Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 164, NWS St. Louis, MO

September 14, 2021Saint Clair County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Sep 14, 2021, 6:45 PM CDT for Saint Clair County, Illinois. It was in force for 30 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
Sep 14, 2021, 6:45 PM CDT (23:45 UTC)
Expired
Sep 14, 2021, 7:15 PM CDT
In force
30 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), 78 km from the middle of the area, began a volume at 23:47 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, 11.8 hours before the alert went out and 225 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 12:00Z on 2021-09-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1485 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 12:00Z on 2021-09-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 207 square meters per square second.193958Sfc1 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
1485 J/kg
Mixed-layer CIN
-96 J/kg
Mixed-layer LCL
988 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
207 m²/s²
0-3 km storm-relative helicity
165 m²/s²
Significant tornado parameter
0.7
Supercell composite
6.6

Open this sounding in Storm Lab

The text

As transmitted.

723 
WUUS53 KLSX 142345
SVRLSX
ILC163-150015-
/O.NEW.KLSX.SV.W.0164.210914T2345Z-210915T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
645 PM CDT Tue Sep 14 2021

The National Weather Service in St Louis has issued a

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

* Until 715 PM CDT.

* At 645 PM CDT, a severe thunderstorm was located over Freeburg,
  moving east at 25 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* This severe thunderstorm will be near...
  New Athens around 650 PM CDT.

Other locations impacted by this severe thunderstorm include
Lenzburg, St. Libory and Fayetteville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3837 9003 3850 8996 3847 8971 3822 8970
TIME...MOT...LOC 2345Z 282DEG 23KT 3842 8989 

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

$$

MRM
2 follow-up statements
195 
WWUS53 KLSX 142353
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
653 PM CDT Tue Sep 14 2021

ILC163-150015-
/O.CON.KLSX.SV.W.0164.000000T0000Z-210915T0015Z/
St. Clair IL-
653 PM CDT Tue Sep 14 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM CDT
FOR SOUTHEASTERN ST. CLAIR COUNTY...

At 653 PM CDT, a severe thunderstorm was located near Freeburg,
moving east at 35 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

This severe thunderstorm will remain over mainly rural areas of
southeastern St. Clair County, including the following locations...
St. Libory, Fayetteville and Lenzburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3849 8993 3847 8971 3822 8970 3838 8994
TIME...MOT...LOC 2353Z 284DEG 29KT 3840 8979 

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

$$

MRM
645 
WWUS53 KLSX 150005
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
705 PM CDT Tue Sep 14 2021

ILC163-150015-
/O.EXP.KLSX.SV.W.0164.000000T0000Z-210915T0015Z/
St. Clair IL-
705 PM CDT Tue Sep 14 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN ST. CLAIR COUNTY
WILL EXPIRE AT 715 PM CDT...
                
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 will be allowed to expire.

LAT...LON 3849 8993 3847 8971 3822 8970 3838 8994
TIME...MOT...LOC 0005Z 282DEG 23KT 3839 8970 

$$

MRM

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.