Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 6, NWS St. Louis, MO

March 23, 2021Monroe County, Saint Clair County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Mar 23, 2021, 11:02 PM CDT for Monroe County, Saint Clair County, Illinois. It was in force for 43 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
Mar 23, 2021, 11:02 PM CDT (04:02 UTC)
Expired
Mar 23, 2021, 11:45 PM CDT
In force
43 min
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Tornado
Possible
Hail
0.75 in
Wind
60.0 mph

Counties Monroe County, IL, Saint Clair County, IL

The radar

The St Louis radar (KLSX), 69 km from the middle of the area, began a volume at 04:05 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 nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 4.0 hours before the alert went out and 239 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-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2021-03-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 281 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2021-03-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 196 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
281 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
642 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
196 m²/s²
0-3 km storm-relative helicity
241 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.4

Open this sounding in Storm Lab

The text

As transmitted.

808 
WUUS53 KLSX 240402
SVRLSX
ILC133-163-240445-
/O.NEW.KLSX.SV.W.0006.210324T0402Z-210324T0445Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
1102 PM CDT Tue Mar 23 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Central Monroe County in southwestern Illinois...
  Central St. Clair County in southwestern Illinois...

* Until 1145 PM CDT.

* At 1102 PM CDT, a severe thunderstorm was located over New Design,
  moving northeast at 35 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Belleville, Waterloo, Freeburg, Smithton, New Athens, New Design,
  Hecker, Floraville, Paderborn and Burksville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This thunderstorm is capable of producing all types of severe weather
including extremely large hail, destructive straight line winds and
tornadoes. Move quickly to a safe shelter such as an interior room, a
bathroom, closet or basement.

&&

LAT...LON 3823 9015 3827 9019 3853 8998 3836 8980
TIME...MOT...LOC 0402Z 223DEG 29KT 3828 9014 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

TES
2 follow-up statements
991 
WWUS53 KLSX 240425
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
1125 PM CDT Tue Mar 23 2021

ILC133-240435-
/O.CAN.KLSX.SV.W.0006.000000T0000Z-210324T0445Z/
Monroe IL-
1125 PM CDT Tue Mar 23 2021

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

LAT...LON 3831 8994 3831 9004 3832 9004 3838 9010
      3853 8998 3836 8980
TIME...MOT...LOC 0425Z 223DEG 29KT 3842 8998 

$$

ILC163-240445-
/O.CON.KLSX.SV.W.0006.000000T0000Z-210324T0445Z/
St. Clair IL-
1125 PM CDT Tue Mar 23 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1145 PM CDT
FOR CENTRAL ST. CLAIR COUNTY...

At 1125 PM CDT, a severe thunderstorm was located over Smithton,
moving northeast at 35 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Belleville, Freeburg, Smithton, New Athens, Floraville and Paderborn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This thunderstorm is capable of producing all types of severe weather
including extremely large hail, destructive straight line winds and
tornadoes. Move quickly to a safe shelter, such as an interior room,
a bathroom or closet or basement.

&&

LAT...LON 3831 8994 3831 9004 3832 9004 3838 9010
      3853 8998 3836 8980
TIME...MOT...LOC 0425Z 223DEG 29KT 3842 8998 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

Glass
119 
WWUS53 KLSX 240449
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
1149 PM CDT Tue Mar 23 2021

ILC163-240458-
/O.EXP.KLSX.SV.W.0006.000000T0000Z-210324T0445Z/
St. Clair IL-
1149 PM CDT Tue Mar 23 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL ST. CLAIR COUNTY HAS
EXPIRED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been allowed to expire.

LAT...LON 3831 8994 3831 9004 3832 9004 3838 9010
      3853 8998 3836 8980
TIME...MOT...LOC 0448Z 223DEG 29KT 3855 8982 

$$

Glass

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 23, 7:04 PM CDTTornado WarningLSXPike41 min
Mar 23, 7:26 PM CDTSevere Thunderstorm WarningLSXCalhoun, Pike34 min
Mar 23, 7:35 PM CDTTornado WarningLSXCalhoun, Pike25 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2021Every 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.