029
FXUS63 KILX 280206
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
906 PM CDT Mon Jul 27 2026

.KEY MESSAGES...

- A Tornado Watch remains in effect until 10pm CDT for counties
  along the Illinois-Indiana border: however, the risk for
  additional severe weather is rapidly diminishing.

&&

.UPDATE...
Issued at 906 PM CDT Sun Jul 26 2026

Clusters of thunderstorms that developed on the northeast
periphery of a prominent upper ridge over the Plains, then
tracked southeastward along a dewpoint gradient from Wisconsin
across northeast Illinois into Indiana have largely exited the
E/SE KILX CWA this evening. 0150z/850pm radar shows a lingering
severe cell over southeast Lawrence County and another just
across the border in Fountain/Parke County, Indiana. This
activity will continue to track slowly S/SE out of central
Illinois over the next hour or so. Meanwhile further northwest,
we are still keeping an eye on an approaching cold front
extending from near Milwaukee to just north of Kansas City.
While CAMs have consistently shown widely scattered convective
development along the boundary by mid to late evening, the
latest satellite/radar mosaic is largely blank except for one
cell well to the N/NE approaching the western suburbs of
Chicago. While MLCAPEs remain high (4000-5000J/kg) along and
immediately ahead of the front, increasing convective inhibition
will act to curtail storm development as the evening progresses.
Have maintained just a 20% chance for thunderstorms ahead of the
front through midnight, but am not expecting additional severe
weather.

&&

.DISCUSSION...
Issued at 218 PM CDT Mon Jul 27 2026

Outside of the storm risk today, it has been very hot and humid
today. Heat indices have been around 100-105 so far but still have
time to increase to about 115 degrees in some spots. The Extreme
Heat Warning continues until tonight at 9 pm. If thunderstorms
materialize and move in during the afternoon and early evening, it
would cool temps/heat indices and would likely end the heat
headlines earlier than 9 pm. Beyond today, temperatures become more
seasonable and less humid with highs in the 80s and lows in the 60s
through next week.

Today`s forecast has been a doozy. The models haven`t been of the
greatest assistance recently with this round of convection. We have
an Enhanced Risk (level 3 of 5) for areas near and north of a Henry
to Marshall line and a Slight Risk (level 2 of 5) elsewhere for
today. Primarily this risk is for damaging winds, potentially
stronger than 70 mph, but there is also a 2% tornado risk for the
area within the Enhanced Risk.

Our 12z sounding shows MUCAPE over 5500 J/kg, effective shear of ~50
knots, and PWATs of nearly 2 inches. A shortwave is pulsing through
this afternoon across Illinois and Indiana, based off GFS 500 mb
vorticity. The storms currently over the Chicago-Land area may clip
eastern IL as it drops south into Indiana and they are evolving into
a damaging wind threat as it transitions to a linear mode rather
than supercellular. It is starting to trend towards areas west of I-
55 may not see any of the severe threat today. There may be some
showers/storms that direction but it looks like the main show will
remain east of I-55 this afternoon/evening. An additional wave may
move behind it that will also drop south, potentially riding the
IL/IN border, but could possibly be weaker in strength, based off
the HRRR. The HRRR`s 16z and 17z runs are picking up the active
convection well. The storms should have exited by 10 pm tonight.
Storms will be moving to the south-southeast at 30-40 mph this
afternoon/evening.

The next chance for showers and thunderstorms comes in on Friday
into Saturday as a shortwave moves through the area.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 653 PM CDT Mon Jul 27 2026

2330z/630pm radar imagery shows the bulk of the convection well
E/SE of the central Illinois terminals. With the synoptic cold
front still to the NW across eastern/southern Iowa, an isolated
shower or thunderstorm will remain possible through the
remainder of the evening. Current satellite trends show mostly
clear skies along/ahead of the front: however, the HRRR/RAP have
been consistently showing a few cells popping along the front
later this evening. Confidence for thunder is low, so have only
mentioned VCSH between 03z and 09z. Once the front passes, winds
will veer to the N/NW late tonight, then to the N/NE Tuesday
morning. Skies will be mostly clear overnight, but low clouds
poised upstream across the Great Lakes will filter southwestward
into the area on Tuesday. Some guidance shows low MVFR ceilings,
but other models such as the HRRR and NAM suggest the clouds may
be MVFR. Given low confidence at that time range, have
introduced SCT015 BKN035 after the 12z-14z time frame.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning until 9 PM CDT this evening for
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

KEY MESSAGES...Barnes
UPDATE...Barnes
DISCUSSION...Copple
AVIATION...Barnes