Alert archive / Illinois / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 311, NWS St. Louis, MO

September 25, 2012Clinton County, Saint Clair County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at Sep 25, 2012, 5:12 PM CDT for Clinton County, Saint Clair County, Illinois. It was in force for 18 min. 1 report 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 25, 2012, 5:12 PM CDT (22:12 UTC)
Expired: Sep 25, 2012, 5:30 PM CDT
In force: 18 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

Counties Clinton County, IL, Saint Clair County, IL

The radar

The St Louis radar (KLSX), 91 km from the middle of the area, began a volume at 22:12 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
Sep 25, 5:12 PM CDT	HAIL 1.75	5 E Mascoutah, 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
Sep 25, 5:05 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.2 hours before the alert went out and 207 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: 221 J/kg
Mixed-layer CIN: -192 J/kg
Mixed-layer LCL: 560 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 108 m²/s²
0-3 km storm-relative helicity: 134 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.7

Open this sounding in Storm Lab

The text

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

688 
WUUS53 KLSX 252212
SVRLSX
ILC027-163-252230-
/O.NEW.KLSX.SV.W.0311.120925T2212Z-120925T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
512 PM CDT TUE SEP 25 2012

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHWESTERN CLINTON COUNTY IN SOUTH CENTRAL ILLINOIS...
  EAST CENTRAL ST. CLAIR COUNTY IN SOUTHWEST ILLINOIS...

* UNTIL 530 PM CDT

* AT 508 PM CDT...A SEVERE THUNDERSTORM WAS LOCATED NEAR MASCOUTAH...
  AND MOVING EAST AT 25 MPH.

  HAZARD...PING PONG BALL SIZE HAIL AND 60 MPH WIND GUSTS.

  SOURCE...TRAINED WEATHER SPOTTERS REPORTED PING PONG BALL SIZED 
           HAIL AT MASCOUTAH AT 509 PM.

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

* LOCATIONS IMPACTED INCLUDE...
  NEW MEMPHIS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

THIS STORM IS PRODUCING LARGE HAIL. SEEK SHELTER NOW INSIDE A STURDY
STRUCTURE AND STAY AWAY FROM WINDOWS.

&&

LAT...LON 3847 8959 3847 8962 3845 8980 3853 8982
      3854 8971 3848 8958
TIME...MOT...LOC 2212Z 255DEG 20KT 3850 8973

HAIL...1.50IN
WIND...60 MPH

$$

TES

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 25, 3:38 AM CDT	Severe Thunderstorm Warning	LSX	Bond, Clinton, Fayette, Marion	22 min
Sep 25, 4:36 AM CDT	Areal Flood Advisory	LSX	Pike	5 hr
Sep 25, 4:29 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Madison, Saint Clair	46 min
Sep 25, 4:39 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Saint Clair	51 min
Sep 25, 5:05 PM CDT	Severe Thunderstorm Warning	LSX	Clinton	55 min
Sep 25, 5:07 PM CDT	Tornado Warning	LSX	Clinton	23 min
Sep 25, 5:09 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Jersey, Madison	51 min
Sep 25, 5:19 PM CDT	Tornado Warning	LSX	Washington	26 min
Sep 25, 5:28 PM CDT	Severe Thunderstorm Warning	LSX	Marion	47 min
Sep 25, 5:34 PM CDT	Tornado Warning Tornado observed	LSX	Washington	41 min
Sep 25, 5:43 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Washington	62 min
Sep 25, 6:08 PM CDT	Severe Thunderstorm Warning	LSX	Madison, Monroe, Saint Clair	52 min
Sep 25, 6:14 PM CDT	Severe Thunderstorm Warning	LSX	Washington	46 min
Sep 25, 6:19 PM CDT	Areal Flood Advisory	LSX	Clinton, Marion, Washington	6 hr
Sep 25, 6:30 PM CDT	Severe Thunderstorm Warning	LSX	Marion	26 min
Sep 25, 6:45 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Madison, Marion, Washington	45 min
Sep 25, 6:50 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Saint Clair	46 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2012 Every 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.