Alert archive / Illinois / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 301, NWS St. Louis, MO

September 7, 2012Clinton County, Saint Clair County, Washington County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Sep 7, 2012, 6:50 PM CDT for Clinton County, Saint Clair County, Washington County, Illinois. It was in force for 40 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
Sep 7, 2012, 6:50 PM CDT (23:50 UTC)
Expired
Sep 7, 2012, 7:30 PM CDT
In force
40 min
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

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

The radar

The St Louis radar (KLSX), 115 km from the middle of the area, began a volume at 23:51 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
Sep 7, 7:08 PM CDTTSTM WND DMGNashville, ILNUMEROUS TREES OF UNKNOWN SIZE BLOWN DOWN ALONG RT 15 NEAR THREE WAY FARMS. TIME ESTIMATED FROM RADAR.
Sep 7, 7:15 PM CDTTSTM WND DMGNashville, ILONE TO TWO INCH TREE LIMBS BLOWN DOWN AROUND TOWN.

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
Sep 7, 2:35 PM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 11.8 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 12:00Z on 2012-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 367 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 2012-09-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 93 square meters per square second.19395878Sfc1 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
367 J/kg
Mixed-layer CIN
-412 J/kg
Mixed-layer LCL
1436 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
93 m²/s²
0-3 km storm-relative helicity
102 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

The text

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

035 
WUUS53 KLSX 072350
SVRLSX
ILC027-163-189-080030-
/O.NEW.KLSX.SV.W.0301.120907T2350Z-120908T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
650 PM CDT FRI SEP 7 2012

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHERN CLINTON COUNTY IN SOUTH CENTRAL ILLINOIS...
  SOUTHEASTERN ST. CLAIR COUNTY IN SOUTHWEST ILLINOIS...
  WASHINGTON COUNTY IN SOUTH CENTRAL ILLINOIS...

* UNTIL 730 PM CDT

* AT 647 PM CDT...A LINE OF SEVERE THUNDERSTORMS WAS LOCATED ALONG A
  LINE EXTENDING FROM CARLYLE TO OKAWVILLE TO NEW ATHENS...AND MOVING
  SOUTHEAST AT 30 MPH.

  HAZARD...60 MPH WIND GUSTS AND PENNY SIZE HAIL.

  SOURCE...RADAR INDICATED.

  IMPACT...MINOR DAMAGE TO VEHICLES...ROOFS AND WINDOWS. MINOR TREE
           DAMAGE...WITH LIMBS UP TO ONE INCH IN DIAMETER BROKEN.

* LOCATIONS IMPACTED INCLUDE...
  NASHVILLE...OKAWVILLE...LIVELY GROVE...WAMAC...IRVINGTON...
  ASHLEY...VENEDY...ST. LIBORY...JOHANNISBURG...POSEY...FROGTOWN...
  COVINGTON...STONE CHURCH...HOFFMAN...ADDIEVILLE...NEW MINDEN...
  HOYLETON...HUEGELY...ELKTON AND CORDES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

TO REPORT SEVERE WEATHER CONTACT YOUR NEAREST LAW ENFORCEMENT AGENCY.
THEY WILL SEND YOUR REPORT TO THE NATIONAL WEATHER SERVICE IN ST
LOUIS.

&&

LAT...LON 3821 8915 3822 8970 3836 8985 3847 8960
      3859 8941 3852 8914
TIME...MOT...LOC 2350Z 294DEG 26KT 3858 8936 3843 8959
          3834 8983

HAIL...0.75IN
WIND...60 MPH

$$

TES
1 follow-up statement
452 
WWUS53 KLSX 080032
SVSLSX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
732 PM CDT FRI SEP 7 2012

ILC027-163-189-080042-
/O.EXP.KLSX.SV.W.0301.000000T0000Z-120908T0030Z/
ST. CLAIR IL-WASHINGTON IL-CLINTON IL-
732 PM CDT FRI SEP 7 2012

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN CLINTON...WASHINGTON
AND SOUTHEASTERN ST. CLAIR COUNTIES HAS EXPIRED...

THE LINE OF STORMS WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE
WARNED AREA.  HOWEVER GUSTY WINDS ARE STILL POSSIBLE WITH THESE
THUNDERSTORMS.

IN ADDITION...STRONG THUNDERSTORMS MAY REDEVELOP...AND A SEVERE 
THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 10 PM CDT.

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
IN ST LOUIS.

LAT...LON 3821 8915 3822 8970 3836 8985 3847 8960
      3859 8941 3852 8914
TIME...MOT...LOC 2350Z 294DEG 26KT 3858 8936 3843 8959
          3834 8983

$$

TES

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 7, 3:36 PM CDTSevere Thunderstorm WarningLSXCalhoun54 min
Sep 7, 4:00 PM CDTSevere Thunderstorm WarningLSXGreene, Jersey45 min
Sep 7, 4:11 PM CDTSevere Thunderstorm WarningLSXMonroe24 min
Sep 7, 4:32 PM CDTSevere Thunderstorm WarningLSXMacoupin43 min
Sep 7, 4:58 PM CDTSevere Thunderstorm WarningLSXSaint Clair, Washington47 min
Sep 7, 5:36 PM CDTSevere Thunderstorm WarningLSXBond, Madison, Montgomery54 min

Nearby

Severe Thunderstorm Warnings in Illinois, 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.