Severe Thunderstorm Warning 140, NWS Lincoln, IL

Area Forecast Discussion
National Weather Service Lincoln IL
900 PM CDT Fri Apr 17 2026

.KEY MESSAGES...

- An intense, multi-hazard severe thunderstorm event appears
  likely this evening into tonight. Areas along and west of a
  Taylorville to Champaign line are in an Enhanced Risk (Level 3
  of 5) of severe storms, while areas to the east are in a
  Slight Risk (Level 2 of 5). Storms are likely to impact areas
  west of I-55 between 5-9 PM, then spread east of I-55 late
  this evening.

- The storms could produce locally heavy rainfall of 2-4".
  Scattered instances of flooding are possible, especially in
  urban, low- lying, or other poor drainage areas. A Flood Watch
  has been issued for areas along and north of Shelby to Edgar
  County.

- Cooler air returns this weekend, and lows in the 30s may
  result in frost development both Saturday night and Sunday
  night.

&&

.UPDATE...
Issued at 900 PM CDT Fri Apr 17 2026

The tornado watch in effect until 11 pm has been expanded
eastward to the Indiana border and as far south as Cumberland
and Clark counties. The flood watch continues until 4 am for
central IL north of I-70 for 1-2 inches of rain per hour with
locally 2-4 inches possible. The QLCS squall line currently was
approaching I-55 and racing ENE at 50-60 mph and forecast to
remain severe as it moves into east central IL during next 1-2
hours. Several tornado and severe thunderstorm warnings along
this line of storms. In addition to possible tornadoes along
this squall line, 1-2 inch hail and damaging winds over 70 mph a
risk, along with the heavy rainfall. The latest CAMs have line
of storms gradually weakening during overnight after 1-2 am as
it moves into southeast IL.

&&

.DISCUSSION...
Issued at 134 PM CDT Fri Apr 17 2026

*** Severe Storms Likely This Evening-Tonight ***

The 'bottom line up front': the forecast largely remains on
track, with an intense, multi-hazard severe thunderstorm event
this evening into tonight.

Sfc low is positioned just north of Duluth, MN as of 18z/1pm,
with the attendant cold front extending south near Minneapolis,
MN, to Des Moines, IA, to Wichita KS. In the last hour, storms
have erupted across eastern IA along a pre-frontal trough, which
extends roughly from the IA/WI border to near Kirksville, MO.
This is an evolution that CAMs highlighted in recent days. Locally,
temps have pushed to near 80F while dewpoints are still in the
mid 60s. Continued advection of the EML and deeper moisture
content have led to instability rising over 2000 J/kg, and PWATs
over 1.2". Vis satellite shows a Cu field quickly expanding
across the ILX CWA, and any capping is weak or non- existent.
Still, the best source of forcing in the short-term will be that
pre-frontal trough noted to our north/west. For our area,
isolated supercells cannot be ruled out this afternoon, and any
mature storms that develop will pose a risk of all severe
hazards.

The more widespread severe threat is expected to come as the
cold front approaches and upscale growth of thunderstorms
occurs. As these storms move into IL, a highly unstable airmass
will still be in place, with increasing low-level shear as the
LLJ ramps up after 00z/7pm. This line of storms could produce
scattered damaging winds, with gusts over 75 mph possible. Line-
embedded tornadoes remain a concern, as 0-1km SRH values surge
above 150 J/kg in response to the LLJ.

CAM timing has not changed much from previous iterations,
although there is some thought that cold pool dominant storm
structures may surge east a smidge faster than CAMs currently
suggest. Our latest thinking is that the line will impact areas
west of I-55 between 5-8 PM, then continue east and reach
portions of the I-57 corridor by 9- 10 PM. The main line of
storms should reach the IL/IN border by about 05z/midnight CT.
Scattered showers may linger for a few hours behind the main
line of severe storms.

*** Flooding Potential ***

In light of recent rains and unseasonable PWATs (95th+
percentile) present with this system, concern is growing that
at least scattered flash flooding will occur with tonight's
storms. Despite the relatively progressive forward motion of the
line, the last few cycles of HREF LPMM guidance have
consistently highlighted an area roughly from the IL River to
the I-72/Danville corridor where localized rainfall amounts of
2-4" are possible. 3-hr Flash Flood Guidance is less than 2" in
most locations, and a recent mesoscale precipitation discussion
from WPC notes storms will be highly efficient rainfall
producers with rates of 1-2" per hour. A Flood Watch was issued
to capture the counties where scattered instances of flooding
seem most likely to arise.

