Damaging Winds in Illinois, June 10, 2026

Area Forecast Discussion
National Weather Service Lincoln IL
1252 PM CDT Wed Jun 10 2026

.KEY MESSAGES...

- Widespread heat continues through Thursday, though increasing
  cloud cover keeps the chance of heat index values exceeding
  100 degrees at around 20 percent south of Interstate 72.

- Two rounds of severe thunderstorms will move across central
  Illinois this afternoon through tonight, bringing a primary
  hazard of damaging winds alongside localized tornado, large
  hail, and flooding threats.

- A cold front brings another round of severe storms Thursday
  evening and overnight, where damaging straight-line winds
  remain the main concern.

&&

.DISCUSSION...
Issued at 1246 PM CDT Wed Jun 10 2026

Short Term Forecast: Heat and Severe Potential

Today and tomorrow will feature widespread temperatures in the
90s, with heat indices climbing into the upper 90s to lower
100s. Confidence in meeting Heat Advisory criteria (max heat
index near 105F) remains low; LREF probabilities for heat
indices exceeding 100F generally hold around 20 percent for
areas south of I-72. Primary limiting factors for higher heat
readings will be increasing cloud cover and precip chances along
with convective debris, particularly on Thursday for the
latter.

Thunderstorms are ongoing early this afternoon across portions
of eastern Iowa and northeastern Missouri, with additional
development expected to our west later this evening. Out ahead
of the initial convective line, temperatures pushing 90 degrees
and dew points in the low to mid-70s are supporting roughly
1500-2000 J/kg of weakly capped MLCAPE across central Illinois.
Instability will further increase through mid-afternoon, peaking
near 2500 J/kg. Effective bulk shear values will increase to
around 30kt with the arrival of storms, sufficient to support an
organized severe threat.

This initial line of storms is expected to lift northeast,
likely staying near or just north of the I-72 corridor. While
low-level flow is currently veered with unimpressive SRH values,
this is forecast to increase ahead of the second line of
storms. DCAPE values around 900-1200 J/kg, coupled with
increasingly steep low-level lapse rates, will support a wind
threat with the first wave of convection. Round two will see
strengthened kinematic fields as storms congeal into a line and
spread ESE across central Illinois late this evening. Damaging
winds will remain the primary threat, though interactions with
remnant outflow boundaries and increasing low-level winds
associated with a strengthening low-level jet will support a
localized tornado threat this evening. This threat will slowly
subside with waning diurnal instability as the system moves east
overnight.

In addition to the severe potential, multiple rounds of storms--
including the possibility for backbuilding and training--pose a
localized flooding threat. Corfidi vectors ahead of the second
line of storms drop below 10 kt and become oriented out of the
northeast, suggesting potential for backbuilding along the
southern periphery of the QLCS. While the severe threat should
diminish overnight, the hydro threat may linger well into or
through the overnight hours.

Thursday and Extended Period
A robust shortwave trough is expected to lift into the Upper
Midwest on Thursday, driving a cold front through central
Illinois Thursday evening and overnight. Ahead of this boundary,
the GFS suggests a broad, unstable warm sector with MLCAPE
values exceeding 3000 J/kg. Coupled with deep-layer shear of
25-35 kt and 0-1km shear of 15-25 kt, the kinematic environment
remains seasonably strong Thursday. While pre-frontal discrete
activity with all severe hazards is possible, the primary
concern remains straight-line winds as convective elements
congeal into a line along and ahead of the front.

Lingering showers and storms over southeast Illinois on Friday
morning will exit quickly, giving way to clearing skies as high
pressure builds into the region. This will provide a brief
return to more seasonal conditions, with highs in the lower to
mid-80s and dew points mixing down into the upper 50s, resulting
in a much more comfortable air mass.

For the weekend and into early next week, the pattern turns
more zonal aloft while a low-level baroclinic zone wobbles over
the region. This setup maintains additional chances for showers
and thunderstorms, though specifics regarding timing and
coverage remain uncertain at this forecast range.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1141 AM CDT Wed Jun 10 2026

Two rounds of thunderstorms, potentially severe, are expected to
impact central Illinois through the period. The first is ongoing
across eastern IA and northeast MO this hour and will move east
across portions of central IL mainly north of the I-72 corridor
this afternoon. The second line of storms will move across the
region late this evening. Outside of the influence of storms,
expect a moderate SSW breeze to prevail with gusts to around
20-25 kt during much of the daytime hours.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday morning for ILZ027>031-036>038-
040>043-047>051.

&&

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

Hazardous Weather Outlook
National Weather Service Lincoln IL
1220 PM CDT Wed Jun 10 2026

ILZ027>031-036>038-040-041-111730-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-
1220 PM CDT Wed Jun 10 2026

This Hazardous Weather Outlook is for central Illinois and west
central Illinois.

.DAY ONE...This afternoon and tonight.

One or more waves of severe thunderstorms are possible (30-45%
chance) this afternoon into tonight. The primary threat will be
damaging winds in excess of 70 mph, though large hail and a tornado
or two are also possible. Areas of flash flooding are also a
concern.

Outside of the storms, the heat index will approach 100 degrees.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

The heat index will again reach 100 degrees on Thursday.

Another round of severe thunderstorms is expected Thursday evening.
The primary risk remains with damaging winds over 70 mph, but large
hail and tornadoes are also possible. Flash flooding is also a
concern, especially wherever heavy rain falls today.

Additional thunderstorms are expected Saturday night. The severe
weather risk is uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed between 130pm and midnight.

Expected storm motion is toward the east around 35 mph.

ILZ042>057-061-111730-
Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-Morgan-
Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar-Shelby-
1220 PM CDT Wed Jun 10 2026

This Hazardous Weather Outlook is for central Illinois, east
central Illinois and west central Illinois.

.DAY ONE...This afternoon and tonight.

The heat index is expected to be around 100 degrees much of the
afternoon.

Strong to severe thunderstorms are expected to move across the area
this evening. The primary risk is damaging winds in excess of 60
mph, although large hail and a tornado or two are also possible.
There is also a level 2 of 4 risk for flash flooding.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

The heat index will again reach 100 degrees on Thursday.

Another round of severe thunderstorms is expected Thursday evening.
The primary risk is with damaging winds over 70 mph, though large
hail and a few tornadoes are also possible. Flash flooding is also a
concern, especially where heavy rain falls today.

Additional thunderstorms are expected Saturday night. The severe
weather risk is uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed between 4 pm and 1 am.

Expected storm motion is toward the east around 40 mph.

ILZ062-063-066>068-071>073-111730-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
1220 PM CDT Wed Jun 10 2026

This Hazardous Weather Outlook is for east central Illinois and
southeast Illinois.

.DAY ONE...This afternoon and tonight.

The heat index is expected to be around 100 degrees much of the
afternoon.

A decaying line of thunderstorms will move into the area after 9 pm.
While the severe weather risk will be decreasing, isolated damaging
wind gusts remain a concern. There is a level 1 of 5 risk for severe
weather.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

A line of severe thunderstorms is expected Thursday evening,
lingering after midnight. The primary risk is with damaging winds
over 60 mph, though large hail and a tornado or two are also
possible.

Additional thunderstorms are expected Saturday night. The severe
weather risk is uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed between 9 pm and 2 am.

Expected storm motion is toward the east around 40 mph.

Bumgardner