Alert archive / Illinois / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 91, NWS St. Louis, MO

April 15, 2012Jersey County, Madison County, Illinois; Saint Charles County, Saint Louis County, Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Apr 15, 2012, 7:38 PM CDT for Jersey County, Madison County, Illinois; Saint Charles County, Saint Louis County, Missouri. It was in force for 32 min. 4 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
Apr 15, 2012, 7:38 PM CDT (00:38 UTC)
Expired
Apr 15, 2012, 8:10 PM CDT
In force
32 min
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Jersey County, IL, Madison County, IL, Saint Charles County, MO, Saint Louis County, MO

The radar

The St Louis radar (KLSX), 32 km from the middle of the area, began a volume at 00:40 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

TimeReportWhereRemark
Apr 15, 7:39 PM CDTTSTM WND GST 652 Ene St. Peters, MOAT CAVE SPRINGS AND MEXICO ROAD.
Apr 15, 7:45 PM CDTTSTM WND DMGSt. Charles, MO12 INCH DIAMETER TREE SNAPPED OFF AT ITS TRUNK IN ST. CHARLES.
Apr 15, 7:49 PM CDTTSTM WND GST 564 Nne Orchard Farms, MO
Apr 15, 7:55 PM CDTTSTM WND DMGElsah, ILDISPATCH REPORTS THAT A TREE HAD TO BE REMOVED FROM A ROAD IN ELSAH.

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.

IssuedProductOfficeLasted
Apr 15, 4:42 PM CDTTornado WatchSPC6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 0.6 hours before the alert went out and 211 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 00:00Z on 2012-04-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 502 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 00:00Z on 2012-04-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 346 square meters per square second.1939587897Sfc1 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
502 J/kg
Mixed-layer CIN
-103 J/kg
Mixed-layer LCL
972 m above ground
0-6 km bulk shear
66 kt
0-1 km storm-relative helicity
346 m²/s²
0-3 km storm-relative helicity
388 m²/s²
Significant tornado parameter
0.8
Supercell composite
5.6

Open this sounding in Storm Lab

The text

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

186 
WUUS53 KLSX 160038
SVRLSX
ILC083-119-MOC183-189-160130-
/O.NEW.KLSX.SV.W.0091.120416T0038Z-120416T0130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
738 PM CDT SUN APR 15 2012

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTH CENTRAL JERSEY COUNTY IN SOUTHWEST ILLINOIS...
  WESTERN MADISON COUNTY IN SOUTHWEST ILLINOIS...
  EASTERN ST. CHARLES COUNTY IN EAST CENTRAL MISSOURI...
  NORTHEASTERN ST. LOUIS COUNTY IN EAST CENTRAL MISSOURI...

* UNTIL 830 PM CDT

* AT 736 PM CDT...A SEVERE THUNDERSTORM WAS LOCATED NEAR MARYLAND
  HEIGHTS...AND MOVING NORTHEAST AT 50 MPH.

  HAZARD...60 MPH WIND GUSTS.

  SOURCE...TRAINED WEATHER SPOTTERS.

  IMPACT...MINOR TREE DAMAGE...WITH LIMBS UP TO ONE INCH IN DIAMETER
           BROKEN.

* LOCATIONS IMPACTED INCLUDE...
  MARYLAND HEIGHTS...ST. CHARLES...OLIVETTE...OVERLAND...UNIVERSITY
  CITY...ST. ANN...BRIDGETON...WOODSON TERRACE...ST. JOHN...LAMBERT
  FIELD...BEL-RIDGE...HILLSDALE...BERKELEY...NORMANDY...KINLOCH...
  HAZELWOOD...COOL VALLEY...NORTHWOODS...FERGUSON AND JENNINGS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. TORNADOES CAN
DEVELOP QUICKLY FROM SEVERE THUNDERSTORMS. ALTHOUGH ONE IS 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.

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
BUILDING.

