Alert archive / Illinois / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 377, NWS St. Louis, MO

June 21, 2011Randolph County, Saint Clair County, Washington County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Jun 21, 2011, 8:43 PM CDT for Randolph County, Saint Clair County, Washington County, Illinois. It was in force for 47 min. 2 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: Jun 21, 2011, 8:43 PM CDT (01:43 UTC)
Expired: Jun 21, 2011, 9:30 PM CDT
In force: 47 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 70.0 mph

Counties Randolph County, IL, Saint Clair County, IL, Washington County, IL

The radar

The St Louis radar (KLSX), 110 km from the middle of the area, began a volume at 01:43 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
Jun 21, 8:47 PM CDT	TSTM WND DMG	1 Nw Tilden, IL	SEVERAL TREES DOWN IN CLARMIN.
Jun 21, 9:00 PM CDT	TSTM WND DMG	Oakdale, IL	SEVERAL TREES DOWN

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
Jun 21, 1:22 PM CDT	Tornado Watch	SPC	9 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 1.7 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: 3122 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 829 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 147 m²/s²
0-3 km storm-relative helicity: 207 m²/s²
Significant tornado parameter: 3.5
Supercell composite: 15.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

326 
WUUS53 KLSX 220143
SVRLSX
ILC157-163-189-220230-
/O.NEW.KLSX.SV.W.0377.110622T0143Z-110622T0230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
843 PM CDT TUE JUN 21 2011

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN RANDOLPH COUNTY IN SOUTHWEST ILLINOIS...
  SOUTHEASTERN ST. CLAIR COUNTY IN SOUTHWEST ILLINOIS...
  SOUTHWESTERN WASHINGTON COUNTY IN SOUTH CENTRAL ILLINOIS...

* UNTIL 930 PM CDT

* AT 840 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
  HAIL...AND DESTRUCTIVE WINDS IN EXCESS OF 70 MPH.  THESE STORMS
  WERE LOCATED ALONG A LINE EXTENDING FROM 6 MILES NORTHEAST OF
  LIVELY GROVE TO TILDEN TO STEELEVILLE...AND MOVING EAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE...
  STEELEVILLE...COULTERVILLE...PERCY...ELKTON...CORDES AND OAKDALE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 3822 8959 3796 8959 3798 8982 3836 8975
      3836 8947 3822 8942
TIME...MOT...LOC 0143Z 279DEG 27KT 3834 8950 3825 8964
          3806 8968
WIND...HAIL 70MPH 1.00IN

$$

GKS

1 follow-up statement

890 
WWUS53 KLSX 220231
SVSLSX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
931 PM CDT TUE JUN 21 2011

ILC157-163-189-220241-
/O.EXP.KLSX.SV.W.0377.000000T0000Z-110622T0230Z/
RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL-
931 PM CDT TUE JUN 21 2011

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN WASHINGTON...
SOUTHEASTERN ST. CLAIR AND NORTHEASTERN RANDOLPH COUNTIES HAS
EXPIRED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR PROPERTY.
 HOWEVER SMALL HAIL...GUSTY WINDS AND HEAVY RAIN ARE STILL POSSIBLE
WITH THIS THUNDERSTORM.

LAT...LON 3822 8959 3796 8959 3798 8982 3836 8975
      3836 8947 3822 8942
TIME...MOT...LOC 0143Z 279DEG 27KT 3825 8964

$$

GKS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 21, 7:28 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Randolph, Saint Clair	47 min
Jun 21, 9:53 PM CDT	Areal Flood Advisory	LSX	Randolph, Saint Clair, Washington	3 hr
Jun 21, 10:12 PM CDT	Flash Flood Warning	LSX	Randolph, Saint Clair, Washington	6 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2011 Every severe thunderstorm warning in 2011

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.