Alert archive / Louisiana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 140, NWS New Orleans, LA

October 27, 202110 parishes in Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Oct 27, 2021, 4:46 PM CDT for 10 parishes in Louisiana. It was in force for 44 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
Oct 27, 2021, 4:46 PM CDT (21:46 UTC)
Expired
Oct 27, 2021, 5:30 PM CDT
In force
44 min
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Hail
0.75 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, Saint John the Baptist Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Oct 27, 1:53 PM CDTTornado WatchSPC8 hr

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 9.8 hours before the alert went out and 104 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-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2021-10-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2021-10-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 186 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1792 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
186 m²/s²
0-3 km storm-relative helicity
274 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

410 
WUUS54 KLIX 272146
SVRLIX
LAC005-007-033-047-057-063-093-095-105-109-272230-
/O.NEW.KLIX.SV.W.0140.211027T2146Z-211027T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service New Orleans LA
446 PM CDT Wed Oct 27 2021

The National Weather Service in New Orleans has issued a

* Severe Thunderstorm Warning for...
  Northwestern St. John The Baptist Parish in southeastern
  Louisiana...
  Ascension Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...
  North central Terrebonne Parish in southeastern Louisiana...
  Livingston Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Northwestern Lafourche Parish in southeastern Louisiana...
  Southwestern Tangipahoa Parish in southeastern Louisiana...
  South central East Baton Rouge Parish in southeastern Louisiana...
  Assumption Parish in southeastern Louisiana...

* Until 530 PM CDT.

* At 445 PM CDT, severe thunderstorms were located along a line
  extending from near Denham Springs to Port Vincent to near Bayou
  Geneve, moving northeast at 60 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Hammond, Thibodaux, Gonzales, Donaldsonville, Napoleonville,
  Reserve, St. Gabriel, Ponchatoula, Walker, Gramercy, Lutcher, White
  Castle, Livingston, Sorrento, French Settlement, Albany, Port
  Vincent, Springfield, Schriever and Geismar.

This includes the following Interstates...
 Interstate 10 in Louisiana between mile markers 167 and 202.
 Interstate 12 between mile markers 14 and 47.
 Interstate 55 in Louisiana between mile markers 20 and 38.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Squall lines can produce brief tornadoes and straight-line wind 
damage. Although a tornado is not immediately likely, it is best to 
move to an interior room on the lowest floor of a building. These 
storms may cause injury and property damage.

A Tornado Watch remains in effect until 1000 PM CDT for southeastern 
Louisiana.


&&

LAT...LON 3020 9115 3032 9107 3060 9077 3065 9059
      3049 9033 3032 9043 3034 9049 3030 9056
      3019 9060 3017 9057 3017 9051 2998 9062
      2955 9097 2965 9111 2981 9110 2985 9119
TIME...MOT...LOC 2145Z 229DEG 51KT 3045 9098 3032 9086 2977 9107 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

JRK
1 follow-up statement
229 
WWUS54 KLIX 272208
SVSLIX

Severe Weather Statement
National Weather Service New Orleans LA
508 PM CDT Wed Oct 27 2021

LAC033-047-272217-
/O.CAN.KLIX.SV.W.0140.000000T0000Z-211027T2230Z/
Iberville LA-East Baton Rouge LA-
508 PM CDT Wed Oct 27 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN IBERVILLE AND
SOUTH CENTRAL EAST BATON ROUGE PARISHES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 1000 PM CDT for southeastern
Louisiana.

LAT...LON 3025 9098 3034 9095 3034 9090 3037 9094
      3047 9090 3064 9057 3048 9033 3032 9043
      3034 9049 3030 9056 3019 9060 3017 9051
      2998 9062 2955 9097 2965 9110
TIME...MOT...LOC 2207Z 244DEG 28KT 3040 9086 3029 9077 2999 9089 2967
9094

$$

LAC005-007-057-063-093-095-105-109-272230-
/O.CON.KLIX.SV.W.0140.000000T0000Z-211027T2230Z/
St. John The Baptist LA-Ascension LA-St. James LA-Terrebonne LA-
Livingston LA-Lafourche LA-Tangipahoa LA-Assumption LA-
508 PM CDT Wed Oct 27 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM CDT
FOR NORTHWESTERN ST. JOHN THE BAPTIST...ASCENSION...ST. JAMES...NORTH
CENTRAL TERREBONNE...LIVINGSTON...NORTHWESTERN LAFOURCHE...
SOUTHWESTERN TANGIPAHOA AND EASTERN ASSUMPTION PARISHES...

