Flash Flood Warning 18, NWS Lincoln, IL

Area Forecast Discussion
National Weather Service Lincoln IL
634 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.

- Thunderstorms will push across central Illinois this
  evening...bringing a risk for damaging wind gusts and
  localized flash flooding.

- 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 /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 634 PM CDT Wed Jun 10 2026

The airmass across central Illinois has temporarily stabilized
early this evening: however, as the nocturnal low-level jet
strengthens after sunset, another round of convection will
develop. 2315z/615pm regional radar mosaic shows clusters of
thunderstorms from near KMLI westward to KMCI. These storms will
rapidly spread/develop eastward and will impact the central
Illinois terminals later this evening. Based on radar timing
tools and the latest HRRR/RAP, have carried a TEMPO group for
thunder and wind gusts to 50kt at KPIA between 02z and 04z, then
further southeast to the I-72 TAF sites between 03z and 06z.
Once the line of storms drops further south, showers will linger
for a couple of hours before dry weather returns across the
board overnight through much of Thursday. The latest guidance
suggests a line of thunderstorms will develop along an advancing
cold front late Thursday, but will remain west of the terminals
until after 00z Fri.

&&

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

&&

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

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

ILZ027>031-036>038-040-041-111915-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-
210 PM CDT Wed Jun 10 2026

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

.DAY ONE...Tonight.

A couple 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.

.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 this afternoon and evening.

Expected storm motion is toward the northeast around 35 mph.

ILZ042>057-061-111915-
Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-Morgan-
Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar-Shelby-
210 PM CDT Wed Jun 10 2026

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

.DAY ONE...Tonight.

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 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 this afternoon and evening.

Expected storm motion is toward the northeast around 35 mph.

ILZ062-063-066>068-071>073-111915-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
210 PM CDT Wed Jun 10 2026

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

.DAY ONE...Tonight.

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.

.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 is not anticipated tonight.

Deubelbeiss

Preliminary Local Storm Report
National Weather Service Lincoln IL
350 PM CDT Wed Jun 10 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0233 PM     Tstm Wnd Dmg     Pekin                   40.57N 89.64W
06/10/2026                   Tazewell           IL   Public

            12 inch tree limb down.

&&

RK

Preliminary Local Storm Report
National Weather Service Lincoln IL
400 PM CDT Wed Jun 10 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0253 PM     Tstm Wnd Dmg     1 S Tremont             40.52N 89.49W
06/10/2026                   Tazewell           IL   Public

            8 to 10 inch tree limbs down. Time estimated
            by radar.

&&

RK

Preliminary Local Storm Report
National Weather Service Lincoln IL
406 PM CDT Wed Jun 10 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0329 PM     Tstm Wnd Dmg     Lexington               40.64N 88.78W
06/10/2026                   McLean             IL   Public

            Trees and power lines down.

&&

RK

Preliminary Local Storm Report
National Weather Service Lincoln IL
426 PM CDT Wed Jun 10 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0404 PM     Tstm Wnd Dmg     Clinton                 40.16N 88.96W
06/10/2026                   De Witt            IL   Public

            Tree downed onto a power line in Clinton.
            Relayed by EM.

&&

RK

Preliminary Local Storm Report
National Weather Service Lincoln IL
431 PM CDT Wed Jun 10 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0233 PM     Tstm Wnd Dmg     Pekin                   40.56N 89.64W
06/10/2026                   Tazewell           IL   Public

            Large tree downed in Pekin. Photos relayed
            by EM.

&&

RK

Preliminary Local Storm Report
National Weather Service Lincoln IL
630 PM CDT Wed Jun 10 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0216 PM     Tstm Wnd Dmg     3 SSE Alta              40.78N 89.61W
06/10/2026                   Peoria             IL   Broadcast Media

            Large tree branch down. Time estimated by
            radar.

&&

RK