Alert archive / Louisiana / Tornado Watches in 2014

Tornado Watch 17

February 20, 201438 parishes in Louisiana; 8 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Feb 20, 2014, 7:22 PM CST for 38 parishes in Louisiana; 8 counties in Mississippi. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued: Feb 20, 2014, 7:22 PM CST (01:22 UTC)
Expired: Feb 21, 2014, 3:00 AM CST
In force: 8 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 46 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Pike County, MS, Walthall 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: 30%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Feb 20, 7:41 PM CST	Severe Thunderstorm Warning	LIX	Tangipahoa, Washington	64 min
Feb 20, 8:51 PM CST	Severe Thunderstorm Warning	LCH	Avoyelles, Evangeline, Saint Landry	39 min
Feb 20, 9:18 PM CST	Severe Thunderstorm Warning	LIX	East Feliciana, Pointe Coupee, West Feliciana	27 min
Feb 20, 9:46 PM CST	Tornado Warning	LIX	Walthall	14 min
Feb 20, 10:55 PM CST	Tornado Warning	LIX	Walthall	20 min
Feb 21, 1:15 AM CST	Severe Thunderstorm Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard	15 min
Feb 21, 1:30 AM CST	Severe Thunderstorm Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard	30 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

Lake Charles Mun, LA (KLCH), launched 00:00Z, 1.4 hours before the alert went out and 155 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: 2092 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 438 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 141 m²/s²
0-3 km storm-relative helicity: 134 m²/s²
Significant tornado parameter: 1.7
Supercell composite: 7.1

Open this sounding in Storm Lab

The text

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

324 
WWUS20 KWNS 210126
SEL7  
SPC WW 210126
LAZ000-MSZ000-CWZ000-210900-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 17
NWS STORM PREDICTION CENTER NORMAN OK
725 PM CST THU FEB 20 2014

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF 
  SOUTHERN LOUISIANA
  SOUTHERN MISSISSIPPI
  COASTAL WATERS

* EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 725 PM
  UNTIL 300 AM CST.

* PRIMARY THREATS INCLUDE...
  SEVERAL TORNADOES POSSIBLE
  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
  A FEW LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 125 STATUTE
MILES EAST AND WEST OF A LINE FROM 40 MILES EAST NORTHEAST OF
BATON ROUGE LOUISIANA TO 30 MILES SOUTH OF INTRACOASTAL CITY
LOUISIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 9...WW 11...WW 13...WW
14...WW 15...WW 16...

DISCUSSION...TSTMS EXPECTED TO PERSIST AND POSSIBLY INCREASE OVER
SRN LA AND ADJACENT MS THROUGH EARLY FRI AS REGION IS GLANCED BY SRN
FRINGE OF SECONDARY UPR IMPULSE /NOW OVER OK/ ROTATING THROUGH BASE
OF LARGER-SCALE MIDWESTERN TROUGH. QUALITY OF LOW-LVL MOISTURE
INFLOW AND MODEST LOW-LVL CONFLUENCE/FORCING FOR ASCENT THAT WILL
DIMINISH LIKELIHOOD FOR STRONGLY-LINEAR CONVECTION SUGGEST A
CONDITIONAL RISK FOR A TORNADO OR TWO...IN ADDITION TO DMGG WIND AND
PERHAPS SVR HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24035.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 20, 6:05 PM CST	Tornado Watch	SPC	East Feliciana, Pointe Coupee, Saint Helena, Saint Landry, Tangipahoa, Washington and 1 more	7 hr
Feb 20, 6:55 PM CST	Mesoscale Discussion	SPC	Allen, Beauregard, Calcasieu, Caldwell, Catahoula, East Carroll and 14 more	95 min
Feb 20, 9:56 PM CST	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Avoyelles, Cameron, Concordia and 26 more	2 hr
Feb 20, 11:43 PM CST	Mesoscale Discussion	SPC	Saint Helena, Washington	62 min
Feb 20, 8:01 PM CST	Mesoscale Discussion	SPC	Itawamba, Tishomingo	89 min
Feb 21, 12:58 AM CST	Severe Thunderstorm Watch	SPC	George, Greene	7 hr

Nearby

Tornado Watches in Louisiana, 2014 Tornado Watches in Mississippi, 2014 Every tornado watch in 2014

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.