Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 26, NWS St. Louis, MO

April 7, 2021Saint Louis County, City of Saint Louis, Missouri; Madison County, Monroe County, Saint Clair County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Apr 7, 2021, 6:27 PM CDT for Saint Louis County, City of Saint Louis, Missouri; Madison County, Monroe County, Saint Clair County, Illinois. It was in force for 49 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 7, 2021, 6:27 PM CDT (23:27 UTC)
Expired: Apr 7, 2021, 7:16 PM CDT
In force: 49 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Tornado: Possible
Hail: 0.88 in
Wind: 60.0 mph

Counties Madison County, IL, Monroe County, IL, Saint Clair County, IL, City of Saint Louis, MO, Saint Louis County, MO

The radar

The St Louis radar (KLSX), 42 km from the middle of the area, began a volume at 23:27 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 7, 12:02 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 11.5 hours before the alert went out and 235 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: 56 J/kg
Mixed-layer CIN: -173 J/kg
Mixed-layer LCL: 1001 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 120 m²/s²
0-3 km storm-relative helicity: 88 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

456 
WUUS53 KLSX 072327
SVRLSX
ILC119-133-163-MOC189-510-080030-
/O.NEW.KLSX.SV.W.0026.210407T2327Z-210408T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
627 PM CDT Wed Apr 7 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Northwestern Monroe County in southwestern Illinois...
  Southwestern Madison County in southwestern Illinois...
  Northern St. Clair County in southwestern Illinois...
  St. Louis City in east central Missouri...
  Southeastern St. Louis County in east central Missouri...

* Until 730 PM CDT.

* At 626 PM CDT, a severe thunderstorm was located over Barnhart,
  moving northeast at 50 mph.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  St. Louis, Belleville, University City, Granite City, O'Fallon,
  Kirkwood, East St. Louis, Collinsville, Edwardsville, Webster
  Groves, Arnold, Fairview Heights, Clayton, Cahokia, Jennings,
  Swansea, Glen Carbon, Shiloh, Crestwood and Bellefontaine
  Neighbors.

This includes the following highways...
 Interstate 64 in Illinois between exits 9 and 19.
 Interstate 44 in Missouri between exits 276 and 277.

This also includes Scott Joplin Historic Site and Horseshoe Lake
State Park.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3817 9030 3819 9034 3824 9036 3834 9037
      3838 9034 3841 9035 3845 9034 3845 9041
      3848 9042 3849 9040 3850 9041 3850 9048
      3882 9018 3883 9014 3881 9012 3884 9011
      3865 8970
TIME...MOT...LOC 2326Z 222DEG 42KT 3835 9041 

TORNADO...POSSIBLE
HAIL...0.88IN
WIND...60MPH
 
$$

BSH

3 follow-up statements

491 
WWUS53 KLSX 072353
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
653 PM CDT Wed Apr 7 2021

ILC133-080003-
/O.CAN.KLSX.SV.W.0026.000000T0000Z-210408T0030Z/
Monroe IL-
653 PM CDT Wed Apr 7 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN MONROE COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 700 PM CDT for
east central Missouri.

LAT...LON 3835 9007 3861 9037 3882 9018 3883 9014
      3881 9012 3884 9011 3865 8970
TIME...MOT...LOC 2353Z 222DEG 42KT 3858 9014 

$$

ILC119-163-MOC189-510-080030-
/O.CON.KLSX.SV.W.0026.000000T0000Z-210408T0030Z/
Madison IL-St. Clair IL-St. Louis City MO-St. Louis MO-
653 PM CDT Wed Apr 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR SOUTHWESTERN MADISON...NORTHERN ST. CLAIR COUNTIES IN
SOUTHWESTERN ILLINOIS AND EAST CENTRAL ST. LOUIS COUNTIES IN EAST
CENTRAL MISSOURI AND ST. LOUIS CITY...

