Alert archive / Mississippi / Tornado Watches in 2021

Tornado Watch 32

March 17, 20214 counties in Arkansas; 21 parishes in Louisiana; 38 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Mar 17, 2021, 12:57 PM CDT for 4 counties in Arkansas; 21 parishes in Louisiana; 38 counties in Mississippi. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Mar 17, 2021, 12:57 PM CDT (17:57 UTC)
Expired
Mar 17, 2021, 7:00 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Particularly dangerous situation
Yes
Largest hail expected
2.5 in
Strongest gust expected
75 kt
All 63 counties

Ashley County, AR, Chicot County, AR, Lee County, AR, Phillips County, AR, Bienville Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Alcorn County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Claiborne County, MS, Coahoma County, MS, DeSoto County, MS, Franklin County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Lafayette County, MS, Lee County, MS, Leflore County, MS, Marshall County, MS, Montgomery County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tishomingo County, MS, Tunica County, MS, Union County, MS, Warren County, MS, Washington County, MS, Webster County, MS, Yalobusha County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 147 km from the middle of the area, began a volume at 18:00 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
90%
One or more EF2 to EF5 tornadoes
80%
Ten or more severe wind reports
80%
One or more gusts of 65 knots or more
80%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
50%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Mar 17, 2:08 PM CDTSevere Thunderstorm WarningSHVBienville, Jackson, Lincoln, Ouachita, Union52 min
Mar 17, 2:16 PM CDTSevere Thunderstorm WarningSHVClaiborne, Lincoln, Union44 min
Mar 17, 2:32 PM CDTTornado WarningSHVUnion43 min
Mar 17, 2:58 PM CDTTornado WarningSHVLincoln, Ouachita, Union47 min
Mar 17, 3:12 PM CDTTornado WarningSHVJackson, Lincoln, Ouachita, Union48 min
Mar 17, 3:18 PM CDTTornado WarningMEGItawamba, Prentiss, Tishomingo27 min
Mar 17, 3:33 PM CDTSevere Thunderstorm WarningJANAshley42 min
Mar 17, 3:34 PM CDTTornado WarningSHVUnion10 min
Mar 17, 4:10 PM CDTTornado WarningJANAdams, Franklin50 min
Mar 17, 4:17 PM CDTSevere Thunderstorm WarningMEGCalhoun, Lafayette, Pontotoc, Union28 min
Mar 17, 4:34 PM CDTSevere Thunderstorm WarningJANMadison, Tensas56 min
Mar 17, 4:43 PM CDTSevere Thunderstorm WarningMEGBenton, Lafayette, Marshall, Union32 min
Mar 17, 4:45 PM CDTSevere Thunderstorm WarningJANChicot60 min
Mar 17, 4:52 PM CDTTornado WarningJANCopiah, Jefferson, Lincoln37 min
Mar 17, 4:52 PM CDTFlash Flood WarningMEGItawamba, Lee, Prentiss, Tishomingo4 hr
Mar 17, 4:56 PM CDTTornado WarningJANChicot29 min
Mar 17, 4:56 PM CDTSevere Thunderstorm WarningMEGChickasaw, Itawamba, Lee, Pontotoc, Prentiss, Union49 min
Mar 17, 4:58 PM CDTSevere Thunderstorm WarningMEGCalhoun, Chickasaw, Pontotoc20 min
Mar 17, 5:15 PM CDTSevere Thunderstorm WarningJANHinds, Madison, Rankin, Yazoo64 min
Mar 17, 5:45 PM CDTSevere Thunderstorm WarningMEGChickasaw, Itawamba, Lee, Monroe45 min
Mar 17, 5:55 PM CDTSevere Thunderstorm WarningJANAttala, Choctaw, Holmes, Leake, Montgomery, Neshoba and 2 more65 min
Mar 17, 5:55 PM CDTFlash Flood WarningMEGCalhoun, Chickasaw4 hr
Mar 17, 5:55 PM CDTTornado WarningMEGChickasaw, Itawamba, Lee, Monroe35 min
Mar 17, 6:42 PM CDTSevere Thunderstorm WarningJANChoctaw, Clay, Kemper, Lowndes, Neshoba, Noxubee and 3 more76 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 12:00Z, 6.0 hours before the alert went out and 140 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 12:00Z on 2021-03-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 687 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 2021-03-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 218 square meters per square second.1939587897Sfc1 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
687 J/kg
Mixed-layer CIN
-86 J/kg
Mixed-layer LCL
713 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
218 m²/s²
0-3 km storm-relative helicity
178 m²/s²
Significant tornado parameter
0.6
Supercell composite
4.9

Open this sounding in Storm Lab

The text

As transmitted.

