Severe Thunderstorm Warning 264, NWS Lincoln, IL

Area Forecast Discussion
National Weather Service Lincoln IL
235 PM CDT Tue Jun 16 2026

.KEY MESSAGES...

- A dangerous severe weather outbreak is projected for for
  central IL on Wednesday, featuring tornadoes, damaging
  straight line winds, and large hail.

- Heavy rainfall rates will create a risk of localized flash
  flooding on Wednesday, particularly for areas near and north
  of I-74.

- Strong, non-convective gradient winds are anticipated
  Wednesday afternoon, with widespread southwest gusts near 45
  mph, particularly for areas near and south of I-72.

&&

.DISCUSSION...
Issued at 235 PM CDT Tue Jun 16 2026

...Isolated severe storms east of I-57 this afternoon...

A vigorous mid-level shortwave is currently pivoting into the
east central WI, with a trailing cold front pushing east of the
IL River at 18z. Ahead of the front dewpoints are climbing to
around 60F over eastern IL, contributing the MLCAPEs around 500
J/kg. Steady cooling aloft south of the upper wave, combined
with deep layer shear around 50 kt, should allow for isolated to
scattered storm development east of I-57 this afternoon.
Thermodynamic profiles support an environment favorable for low-
topped supercells capable of hail greater than 1" diameter and
isolated damaging wind gusts. This activity should push south
near I-70 by early evening in a weakening mode as the upper
support pulls farther northeast.

...Moderate risk of severe weather Wednesday...

A strong mid-level shortwave will track into the Upper
Mississippi Valley, associated with and unseasonably strong 990
mb surface low. Mass field response south of the low is
impressive, with ECMWF EFI highlighting an event at the top of
mid June climatology in several kinematic and moisture fields.
A 50-60 knot 850mb low- level jet will aggressively transport
deep moisture into central and southeast Illinois overnight and
into Wednesday morning. Precipitable water values are forecast
to climb toward 2.0 inches, creating a high-efficiency
environment for torrential rainfall. Strong low and deep layer
shear will promote well organized and long lived storms capable
of strong, long-track tornadoes, destructive straight line
winds, and large hail.

The first round of convective activity is projected to move
into the region from the west during the morning hours, roughly
between 7 AM and 1 PM. CAMs suggest this activity will
primarily affect areas north of the I-72 corridor. High rain
rates accompanying this round, combined with antecedent soil
moisture, create a distinct threat for localized flash flooding.
Training storm cells are likely, particularly near and north of
I-74, prompting the issuance of a Flash Flood Watch for these
locations. In addition to the flash flood threat, the morning
round of storms looks to mainly be elevated but supported by
strong effective shear. Consequently, these storms will
primarily carry a risk for large hail. If storms can become
rooted to the surface, there is a non-zero risk for damaging
winds and a few tornadoes. The morning activity is significant
not only for its immediate hazards but also for its potential to
deposit an outflow boundary/effective warm front across the
region, which will play a crucial role in the evolution of the
atmosphere ahead of the primary afternoon severe weather event.

The atmosphere is primed for a significant severe weather event
Wed afternoon. Behind the morning convective activity, rapid
destabilization is projected, with MLCAPE values likely surging
into the 2500–3500 J/kg range and dewpoints reaching the lower
70s south of the boundary. This instability, combined with
impressive bulk shear values (60-75 knots), creates a highly
favorable environment for high-end severe storms. SPC’s Day 2
Outlook highlights a Moderate Risk (Level 4/5) for our area,
reflecting the high confidence in an outbreak of all severe
hazards. Discrete supercells are projected to initiate mid-to-
late afternoon along a strong cold front pushing into central
IL. These storms will pose an immediate threat for large hail,
potentially exceeding 2 inches in diameter, and the development
of strong (EF3+), long-tracked tornadoes. Shear vectors oriented
favorably off the boundary will likely promote discrete cells
persisting for several hours. Given the strong mid-level flow,
storm motion will be fast at 50-60 mph to the east, or southeast
for right movers. Eventually, cold pool interactions will
foster upscale growth of these supercells into a linear
structure during the evening. This line will will favor
destructive, straight-line wind gusts for east central and SE
IL, with line- embedded mesovortex tornadoes possible.

Looking at possible failure modes for widespread/intense
severe...while parameters are lining up well, forecast
soundings exhibit mid level winds at 70-90 kt. Local studies
have noted in past events when mid level winds exceed 80 kt,
updrafts have difficulty persisting and can get tilted/blown
downstream before growing tall enough to produce significant
severe weather. Will have to see if this has any impact on
coverage or intensity of this event.

Aside from the storm related hazards, an out of season
gradient wind event appears likely Wednesday afternoon driven by
the deep surface low just to our north. High-res guidance shows
southwesterly 45 mph wind gusts becoming likely, particularly
near and south of I-72. A Wind Advisory has been issued for
these areas from 1 PM to 7 PM. Crop canopy looks to be fairly
closed at this point, though any fields that remain
open/recently worked will carry a blowing dust risk.

Calmer, more stable conditions arrive Thursday and Friday as
the system departs and high pressure builds across the region.
Temperatures will remain seasonable, generally in the mid 70s
to low 80s.

By Saturday night and into the start of next week, the upper-
level pattern transitions into a zonal flow, reintroducing
active weather. The GFS and ECMWF show some divergence regarding
the specific timing of shortwave impulses, resulting in lower
confidence for exact precipitation timing. However, an unsettled
pattern is the most likely outcome, with the CPC 6-10 day
outlook suggesting a trend toward below-normal temperatures and
above-normal precipitation. AI/ML severe products show some low
probabilities for severe working back into the Midwest on
Sunday.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1224 PM CDT Tue Jun 16 2026

A cold front was located just west of KPIA at 17z, and will push
east across the central IL terminals this afternoon. Winds will
veer SW to W behind the front, gusting 20-25 kt until rapidly
diminishing by early evening. There is a 20-30% chance that TSRA
will redevelop along the front this afternoon - the only
terminal that appears to risk seeing this is KCMI. Another round
of storms is expected to develop after 12z Wed, affecting mainly
near and north of I-74, so included a TEMPO or PROB30 mention at
the terminals. Gusty southeast winds will develop after sunrise.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch from Wednesday morning through Wednesday evening
for ILZ027>031-036>038.
Wind Advisory from 1 PM to 7 PM CDT Wednesday for ILZ040>057-
061>063-066>068-071>073.

&&

KEY MESSAGES...25
DISCUSSION...25
AVIATION...25

Hazardous Weather Outlook
National Weather Service Lincoln IL
247 PM CDT Tue Jun 16 2026

ILZ027>031-036>038-040>057-061>063-066>068-071>073-172000-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-
Morgan-Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar-Shelby-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
247 PM CDT Tue Jun 16 2026

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

.DAY ONE...Tonight.

There is a marginal risk that some of the storms late this afternoon
could become severe east of I-57, with hail and wind gusts up to 60
mph.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Severe thunderstorms will move through the area Wednesday into
Wednesday night. There is a moderate risk (level 4 of 5) that these
storms will be severe. The risks are for strong tornadoes, damaging
winds, and large hail. Flash flooding is also possible due to storms
producing up to 2 inches of rainfall in a short amount of time.

River flooding is ongoing for portions of central IL. Please refer
to the latest flood statements for details.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight.

25

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