Alert archive / Illinois / Tornado Warnings in 2026

Tornado Warning 16, NWS St. Louis, MO

April 17, 2026Adams County, Illinois; Lewis County, Missouri

NWS St. Louis, MO issued this tornado warning at Apr 17, 2026, 5:38 PM CDT for Adams County, Illinois; Lewis County, Missouri. It was in force for 52 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 17, 2026, 5:38 PM CDT (22:38 UTC)
Expired: Apr 17, 2026, 6:30 PM CDT
In force: 52 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.75 in

Counties Adams County, IL, Lewis County, MO

The radar

The Quad Cities radar (KDVN), 179 km from the middle of the area, began a volume at 22:40 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.

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, 3:31 PM CDT	Tornado Watch	SPC	8 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.6 hours before the alert went out and 250 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: 84 J/kg
Mixed-layer CIN: -150 J/kg
Mixed-layer LCL: 1053 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 65 m²/s²
0-3 km storm-relative helicity: 164 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

830 
WFUS53 KLSX 172238
TORLSX
ILC001-MOC111-172330-
/O.NEW.KLSX.TO.W.0016.260417T2238Z-260417T2330Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service St Louis MO
538 PM CDT Fri Apr 17 2026

The National Weather Service in St Louis has issued a

* Tornado Warning for...
  Northwestern Adams County in west central Illinois...
  Central Lewis County in northeastern Missouri...

* Until 630 PM CDT.

* At 538 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Lewistown, or 15 miles west of Canton, moving
  northeast at 50 mph.

  HAZARD...Tornado and golf ball size hail.

  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.

* This tornado will be near...
  Lewistown and Ewing around 540 PM CDT.
  Canton around 555 PM CDT.

Other locations impacted by the tornado include Monticello and Meyer.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to an interior room on the lowest floor of a well-built building
away from 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.

&&

LAT...LON 3998 9174 4012 9186 4025 9168 4025 9150
      4024 9150 4024 9151 4023 9150 4022 9150
      4021 9151 4020 9151 4020 9130 4011 9122
TIME...MOT...LOC 2238Z 228DEG 41KT 4008 9180

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.75 IN

$$

Elmore

3 follow-up statements

349 
WWUS53 KLSX 172252
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
552 PM CDT Fri Apr 17 2026

ILC001-MOC111-172330-
/O.CON.KLSX.TO.W.0016.000000T0000Z-260417T2330Z/
Adams IL-Lewis MO-
552 PM CDT Fri Apr 17 2026

...TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR
NORTHWESTERN ADAMS AND CENTRAL LEWIS COUNTIES...

At 552 PM CDT, a severe thunderstorm capable of producing a tornado
was located 6 miles northwest of Canton, moving northeast at 45 mph.

HAZARD...Tornado and half dollar size hail.

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.

This tornado will be near...
  Canton around 555 PM CDT.

Other locations impacted by the tornado include Monticello, Meyer and
Lima.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to an interior room on the lowest floor of a well-built building
away from 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.

&&

LAT...LON 4000 9165 4015 9181 4025 9168 4025 9150
      4024 9151 4023 9150 4021 9151 4020 9151
      4020 9130 4011 9122
TIME...MOT...LOC 2238Z 234DEG 39KT 4008 9179

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.25 IN

$$

Elmore

630 
WWUS53 KLSX 172301
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
601 PM CDT Fri Apr 17 2026

ILC001-MOC111-172330-
/O.CON.KLSX.TO.W.0016.000000T0000Z-260417T2330Z/
Adams IL-Lewis MO-
601 PM CDT Fri Apr 17 2026

...TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR
NORTHWESTERN ADAMS AND NORTHEASTERN LEWIS COUNTIES...

At 601 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Canton, moving northeast at 25 mph.

HAZARD...Tornado and quarter size hail.

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.

This tornado will be near...
  Canton around 610 PM CDT.

Other locations impacted by the tornado include Monticello, Meyer and
Lima.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to an interior room on the lowest floor of a well-built building
away from 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.

&&

LAT...LON 4006 9168 4019 9175 4025 9168 4025 9150
      4024 9151 4023 9150 4022 9151 4020 9151
      4020 9130 4011 9122
TIME...MOT...LOC 2252Z 243DEG 22KT 4013 9167

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

Elmore

528 
WWUS53 KLSX 172314
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
614 PM CDT Fri Apr 17 2026

ILC001-MOC111-172330-
/O.CON.KLSX.TO.W.0016.000000T0000Z-260417T2330Z/
Adams IL-Lewis MO-
614 PM CDT Fri Apr 17 2026

...TORNADO WARNING REMAINS IN EFFECT UNTIL 630 PM CDT FOR
NORTHWESTERN ADAMS AND NORTHEASTERN LEWIS COUNTIES...

At 614 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Canton, moving northeast at 25 mph.

HAZARD...Tornado and quarter size hail.

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.

This tornadic storm will remain over mainly rural areas of
Northwestern Adams and Northeastern Lewis Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to an interior room on the lowest floor of a well-built building
away from 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.

&&

LAT...LON 4012 9164 4021 9173 4025 9168 4025 9150
      4024 9151 4023 9150 4022 9151 4020 9151
      4020 9131
TIME...MOT...LOC 2301Z 243DEG 22KT 4016 9161

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

Elmore

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 17, 7:57 AM CDT	Flood Watch	LSX	Adams, Brown, Calhoun, Greene, Jersey, Macoupin and 2 more	19 hr
Apr 17, 3:10 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun	50 min
Apr 17, 3:26 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Jersey, Madison	49 min
Apr 17, 3:39 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Greene, Jersey, Pike	49 min
Apr 17, 3:45 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Pike	32 min
Apr 17, 4:11 PM CDT	Severe Thunderstorm Warning	LSX	Jersey, Macoupin, Madison	25 min
Apr 17, 4:22 PM CDT	Severe Thunderstorm Warning	LSX	Brown, Pike	38 min
Apr 17, 6:13 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Adams	47 min
Apr 17, 6:23 PM CDT	Tornado Warning	LSX	Adams	41 min
Apr 17, 6:53 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Adams	52 min
Apr 17, 3:06 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Callaway	39 min
Apr 17, 3:30 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Shelby	45 min
Apr 17, 3:40 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Monroe, Ralls	37 min
Apr 17, 4:04 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis	23 min
Apr 17, 5:03 PM CDT	Tornado Warning	LSX	Knox, Lewis, Shelby	42 min
Apr 17, 5:51 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Knox, Shelby	54 min
Apr 17, 5:58 PM CDT	Tornado Warning	LSX	Knox	32 min
Apr 17, 6:46 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Marion, Monroe, Ralls, Shelby	44 min

Nearby

Tornado Warnings in Illinois, 2026 Tornado Warnings in Missouri, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.