Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 353
The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2021, 7:20 PM CDT for Colbert County, Lauderdale County, Alabama; 4 counties in Mississippi; 15 counties in Tennessee. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Apr 9, 2021, 7:20 PM CDT (00:20 UTC)
- Expired
- Apr 9, 2021, 9:15 PM CDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 80
All 21 counties
Colbert County, AL, Lauderdale County, AL, Alcorn County, MS, Lee County, MS, Prentiss County, MS, Tishomingo County, MS, Benton County, TN, Carroll County, TN, Chester County, TN, Decatur County, TN, Hardin County, TN, Henderson County, TN, Henry County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lawrence County, TN, Lewis County, TN, McNairy County, TN, Perry County, TN, Wayne County, TN
The radar
The Columbus AFB radar (KGWX), 141 km from the middle of the area, began a volume at 00:24 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, 0.3 hours before the alert went out and 158 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2032 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 326 m²/s²
- 0-3 km storm-relative helicity
- 590 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
511
ACUS11 KWNS 100020
SWOMCD
SPC MCD 100020
TNZ000-ALZ000-MSZ000-100215-
Mesoscale Discussion 0353
NWS Storm Prediction Center Norman OK
0720 PM CDT Fri Apr 09 2021
Areas affected...western and middle Tennessee...northwestern Alabama
Concerning...Severe Thunderstorm Watch 80...
Valid 100020Z - 100215Z
The severe weather threat for Severe Thunderstorm Watch 80
continues.
SUMMARY...Storms producing hail persist from northeast Mississippi
into western Tennessee, and may extend east of WW 80 from northwest
Alabama into western Middle Tennessee. It is unclear whether an
additional watch will be needed.
DISCUSSION...A north-south line of cells likely producing hail
currently extend from Pontotoc County MS to Chester County TN. These
storms are located near the northeastern extend of the better
instability, with MLCAPE up to 1500 J/kg into southwestern TN.
Modest low-level moist advection may support these storms for a
couple hours as the line drifts eastward into northwest AL and
middle TN. The most likely area for a prolonged hail threat is from
northeast MS into northwest AL, in closer proximity to the mid 60s F
dewpoints. Other storms approaching Middle Tennessee are more likely
to weaken as they encounter drier air and the boundary layer cools
further.
..Jewell.. 04/10/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...HUN...MEG...
LAT...LON 34318902 34928873 35388877 35888874 36278885 36468787
36238750 35798731 35078726 34698738 34458795 34278845
34248879 34318902SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 9:15 PM CDT | Severe Thunderstorm Watch | SPC | Bibb, Colbert, Cullman, Dallas, Fayette, Franklin and 14 more | 7 hr |
| Apr 9, 10:25 PM CDT | Severe Thunderstorm Watch | SPC | Choctaw, Clarke, Washington, Wilcox | 6 hr |
| Apr 10, 1:52 AM CDT | Mesoscale Discussion | SPC | Baldwin, Butler, Clarke, Coffee, Conecuh, Covington and 8 more | 113 min |
| Apr 10, 2:30 AM CDT | Tornado Watch | SPC | Baldwin, Butler, Coffee, Conecuh, Covington, Crenshaw and 7 more | 8 hr |
| Apr 10, 4:06 AM CDT | Mesoscale Discussion | SPC | Baldwin, Butler, Clarke, Coffee, Conecuh, Covington and 8 more | 114 min |
| Apr 10, 7:10 AM CDT | Mesoscale Discussion | SPC | Dale, Geneva, Houston | 2 hr |
| Apr 9, 11:00 PM CDT | Mesoscale Discussion | SPC | Adams, Amite, Copiah, Covington, Franklin, Jefferson and 10 more | 2 hr |
| Apr 10, 12:16 AM CDT | Tornado Watch | SPC | Amite, Covington, Forrest, George, Greene, Hancock and 15 more | 7 hr |
Nearby
Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Mississippi, 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.