Severe Thunderstorm Warning 108, NWS Lincoln, IL

Area Forecast Discussion
National Weather Service Lincoln IL
622 PM CDT Thu Apr 2 2026

.KEY MESSAGES...

- This afternoon and evening, strong winds pose a double
  threat. Non-thunderstorm gusts are expected to reach 40-50
  mph. Furthermore, thunderstorm wind gusts could be stronger,
  ranging from 55 to 75 mph. Given the recently saturated soils,
  these high winds will not only create difficulties for high-
  profile vehicles but also present a risk of uprooted trees.

- In addition to the damaging wind concerns, there remains a
  localized threat for tornadoes and large hail through this
  evening as a cold front pushes through the region.

- Another round of severe weather and potential flooding is
  expected Friday afternoon and evening. Rainfall totals between
  Friday and Saturday have a medium-high probability (50-70%)
  of exceeding 1 inch areawide.

- Overnight lows are likely (50-80% chance) to fall into the
  mid 30s or lower each morning Sunday through Tuesday. Action
  may be needed to protect newly- emerged, tender vegetation.

&&

.DISCUSSION...
Issued at 1133 AM CDT Thu Apr 2 2026

A quick glance at the mid-level water vapor imagery depicts our
compact, negatively-tilted shortwave trough lifting across the
Missouri Valley with its attendant surface low positioned over
central Iowa.

Scattered, elevated morning convection has been observed out
ahead of the cold front within a broad warm sector and beneath
strong ascent characterized by an upper-level difluent zone and
strong kinematic profile.

High-resolution model guidance consistently predicts widespread
thunderstorms developing across west-central Illinois early
this afternoon. The environment, characterized by surface
temperatures in the low 70s and dewpoints in the low 60s, is
expected to quickly destabilize due to low-level jet (LLJ)
moisture transport, synoptic lift, and adiabatic cooling aloft.

With MLCAPE values ranging from 500-1500 J/kg and deep-layer
shear between 40-50 kts, supercells and multicell clusters are
anticipated this afternoon and evening as a pre-frontal trough
advances from the west. The robust low-level wind field,
highlighted by a 60 kt LLJ core veering ahead of the cold front,
will promote rapidly rotating updrafts. This potential is well-
supported by 0-3 km Storm Relative Helicity (SRH) values
exceeding 300 m2/s2 and a pronounced, humped low-level
hodograph.

While the parameter space clearly supports a tornado threat
this afternoon through early evening across central Illinois,
the uncapped warm sector will likely hinder supercells from
staying discrete. The reality may be a much messier storm-scale
environment with numerous mergers, nudgers, and boundary
interactions.

Aside from the tornado risk, a significant wind threat also
exists given the top-shelf kinematic field in place. The
momentum transfer augmented by precip-loading within any storm
this afternoon and evening has the potential to put down 60 mph
gusts, with the upshot being 75 mph gusts within any bowing
segments or RFD surges that develop.

The hail risk might be highest later this evening behind the
pre-frontal trough and immediately along the cold front as a
mid-level cold pocket overtakes the front and increases CAPEs
through the hail growth zone. The current outlook supports hail
up to the size of golf balls.

Storms will exit the area late this evening, moving from
northwest to southeast, as the cold front traverses central
Illinois and becomes stationary. This stalled front will quickly
retreat northward on Friday as a warm front, ahead of a
significant upper-level trough that will track across the
Missouri Valley toward the Upper-Mississippi Valley.

This approaching disturbance and its associated surface low
will set the stage for another round of nocturnal convection in
central Illinois on Friday evening, likely taking the form of a
decaying squall line pushing into west-central Illinois
overnight.

While a damaging wind risk is possible upon the squall lines
arrival, the primary concern is the potential for flooding.
Despite diminishing instability overnight, strong isentropic
ascent preceding the front and weak low-pressure development
along the front are expected to produce a long-duration rainfall
event through Saturday morning. With the ground already
saturated from recent heavy rains, widespread urban and small
stream flooding, and potentially localized flash flooding, is
anticipated by Saturday morning. Recent NBM guidance supports a
medium-high probability (50-70%) of exceeding 1 during the
Friday-Saturday timeframe.

A transition to a drier and seasonably cool pattern is expected
next week as elongated surface high pressure establishes itself
over the central US. Current NBM guidance consistently
forecasts daily high temperatures in the 50s from Sunday through
Tuesday, with overnight lows in the 30s, raising renewed
concerns for frost and freeze given the start of the growing
season. Temperatures are then anticipated to rebound to warmer
levels by the middle of next week as the high pressure system
moves out and a southerly flow returns across the Plains and
Midwest.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 622 PM CDT Thu Apr 2 2026

Line of strong to severe thunderstorms is most likely to impact
KPIA over the next couple hours. It may take a few hours for
any storms to get over into eastern Illinois. With KPIA most
likely, will cover the threat with a TEMPO group, but use PROB30
for the other sites. Currently thinking the thunder threat
should be out of the terminals before 06z.

