Alert archive / Missouri / Tornado Warnings in 2012

Tornado Warning 20, NWS St. Louis, MO

August 31, 2012Lincoln County, Saint Charles County, Missouri

NWS St. Louis, MO issued this tornado warning at Aug 31, 2012, 5:34 PM CDT for Lincoln County, Saint Charles County, Missouri. It was in force for 11 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, 5:34 PM CDT (22:34 UTC)
Expired: Aug 31, 2012, 5:45 PM CDT
In force: 11 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Lincoln County, MO, Saint Charles County, MO

The radar

The St Louis radar (KLSX), 25 km from the middle of the area, began a volume at 22:36 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.

Issued	Product	Office	Lasted
Aug 31, 1:56 PM CDT	Tornado Watch	SPC	8 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.6 hours before the alert went out and 224 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: 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.

957 
WFUS53 KLSX 312234
TORLSX
MOC113-183-312300-
/O.NEW.KLSX.TO.W.0020.120831T2234Z-120831T2300Z/

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

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHEASTERN LINCOLN COUNTY IN EAST CENTRAL MISSOURI...
  NORTH CENTRAL ST. CHARLES COUNTY IN EAST CENTRAL MISSOURI...

* UNTIL 600 PM CDT

* AT 532 PM CDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A
  TORNADO WAS LOCATED NEAR O'FALLON...AND MOVING NORTH AT 25 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...
  ST. PAUL AND WINFIELD.

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 3899 9068 3893 9067 3889 9062 3880 9061
      3880 9073 3901 9075 3901 9069
TIME...MOT...LOC 2234Z 175DEG 22KT 3882 9067

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

$$

BROWNING

1 follow-up statement

430 
WWUS53 KLSX 312245
SVSLSX

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

MOC113-183-312255-
/O.CAN.KLSX.TO.W.0020.000000T0000Z-120831T2300Z/
LINCOLN MO-ST. CHARLES MO-
545 PM CDT FRI AUG 31 2012

...THE TORNADO WARNING FOR NORTH CENTRAL ST. CHARLES AND SOUTHEASTERN
LINCOLN 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 3899 9068 3893 9067 3889 9062 3880 9061
      3880 9073 3901 9075 3901 9069
TIME...MOT...LOC 2245Z 175DEG 22KT 3889 9068

$$

BROWNING

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 2:48 PM CDT	Tornado Warning	LSX	Saint Charles, Saint Louis	17 min
Aug 31, 6:52 PM CDT	Areal Flood Advisory	LSX	Audrain	3 hr

Nearby

Tornado Warnings in Missouri, 2012 Every tornado warning in 2012 Tornadoes 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.