Alert archive / Illinois / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 375, NWS St. Louis, MO

June 21, 2011Randolph County, Illinois; Sainte Genevieve County, Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Jun 21, 2011, 6:34 PM CDT for Randolph County, Illinois; Sainte Genevieve County, Missouri. It was in force for 41 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, 6:34 PM CDT (23:34 UTC)
Expired: Jun 21, 2011, 7:15 PM CDT
In force: 41 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Randolph County, IL, Sainte Genevieve County, MO

The radar

The St Louis radar (KLSX), 115 km from the middle of the area, began a volume at 23:35 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, 6:43 PM CDT	TSTM WND DMG	1 E Chester, IL	TREES DOWN BLOCKING A FARM ROAD JUST EAST OF CHESTER
Jun 21, 7:05 PM CDT	HAIL 0.88	1 Wsw Steeleville, 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
Jun 21, 1:22 PM CDT	Tornado Watch	SPC	9 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 11.6 hours before the alert went out and 266 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: 489 J/kg
Mixed-layer CIN: -145 J/kg
Mixed-layer LCL: 1353 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: -245 m²/s²
0-3 km storm-relative helicity: -164 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -5.5

Open this sounding in Storm Lab

The text

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

873 
WUUS53 KLSX 212334
SVRLSX
ILC157-MOC186-220015-
/O.NEW.KLSX.SV.W.0375.110621T2334Z-110622T0015Z/

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

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  RANDOLPH COUNTY IN SOUTHWEST ILLINOIS...
  EAST CENTRAL STE. GENEVIEVE COUNTY IN SOUTHEAST MISSOURI...

* UNTIL 715 PM CDT

* AT 632 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  CHESTER...AND MOVING EAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
  CHESTER...SPARTA...BREMEN...STEELEVILLE...PERCY...NEW PALESTINE...
  WALSH...WELGE...BLAIR AND EDEN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. TORNADOES CAN
DEVELOP QUICKLY FROM SEVERE THUNDERSTORMS. ALTHOUGH NOT IMMEDIATELY
LIKELY...IF A TORNADO IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF
SAFETY INSIDE A STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL
INTERIOR ROOM.

&&

LAT...LON 3788 8964 3785 8976 3785 8979 3788 8980
      3790 8984 3787 8990 3787 8999 3795 9013
      3822 8965 3822 8961 3796 8959
TIME...MOT...LOC 2333Z 253DEG 23KT 3790 8987
WIND...HAIL 60MPH 1.00IN

$$

GKS

2 follow-up statements

009 
WWUS53 KLSX 212354
SVSLSX

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

MOC186-220003-
/O.CAN.KLSX.SV.W.0375.000000T0000Z-110622T0015Z/
STE. GENEVIEVE MO-
654 PM CDT TUE JUN 21 2011

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL STE. GENEVIEVE
COUNTY IS CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED EAST OF THE WARNED 
AREA.

LAT...LON 3788 8964 3785 8979 3788 8980 3790 8984
      3788 8988 3789 8990 3793 8996 3796 8993
      3797 8994 3796 8999 3800 9004 3822 8965
      3822 8961 3796 8959
TIME...MOT...LOC 2353Z 253DEG 23KT 3794 8971

$$

ILC157-220015-
/O.CON.KLSX.SV.W.0375.000000T0000Z-110622T0015Z/
RANDOLPH IL-
654 PM CDT TUE JUN 21 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR RANDOLPH
COUNTY UNTIL 715 PM CDT...

AT 650 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING PING PONG BALL SIZE HAIL...
AND DESTRUCTIVE WINDS IN EXCESS OF 70 MPH.  THIS STORM WAS LOCATED
NEAR BREMEN...OR NEAR CHESTER...MOVING EAST AT 30 MPH.

LOCATIONS IMPACTED INCLUDE...
  SPARTA...STEELEVILLE...PERCY...WELGE...BLAIR AND EDEN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. TORNADOES CAN
DEVELOP QUICKLY FROM SEVERE THUNDERSTORMS. ALTHOUGH NOT IMMEDIATELY
LIKELY...IF A TORNADO IS SPOTTED ACT QUICKLY AND MOVE TO A PLACE OF
SAFETY INSIDE A STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL
INTERIOR ROOM.

THIS IS A SUPERCELL THUNDERSTORM. DUE TO THE ROTATING NATURE OF
SUPERCELLS...THEY ARE CAPABLE OF PRODUCING ALL TYPES OF SEVERE
WEATHER...INCLUDING EXTREMELY LARGE HAIL...DESTRUCTIVE STRAIGHT LINE
WINDS AND POSSIBLY TORNADOES. BE PREPARED TO ACT QUICKLY SHOULD A
TORNADO OCCUR OR A TORNADO WARNING BE ISSUED.

&&

LAT...LON 3788 8964 3785 8979 3788 8980 3790 8984
      3788 8988 3789 8990 3793 8996 3796 8993
      3797 8994 3796 8999 3800 9004 3822 8965
      3822 8961 3796 8959
TIME...MOT...LOC 2353Z 253DEG 23KT 3794 8971
WIND...HAIL 70MPH 1.50IN

$$

GKS

946 
WWUS53 KLSX 220015
SVSLSX

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

ILC157-220025-
/O.EXP.KLSX.SV.W.0375.000000T0000Z-110622T0015Z/
RANDOLPH IL-
715 PM CDT TUE JUN 21 2011

...THE SEVERE THUNDERSTORM WARNING FOR RANDOLPH COUNTY HAS EXPIRED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED
AREA.

ADDITIONAL STRONG THUNDERSTORMS ARE STILL POSSIBLE...AND A TORNADO 
WATCH REMAINS IN EFFECT UNTIL 800 PM.

LAT...LON 3788 8964 3785 8979 3788 8980 3790 8984
      3788 8988 3789 8990 3793 8996 3796 8993
      3797 8994 3796 8999 3800 9004 3822 8965
      3822 8961 3796 8959
TIME...MOT...LOC 2354Z 253DEG 23KT 3794 8970

$$

GKS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 21, 2:44 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Saint Clair	46 min
Jun 21, 3:14 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Randolph, Saint Clair, Washington	46 min
Jun 21, 3:43 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Randolph, Saint Clair, Washington	47 min
Jun 21, 4:09 PM CDT	Severe Thunderstorm Warning	LSX	Bond, Clinton, Fayette, Madison, Marion, Montgomery	51 min
Jun 21, 4:40 PM CDT	Tornado Warning	LSX	Fayette, Marion	31 min
Jun 20, 8:52 PM CDT	River Flood Warning	LSX	Lewis	47 hr
Jun 21, 1:46 PM CDT	Severe Thunderstorm Warning	LSX	Iron, Madison, Reynolds, Sainte Genevieve, Saint Francois	44 min
Jun 21, 2:07 PM CDT	Severe Thunderstorm Warning	LSX	Jefferson, Saint Francois, Washington	53 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2011 Severe Thunderstorm Warnings in Missouri, 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.