&&

LAT...LON 3870 9021 3873 9021 3875 9018 3878 9018
      3868 9028 3859 9055 3882 9062 3887 9058
      3888 9054 3891 9050 3897 9045 3897 9047
      3913 9031 3878 8994
TIME...MOT...LOC 0038Z 233DEG 46KT 3873 9051

HAIL...<.75IN
WIND...60 MPH

$$

BRITT
2 follow-up statements
532 
WWUS53 KLSX 160050
SVSLSX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
750 PM CDT SUN APR 15 2012

ILC083-119-MOC183-189-160130-
/O.CON.KLSX.SV.W.0091.000000T0000Z-120416T0130Z/
JERSEY IL-MADISON IL-ST. CHARLES MO-ST. LOUIS MO-
750 PM CDT SUN APR 15 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHEASTERN
ST. LOUIS...NORTHEASTERN ST. CHARLES...NORTHWESTERN MADISON AND SOUTH
CENTRAL JERSEY COUNTIES UNTIL 830 PM CDT...

AT 749 PM CDT...A LINE OF SEVERE THUNDERSTORMS WAS LOCATED ALONG A
LINE EXTENDING FROM ELSAH TO BERKELEY...AND MOVING NORTHEAST AT 55
MPH.

HAZARD...60 MPH WIND GUSTS.

SOURCE...TRAINED WEATHER SPOTTERS.

IMPACT...MINOR TREE DAMAGE...WITH LIMBS UP TO ONE INCH IN DIAMETER
         BROKEN.

LOCATIONS IMPACTED INCLUDE...
COOL VALLEY...NORTHWOODS...FLORISSANT...FERGUSON...JENNINGS...
DELLWOOD...BLACK JACK...BELLEFONTAINE NEIGHBORS...SPANISH LAKE...
GODFREY...ALTON...WOOD RIVER...EDWARDSVILLE...ELSAH...PORTAGE DES
SIOUX...WEST ALTON...HARTFORD...ROXANA...MCCLUSKY AND DELHI.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. TORNADOES CAN
DEVELOP QUICKLY FROM SEVERE THUNDERSTORMS. ALTHOUGH ONE IS 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.

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
BUILDING.

&&

LAT...LON 3870 9021 3873 9021 3875 9018 3877 9017
      3878 9018 3868 9028 3862 9047 3887 9058
      3888 9054 3891 9050 3897 9045 3897 9047
      3913 9031 3878 8994
TIME...MOT...LOC 0050Z 233DEG 46KT 3895 9038 3874 9033

HAIL...<.75IN
WIND...60 MPH

$$

BRITT
590 
WWUS53 KLSX 160110
SVSLSX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
810 PM CDT SUN APR 15 2012

ILC083-119-MOC183-189-160119-
/O.CAN.KLSX.SV.W.0091.000000T0000Z-120416T0130Z/
JERSEY IL-MADISON IL-ST. CHARLES MO-ST. LOUIS MO-
810 PM CDT SUN APR 15 2012

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN ST. LOUIS...
NORTHEASTERN ST. CHARLES...NORTHWESTERN MADISON AND SOUTH CENTRAL
JERSEY COUNTIES IS CANCELLED...

THE LINE OF STORMS 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 MIDNIGHT CDT.

LAT...LON 3870 9021 3873 9021 3875 9018 3877 9017
      3878 9018 3868 9028 3862 9047 3887 9058
      3888 9054 3891 9050 3897 9045 3897 9047
      3913 9031 3878 8994
TIME...MOT...LOC 0109Z 233DEG 46KT 3909 9013 3888 9008

$$

BRITT

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 15, 7:52 PM CDTSevere Thunderstorm WarningLSXMonroe, Saint Clair38 min
Apr 15, 8:01 PM CDTSevere Thunderstorm WarningLSXJersey, Macoupin, Madison30 min
Apr 16, 6:19 AM CDTRiver Flood WarningLSXSaint Charles6 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2012Severe Thunderstorm Warnings in Missouri, 2012Every severe thunderstorm warning in 2012

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.