At 653 PM CDT, a severe thunderstorm was located over Cahokia Parks
Airport, moving northeast at 50 mph.

HAZARD...60 mph wind gusts and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
St. Louis, Belleville, University City, Granite City, O'Fallon, East
St. Louis, Collinsville, Edwardsville, Webster Groves, Fairview
Heights, Clayton, Cahokia, Jennings, Swansea, Glen Carbon, Shiloh,
Bellefontaine Neighbors, Troy, Columbia and Richmond Heights.

This also includes Scott Joplin Historic Site and Horseshoe Lake
State Park.
 
This includes Interstate 64 in Illinois between exits 9 and 19.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3835 9007 3861 9037 3882 9018 3883 9014
      3881 9012 3884 9011 3865 8970
TIME...MOT...LOC 2353Z 222DEG 42KT 3858 9014 

TORNADO...POSSIBLE
HAIL...0.88IN
WIND...60MPH
 
$$

BSH

602 
WWUS53 KLSX 080008
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
708 PM CDT Wed Apr 7 2021

ILC163-MOC189-510-080018-
/O.CAN.KLSX.SV.W.0026.000000T0000Z-210408T0030Z/
St. Clair IL-St. Louis City MO-St. Louis MO-
708 PM CDT Wed Apr 7 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN ST. CLAIR AND EAST
CENTRAL ST. LOUIS COUNTIES AND ST. LOUIS CITY IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 3866 9018 3872 9021 3877 9017 3880 9012
      3884 9011 3866 8971
TIME...MOT...LOC 0008Z 222DEG 42KT 3871 8999 

$$

ILC119-080030-
/O.CON.KLSX.SV.W.0026.000000T0000Z-210408T0030Z/
Madison IL-
708 PM CDT Wed Apr 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR SOUTHWESTERN MADISON COUNTY IN SOUTHWESTERN ILLINOIS...

At 708 PM CDT, a severe thunderstorm was located over Maryville,
moving northeast at 50 mph.

HAZARD...60 mph wind gusts and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Granite City, Collinsville, Edwardsville, Glen Carbon, Troy,
Maryville, Pontoon Beach, Madison, Venice, Fairmont City, South
Roxana, Roxana, Hartford, Brooklyn, Poag and Mitchell.

This also includes Horseshoe Lake State Park.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3866 9018 3872 9021 3877 9017 3880 9012
      3884 9011 3866 8971
TIME...MOT...LOC 0008Z 222DEG 42KT 3871 8999 

TORNADO...POSSIBLE
HAIL...0.88IN
WIND...60MPH
 
$$

BSH

149 
WWUS53 KLSX 080016
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
716 PM CDT Wed Apr 7 2021

ILC119-080026-
/O.CAN.KLSX.SV.W.0026.000000T0000Z-210408T0030Z/
Madison IL-
716 PM CDT Wed Apr 7 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN MADISON COUNTY IN
SOUTHWESTERN ILLINOIS IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.

LAT...LON 3866 9018 3872 9021 3877 9017 3880 9012
      3884 9011 3866 8971
TIME...MOT...LOC 0014Z 222DEG 42KT 3879 8990 

$$

BSH

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 7, 3:06 PM CDT	Severe Thunderstorm Warning	LSX	Moniteau	39 min
Apr 7, 4:04 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Cole, Moniteau, Osage	26 min
Apr 7, 4:27 PM CDT	Areal Flood Advisory	LSX	Boone, Cole, Moniteau	3 hr
Apr 7, 5:09 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Marion, Monroe, Ralls, Shelby	19 min
Apr 7, 5:37 PM CDT	Severe Thunderstorm Warning	LSX	Franklin, Jefferson, Saint Francois, Washington	68 min
Apr 7, 6:38 PM CDT	Severe Thunderstorm Warning	LSX	Adams, Brown	17 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2021 Severe Thunderstorm Warnings in Missouri, 2021 Every severe thunderstorm warning in 2021

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.