Alert archive / Mississippi / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 86

April 9, 20214 counties in Alabama; 16 parishes in Louisiana; 33 counties in Mississippi

The Storm Prediction Center issued this severe thunderstorm watch at Apr 9, 2021, 10:25 PM CDT for 4 counties in Alabama; 16 parishes in Louisiana; 33 counties in Mississippi. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Apr 9, 2021, 10:25 PM CDT (03:25 UTC)
Expired
Apr 10, 2021, 4:00 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
70 kt
All 53 counties

Choctaw County, AL, Clarke County, AL, Washington County, AL, Wilcox County, AL, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Greene County, MS, Hinds County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Lincoln County, MS, Lowndes County, MS, Marion County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 95 km from the middle of the area, began a volume at 03:28 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
20%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
60%
One or more gusts of 65 knots or more
40%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

38 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Apr 9, 10:53 PM CDTFlash Flood WarningJANRankin, Scott, Smith2 hr
Apr 9, 11:45 PM CDTSevere Thunderstorm WarningJANJasper, Newton, Scott, Smith45 min
Apr 9, 11:52 PM CDTSevere Thunderstorm WarningJANJefferson Davis, Lawrence, Lincoln38 min
Apr 9, 11:57 PM CDTSevere Thunderstorm WarningLIXAmite, Pike36 min
Apr 10, 12:01 AM CDTFlash Flood WarningJANConcordia3 hr
Apr 10, 12:12 AM CDTSevere Thunderstorm WarningLIXWalthall33 min
Apr 10, 12:28 AM CDTSevere Thunderstorm WarningLCHAvoyelles, Rapides47 min
Apr 10, 12:31 AM CDTTornado WarningJANJefferson Davis, Lamar, Marion44 min
Apr 10, 12:41 AM CDTSevere Thunderstorm WarningLIXSaint Tammany, Washington11 min
Apr 10, 12:46 AM CDTSevere Thunderstorm WarningLIXAmite, Pike, Walthall43 min
Apr 10, 12:50 AM CDTSevere Thunderstorm WarningJANClarke, Jasper55 min
Apr 10, 12:53 AM CDTTornado WarningLCHAvoyelles, Rapides22 min
Apr 10, 12:53 AM CDTFlash Flood WarningJANCovington, Jasper, Jefferson Davis, Jones, Lawrence, Simpson and 1 more3 hr
Apr 10, 1:02 AM CDTTornado WarningJANForrest, Lamar38 min
Apr 10, 1:06 AM CDTSevere Thunderstorm WarningMOBChoctaw54 min
Apr 10, 1:09 AM CDTFlash Flood WarningJANClarke, Lauderdale3 hr
Apr 10, 1:10 AM CDTTornado WarningLCHAvoyelles35 min
Apr 10, 1:13 AM CDTSevere Thunderstorm WarningLCHAvoyelles, Evangeline, Saint Landry47 min
Apr 10, 1:15 AM CDTSevere Thunderstorm WarningMOBChoctaw, Washington45 min
Apr 10, 1:22 AM CDTTornado WarningLCHAvoyelles, Saint Landry23 min
Apr 10, 1:24 AM CDTSevere Thunderstorm WarningJANCatahoula, Concordia51 min
Apr 10, 1:34 AM CDTSevere Thunderstorm WarningLCHSaint Landry41 min
Apr 10, 1:40 AM CDTTornado WarningLCHAvoyelles, Saint Landry18 min
Apr 10, 1:42 AM CDTTornado WarningLCHSaint Landry33 min
Apr 10, 1:45 AM CDTTornado WarningLIXPointe Coupee, West Feliciana45 min
Apr 10, 1:48 AM CDTFlash Flood WarningJANForrest, Jones, Lamar, Marion3 hr
Apr 10, 1:58 AM CDTSevere Thunderstorm WarningMOBChoctaw, Clarke, Washington, Wilcox62 min
Apr 10, 2:01 AM CDTSevere Thunderstorm WarningLIXSaint Tammany, Washington29 min
Apr 10, 2:11 AM CDTTornado WarningLCHSaint Landry34 min
Apr 10, 2:14 AM CDTFlash Flood WarningJANCatahoula3 hr
Apr 10, 2:28 AM CDTSevere Thunderstorm WarningLIXPointe Coupee, West Feliciana47 min
Apr 10, 2:35 AM CDTSevere Thunderstorm WarningMOBGeorge, Greene25 min
Apr 10, 2:48 AM CDTSevere Thunderstorm WarningLIXEast Baton Rouge, East Feliciana, Saint Helena, West Feliciana39 min
Apr 10, 2:53 AM CDTFlash Flood WarningJANConcordia118 min
Apr 10, 2:58 AM CDTSevere Thunderstorm WarningLIXSaint Helena, Tangipahoa35 min
Apr 10, 2:59 AM CDTSevere Thunderstorm WarningMOBBaldwin, Butler, Clarke, Conecuh, Escambia, Mobile and 3 more61 min
Apr 10, 3:20 AM CDTSevere Thunderstorm WarningLIXEast Baton Rouge, East Feliciana, Pointe Coupee, West Baton Rouge, West Feliciana33 min
Apr 10, 3:53 AM CDTSevere Thunderstorm WarningMOBBaldwin, Butler, Conecuh, Covington, Escambia, Mobile and 2 more67 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

