Alert archive / Illinois / Tornado Warnings in 2026

Tornado Warning 21, NWS Chicago, IL

April 17, 2026LaSalle County, Lee County, Illinois

NWS Chicago, IL issued this tornado warning at Apr 17, 2026, 8:07 PM CDT for LaSalle County, Lee County, Illinois. It was in force for 38 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Apr 17, 2026, 8:07 PM CDT (01:07 UTC)
Expired: Apr 17, 2026, 8:45 PM CDT
In force: 38 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.0 in

Counties LaSalle County, IL, Lee County, IL

The radar

The Chicago radar (KLOT), 85 km from the middle of the area, began a volume at 01:06 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Apr 17, 8:25 PM CDT	TSTM WND DMG	3 E Mendota, IL	Several semi trucks were overturned on I-39 east of Mendota. Time estimated using radar.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 17, 12:40 PM CDT	Tornado Watch	SPC	9 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.1 hours before the alert went out and 116 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 30 J/kg
Mixed-layer CIN: -223 J/kg
Mixed-layer LCL: 1085 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 202 m²/s²
0-3 km storm-relative helicity: 202 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

450 
WFUS53 KLOT 180107
TORLOT
ILC099-103-180145-
/O.NEW.KLOT.TO.W.0021.260418T0107Z-260418T0145Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Chicago/Romeoville
807 PM CDT Fri Apr 17 2026

The National Weather Service in Chicago has issued a

* Tornado Warning for...
  Northwestern La Salle County in north central Illinois...
  Southeastern Lee County in north central Illinois...

* Until 845 PM CDT.

* At 807 PM CDT, severe thunderstorms capable of producing both
  tornadoes and extensive straight line wind damage were located
  along a line extending from 6 miles west of La Moille to 6 miles
  northwest of Ladd to Hennepin, moving northeast at 60 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* These dangerous storms will be near...
  Peru, La Salle, Mendota, Sublette, and Woodhaven Lakes around 815 
  PM CDT.
  Paw Paw around 825 PM CDT.

Other locations in the path of these tornadic storms include
Earlville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

This line of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4189 8894 4136 8893 4123 8916 4158 8917
      4159 8951
TIME...MOT...LOC 0107Z 226DEG 54KT 4154 8941 4144 8931 4126 8929 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Birk

1 follow-up statement

833 
WWUS53 KLOT 180113 RRA
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
813 PM CDT Fri Apr 17 2026

ILC099-103-180145-
/O.CON.KLOT.TO.W.0021.000000T0000Z-260418T0145Z/
La Salle IL-Lee IL-
813 PM CDT Fri Apr 17 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 845 PM CDT FOR
NORTHWESTERN LA SALLE AND SOUTHEASTERN LEE COUNTIES...

At 813 PM CDT, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located along a
line extending from near La Moille to near Ladd to near Granville,
moving northeast at 60 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

These dangerous storms will be near...
  Peru, La Salle, Mendota, Oglesby, North Utica, Sublette, and 
  Woodhaven Lakes around 820 PM CDT.

Other locations in the path of these tornadic storms include
Earlville and Paw Paw.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

This line of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4189 8894 4136 8893 4123 8916 4158 8917
      4159 8951
TIME...MOT...LOC 0113Z 236DEG 50KT 4159 8933 4142 8921 4125 8919 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Birk

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 17, 7:09 PM CDT	Tornado Warning	LOT	Boone, Winnebago	36 min
Apr 17, 7:16 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Boone, DeKalb, Kane, McHenry	74 min
Apr 17, 7:26 PM CDT	Flash Flood Warning	LOT	Winnebago	4 hr
Apr 17, 7:28 PM CDT	Tornado Warning	LOT	McHenry	47 min
Apr 17, 7:31 PM CDT	Areal Flood Advisory	LOT	Lee, Ogle	3 hr
Apr 17, 7:49 PM CDT	Tornado Warning	LOT	DeKalb, Ogle	41 min
Apr 17, 7:58 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	DeKalb, LaSalle, Lee	77 min
Apr 17, 8:04 PM CDT	Tornado Warning	LOT	Lake	56 min
Apr 17, 8:06 PM CDT	Special Marine Warning	LOT		114 min
Apr 17, 8:12 PM CDT	Flash Flood Warning	LOT	Boone, Lake, McHenry	6 hr
Apr 17, 8:18 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Cook, Lake	72 min
Apr 17, 8:29 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Kane, McHenry	31 min
Apr 17, 8:29 PM CDT	Tornado Warning	LOT	DeKalb, LaSalle	46 min
Apr 17, 8:36 PM CDT	Tornado Warning	LOT	Lake, McHenry	39 min
Apr 17, 8:46 PM CDT	Tornado Warning	LOT	LaSalle, Livingston	47 min
Apr 17, 8:47 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	DuPage, Grundy, Kane, Kendall, Will	73 min
Apr 17, 9:04 PM CDT	Special Marine Warning	LOT		116 min
Apr 17, 9:05 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Ford, Iroquois, Kankakee, Livingston, Will	70 min
Apr 17, 9:15 PM CDT	Tornado Warning	LOT	Ford, Iroquois, Livingston	60 min
Apr 17, 9:23 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Will	82 min
Apr 17, 9:23 PM CDT	Tornado Warning	LOT	Grundy, Kankakee, Kendall, Livingston, Will	52 min
Apr 17, 9:41 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Will	6 hr
Apr 17, 9:46 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Iroquois, Kankakee	59 min
Apr 17, 9:59 PM CDT	Special Marine Warning	LOT		91 min
Apr 17, 10:15 PM CDT	Tornado Warning	LOT	Kankakee	17 min
Apr 17, 10:31 PM CDT	Tornado Warning	LOT	Cook, Will	29 min
Apr 17, 10:57 PM CDT	River Flood Watch	LOT	Winnebago	36 hr
Apr 17, 10:59 PM CDT	River Flood Warning	LOT	Cook	22 hr
Apr 18, 1:54 AM CDT	Areal Flood Warning	LOT	Boone, Lake, McHenry	6 hr
Apr 18, 5:44 AM CDT	River Flood Warning	LOT	LaSalle	15 hr
Apr 18, 12:41 PM CDT	River Flood Warning	LOT	LaSalle	23 hr
Apr 18, 1:29 PM CDT	Frost Advisory	LOT	Boone, DeKalb, DuPage, Ford, Grundy, Iroquois and 11 more	20 hr
Apr 18, 1:29 PM CDT	Freeze Watch	LOT	Boone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more	12 hr
Apr 18, 1:45 PM CDT	River Flood Watch	LOT	Lee, Ogle	32 hr
Apr 18, 2:20 PM CDT	Areal Flood Warning	LOT	Lake, McHenry	13 days

Nearby

Tornado Warnings in Illinois, 2026 Every tornado warning in 2026 Tornadoes in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.