Alert archive / Louisiana / Tornado Watches in 2012
Tornado Watch 96
The Storm Prediction Center issued this tornado watch at Mar 21, 2012, 5:04 AM CDT for 39 parishes in Louisiana; 9 counties in Mississippi. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 21, 2012, 5:04 AM CDT (10:04 UTC)
- Expired
- Mar 21, 2012, 12:00 PM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 48 counties
Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jackson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tensas Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, West Baton Rouge Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Franklin County, MS, Issaquena County, MS, Jefferson County, MS, Sharkey County, MS, Warren County, MS, Wilkinson County, MS
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
36 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 21, 5:17 AM CDT | Tornado Warning | LCH | Vermilion | 28 min |
| Mar 21, 5:34 AM CDT | Severe Thunderstorm Warning | LCH | Acadia, Evangeline, Lafayette, Saint Landry, Vermilion | 56 min |
| Mar 21, 5:41 AM CDT | Tornado Warning | SHV | Jackson, Winn | 34 min |
| Mar 21, 5:51 AM CDT | Tornado Warning | LCH | Lafayette, Vermilion | 24 min |
| Mar 21, 6:47 AM CDT | Flash Flood Warning | SHV | Grant, Natchitoches, Red River, Sabine, Winn | 4 hr |
| Mar 21, 7:20 AM CDT | Severe Thunderstorm Warning | LCH | Iberia, Saint Martin, St. Mary | 39 min |
| Mar 21, 7:24 AM CDT | Severe Thunderstorm Warning | LCH | Iberia, Saint Martin | 47 min |
| Mar 21, 7:29 AM CDT | Tornado Warning | JAN | Catahoula, Concordia | 46 min |
| Mar 21, 7:34 AM CDT | Severe Thunderstorm Warning | LIX | East Baton Rouge, Iberville, Livingston, Pointe Coupee, West Baton Rouge, West Feliciana | 56 min |
| Mar 21, 8:10 AM CDT | Severe Thunderstorm Warning | LCH | Iberia, Saint Martin, St. Mary | 65 min |
| Mar 21, 8:30 AM CDT | Severe Thunderstorm Warning | LIX | Ascension, Assumption, East Baton Rouge, Iberville | 60 min |
| Mar 21, 8:32 AM CDT | Severe Thunderstorm Warning | LIX | East Baton Rouge, East Feliciana, Iberville, Pointe Coupee, West Baton Rouge, West Feliciana | 58 min |
| Mar 21, 8:49 AM CDT | Tornado Warning | LIX | Ascension, Assumption, Iberville, Saint James | 38 min |
| Mar 21, 9:03 AM CDT | Tornado Warning | JAN | Catahoula, Franklin | 42 min |
| Mar 21, 9:10 AM CDT | Severe Thunderstorm Warning | LIX | East Baton Rouge, East Feliciana, Saint Helena, West Feliciana | 65 min |
| Mar 21, 9:18 AM CDT | Severe Thunderstorm Warning | LIX | Ascension, Assumption, Lafourche, Saint James, Terrebonne | 57 min |
| Mar 21, 9:19 AM CDT | Tornado Warning | LIX | Ascension, East Baton Rouge, Iberville, Livingston | 26 min |
| Mar 21, 9:36 AM CDT | Severe Thunderstorm Warning | LIX | Ascension, Livingston, Saint Helena, Tangipahoa | 54 min |
| Mar 21, 9:38 AM CDT | Severe Thunderstorm Warning | JAN | Richland | 41 min |
| Mar 21, 9:42 AM CDT | Severe Thunderstorm Warning | JAN | Adams | 40 min |
| Mar 21, 9:49 AM CDT | Flash Flood Warning | JAN | Franklin, Richland | 116 min |
| Mar 21, 9:49 AM CDT | Tornado Warning | LIX | East Baton Rouge, East Feliciana, Livingston, Saint Helena | 56 min |
| Mar 21, 10:07 AM CDT | Severe Thunderstorm Warning | LIX | Jefferson, Lafourche, Saint Charles, Saint John the Baptist, Saint Tammany, Tangipahoa and 1 more | 53 min |
| Mar 21, 10:16 AM CDT | Tornado Warning | LIX | Livingston, Saint John the Baptist, Tangipahoa | 44 min |
| Mar 21, 10:18 AM CDT | Severe Thunderstorm Warning | JAN | Franklin, Jefferson | 42 min |
| Mar 21, 10:24 AM CDT | Severe Thunderstorm Warning | LIX | Livingston, Saint Helena, Tangipahoa, Washington | 51 min |
| Mar 21, 10:24 AM CDT | Tornado Warning | JAN | Jefferson | 27 min |
| Mar 21, 10:29 AM CDT | Tornado Warning | JAN | Claiborne, Jefferson | 40 min |
| Mar 21, 10:35 AM CDT | Severe Thunderstorm Warning | JAN | Franklin, Lincoln | 55 min |
| Mar 21, 10:35 AM CDT | Severe Thunderstorm Warning | LIX | Amite, Pike | 55 min |
| Mar 21, 10:48 AM CDT | Severe Thunderstorm Warning | JAN | Madison | 57 min |
| Mar 21, 10:51 AM CDT | Flash Flood Warning | SHV | Grant, Natchitoches, Winn | 3 hr |
| Mar 21, 10:55 AM CDT | Tornado Warning | JAN | Claiborne, Warren | 33 min |
| Mar 21, 11:05 AM CDT | Severe Thunderstorm Warning | LIX | Jefferson, Lafourche, Saint Charles, Saint John the Baptist, Tangipahoa, Terrebonne | 55 min |
| Mar 21, 11:32 AM CDT | Severe Thunderstorm Warning | JAN | Issaquena, Sharkey, Yazoo | 58 min |
| Mar 21, 11:52 AM CDT | Severe Thunderstorm Warning | LIX | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles | 53 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Slidell Radar S, LA (KSIL), launched 00:00Z, 10.1 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.