Otherwise, the strong southerly winds will gradually ease up
this evening, as they shift more toward the west. By daybreak,
winds should be relatively light as a front settles over the
area, but will go back southerly again through Friday morning.
On the north side of the front, a period of MVFR ceilings
appears likely during the morning into early afternoon. Late in
the period, another chance of thunderstorms.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM CDT this evening for ILZ027>031-
036>038-040>057-061>063-066>068-071>073.

&&

KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...Geelhart

Hazardous Weather Outlook
National Weather Service Lincoln IL
305 PM CDT Thu Apr 2 2026

ILZ027>031-036>038-040>043-047>053-031100-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Cass-Menard-Scott-Morgan-Sangamon-Christian-
Macon-
305 PM CDT Thu Apr 2 2026

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

.DAY ONE...Tonight.

Scattered thunderstorms are expected through the first half of the
evening, with the highest threat of severe weather near and west of
the Illinois River. Damaging winds, potentially as high as 75 mph,
will be the primary threat, though large hail and a few tornadoes are
also possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Another round of severe storms is forecast Friday night into the
overnight hours, with all hazards possible.

Minor flooding may develop along portions of the Illinois River
early next week, mainly from Havana to Beardstown.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed until 9 pm.

Expected storm motion is toward the northeast, around 50 mph.

ILZ044>046-054>057-061>063-066>068-071>073-031100-
Piatt-Champaign-Vermilion-Moultrie-Douglas-Coles-Edgar-Shelby-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
305 PM CDT Thu Apr 2 2026

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

.DAY ONE...Tonight.

Periods of thunderstorms are expected through the evening, lingering
past midnight south of I-70. Some of the storms will be severe.
Damaging winds, potentially as high as 60 to 70 mph, will be the
primary threat, though there is also a low threat of tornadoes.

Outside of the storms, strong south winds with gusts 40 to 50 mph
will continue into early evening. This could cause difficult driving
conditions for high profile vehicles, especially on east west
oriented roadways.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorms are expected to develop again by late afternoon Friday,
and continue into the first part of Saturday. Some of the storms may
be strong after midnight Friday night.

Minor flooding is possible along the Wabash River, beginning this
weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through this evening.

Expected storm motion is toward the northeast, around 50 mph.

Geelhart

Preliminary Local Storm Report
National Weather Service Lincoln IL
402 PM CDT Thu Apr 2 2026

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

0700 AM     Rain             1 W Galesburg           40.95N 90.39W
04/02/2026  M1.28 Inch       Knox               IL   CO-OP Observer

            CO-OP Observer station GBGI2 Galesburg.

0355 PM     Rain             Galesburg Airport       40.93N 90.43W
04/02/2026  M1.11 Inch       Knox               IL   AWOS

            AWOS station KGBG Galesburg Arpt.

0700 AM     Rain             3 NNW Sparland          41.08N 89.47W
04/02/2026  M1.09 Inch       Marshall           IL   Cocorahs

            Cocorahs station IL-MH-4 Sparland 3.4 NNW.

0700 AM     Rain             1 NW Knoxville          40.91N 90.29W
04/02/2026  M1.03 Inch       Knox               IL   Cocorahs

            Cocorahs station IL-KX-9 Knoxville 0.7 NW.

&&

Preliminary Local Storm Report
National Weather Service Lincoln IL
449 PM CDT Thu Apr 2 2026

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

0423 PM     Non-Tstm Wnd Gst 1 NW Lincoln            40.16N 89.37W
04/02/2026  M52 MPH          Logan              IL   Public

&&

Preliminary Local Storm Report
National Weather Service Lincoln IL
544 PM CDT Thu Apr 2 2026

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

0532 PM     Funnel Cloud     Galesburg               40.95N 90.37W
04/02/2026                   Knox               IL   Fire Dept/Rescue

            Funnel reported on south side of Galesburg.

&&

Shimon

Preliminary Local Storm Report
National Weather Service Lincoln IL
548 PM CDT Thu Apr 2 2026

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

0535 PM     Tstm Wnd Gst     Galesburg               40.95N 90.37W
04/02/2026  M49 MPH          Knox               IL   ASOS

&&

Shimon

Preliminary Local Storm Report
National Weather Service Lincoln IL
551 PM CDT Thu Apr 2 2026

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

0532 PM     Funnel Cloud     Galesburg               40.94N 90.37W
04/02/2026                   Knox               IL   Trained Spotter

            Reported outside of the Public Safety
            Building at 150 S Broad Street in Galesburg.

&&

Shimon

Preliminary Local Storm Report
National Weather Service Lincoln IL
620 PM CDT Thu Apr 2 2026

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

0542 PM     Non-Tstm Wnd Gst Central Illinois Airpor 40.48N 88.91W
04/02/2026  M51 MPH          McLean             IL   AWOS

            AWOS station KBMI Bloomington Arpt.

&&