174 
WWUS20 KWNS 171755
SEL2  
SPC WW 171755
ARZ000-LAZ000-MSZ000-180000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 32
NWS Storm Prediction Center Norman OK
1155 AM CST Wed Mar 17 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southeast Arkansas
  Northern Louisiana
  Northern and western Mississippi

* Effective this Wednesday morning and evening from 1155 AM until
  600 PM CST.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

* Primary threats include...
  Several tornadoes and a few intense tornadoes likely
  Widespread damaging winds and scattered significant gusts to 85
    mph likely
  Scattered large hail likely with isolated very large hail events
    to 2.5 inches in diameter possible

SUMMARY...Discrete supercells and linear clusters are expected to
intensify and becoming increasingly widespread across the
Ark-La-Miss region through this evening. At least a few significant
tornadoes are expected, one or more of which may become
long-tracked.

The tornado watch area is approximately along and 80 statute miles
east and west of a line from 40 miles north of Oxford MS to 25 miles
west of Alexandria LA. For a complete depiction of the watch see the
associated watch outline update (WOUS64 KWNS WOU2).

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 26...WW 27...WW 28...WW
29...WW 30...WW 31...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 75 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 24035.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 17, 12:45 AM CDTMesoscale DiscussionSPCBenton, Washington90 min
Mar 17, 1:32 AM CDTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Clark, Cleveland, Columbia and 27 more118 min
Mar 17, 4:04 AM CDTMesoscale DiscussionSPCColumbia, Hempstead, Lafayette, Little River, Miller, Sevier86 min
Mar 17, 4:37 AM CDTSevere Thunderstorm WatchSPCHempstead, Howard, Lafayette, Little River, Miller, Nevada and 1 more5 hr
Mar 17, 5:34 AM CDTMesoscale DiscussionSPCArkansas, Crittenden, Cross, Desha, Lee, Lincoln and 3 more86 min
Mar 17, 5:53 AM CDTTornado WatchSPCArkansas, Bradley, Cleveland, Crittenden, Desha, Drew and 8 more7 hr
Mar 17, 6:40 AM CDTMesoscale DiscussionSPCCalhoun, Clark, Columbia, Crawford, Dallas, Franklin and 19 more95 min
Mar 17, 7:38 AM CDTMesoscale DiscussionSPCCrittenden, Lee, Monroe, Phillips, St. Francis67 min
Mar 17, 7:47 AM CDTTornado WatchSPCCalhoun, Clark, Conway, Dallas, Faulkner, Garland and 15 more5 hr
Mar 17, 8:43 AM CDTTornado WatchSPCColumbia, Union4 hr
Mar 17, 12:15 PM CDTMesoscale DiscussionSPCAshley, Chicot, Desha, Drew, Phillips90 min
Mar 17, 1:18 PM CDTMesoscale DiscussionSPCBenton, Boone, Carroll, Clark, Crawford, Franklin and 22 more57 min
Mar 17, 2:00 PM CDTTornado WatchSPCBenton, Boone, Carroll, Crawford, Franklin, Johnson and 12 more7 hr
Mar 17, 2:56 PM CDTMesoscale DiscussionSPCAshley, Chicot, Desha, Drew94 min
Mar 17, 3:37 PM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Crawford, Franklin and 5 more83 min
Mar 17, 6:09 PM CDTMesoscale DiscussionSPCCrittenden, Cross66 min
Mar 17, 11:35 AM CDTMesoscale DiscussionSPCAllen, Beauregard, Bienville, Calcasieu, Cameron, De Soto and 8 more85 min
Mar 17, 11:53 AM CDTTornado WatchSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 7 more6 hr
Mar 17, 1:45 PM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 18 more90 min
Mar 17, 2:38 PM CDTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 19 more8 hr
Mar 17, 10:56 AM CDTMesoscale DiscussionSPCAttala, Choctaw, Clarke, Clay, Copiah, Covington and 26 more2 hr
Mar 17, 11:36 AM CDTTornado Watch PDSSPCAttala, Choctaw, Clarke, Clay, Copiah, Covington and 28 more7 hr
Mar 17, 12:02 PM CDTMesoscale DiscussionSPCClarke, Jones, Wayne58 min
Mar 17, 1:19 PM CDTMesoscale DiscussionSPCJefferson Davis, Lawrence, Lincoln, Simpson, Smith86 min
Mar 17, 5:49 PM CDTMesoscale DiscussionSPCClarke, Covington, Forrest, George, Greene, Jasper and 13 more86 min
Mar 17, 6:48 PM CDTTornado Watch PDSSPCAttala, Choctaw, Clarke, Clay, Covington, Forrest and 20 more8 hr

Nearby

Tornado Watches in Mississippi, 2021Tornado Watches in Louisiana, 2021Tornado Watches in Arkansas, 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; radar from the NEXRAD Level II archive.