Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 2013
The Storm Prediction Center issued this mesoscale discussion at Dec 11, 2021, 2:00 AM CST for 5 states. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Dec 11, 2021, 2:00 AM CST (08:00 UTC)
- Expired
- Dec 11, 2021, 3:30 AM CST
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 558
All 106 counties
Colbert County, AL, Franklin County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Morgan County, AL, Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Desha County, AR, Drew County, AR, Lincoln County, AR, Phillips County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Claiborne Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Alcorn County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Clay County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Humphreys 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, Washington County, MS, Webster County, MS, Yalobusha County, MS, Bedford County, TN, Benton County, TN, Cannon County, TN, Carroll County, TN, Cheatham County, TN, Chester County, TN, Clay County, TN, Coffee County, TN, Cumberland County, TN, Davidson County, TN, Decatur County, TN, DeKalb County, TN, Dickson County, TN, Fayette County, TN, Franklin County, TN, Giles County, TN, Grundy County, TN, Hardeman County, TN, Hardin County, TN, Henderson County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Jackson County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Macon County, TN, Madison County, TN, Marshall County, TN, Maury County, TN, McNairy County, TN, Moore County, TN, Overton County, TN, Perry County, TN, Putnam County, TN, Robertson County, TN, Rutherford County, TN, Smith County, TN, Sumner County, TN, Trousdale County, TN, Van Buren County, TN, Warren County, TN, Wayne County, TN, White County, TN, Williamson County, TN, Wilson County, TN
The radar
The Columbus AFB radar (KGWX), 89 km from the middle of the area, began a volume at 08:03 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, 8.0 hours before the alert went out and 93 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
- 1725 J/kg
- Mixed-layer CIN
- -13 J/kg
- Mixed-layer LCL
- 759 m above ground
- 0-6 km bulk shear
- 78 kt
- 0-1 km storm-relative helicity
- 398 m²/s²
- 0-3 km storm-relative helicity
- 420 m²/s²
- Significant tornado parameter
- 4.8
- Supercell composite
- 16.2
The text
As transmitted.
489
ACUS11 KWNS 110800
SWOMCD
SPC MCD 110800
TNZ000-KYZ000-ALZ000-MSZ000-ARZ000-LAZ000-110930-
Mesoscale Discussion 2013
NWS Storm Prediction Center Norman OK
0200 AM CST Sat Dec 11 2021
Areas affected...portions of northern Louisiana into eastern
Arkansas...northern Mississippi...western and middle Tennessee...and
northern Alabama
Concerning...Tornado Watch 558...
Valid 110800Z - 110930Z
The severe weather threat for Tornado Watch 558 continues.
SUMMARY...The severe threat continues across Tornado Watch 558, with
all severe hazards remaining a concern. A downstream Tornado Watch
issuance may be needed across portions of northern Alabama into
Middle Tennessee in the next few hours.
DISCUSSION...An expansive line of storms/QLCS is progressing across
Tornado Watch 558, where around 1000 J/kg MLCAPE is present amid a
moist low-level environment with minimal MLCINH. Given predominantly
linear storm modes oriented nearly parallel to the effective
bulk-shear vector, damaging wind gusts are expected to be the main
threat with the stronger storms. Nonetheless, JAN, GWX and HTX VWPs
around 0730Z show long, modestly curved hodographs contributing to
250-300 m2/s2 0-1 km SRH, so some tornado threat still exists with
the more intense circulations embedded in the QLCS. North-south
oriented line segments that are aligned more orthogonal to the
deep-layer shear vector will have the highest tornado potential. As
low-level shear and deep-layer ascent increase across northern
Alabama into Middle Tennessee, a downstream Tornado Watch may be
needed to address the eastward-expanding severe threat.
..Squitieri/Edwards.. 12/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...LMK...OHX...BMX...HUN...MEG...JAN...LZK...
SHV...
LAT...LON 32969071 32409233 32289357 32459387 33019344 33819221
34669098 35298941 36348805 36608653 36638532 36508501
35928495 35348548 34818602 34388664 34048786 33578881
33119049 32969071SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 11, 3:15 AM CST | Mesoscale Discussion | SPC | Colbert, Franklin, Lauderdale, Marion | 90 min |
| Dec 11, 3:41 AM CST | Tornado Watch | SPC | Colbert, Cullman, DeKalb, Fayette, Franklin, Jackson and 10 more | 6 hr |
| Dec 11, 6:15 AM CST | Mesoscale Discussion | SPC | Cullman, Fayette, Franklin, Jackson, Lamar, Lawrence and 6 more | 90 min |
| Dec 11, 7:34 AM CST | Mesoscale Discussion | SPC | Bibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 8 more | 86 min |
| Dec 11, 10:47 AM CST | Mesoscale Discussion | SPC | Autauga, Bullock, Butler, Chambers, Clarke, Clay and 15 more | 118 min |
| Dec 10, 6:22 PM CST | Mesoscale Discussion | SPC | Craighead, Greene, Jackson, Mississippi, Poinsett | 53 min |
| Dec 10, 6:34 PM CST | Tornado Watch | SPC | Columbia, Hempstead, Howard, Lafayette, Little River, Miller and 2 more | 4 hr |
| Dec 10, 6:37 PM CST | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 10 more | 83 min |
| Dec 10, 6:51 PM CST | Tornado Watch | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 10 more | 4 hr |
| Dec 10, 7:34 PM CST | Mesoscale Discussion | SPC | Clark, Crittenden, Cross, Faulkner, Garland, Grant and 16 more | 86 min |
| Dec 10, 7:54 PM CST | Mesoscale Discussion | SPC | Boone, Carroll, Crawford, Franklin, Johnson, Logan and 7 more | 2 hr |
| Dec 10, 9:40 PM CST | Mesoscale Discussion | SPC | Arkansas, Clark, Cleveland, Craighead, Crittenden, Cross and 13 more | 2 hr |
| Dec 10, 10:00 PM CST | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Chicot, Columbia, Desha and 5 more | 90 min |
| Dec 10, 10:09 PM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 17 more | 96 min |
| Dec 10, 10:44 PM CST | Tornado Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 16 more | 6 hr |
| Dec 11, 1:36 AM CST | Mesoscale Discussion | SPC | Beauregard, Caldwell, De Soto, Grant, LaSalle, Natchitoches and 4 more | 114 min |
| Dec 11, 4:02 AM CST | Mesoscale Discussion | SPC | Allen, Avoyelles, Beauregard, Calcasieu, Caldwell, Catahoula and 9 more | 118 min |
| Dec 10, 6:21 PM CST | Tornado Watch | SPC | Alcorn, Benton, Itawamba, Lafayette, Lee, Pontotoc and 4 more | 10 hr |
| Dec 10, 7:41 PM CST | Mesoscale Discussion | SPC | Dyer, Gibson, Henry, Lake, Obion, Weakley | 64 min |
| Dec 10, 8:35 PM CST | Mesoscale Discussion | SPC | Montgomery | 85 min |
| Dec 10, 11:36 PM CST | Mesoscale Discussion | SPC | Cheatham, Dickson, Henry, Houston, Montgomery, Robertson and 2 more | 54 min |
| Dec 11, 2:51 AM CST | Mesoscale Discussion | SPC | Cheatham, Davidson, Rutherford, Williamson, Wilson | 84 min |
| Dec 11, 5:32 AM CST | Mesoscale Discussion | SPC | Anderson, Campbell, Claiborne, Fentress, Morgan, Pickett and 2 more | 88 min |
Nearby
Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Arkansas, 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.