Jackson, MS (KJAN), launched 00:00Z, 3.4 hours before the alert went out and 102 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, Jackson, MS at 00:00Z on 2021-04-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2299 joules per kilogram.LCLEL10008507005003002001001 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, Jackson, MS at 00:00Z on 2021-04-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 51 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
2299 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
1555 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
51 m²/s²
0-3 km storm-relative helicity
70 m²/s²
Significant tornado parameter
0.3
Supercell composite
3.9

Open this sounding in Storm Lab

The text

As transmitted.

793 
WWUS20 KWNS 100322
SEL6  
SPC WW 100322
ALZ000-LAZ000-MSZ000-100900-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 86
NWS Storm Prediction Center Norman OK
1025 PM CDT Fri Apr 9 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Southwest Alabama
  Central to eastern Louisiana
  Southern to eastern Mississippi

* Effective this Friday night and Saturday morning from 1025 PM
  until 400 AM CDT.

* Primary threats include...
  Scattered damaging winds likely with isolated significant gusts
    to 80 mph possible
  Isolated large hail events to 1.5 inches in diameter possible
  A tornado or two possible

SUMMARY...Long-lived, but slow-moving QLCS should sag southeast in
the near-term. This should intensify overnight as the surface front
approaches.

The severe thunderstorm watch area is approximately along and 55
statute miles north and south of a line from 65 miles east southeast
of Meridian MS to 30 miles southwest of Alexandria LA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU6).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 80...WW 81...WW 82...WW
83...WW 84...WW 85...

AVIATION...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
29030.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 9, 7:20 PM CDTMesoscale DiscussionSPCColbert, Lauderdale115 min
Apr 9, 9:15 PM CDTSevere Thunderstorm WatchSPCBibb, Colbert, Cullman, Dallas, Fayette, Franklin and 14 more7 hr
Apr 10, 1:52 AM CDTMesoscale DiscussionSPCBaldwin, Butler, Clarke, Coffee, Conecuh, Covington and 8 more113 min
Apr 10, 2:30 AM CDTTornado WatchSPCBaldwin, Butler, Coffee, Conecuh, Covington, Crenshaw and 7 more8 hr
Apr 10, 4:06 AM CDTMesoscale DiscussionSPCBaldwin, Butler, Clarke, Coffee, Conecuh, Covington and 8 more114 min
Apr 10, 7:10 AM CDTMesoscale DiscussionSPCDale, Geneva, Houston2 hr
Apr 9, 10:47 PM CDTMesoscale DiscussionSPCDe Soto, Natchitoches, Red River, Sabine, Vernon118 min
Apr 9, 11:00 PM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Avoyelles, Concordia, East Baton Rouge and 16 more2 hr
Apr 10, 12:16 AM CDTTornado WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, East Baton Rouge and 19 more7 hr
Apr 10, 12:52 AM CDTSevere Thunderstorm WatchSPCBienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more3 hr

Nearby

Severe Thunderstorm Watches in Mississippi, 2021Severe Thunderstorm Watches in Louisiana, 2021Severe Thunderstorm Watches in Alabama, 2021Every severe thunderstorm 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; radar from the NEXRAD Level II archive.