Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 16, NWS St. Louis, MO

March 27, 20214 counties in Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Mar 27, 2021, 7:06 PM CDT for 4 counties in Illinois. It was in force for 39 min. 7 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Mar 27, 2021, 7:06 PM CDT (00:06 UTC)
Expired: Mar 27, 2021, 7:45 PM CDT
In force: 39 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Clinton County, IL, Monroe County, IL, Saint Clair County, IL, Washington County, IL

The radar

The St Louis radar (KLSX), 92 km from the middle of the area, began a volume at 00:05 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.

What was reported inside it

Time	Report	Where	Remark
Mar 27, 7:07 PM CDT	HAIL 0.75	Millstadt, IL	REPORT FROM MPING: DIME (0.75 IN.).
Mar 27, 7:09 PM CDT	HAIL 0.25	Millstadt, IL
Mar 27, 7:19 PM CDT	FUNNEL CLOUD	2 S Scott Afb, IL	OBSERVERS AT SCOTT AFB SPOTTED A FUNNEL CLOUD SOUTH OF THE BASE AT 719 PM LOCAL TIME.
Mar 27, 7:22 PM CDT	HAIL 0.5	Scott Afb, IL
Mar 27, 7:33 PM CDT	HAIL 0.25	3 S Mascoutah, IL
Mar 27, 7:37 PM CDT	HAIL 0.25	2 S New Baden, IL
Mar 27, 7:41 PM CDT	HAIL 0.88	1 Sw New Memphis, IL

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Mar 27, 4:44 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 0.1 hours before the alert went out and 212 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: 933 m above ground
0-6 km bulk shear: 86 kt
0-1 km storm-relative helicity: -3 m²/s²
0-3 km storm-relative helicity: 202 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

352 
WUUS53 KLSX 280006
SVRLSX
ILC027-133-163-189-280045-
/O.NEW.KLSX.SV.W.0016.210328T0006Z-210328T0045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service St Louis MO
706 PM CDT Sat Mar 27 2021

The National Weather Service in St Louis has issued a

* Severe Thunderstorm Warning for...
  Southwestern Clinton County in south central Illinois...
  Central Monroe County in southwestern Illinois...
  Northwestern Washington County in south central Illinois...
  St. Clair County in southwestern Illinois...

* Until 745 PM CDT.

* At 706 PM CDT, a severe thunderstorm was located over Millstadt,
  moving east at 45 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Belleville, O'Fallon, Fairview Heights, Cahokia, Swansea, Shiloh,
  Waterloo, Columbia, Mascoutah, Centreville, Breese, Lebanon,
  Freeburg, Dupo, Millstadt, New Baden, Carlyle, Nashville, Scott AFB
  and Smithton.

This includes Interstate 64 in Illinois between exits 19 and 50.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect for the warned area. Tornadoes can
develop quickly from severe thunderstorms. Although a tornado is not
immediately likely, if one is spotted, act quickly and move to a
place of safety inside a sturdy structure such as a basement or small
interior room.

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

&&

LAT...LON 3835 8934 3831 9015 3855 9020 3864 8937
TIME...MOT...LOC 0006Z 261DEG 37KT 3845 9004 

HAIL...1.00IN
WIND...60MPH
 
$$

BRC

1 follow-up statement

037 
WWUS53 KLSX 280027
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
727 PM CDT Sat Mar 27 2021

ILC133-280036-
/O.CAN.KLSX.SV.W.0016.000000T0000Z-210328T0045Z/
Monroe IL-
727 PM CDT Sat Mar 27 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.

A Severe Thunderstorm Watch remains in effect until 900 PM CDT for
south central and southwestern Illinois.

LAT...LON 3835 8934 3832 8999 3858 8993 3864 8937
TIME...MOT...LOC 0026Z 261DEG 37KT 3848 8977 

$$

ILC027-163-189-280045-
/O.CON.KLSX.SV.W.0016.000000T0000Z-210328T0045Z/
Clinton IL-Washington IL-St. Clair IL-
727 PM CDT Sat Mar 27 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM CDT
FOR SOUTHWESTERN CLINTON...NORTHWESTERN WASHINGTON AND EASTERN ST.
CLAIR COUNTIES...

At 726 PM CDT, a severe thunderstorm was located over Mascoutah,
moving east at 45 mph.

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

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Belleville, O'Fallon, Shiloh, Mascoutah, Breese, Lebanon, Freeburg,
New Baden, Carlyle, Nashville, Scott AFB, Trenton, New Athens,
Aviston, Okawville, Germantown, Albers, Beckemeyer, New Memphis and
St. Libory.

This includes Interstate 64 in Illinois between exits 19 and 50.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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

&&

LAT...LON 3835 8934 3832 8999 3858 8993 3864 8937
TIME...MOT...LOC 0026Z 261DEG 37KT 3848 8977 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

BRC

The office that day

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

Issued	Product	Office	Counties	Lasted
Mar 27, 7:03 PM CDT	Tornado Warning	LSX	Bond, Clinton, Madison, Saint Clair	42 min
Mar 27, 7:13 PM CDT	Tornado Warning	LSX	Clinton, Saint Clair, Washington	47 min
Mar 27, 7:27 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Randolph, Saint Clair, Washington	48 min
Mar 27, 7:43 PM CDT	Severe Thunderstorm Warning	LSX	Bond, Clinton, Fayette, Madison, Marion, Saint Clair and 1 more	47 min
Mar 27, 7:45 PM CDT	Tornado Warning	LSX	Bond, Clinton, Fayette, Marion	45 min
Mar 27, 7:59 PM CDT	Tornado Warning	LSX	Clinton, Marion, Washington	31 min
Mar 27, 8:11 PM CDT	Severe Thunderstorm Warning	LSX	Randolph, Saint Clair, Washington	64 min
Mar 27, 8:21 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Fayette, Marion, Washington	39 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.