Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 291
The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2021, 8:42 PM CDT for 32 counties in Mississippi; 6 counties in Tennessee. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Mar 27, 2021, 8:42 PM CDT (01:42 UTC)
- Expired
- Mar 27, 2021, 10:15 PM CDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 59
All 38 counties
Alcorn County, MS, Benton County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Issaquena 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, Washington County, MS, Webster County, MS, Yalobusha County, MS, Yazoo County, MS, Chester County, TN, Fayette County, TN, Hardeman County, TN, Hardin County, TN, McNairy County, TN, Shelby County, TN
The radar
The Memphis radar (KNQA), 123 km from the middle of the area, began a volume at 01:46 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 00:00Z, 1.7 hours before the alert went out and 71 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
- 894 J/kg
- Mixed-layer CIN
- -17 J/kg
- Mixed-layer LCL
- 1261 m above ground
- 0-6 km bulk shear
- 79 kt
- 0-1 km storm-relative helicity
- 64 m²/s²
- 0-3 km storm-relative helicity
- 209 m²/s²
- Significant tornado parameter
- 0.7
- Supercell composite
- 8.7
The text
As transmitted.
184
ACUS11 KWNS 280142
SWOMCD
SPC MCD 280142
ALZ000-TNZ000-MSZ000-ARZ000-LAZ000-280315-
Mesoscale Discussion 0291
NWS Storm Prediction Center Norman OK
0842 PM CDT Sat Mar 27 2021
Areas affected...western Tennessee into northern Mississippi
Concerning...Tornado Watch 59...
Valid 280142Z - 280315Z
The severe weather threat for Tornado Watch 59 continues.
SUMMARY...A replacement tornado watch will be issued, which will
extend farther south into northern Mississippi.
DISCUSSION...Numerous storms persist from southern AR into TN, with
supercells approaching northwest MS over the next 1-2 hours. MLCAPE
over 2000 J/kg remains over the region owing to a very moist air
mass. Strong southwesterlies aloft are resulting in long hodographs,
with southerly low-level flow aiding supercell potential as well.
Area VWPs show effective SRH generally averaging 200-300 m2/s2,
which will support a continued supercell threat. While cellular
storm mode is likely for a few hours, the eventual arrival of the
cold front as well as merging outflows may result in a linear mode
later tonight. All modes of severe will be possible.
..Jewell/Grams.. 03/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...HUN...MEG...JAN...
LAT...LON 35498796 35188799 34808814 33988882 32958976 32689059
32669096 32899115 33589090 34189076 34789049 35369000
35578906 35498796SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 27, 9:01 PM CDT | Tornado Watch | SPC | Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 33 more | 7 hr |
| Mar 27, 10:45 PM CDT | Mesoscale Discussion | SPC | Alcorn, Benton, Bolivar, Calhoun, Carroll, Chickasaw and 23 more | 90 min |
| Mar 28, 1:57 AM CDT | Mesoscale Discussion | SPC | Itawamba, Monroe | 93 min |
| Mar 27, 11:27 PM CDT | Tornado Watch | SPC | Bedford, Coffee, Franklin, Giles, Grundy, Hickman and 6 more | 8 hr |
| Mar 28, 1:25 AM CDT | Mesoscale Discussion | SPC | Anderson, Bedford, Bledsoe, Blount, Bradley, Campbell and 42 more | 2 hr |
| Mar 28, 2:07 AM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bledsoe, Blount, Bradley, Cumberland, Hamilton and 14 more | 6 hr |
| Mar 28, 4:56 AM CDT | Mesoscale Discussion | SPC | Bradley | 94 min |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Tennessee, 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.