Alert archive / Louisiana / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 18, NWS New Orleans, LA

April 9, 20208 parishes in Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Apr 9, 2020, 9:43 PM CDT for 8 parishes in Louisiana. It was in force for 47 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 9, 2020, 9:43 PM CDT (02:43 UTC)
Expired: Apr 9, 2020, 10:30 PM CDT
In force: 47 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, Iberville Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Saint James Parish, LA, West Baton Rouge Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 2.7 hours before the alert went out and 121 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: 2230 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 1009 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: -28 m²/s²
0-3 km storm-relative helicity: 59 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -0.4

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 9, 7:28 PM CDT, 2 hours 15 minutes earlier.

Area forecast discussion, Apr 9, 7:28 PM CDT, 2 hours 15 minutes before

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In the hours before

Special weather statement, Apr 9, 8:48 PM CDT, 55 minutes before

Special Weather Statement
National Weather Service New Orleans LA
848 PM CDT Thu Apr 9 2020

LAZ034-046-047-100215-
Iberville-Pointe Coupee-West Baton Rouge-
848 PM CDT Thu Apr 9 2020

...A STRONG THUNDERSTORM WILL AFFECT WEST CENTRAL WEST BATON ROUGE...
SOUTHERN POINTE COUPEE AND NORTHWESTERN IBERVILLE PARISHES...

At 848 PM CDT, a strong thunderstorm was located over Lottie, or 7
miles east of Krotz Springs, moving east at 40 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Livonia, Maringouin, Fordoche, Rosedale, Lottie and Erwinville.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 3064 9174 3062 9138 3043 9141 3046 9144
      3047 9167 3050 9171 3050 9175 3051 9175
      3051 9173 3056 9176 3061 9176
TIME...MOT...LOC 0148Z 277DEG 36KT 3052 9163

KLG

Special weather statement, Apr 9, 9:26 PM CDT, 17 minutes before

Special Weather Statement
National Weather Service New Orleans LA
926 PM CDT Thu Apr 9 2020

LAZ034-047-048-100315-
Pointe Coupee-West Baton Rouge-East Baton Rouge-
926 PM CDT Thu Apr 9 2020

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL WEST BATON ROUGE...
SOUTHEASTERN POINTE COUPEE AND CENTRAL EAST BATON ROUGE PARISHES...

At 926 PM CDT, a strong thunderstorm was located near Erwinville, or
8 miles west of Port Allen, moving east at 35 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Baton Rouge, Baker, Merrydale, Erwinville, Brownfields, Greenwell
Spring and Baton Rouge Airport.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 3061 9145 3061 9095 3058 9099 3056 9097
      3052 9098 3051 9097 3047 9098 3046 9144
      3048 9145 3047 9146 3048 9148
TIME...MOT...LOC 0226Z 269DEG 31KT 3048 9134

KLG

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 9, 8:39 PM CDT	Severe Thunderstorm Warning	LIX	Iberville	36 min
Apr 9, 8:48 PM CDT	Special Weather Statement	LIX	Pointe Coupee	27 min
Apr 9, 9:08 PM CDT	Severe Thunderstorm Warning	LIX	East Baton Rouge, Iberville, West Baton Rouge	37 min
Apr 9, 9:26 PM CDT	Special Weather Statement	LIX	East Baton Rouge, West Baton Rouge	49 min
Apr 9, 9:50 PM CDT	Special Weather Statement	LIX	East Baton Rouge, Saint Helena, Tangipahoa	55 min
Apr 9, 10:26 PM CDT	Special Weather Statement	LIX	Ascension, Assumption, Saint James, Saint John the Baptist	49 min
Apr 9, 10:30 PM CDT	Special Weather Statement	LIX	Livingston, Saint Tammany, Tangipahoa, Washington	45 min
Apr 9, 10:33 PM CDT	Special Marine Warning	LIX		87 min
Apr 9, 10:46 PM CDT	Special Weather Statement	LIX	Saint Tammany	59 min
Apr 9, 11:14 PM CDT	Special Weather Statement	LIX	Orleans	46 min
Apr 9, 11:23 PM CDT	Severe Thunderstorm Warning	LIX	Orleans, Saint Tammany	37 min
Apr 9, 11:25 PM CDT	Special Marine Warning	LIX		61 min
Apr 9, 11:32 PM CDT	Severe Thunderstorm Warning	LIX	Orleans, Saint Bernard	43 min
Apr 10, 12:07 AM CDT	Special Marine Warning	LIX		109 min
Apr 10, 4:04 PM CDT	Small Craft Advisory	LIX		54 hr
Apr 9, 11:49 PM CDT	Special Weather Statement	LIX	Hancock, Harrison, Jackson	56 min
Apr 10, 12:04 AM CDT	Special Weather Statement	LIX	Jackson	56 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2020 Every severe thunderstorm warning in 2020

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.