Alert archive / Missouri / Tornado Warnings in 2012

Tornado Warning 18, NWS St. Louis, MO

August 31, 2012Saint Charles County, Saint Louis County, Missouri; Madison County, Illinois

NWS St. Louis, MO issued this tornado warning at Aug 31, 2012, 2:48 PM CDT for Saint Charles County, Saint Louis County, Missouri; Madison County, Illinois. It was in force for 17 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 31, 2012, 2:48 PM CDT (19:48 UTC)
Expired
Aug 31, 2012, 3:05 PM CDT
In force
17 min
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Tornado
Radar indicated
Hail
0.75 in

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

The radar

The St Louis radar (KLSX), 47 km from the middle of the area, began a volume at 19:51 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 31, 1:56 PM CDTTornado WatchSPC8 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 7.8 hours before the alert went out and 202 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 2012-08-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 947 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 2012-08-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -60 square meters per square second.1939Sfc1 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
947 J/kg
Mixed-layer CIN
-143 J/kg
Mixed-layer LCL
1049 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
-60 m²/s²
0-3 km storm-relative helicity
-45 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.3

Open this sounding in Storm Lab

The text

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

881 
WFUS53 KLSX 311948
TORLSX
ILC119-MOC183-189-312015-
/O.NEW.KLSX.TO.W.0018.120831T1948Z-120831T2015Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
248 PM CDT FRI AUG 31 2012

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* TORNADO WARNING FOR...
  WESTERN MADISON COUNTY IN SOUTHWEST ILLINOIS...
  EXTREME NORTHEASTERN ST. CHARLES COUNTY IN EAST CENTRAL MISSOURI...
  NORTHEASTERN ST. LOUIS COUNTY IN EAST CENTRAL MISSOURI...

* UNTIL 315 PM CDT

* AT 246 PM CDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A
  TORNADO WAS LOCATED NEAR HARTFORD...AND MOVING NORTH AT 30 MPH.

  HAZARD...DEVELOPING TORNADO.

  SOURCE...RADAR INDICATED ROTATION.

  IMPACT...SIGNIFICANT HOUSE AND BUILDING DAMAGE POSSIBLE. MOBILE
           HOMES COMPLETELY DESTROYED IF HIT. SOME TREES UPROOTED OR
           SNAPPED. VEHICLES WILL LIKELY BE THROWN BY TORNADIC WINDS.

* LOCATIONS IMPACTED INCLUDE...
  WOOD RIVER...BETHALTO...ALTON...GODFREY...HARTFORD...ROXANA...WEST
  ALTON AND FOSTERBURG.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 3868 9019 3870 9021 3873 9021 3875 9018
      3877 9017 3873 9022 3898 9025 3899 9003
      3898 9002 3869 8999
TIME...MOT...LOC 1948Z 175DEG 25KT 3879 9012

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

BROWNING
1 follow-up statement
974 
WWUS53 KLSX 312005
SVSLSX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
305 PM CDT FRI AUG 31 2012

ILC119-MOC183-189-312015-
/O.CAN.KLSX.TO.W.0018.000000T0000Z-120831T2015Z/
MADISON IL-ST. CHARLES MO-ST. LOUIS MO-
305 PM CDT FRI AUG 31 2012

...THE TORNADO WARNING FOR EXTREME NORTHEASTERN ST. LOUIS...EXTREME
NORTHEASTERN ST. CHARLES AND WESTERN MADISON COUNTIES IS CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR PROPERTY.

ADDITIONAL STRONG THUNDERSTORMS ARE STILL POSSIBLE...AND A TORNADO 
WATCH REMAINS IN EFFECT UNTIL 10 PM CDT.

LAT...LON 3868 9019 3870 9021 3873 9021 3875 9018
      3877 9017 3873 9022 3898 9025 3899 9003
      3898 9002 3869 8999
TIME...MOT...LOC 2005Z 175DEG 25KT 3891 9013

$$

BROWNING

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 5:34 PM CDTTornado WarningLSXLincoln, Saint Charles11 min
Aug 31, 6:52 PM CDTAreal Flood AdvisoryLSXAudrain3 hr
Aug 31, 2:44 PM CDTTornado WarningLSXGreene, Jersey, Pike31 min
Aug 31, 3:27 PM CDTTornado WarningLSXGreene, Pike48 min

Nearby

Tornado Warnings in Missouri, 2012Tornado Warnings in Illinois, 2012Every tornado warning in 2012Tornadoes 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.