At 507 PM CDT, severe thunderstorms were located along a line
extending from near Port Vincent to near French Settlement to near
Convent to 7 miles southwest of Schriever, moving northeast at 30
mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Hammond, Thibodaux, Gonzales, Donaldsonville, Napoleonville, Reserve,
Ponchatoula, Walker, Gramercy, Lutcher, Livingston, Sorrento, French
Settlement, Albany, Port Vincent, Springfield, Schriever, Garyville,
Supreme and Natalbany.

This includes the following Interstates...
 Interstate 10 in Louisiana between mile markers 175 and 202.
 Interstate 12 between mile markers 14 and 47.
 Interstate 55 in Louisiana between mile markers 19 and 38.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM CDT for southeastern
Louisiana.

Squall lines can produce brief tornadoes and straight-line wind 
damage. Although a tornado is not immediately likely, it is best to 
move to an interior room on the lowest floor of a building. These 
storms may cause serious injury and significant property damage.

&&

LAT...LON 3025 9098 3034 9095 3034 9090 3037 9094
      3047 9090 3064 9057 3048 9033 3032 9043
      3034 9049 3030 9056 3019 9060 3017 9051
      2998 9062 2955 9097 2965 9110
TIME...MOT...LOC 2207Z 244DEG 28KT 3040 9086 3029 9077 2999 9089 2967
9094

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 27, 1:47 PM CDTTornado WarningLIXEast Baton Rouge, East Feliciana43 min
Oct 27, 1:48 PM CDTTornado WarningLIXEast Feliciana, West Feliciana42 min
Oct 27, 1:51 PM CDTSpecial Marine WarningLIX41 min
Oct 27, 2:03 PM CDTTornado WarningLIXLivingston, Tangipahoa42 min
Oct 27, 2:16 PM CDTSevere Thunderstorm WarningLIXIberville, Pointe Coupee, West Feliciana59 min
Oct 27, 3:10 PM CDTSevere Thunderstorm WarningLIXEast Baton Rouge, East Feliciana, Iberville, Pointe Coupee, West Baton Rouge, West Feliciana50 min
Oct 27, 3:17 PM CDTSpecial Marine WarningLIX28 min
Oct 27, 3:19 PM CDTTornado WarningLIXEast Feliciana, West Feliciana26 min
Oct 27, 3:22 PM CDTSpecial Marine WarningLIX53 min
Oct 27, 3:56 PM CDTSevere Thunderstorm WarningLIXEast Baton Rouge, East Feliciana, Iberville, Livingston, Saint Helena, West Baton Rouge49 min
Oct 27, 4:06 PM CDTSevere Thunderstorm WarningLIXAscension, Assumption, East Baton Rouge, Iberville, Livingston, Saint James and 1 more39 min
Oct 27, 4:54 PM CDTAreal Flood AdvisoryLIXLivingston, Saint Tammany, Tangipahoa, Washington3 hr
Oct 27, 4:59 PM CDTSpecial Marine WarningLIX91 min
Oct 27, 5:19 PM CDTSevere Thunderstorm WarningLIXSaint Tammany, Washington26 min
Oct 27, 5:22 PM CDTSevere Thunderstorm WarningLIXAscension, Assumption, Lafourche, Livingston, Saint Charles, Saint James and 2 more38 min
Oct 27, 5:26 PM CDTSpecial Marine WarningLIX94 min
Oct 27, 5:28 PM CDTFlash Flood WarningLIXSaint Tammany, Tangipahoa, Washington3 hr
Oct 27, 5:56 PM CDTSevere Thunderstorm WarningLIXJefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 2 more49 min
Oct 27, 6:10 PM CDTSevere Thunderstorm WarningLIXSaint Tammany50 min
Oct 27, 6:19 PM CDTFlash Flood WarningLIXSaint Tammany, Washington2 hr
Oct 27, 6:23 PM CDTSpecial Marine WarningLIX97 min
Oct 27, 6:28 PM CDTTornado WarningLIXJefferson, Lafourche32 min
Oct 27, 6:37 PM CDTSpecial Marine WarningLIX83 min
Oct 27, 6:47 PM CDTAreal Flood AdvisoryLIXJefferson, Orleans, Saint Bernard, Saint Charles109 min
Oct 27, 6:49 PM CDTSevere Thunderstorm WarningLIXJefferson, Lafourche, Orleans, Plaquemines, Saint Bernard41 min
Oct 27, 6:53 PM CDTAreal Flood AdvisoryLIXSaint Tammany3 hr

Nearby

Severe Thunderstorm Warnings in Louisiana, 2021Every 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.