Alert archive / Louisiana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 104, NWS New Orleans, LA

May 11, 20214 parishes in Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at May 11, 2021, 10:37 PM CDT for 4 parishes in Louisiana. It was in force for 30 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 11, 2021, 10:37 PM CDT (03:37 UTC)
Expired: May 11, 2021, 11:07 PM CDT
In force: 30 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, Iberville Parish, LA, Saint James Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 3.6 hours before the alert went out and 143 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: 618 J/kg
Mixed-layer CIN: -59 J/kg
Mixed-layer LCL: 924 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 212 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 4.7

Open this sounding in Storm Lab

The text

As transmitted.

425 
WUUS54 KLIX 120337
SVRLIX
LAC005-007-047-093-120445-
/O.NEW.KLIX.SV.W.0104.210512T0337Z-210512T0445Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service New Orleans LA
1037 PM CDT Tue May 11 2021

The National Weather Service in New Orleans has issued a

* Severe Thunderstorm Warning for...
  Western Ascension Parish in southeastern Louisiana...
  Northern St. James Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Northern Assumption Parish in southeastern Louisiana...

* Until 1145 PM CDT.

* At 1037 PM CDT, a severe thunderstorm was located over Pierre Part,
  or near Belle River, moving northeast at 25 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Gonzales, Donaldsonville, Napoleonville, St. Gabriel, White Castle,
  Sorrento, Paincourtville, Geismar, Convent and Belle Rose.

This includes Interstate 10 in Louisiana between mile markers 174 and
187.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3030 9094 3005 9071 2984 9117 2986 9120
      2990 9121 2992 9123 2993 9123 2997 9126
      3000 9126 3000 9123 3004 9122 3003 9124
      3006 9127 3006 9134
TIME...MOT...LOC 0337Z 236DEG 26KT 2998 9117 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

LN

1 follow-up statement

292 
WWUS54 KLIX 120407
SVSLIX

Severe Weather Statement
National Weather Service New Orleans LA
1107 PM CDT Tue May 11 2021

LAC005-007-047-093-120417-
/O.CAN.KLIX.SV.W.0104.000000T0000Z-210512T0445Z/
Ascension LA-St. James LA-Iberville LA-Assumption LA-
1107 PM CDT Tue May 11 2021

...THE SEVERE THUNDERSTORM WARNING FOR WESTERN ASCENSION...NORTHERN
ST. JAMES...SOUTHEASTERN IBERVILLE AND NORTHERN ASSUMPTION PARISHES
IS CANCELLED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been cancelled but a new severe 
thunderstorm warning has been issued to the southeast. 

LAT...LON 3030 9094 3005 9071 2984 9117 2986 9120
      2990 9121 2992 9123 2993 9123 2997 9126
      3000 9126 3000 9123 3004 9122 3003 9124
      3006 9127 3006 9134
TIME...MOT...LOC 0405Z 236DEG 26KT 2991 9128 

$$

LN

The office that day

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

Issued	Product	Office	Counties	Lasted
May 11, 8:49 PM CDT	River Flood Warning	LIX	Saint Tammany	14 hr
May 11, 9:24 PM CDT	Special Weather Statement	LIX	Assumption	51 min
May 11, 10:15 PM CDT	Special Weather Statement	LIX	Ascension	30 min
May 11, 10:35 PM CDT	Special Weather Statement	LIX	Ascension, Assumption, Saint James	40 min
May 11, 10:38 PM CDT	Flash Flood Warning	LIX	Ascension, Assumption, Iberville, Saint James	3 hr
May 11, 11:05 PM CDT	Severe Thunderstorm Warning	LIX	Ascension, Assumption, Lafourche, Saint James, Saint John the Baptist	40 min
May 11, 11:41 PM CDT	Severe Thunderstorm Warning	LIX	Ascension, Assumption, Lafourche, Saint Charles, Saint James, Saint John the Baptist	64 min
May 12, 12:18 AM CDT	Special Weather Statement	LIX	Assumption	27 min
May 12, 12:31 AM CDT	Areal Flood Advisory	LIX	Assumption, Jefferson, Lafourche, Saint Charles, Saint James, Saint John the Baptist	2 hr
May 12, 12:33 AM CDT	Special Weather Statement	LIX	Saint Charles	42 min
May 12, 12:48 AM CDT	Special Weather Statement	LIX	Lafourche	57 min
May 12, 1:12 AM CDT	Special Weather Statement	LIX	Saint Charles	33 min
May 12, 1:41 AM CDT	Special Weather Statement	LIX	Lafourche, Orleans, Saint Charles, Saint Tammany	49 min
May 12, 1:46 AM CDT	Special Marine Warning	LIX		44 min
May 12, 1:58 AM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	81 min
May 12, 1:58 AM CDT	Severe Thunderstorm Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	32 min
May 12, 2:08 AM CDT	Tornado Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard	12 min
May 12, 2:30 AM CDT	Special Marine Warning	LIX		46 min
May 12, 2:47 AM CDT	Special Marine Warning	LIX		43 min
May 12, 3:14 AM CDT	Special Marine Warning	LIX		108 min
May 12, 4:25 AM CDT	Special Marine Warning	LIX		65 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2021 Every severe thunderstorm warning in 2021

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.