Tornadoes · United States · Louisiana · 2021
Unrated tornado, Saint Bernard Parish, Louisiana, September 15, 2021
This Unrated tornado ran 1.9 miles across Saint Bernard Parish on September 15, 2021, touching down at 4:07 AM CDT and reaching 25 yards wide. It killed nobody.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unratedthis tornado
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.
The record
- Rating
- Unrated
- Date
- September 15, 2021
- Touchdown
- 4:07 AM CDT (09:07 UTC)
- Lifted
- 4:12 AM CDT (09:12 UTC)
- On the ground
- 5 minutes
- Path length
- 1.9 miles (3.0 km)
- Path width
- 25 yards (23 m)
- Deaths
- 0
- Injuries
- 0
- County
- Saint Bernard Parish
- Touchdown point
- 29.815, -89.821
- Lift-off point
- 29.835, -89.835
- Record number
- 2109150307-01
The damage survey
6 damage points were recorded along this path by NWS LIX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EFU.
- Apparent damage to marsh on high resolution satellite imagery.
- Damage to marsh on high resolution satellite imagery.
- Estimated location of tornado per weak TDS on KLIX.
- Damage to marsh on high resolution satellite imagery. Estimated end point of tornado.
Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.
The warnings
No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 15:41 UTC | 17:45 UTC | Flood Advisory | LIX |
| 16:41 UTC | 19:45 UTC | Flash Flood Warning | LIX |
| 16:46 UTC | 00:00 UTC | Coastal Flood Advisory | LIX |
| 07:33 UTC | 09:30 UTC | Flood Advisory | LIX |
| 08:29 UTC | 09:00 UTC | Tornado Warning | LIX |
| 09:09 UTC | 09:22 UTC | Tornado Warning | LIX |
Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.
The forecast that day
The Storm Prediction Center had this point in a Marginal Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 05:41 UTC.
SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.
The air that afternoon
The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.
Slidell Radar S, LA (KSIL), 00:00Z
9.1 hours before the tornado, 49 km from the path. September 15, 2021.
- Mixed-layer CAPE
- 136 J/kg
- Mixed-layer CIN
- -10 J/kg
- Surface CAPE
- 149 J/kg
- Mixed-layer LCL
- 589 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 29 m²/s²
- 0-3 km storm-relative helicity
- 181 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
- 0-3 km lapse rate
- 5.1 K/km
Slidell Radar S, LA (KSIL), 12:00Z
2.9 hours after it, 49 km from the path. September 15, 2021.
- Mixed-layer CAPE
- 84 J/kg
- Mixed-layer CIN
- -69 J/kg
- Surface CAPE
- 130 J/kg
- Mixed-layer LCL
- 695 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 120 m²/s²
- 0-3 km storm-relative helicity
- 285 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 4.7 K/km
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 07:56 UTC | FLASH FLOOD | Luling | St. Charles, LA | WATER IN HOMES AND NUMEROUS ROADS FLOODED. |
| 08:01 UTC | MARINE TSTM WIND 39 | 12 Ssw Mandeville | Gmz530, LA | WEATHERFLOW OBSERVATION AT THE MIDPOINT OF THE CAUSEWAY MEASURED A WIND GUST OF 39 MPH. |
| 08:03 UTC | FLASH FLOOD | Bayou Gauche | St. Charles, LA | WATER IN HOMES AND NUMEROUS ROADS FLOODED. |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2021 tornado in LouisianaEvery tornado in Louisiana since 1950Warnings in force in Louisiana nowThe forecast where you are
What this means
Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.