Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 213
The Storm Prediction Center issued this mesoscale discussion at Mar 17, 2021, 6:09 PM CDT for 4 states. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- Mar 17, 2021, 6:09 PM CDT (23:09 UTC)
- Expired
- Mar 17, 2021, 7:15 PM CDT
- In force
- 66 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 32
All 50 counties
Colbert County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Marion County, AL, Crittenden County, AR, Cross County, AR, Alcorn County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Leflore County, MS, Marshall County, MS, Monroe County, MS, Montgomery County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Quitman County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tishomingo County, MS, Tunica County, MS, Union County, MS, Webster County, MS, Yalobusha County, MS, Chester County, TN, Fayette County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Lawrence County, TN, Madison County, TN, McNairy County, TN, Shelby County, TN, Tipton County, TN, Wayne County, TN
The radar
The Memphis radar (KNQA), 85 km from the middle of the area, began a volume at 23:09 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.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Little Rock, AR (KLZK), launched 12:00Z, 11.2 hours before the alert went out and 43 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
- 18 J/kg
- Mixed-layer CIN
- -262 J/kg
- Mixed-layer LCL
- 1466 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- 217 m²/s²
- 0-3 km storm-relative helicity
- 186 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.5
The text
As transmitted.
378
ACUS11 KWNS 172310
SWOMCD
SPC MCD 172309
ALZ000-TNZ000-MSZ000-ARZ000-180015-
Mesoscale Discussion 0213
NWS Storm Prediction Center Norman OK
0609 PM CDT Wed Mar 17 2021
Areas affected...Far eastern Arkansas...Northern Mississippi and
Alabama...into southern Tennessee.
Concerning...Tornado Watch 32...
Valid 172309Z - 180015Z
The severe weather threat for Tornado Watch 32 continues.
SUMMARY...A replacement tornado watch for the northwestern half of
Tornado watch #32 will be coordinated shortly.
DISCUSSION...Numerous thunderstorms including semi discrete
supercells are ongoing across the area. Strong low-level shear
(450-500 0-1km SRH) sampled from the MEG VWP suggests the tornado
threat is likely to continue after the 00z expiration time of WW32.
Expansive convective coverage into north-central Alabama may
somewhat impact buoyancy near the diffuse warm front across southern
Tennessee. However, additional thunderstorm development across far
eastern Arkansas may support the severe threat well into the night
across north-central Alabama. A new tornado watch will be
coordinated shortly.
..Lyons/Guyer.. 03/17/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...BMX...HUN...MEG...JAN...LZK...
LAT...LON 35419105 35049070 34399075 33809098 33539099 33179049
33228956 33938766 34438721 34898700 35318735 35628859
35618951 35559051 35419105SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 10:56 AM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Chilton, Choctaw, Clarke, Coosa and 17 more | 2 hr |
| Mar 17, 11:36 AM CDT | Tornado Watch | SPC | Autauga, Bibb, Blount, Chilton, Choctaw, Clarke and 25 more | 7 hr |
| Mar 17, 12:02 PM CDT | Mesoscale Discussion | SPC | Choctaw, Clarke, Marengo | 58 min |
| Mar 17, 1:01 PM CDT | Mesoscale Discussion | SPC | Autauga, Chilton, Coosa, Elmore, Lowndes, Montgomery and 1 more | 89 min |
| Mar 17, 1:26 PM CDT | Tornado Watch | SPC | Calhoun, Chambers, Cherokee, Cleburne, Elmore, Etowah and 7 more | 5 hr |
| Mar 17, 1:45 PM CDT | Mesoscale Discussion | SPC | Mobile | 90 min |
| Mar 17, 2:24 PM CDT | Mesoscale Discussion | SPC | Bibb, Chilton, Dallas, Hale, Marengo, Perry | 96 min |
| Mar 17, 5:49 PM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Blount, Bullock, Butler, Calhoun and 32 more | 86 min |
| Mar 17, 6:48 PM CDT | Tornado Watch | SPC | Autauga, Baldwin, Barbour, Bibb, Blount, Bullock and 44 more | 8 hr |
| Mar 17, 12:45 AM CDT | Mesoscale Discussion | SPC | Benton, Washington | 90 min |
| Mar 17, 1:32 AM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Clark, Cleveland, Columbia and 27 more | 118 min |
| Mar 17, 4:04 AM CDT | Mesoscale Discussion | SPC | Columbia, Hempstead, Lafayette, Little River, Miller, Sevier | 86 min |
| Mar 17, 4:37 AM CDT | Severe Thunderstorm Watch | SPC | Hempstead, Howard, Lafayette, Little River, Miller, Nevada and 1 more | 5 hr |
| Mar 17, 5:34 AM CDT | Mesoscale Discussion | SPC | Arkansas, Crittenden, Cross, Desha, Lee, Lincoln and 3 more | 86 min |
| Mar 17, 5:53 AM CDT | Tornado Watch | SPC | Arkansas, Bradley, Cleveland, Crittenden, Desha, Drew and 8 more | 7 hr |
| Mar 17, 6:40 AM CDT | Mesoscale Discussion | SPC | Calhoun, Clark, Columbia, Crawford, Dallas, Franklin and 19 more | 95 min |
| Mar 17, 7:38 AM CDT | Mesoscale Discussion | SPC | Crittenden, Lee, Monroe, Phillips, St. Francis | 67 min |
| Mar 17, 7:47 AM CDT | Tornado Watch | SPC | Calhoun, Clark, Conway, Dallas, Faulkner, Garland and 15 more | 5 hr |
| Mar 17, 8:43 AM CDT | Tornado Watch | SPC | Columbia, Union | 4 hr |
| Mar 17, 12:15 PM CDT | Mesoscale Discussion | SPC | Ashley, Chicot, Desha, Drew, Phillips | 90 min |
| Mar 17, 12:57 PM CDT | Tornado Watch | SPC | Ashley, Chicot, Lee, Phillips | 6 hr |
| Mar 17, 1:18 PM CDT | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Clark, Crawford, Franklin and 22 more | 57 min |
| Mar 17, 2:00 PM CDT | Tornado Watch | SPC | Benton, Boone, Carroll, Crawford, Franklin, Johnson and 12 more | 7 hr |
| Mar 17, 2:56 PM CDT | Mesoscale Discussion | SPC | Ashley, Chicot, Desha, Drew | 94 min |
| Mar 17, 3:37 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 5 more | 83 min |
| Mar 17, 1:19 PM CDT | Mesoscale Discussion | SPC | Jefferson Davis, Lawrence, Lincoln, Simpson, Smith | 86 min |
| Mar 17, 2:38 PM CDT | Tornado Watch | SPC | Amite, Hancock, Harrison, Jackson, Pearl River, Pike and 2 more | 8 hr |
| Mar 17, 12:59 PM CDT | Tornado Watch | SPC | Benton, Carroll, Chester, Crockett, Decatur, Dyer and 13 more | 6 hr |
| Mar 17, 2:16 PM CDT | Mesoscale Discussion | SPC | Bedford, Benton, Cannon, Coffee, Davidson, Decatur and 18 more | 59 min |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Alabama, 2021Every mesoscale discussion 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.