*** Rest of the Weekend ***

Following tonight's FROPA, breezy northwest winds will persist
into Sat. Highs are likely to be cooler over the weekend, in
the 50s or low 60s. No major changes to the frost/freeze outlook
for Saturday night and Sunday night. Frost chances could extend
as far south as I- 70 both nights, but the chances for frost
generally increase with northward extent. The gridded forecast
reflects this. While some spots, particular those in low-lying
areas, could drop below 32F, a widespread freeze appears
unlikely.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 620 PM CDT Fri Apr 17 2026

Line of TSRA present along the IL/IA border as of 2315z, moving
west in time, with scattered TSRA ahead of the line. Main
concern for this TAF period will be timing out the storms,
which could bring severe wind gusts and large hail. Based on
radar trends, slowed the timing by an hour or two at each
terminal. Storms should be past CMI by 06z. These storms are
associated with a front which will swing winds to northwesterly
and a brief period of MVFR ceilings along/behind the front.
Winds will remain gusty into Saturday, while ceilings improve
and skies clear into the day.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 4 AM CDT Saturday for ILZ027>031-036>038-
040>057-061.

&&

KEY MESSAGES...Erwin
UPDATE...07
DISCUSSION...Erwin
AVIATION...Erwin

Hazardous Weather Outlook
National Weather Service Lincoln IL
307 PM CDT Fri Apr 17 2026

ILZ027>031-036>038-040>045-047>054-061-181200-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Champaign-Cass-Menard-Scott-Morgan-
Sangamon-Christian-Macon-Moultrie-Shelby-
307 PM CDT Fri Apr 17 2026

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

.DAY ONE...Tonight.

Isolated thunderstorms are possible by mid to late afternoon and
will be capable of producing damaging wind gusts up to 70 mph, large
hail, and possibly a strong tornado.

A line of thunderstorms will move across the area this evening and
tonight. Damaging wind gusts over 75 mph will be the primary hazard,
but an isolated tornado cannot be ruled out. Locally heavy rain is
also possible.

Minor flooding is ongoing or occurring along the Illinois River from
Henry downstream.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Much colder air will bring the potential for patchy frost Saturday
night and Sunday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed between 3 and 10 pm.

Expected storm motion is toward the east-northeast around 45 to 50
mph.

ILZ046-055>057-062-063-066>068-071>073-181200-
Vermilion-Douglas-Coles-Edgar-Cumberland-Clark-Effingham-Jasper-
Crawford-Clay-Richland-Lawrence-
307 PM CDT Fri Apr 17 2026

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

.DAY ONE...Tonight.

A line of thunderstorms will move across the area this evening and
tonight. Damaging wind gusts of 70 to 75 mph will be the primary
hazard, but an isolated tornado cannot be ruled out. Locally heavy
rain is also possible.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Much colder air will bring the potential for patchy frost Saturday
night and Sunday night, especially north of I-70.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed between 8 pm and 1 am.

Expected storm motion is toward the east-northeast around 45 to 50
mph.

Auten

Preliminary Local Storm Report
National Weather Service Lincoln IL
927 PM CDT Fri Apr 17 2026

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

0832 PM     Tornado          Middletown              40.10N 89.59W
04/17/2026                   Logan              IL   Trained Spotter

&&

Barnes

Preliminary Local Storm Report
National Weather Service Lincoln IL
933 PM CDT Fri Apr 17 2026

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

0857 PM     Tstm Wnd Dmg     Minonk                  40.90N 89.03W
04/17/2026                   Woodford           IL   Emergency Mngr

            Power lines were blown down across IL-251.

&&

Barnes

Preliminary Local Storm Report
National Weather Service Lincoln IL
935 PM CDT Fri Apr 17 2026

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

0826 PM     Tstm Wnd Dmg     San Jose                40.31N 89.60W
04/17/2026                   Logan              IL   Emergency Mngr

            Power lines were blown down.

&&

Barnes

Preliminary Local Storm Report
National Weather Service Lincoln IL
938 PM CDT Fri Apr 17 2026

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

0900 PM     Tstm Wnd Dmg     2 ESE Normal            40.50N 88.95W
04/17/2026                   McLean             IL   Broadcast Media

            Power poles were snapped along GE Road.

&&

Barnes

Preliminary Local Storm Report
National Weather Service Lincoln IL
939 PM CDT Fri Apr 17 2026

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

0906 PM     Tstm Wnd Gst     Normal                  40.51N 88.98W
04/17/2026  M85 MPH          McLean             IL   Public

            Wind gust measured with anemometer.

&&

Barnes

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