Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 152, NWS St. Louis, MO

August 23, 2021Saint Clair County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Aug 23, 2021, 4:23 PM CDT for Saint Clair County, Illinois. It was in force for 26 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: Aug 23, 2021, 4:23 PM CDT (21:23 UTC)
Expired: Aug 23, 2021, 4:49 PM CDT
In force: 26 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Saint Clair County, IL

The radar

The St Louis radar (KLSX), 66 km from the middle of the area, began a volume at 21:24 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 12:00Z, 9.4 hours before the alert went out and 218 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1261 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 118 m²/s²
0-3 km storm-relative helicity: 87 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

057 
WUUS53 KLSX 232123
SVRLSX
ILC163-232200-
/O.NEW.KLSX.SV.W.0152.210823T2123Z-210823T2200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
423 PM CDT Mon Aug 23 2021

The National Weather Service in St Louis has issued a

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

* Until 500 PM CDT.

* At 423 PM CDT, a severe thunderstorm was located over Belleville,
  moving east at 10 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Belleville, O'Fallon, Fairview Heights, Swansea, Shiloh, Mascoutah,
  Lebanon, Freeburg, Caseyville, Millstadt, Scott AFB, Smithton and
  Fayetteville.

This includes Interstate 64 in Illinois between exits 12 and 23.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

&&

LAT...LON 3845 9015 3864 9001 3862 8976 3833 8980
TIME...MOT...LOC 2123Z 282DEG 11KT 3852 8998 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Byrd

1 follow-up statement

466 
WWUS53 KLSX 232149
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
449 PM CDT Mon Aug 23 2021

ILC163-232159-
/O.CAN.KLSX.SV.W.0152.000000T0000Z-210823T2200Z/
St. Clair IL-
449 PM CDT Mon Aug 23 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL ST. CLAIR COUNTY 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.  However gusty winds and
heavy rain are still possible with this thunderstorm.

LAT...LON 3845 9015 3864 9001 3862 8976 3833 8980
TIME...MOT...LOC 2148Z 282DEG 11KT 3850 8988 

$$

Byrd

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 23, 6:04 PM CDT	Areal Flood Advisory	LSX	Monroe, Randolph	3 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 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.