Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 2078
The Storm Prediction Center issued this mesoscale discussion at Dec 29, 2021, 4:38 PM CST for 12 counties in Alabama; 12 counties in Mississippi; 4 counties in Tennessee. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 29, 2021, 4:38 PM CST (22:38 UTC)
- Expired
- Dec 29, 2021, 6:45 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 569...570
All 28 counties
Colbert County, AL, Fayette County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Morgan County, AL, Walker County, AL, Winston County, AL, Calhoun County, MS, Chickasaw County, MS, Clay County, MS, Itawamba County, MS, Lee County, MS, Lowndes County, MS, Monroe County, MS, Oktibbeha County, MS, Pontotoc County, MS, Prentiss County, MS, Tishomingo County, MS, Webster County, MS, Giles County, TN, Lawrence County, TN, Lincoln County, TN, Wayne County, TN
The radar
The Columbus AFB radar (KGWX), 71 km from the middle of the area, began a volume at 22:39 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 nearest sounding before it
Little Rock, AR (KLZK), launched 12:00Z, 10.6 hours before the alert went out and 178 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
- 1900 m above ground
- 0-6 km bulk shear
- 68 kt
- 0-1 km storm-relative helicity
- 131 m²/s²
- 0-3 km storm-relative helicity
- 106 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
966
ACUS11 KWNS 292238
SWOMCD
SPC MCD 292238
TNZ000-ALZ000-MSZ000-300045-
Mesoscale Discussion 2078
NWS Storm Prediction Center Norman OK
0438 PM CST Wed Dec 29 2021
Areas affected...northeast Mississippi into northern Alabama and
southern Middle Tennessee
Concerning...Tornado Watch 569...570...
Valid 292238Z - 300045Z
The severe weather threat for Tornado Watch 569, 570 continues.
SUMMARY...Conditions will remain most favorable for tornadoes over
the next several hours from northeast Mississippi into northern
Alabama and southern Middle Tennessee.
DISCUSSION...A cold front currently extends from Middle TN across
northern MS and into southeast AR, enhanced by outflow. Recently, a
line of cells has developed from TN into northern MS, with the
orientation of these cells removed from the cold front.
Areas of rotation have been noted with cells both along the cold
front near the TN/MS border, and farther southwest. Given the
deep-layer shear vector orientation, and strong 60 kt magnitudes, it
is anticipated that a few of these cells may remain enough ahead of
the cold front to become tornadic supercells, whereas farther north
into TN, a QLCS is most likely.
Strong west/southwest 850 mb flow will continue to advect theta-e
northeastward ahead of these cells. 0-1 SRH of 200-300 m2/s2 exists
per objective analysis, maximized near the old outflow boundary.
Therefore, a tornadic supercell or two appears possible as cells
mature within the high-shear environment. In addition, damaging
winds will be likely with solid portions of the line, and additional
counties may need watch consideration later this evening downstream
into eastern TN and northern GA.
..Jewell.. 12/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...BMX...HUN...MEG...JAN...
LAT...LON 35518746 35528730 35448665 35068640 34448668 33678741
33428816 33398876 33428946 33568970 34058954 34368912
34828856 35188805 35518746SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 29, 10:44 AM CST | Mesoscale Discussion | SPC | Colbert, Franklin, Lamar, Marion | 2 hr |
| Dec 29, 12:24 PM CST | Mesoscale Discussion | SPC | Geneva, Houston | 96 min |
| Dec 29, 2:36 PM CST | Mesoscale Discussion | SPC | Blount, Calhoun, Cherokee, Colbert, Cullman, DeKalb and 16 more | 2 hr |
| Dec 29, 3:53 PM CST | Tornado Watch | SPC | Bibb, Blount, Calhoun, Cherokee, Colbert, Cullman and 24 more | 6 hr |
| Dec 29, 12:05 PM CST | Tornado Watch | SPC | Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 34 more | 7 hr |
| Dec 29, 1:18 PM CST | Mesoscale Discussion | SPC | Bolivar, Calhoun, Carroll, Chickasaw, Coahoma, Grenada and 15 more | 87 min |
| Dec 29, 2:03 PM CST | Mesoscale Discussion | SPC | Adams, Claiborne, Copiah, Covington, Franklin, Hinds and 18 more | 87 min |
| Dec 29, 2:49 PM CST | Mesoscale Discussion | SPC | Forrest, Lamar, Marion, Pearl River, Perry | 86 min |
| Dec 29, 3:41 PM CST | Mesoscale Discussion | SPC | Alcorn, Benton, Bolivar, Calhoun, Carroll, Chickasaw and 26 more | 64 min |
Nearby
Mesoscale Discussions in Alabama, 2021Mesoscale 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.