Alert archive / Louisiana / Tornado Watches in 2021
Tornado Watch 87
The Storm Prediction Center issued this tornado watch at Apr 10, 2021, 12:16 AM CDT for 25 parishes in Louisiana; 21 counties in Mississippi. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 10, 2021, 12:16 AM CDT (05:16 UTC)
- Expired
- Apr 10, 2021, 7:00 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 70 kt
All 46 counties
Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS, Wayne 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
- 50%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 70%
- One or more gusts of 65 knots or more
- 60%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
40 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 10, 12:28 AM CDT | Severe Thunderstorm Warning | LCH | Avoyelles, Rapides | 47 min |
| Apr 10, 12:31 AM CDT | Tornado Warning | JAN | Jefferson Davis, Lamar, Marion | 44 min |
| Apr 10, 12:41 AM CDT | Severe Thunderstorm Warning | LIX | Saint Tammany, Washington | 11 min |
| Apr 10, 12:46 AM CDT | Severe Thunderstorm Warning | LIX | Amite, Pike, Walthall | 43 min |
| Apr 10, 12:53 AM CDT | Tornado Warning | LCH | Avoyelles, Rapides | 22 min |
| Apr 10, 12:53 AM CDT | Flash Flood Warning | JAN | Covington, Jasper, Jefferson Davis, Jones, Lawrence, Simpson and 1 more | 3 hr |
| Apr 10, 1:02 AM CDT | Tornado Warning | JAN | Forrest, Lamar | 38 min |
| Apr 10, 1:06 AM CDT | Severe Thunderstorm Warning | MOB | Wayne | 54 min |
| Apr 10, 1:10 AM CDT | Tornado Warning | LCH | Avoyelles | 35 min |
| Apr 10, 1:13 AM CDT | Severe Thunderstorm Warning | LCH | Avoyelles, Evangeline, Saint Landry | 47 min |
| Apr 10, 1:15 AM CDT | Severe Thunderstorm Warning | MOB | Greene, Perry, Wayne | 45 min |
| Apr 10, 1:22 AM CDT | Tornado Warning | LCH | Avoyelles, Saint Landry | 23 min |
| Apr 10, 1:34 AM CDT | Severe Thunderstorm Warning | LCH | Saint Landry | 41 min |
| Apr 10, 1:40 AM CDT | Tornado Warning | LCH | Avoyelles, Saint Landry | 18 min |
| Apr 10, 1:42 AM CDT | Tornado Warning | LCH | Saint Landry | 33 min |
| Apr 10, 1:45 AM CDT | Tornado Warning | LIX | Pointe Coupee, West Feliciana | 45 min |
| Apr 10, 1:48 AM CDT | Flash Flood Warning | JAN | Forrest, Jones, Lamar, Marion | 3 hr |
| Apr 10, 1:58 AM CDT | Severe Thunderstorm Warning | MOB | Greene, Perry, Wayne | 62 min |
| Apr 10, 2:01 AM CDT | Severe Thunderstorm Warning | LIX | Saint Tammany, Washington | 29 min |
| Apr 10, 2:05 AM CDT | Tornado Warning | LIX | Saint Tammany | 10 min |
| Apr 10, 2:11 AM CDT | Tornado Warning | LCH | Saint Landry | 34 min |
| Apr 10, 2:28 AM CDT | Severe Thunderstorm Warning | LIX | Pointe Coupee, West Feliciana | 47 min |
| Apr 10, 2:35 AM CDT | Severe Thunderstorm Warning | MOB | George, Greene | 25 min |
| Apr 10, 2:42 AM CDT | Severe Thunderstorm Warning | LIX | Hancock, Harrison | 33 min |
| Apr 10, 2:43 AM CDT | Severe Thunderstorm Warning | MOB | George | 17 min |
| Apr 10, 2:48 AM CDT | Severe Thunderstorm Warning | LIX | East Baton Rouge, East Feliciana, Saint Helena, West Feliciana | 39 min |
| Apr 10, 2:58 AM CDT | Severe Thunderstorm Warning | LIX | Saint Helena, Tangipahoa | 35 min |
| Apr 10, 2:59 AM CDT | Severe Thunderstorm Warning | MOB | George | 61 min |
| Apr 10, 3:11 AM CDT | Severe Thunderstorm Warning | LIX | Harrison, Jackson | 49 min |
| Apr 10, 3:11 AM CDT | Severe Thunderstorm Warning | MOB | George, Stone | 37 min |
| Apr 10, 3:20 AM CDT | Severe Thunderstorm Warning | LIX | East Baton Rouge, East Feliciana, Pointe Coupee, West Baton Rouge, West Feliciana | 33 min |