- Mixed-layer CAPE
- 1474 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 578 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 151 m²/s²
- 0-3 km storm-relative helicity
- 239 m²/s²
- Significant tornado parameter
- 1.2
- Supercell composite
- 8.0
The text
As transmitted, in the capitals the NWS used until 2016.
187
WWUS20 KWNS 211005
SEL6
SPC WW 211005
LAZ000-MSZ000-CWZ000-211700-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 96
NWS STORM PREDICTION CENTER NORMAN OK
505 AM CDT WED MAR 21 2012
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
CENTRAL AND EASTERN LOUISIANA
SOUTHWEST MISSISSIPPI
COASTAL WATERS
EFFECTIVE THIS WEDNESDAY MORNING FROM 505 AM UNTIL NOON CDT.
TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 35 MILES SOUTHEAST OF
INTRACOASTAL CITY LOUISIANA TO 50 MILES NORTHEAST OF MONROE
LOUISIANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 95...
DISCUSSION...N-S CONVECTIVE BAND /WITH EMBEDDED SUPERCELLS/ IS
EXPECTED TO MIGRATE VERY SLOWLY EWD ACROSS THE WATCH AREA THIS
MORNING...DOWNSTREAM FROM DEEP-LAYER CYCLONE OVER THE SRN PLAINS.
THE PRESENCE OF A 40+ KT SLY LLJ WILL MAINTAIN A FEED OF HIGH
THETA-E AIR INTO ONGOING STORMS...AS WELL AS ENHANCE LOW-LEVEL
SHEAR. AS SUCH...A RISK FOR A FEW TORNADOES AND LOCALLY DAMAGING
WIND GUSTS WILL CONTINUE.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400.
MEAN STORM MOTION VECTOR 20030.
...MEADSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 20, 8:02 PM CDT | Tornado Watch | SPC | Beauregard, Calcasieu, Cameron, Vernon | 4 hr |
| Mar 20, 10:23 PM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Jefferson Davis, Natchitoches, Vernon | 67 min |
| Mar 20, 10:59 PM CDT | Tornado Watch | SPC | Acadia, Allen, Beauregard, Bienville, Calcasieu, Caldwell and 17 more | 7 hr |
| Mar 21, 2:17 AM CDT | Mesoscale Discussion | SPC | Acadia, Avoyelles, Caldwell, Catahoula, Concordia, Evangeline and 17 more | 118 min |
| Mar 21, 4:38 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Avoyelles, Catahoula, Concordia, East Baton Rouge and 19 more | 97 min |
| Mar 21, 7:48 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Avoyelles, East Baton Rouge, East Feliciana, Iberville and 10 more | 87 min |
| Mar 21, 9:25 AM CDT | Mesoscale Discussion | SPC | Ascension, Concordia, East Baton Rouge, East Carroll, East Feliciana, Franklin and 17 more | 95 min |
| Mar 21, 10:07 AM CDT | Tornado Watch | SPC | Ascension, East Carroll, East Feliciana, Franklin, Jefferson, Lafourche and 17 more | 8 hr |
| Mar 21, 12:19 PM CDT | Mesoscale Discussion | SPC | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Tammany and 1 more | 86 min |
| Mar 21, 3:47 PM CDT | Mesoscale Discussion | SPC | Saint Bernard | 88 min |
| Mar 21, 5:40 PM CDT | Mesoscale Discussion | SPC | Orleans, Plaquemines, Saint Bernard | 35 min |
| Mar 21, 6:02 PM CDT | Tornado Watch | SPC | Plaquemines, Saint Bernard | 9 hr |
Nearby
Tornado Watches in Louisiana, 2012Tornado Watches in Mississippi, 2012Every tornado watch 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.