms could be strong to severe.

&&

.DISCUSSION...
Issued at 107 AM CST Sat Mar 7 2026

*** SATURDAY ***

At 1230am/0630z Sat morning, a 1004-mb sfc low was analyzed near
western WI, with a sharp cold front extending SW to near Des
Moines, IA, and Kansas City, MO. Sfc obs capture a sharp
temperature gradient, with areas just ahead of the front still in
the mid 60s while areas behind the front have plunged into the mid
30s. Regional radar mosaics depict two corridors of rain/storms,
one out ahead of the sfc front (extending from near Springfield,
MO, to Galesburg, IL, to Milwaukee, WI, as of 1230am/0630z), and
the other along the cold front.

While storms have generally been sub-severe over the last several
hours, the KILX VWP is sampling a robust and strengthening LLJ
with wind speeds approaching 70 kts at 1km AGL. Forecast soundings
show a strong low-level warm nose in response to this LLJ, so
storms are unlikely to be sfc-based overnight, but can`t rule out
downward transport of stronger winds to the sfc. There were
reports of 50-60 mph winds in Moline, IL, as showers went through
earlier, highlighting the potential to mix these stronger LLJ
winds to the sfc.

CAMs suggest the western edge of precip activity pushing east of I-
55 by 6am/12z this morning, continuing to progress across eastern
IL before departing to the east by 12pm/18z. The NAM suite still
highlights modest MUCAPE values across eastern IL (around 1000
J/kg), and these areas were not worked over by Fri afternoon
storms so this depiction seems plausible. Can`t rule out some
strengthening as scattered showers/storms track into eastern IL
this morning, but the diurnal timing still appears unfavorable
(most CAMs bring the leading edge of precip to the IL/IN border
around 6am/12z).

As that strong front moves across the area, non-diurnal temp
trends are likely. Highs will occur this morning when temps are
still in the 60s across the warm sector, then falling temps are
expected after the frontal passage. A sfc ridge axis will be
draped from OK towards MI tonight, with cloud cover decreasing
from northwest to southeast in time. Clear skies, weak winds, and
the cooler post-frontal airmass should result in lows in the mid
30s across most of the forecast area. The exception is far
eastern/southeastern IL, where the lingering cloud cover could
keep lows near 40 degF.

*** SUNDAY INTO NEXT WEEK ***

The sfc high shifts east by Sun, reestablishing SW flow across the
local area. Above normal temps persist, with highs likely to be in
the 60s on Sun (60-90% chance, highest west of the IL River),
then into the 70s for Mon-Tues. Moisture return will be slow at
first, as Gulf moisture remains blocked by a cold front over the
deep south. With dewpoints only in the 30s on Sun, may need to
keep an eye on fire wx concerns. The concern is low at this point
though, as gusts of 20-25 mph are fairly low, minimum RH values
are above 30%, and fuel moisture may be higher after recent
rains. The Gulf becomes unblocked early next week, with return
flow pushing dewpoints into the 50s by Mon, and potentially into
the 60s by Tues.

The cut-off low near the SW US remains progged to lift NE towards
the plains by Tues, while a phased northern stream wave deepens to
its north. These features favor strong synoptic scale ascent
downstream, which in conjunction with the Gulf moisture advection
set the stage for another round of widespread showers/storms from
Tues eve into Wed. The severe storm potential will need to be
monitored. The latest LREF Grand Ensemble has the joint
probabilities of MUCAPE over 1000 J/kg and deep layer shear over
40 kts at 40-60%. Machine learning guidance sources broadly
highlight the warm sector of this system as posing some degree of
severe storm threat, but vary on the exact probabilities. At the
least, this system should offer another chance for beneficial
rainfall, with a 60-80% chance of at least 1" of rain per the NBM,
and a 20-40% chance for over 2".

Following another cold front associated with this mid-week system,
temps are expected to trend cooler for Thurs, with the ensemble
interquartile range showing highs in the mid 40s to mid 50s.

Erwin

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1145 PM CST Fri Mar 6 2026

Another round of storms will be moving through the TAF sites
overnight. Based on HiRes models and current radar loops, this
looks very likely, so will opt for TEMPO group at all sites for
the first 4 hours of when storms should affect the sites. Then
will go with PROB30 groups as the main line should have moved
through the then isolated storms will be possible on the back side
into the morning hours. Cigs will drop into MVFR category behind
the boundary/front/precip during the morning hours but then
improve at SPI, DEC, CMI...while PIA and CMI remain higher MVFR in
hte afternoon. Southerly winds will be very windy through the
night becoming southwest later tonight/toward morning. Then expect
winds to become westerly late morning through afternoon and then
west to northwest afternoon into the evening hours. Very windy
until later this afternoon/evening.

Auten

&&

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

$$