Alert archive / Louisiana / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 65, NWS New Orleans, LA

April 12, 20094 parishes in Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Apr 12, 2009, 2:24 PM CDT for 4 parishes in Louisiana. It was in force for 66 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Apr 12, 2009, 2:24 PM CDT (19:24 UTC)
Expired: Apr 12, 2009, 3:30 PM CDT
In force: 66 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon

Counties Iberville Parish, LA, Pointe Coupee Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA

The watch it was issued in

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

Issued	Product	Office	Lasted
Apr 12, 1:53 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 7.4 hours before the alert went out and 178 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: 880 J/kg
Mixed-layer CIN: -259 J/kg
Mixed-layer LCL: 506 m above ground
0-6 km bulk shear: 49 kt
0-1 km storm-relative helicity: 326 m²/s²
0-3 km storm-relative helicity: 463 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS New Orleans, LA wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 12, 12:52 PM CDT, 1 hour 32 minutes earlier.

Area forecast discussion, Apr 12, 12:52 PM CDT, 1 hour 32 minutes before

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Hazardous weather outlook, Apr 12, 10:59 AM CDT, 3 hours 25 minutes before

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In the hours before

Special weather statement, Apr 12, 9:06 AM CDT, 5 hours 18 minutes before

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Special weather statement, Apr 12, 2:04 PM CDT, 20 minutes before

LAZ034>037-046>050-056-057-MSZ068-069-122100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
204 PM CDT SUN APR 12 2009

...LINE OF STRONG THUNDERSTORMS MOVING EAST TOWARDS IBERVILLE
   PARISH...POINTE COUPEE PARISH...EAST FELICIANA
   PARISH...LIVINGSTON PARISH...EAST BATON ROUGE PARISH...ASSUMPTION
   PARISH...ST. HELENA PARISH...WEST BATON ROUGE PARISH...ST. JAMES
   PARISH...ASCENSION PARISH...AMITE COUNTY...WILKINSON
   COUNTY...WEST FELICIANA PARISH...

AT 158 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF STRONG THUNDERSTORMS FROM 43 MILES NORTHWEST OF NEW ROADS TO
72 MILES WEST OF PLAQUEMINE...MOVING EAST AT 40 MPH.

THE LINE OF STRONG THUNDERSTORMS WILL BE NEAR...
  LETTSWORTH BY 235 PM...
  BATCHELOR BY 240 PM...
  LOTTIE BY 245 PM...
  MORGANZA AND LOTTIE BY 250 PM...
  LIVONIA BY 255 PM...
  NEW ROADS AND MARINGOUIN BY 300 PM...

THE PRIMARY THREAT FROM THESE STORMS IS WIND GUSTS NEAR 50 MPH...
WHICH COULD DOWN TREE LIMBS AND BLOW AROUND UNSECURED SMALL OBJECTS.
SEEK SHELTER IN A SAFE HOME OR BUILDING UNTIL THESE STORMS HAVE
PASSED. SEVERE THUNDERSTORMS AND ISOLATED TORNADOES MAY OCCUR WITH
THIS STRONG SQUALL LINE PASSAGE.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM SUNDAY EVENING FOR
SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. STAY TUNED FOR LATER
STATEMENTS AND POSSIBLE WARNINGS FOR YOUR AREA THIS AFTERNOON.

24/RR

The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 12, 3:45 AM CDT	Small Craft Advisory	LIX		29 hr
Apr 12, 3:03 PM CDT	Coastal Flood Statement	LIX	Saint Bernard	10 hr
Apr 12, 5:38 PM CDT	Severe Thunderstorm Warning	LIX	Pointe Coupee	18 min
Apr 12, 5:54 PM CDT	Severe Thunderstorm Warning	LIX	Pointe Coupee, West Feliciana	18 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2009 Every severe thunderstorm warning in 2009

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.