| Apr 10, 3:29 AM CDT | Severe Thunderstorm Warning | LIX | Harrison, Jackson | 31 min |
| Apr 10, 3:55 AM CDT | Severe Thunderstorm Warning | LIX | Harrison, Jackson | 14 min |
| Apr 10, 4:06 AM CDT | Flash Flood Warning | LIX | Hancock, Pearl River | 3 hr |
| Apr 10, 4:23 AM CDT | Tornado Warning | LIX | Saint James, Saint John the Baptist | 19 min |
| Apr 10, 4:40 AM CDT | Flash Flood Warning | LIX | Saint Tammany, Tangipahoa, Washington | 3 hr |
| Apr 10, 4:58 AM CDT | Severe Thunderstorm Warning | LIX | Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles, Saint Tammany | 47 min |
| Apr 10, 5:16 AM CDT | Flash Flood Warning | MOB | George, Perry, Stone | 4 hr |
| Apr 10, 5:53 AM CDT | Flash Flood Warning | MOB | George | 6 hr |
| Apr 10, 6:01 AM CDT | Severe Thunderstorm Warning | LCH | Calcasieu, Cameron, Jefferson Davis | 29 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 00:00Z, 5.3 hours before the alert went out and 153 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.
- Mixed-layer CAPE
- 2977 J/kg
- Mixed-layer CIN
- -20 J/kg
- Mixed-layer LCL
- 599 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 243 m²/s²
- 0-3 km storm-relative helicity
- 269 m²/s²
- Significant tornado parameter
- 3.4
- Supercell composite
- 18.1
The text
As transmitted.
607
WWUS20 KWNS 100513
SEL7
SPC WW 100513
LAZ000-MSZ000-CWZ000-101200-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 87
NWS Storm Prediction Center Norman OK
1215 AM CDT Sat Apr 10 2021
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Central and southern Louisiana
Southeast Mississippi
Coastal Waters
* Effective this Saturday morning from 1215 AM until 700 AM CDT.
* Primary threats include...
A few tornadoes and a couple intense tornadoes possible
Scattered damaging winds and isolated significant gusts to 80
mph likely
Isolated large hail events to 1.5 inches in diameter possible
SUMMARY...As a slow-moving squall line intersects more discrete
storms forming ahead of it, the tornado threat will increase.
Otherwise, the squall line should intensify and accelerate with
bowing segments capable of significant severe wind damage.
The tornado watch area is approximately along and 55 statute miles
north and south of a line from 55 miles west northwest of Lafayette
LA to 55 miles east southeast of Pine Belt MS. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU7).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 84...WW 85...WW 86...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1.5 inches. Extreme turbulence and surface wind
gusts to 70 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 29035.
...GramsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 10:25 PM CDT | Severe Thunderstorm Watch | SPC | Avoyelles, Catahoula, Concordia, East Baton Rouge, East Feliciana, Evangeline and 10 more | 6 hr |
| Apr 9, 10:47 PM CDT | Mesoscale Discussion | SPC | De Soto, Natchitoches, Red River, Sabine, Vernon | 118 min |
| Apr 9, 11:00 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Avoyelles, Concordia, East Baton Rouge and 16 more | 2 hr |
| Apr 10, 12:52 AM CDT | Severe Thunderstorm Watch | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more | 3 hr |
| Apr 9, 7:20 PM CDT | Mesoscale Discussion | SPC | Alcorn, Lee, Prentiss, Tishomingo | 115 min |
| Apr 10, 1:52 AM CDT | Mesoscale Discussion | SPC | George, Greene, Jackson | 113 min |
| Apr 10, 4:06 AM CDT | Mesoscale Discussion | SPC | George, Greene, Jackson | 114 min |
Nearby
Tornado Watches in Louisiana, 2021Tornado Watches in Mississippi, 2021Every tornado watch 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.