Alert archive / Louisiana / Severe Thunderstorm Watches in 2016

Severe Thunderstorm Watch 131

April 30, 201622 parishes in Louisiana; 8 counties in Mississippi

The Storm Prediction Center issued this severe thunderstorm watch at Apr 30, 2016, 11:38 AM CDT for 22 parishes in Louisiana; 8 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Apr 30, 2016, 11:38 AM CDT (16:38 UTC)
Expired: Apr 30, 2016, 7:00 PM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 30 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee 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 Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne 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: 20%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 30%
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: 10%
Six or more combined severe hail and wind reports: 50%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 30, 11:38 AM CDT	Tornado Warning	LIX	Pointe Coupee	37 min
Apr 30, 11:56 AM CDT	Tornado Warning	LIX	Pointe Coupee, West Feliciana	15 min
Apr 30, 12:16 PM CDT	Severe Thunderstorm Warning	LIX	East Baton Rouge, Iberville, Pointe Coupee, West Baton Rouge, West Feliciana	44 min
Apr 30, 12:21 PM CDT	Tornado Warning	LIX	East Feliciana, West Feliciana	24 min
Apr 30, 12:55 PM CDT	Severe Thunderstorm Warning	LIX	East Baton Rouge, East Feliciana, Livingston, Pointe Coupee, West Baton Rouge, West Feliciana	50 min
Apr 30, 1:09 PM CDT	Tornado Warning	LIX	Saint Helena	36 min
Apr 30, 1:11 PM CDT	Tornado Warning	LIX	Tangipahoa	34 min
Apr 30, 1:13 PM CDT	Severe Thunderstorm Warning	LIX	East Feliciana, Saint Helena, Tangipahoa	32 min
Apr 30, 1:23 PM CDT	Tornado Warning	LIX	Tangipahoa	24 min
Apr 30, 1:24 PM CDT	Tornado Warning	LIX	Tangipahoa, Washington	36 min
Apr 30, 1:42 PM CDT	Severe Thunderstorm Warning	LIX	East Feliciana, Saint Helena, Tangipahoa, Washington	33 min
Apr 30, 1:45 PM CDT	Tornado Warning	LIX	East Baton Rouge, Livingston	30 min
Apr 30, 1:57 PM CDT	Tornado Warning	LIX	Pike, Walthall	33 min
Apr 30, 2:14 PM CDT	Severe Thunderstorm Warning	LIX	Ascension, Livingston, Saint Helena, Saint John the Baptist, Saint Tammany, Tangipahoa and 1 more	61 min
Apr 30, 2:40 PM CDT	Tornado Warning	LIX	Tangipahoa	17 min
Apr 30, 3:07 PM CDT	Severe Thunderstorm Warning	LIX	Lafourche, Saint Charles	23 min
Apr 30, 3:13 PM CDT	Severe Thunderstorm Warning	LIX	Saint John the Baptist, Saint Tammany, Tangipahoa, Washington	69 min
Apr 30, 3:16 PM CDT	Severe Thunderstorm Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	89 min
Apr 30, 4:29 PM CDT	Tornado Warning	LIX	Orleans, Saint Tammany	19 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 12:00Z, 4.6 hours before the alert went out and 102 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: 1180 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 565 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 114 m²/s²
0-3 km storm-relative helicity: 97 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 3.9

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 29, 8:56 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more	94 min
Apr 29, 9:58 PM CDT	Severe Thunderstorm Watch	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more	7 hr
Apr 29, 11:42 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 5 more	93 min
Apr 30, 3:23 AM CDT	Mesoscale Discussion	SPC	Beauregard, Bienville, Bossier, Claiborne, De Soto, Lincoln and 5 more	97 min
Apr 30, 5:11 AM CDT	Severe Thunderstorm Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 22 more	9 hr
Apr 30, 7:38 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 2 more	67 min
Apr 30, 10:22 AM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge and 16 more	53 min
Apr 30, 1:35 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 22 more	55 min
Apr 30, 4:00 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, Jefferson, Lafourche, Livingston, Orleans and 10 more	2 hr

Nearby

Severe Thunderstorm Watches in Louisiana, 2016 Severe Thunderstorm Watches in Mississippi, 2016 Every severe thunderstorm watch in 2016

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.