Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 2080
The Storm Prediction Center issued this mesoscale discussion at Dec 29, 2021, 7:27 PM CST for 21 counties in Alabama; 11 counties in Georgia; 8 counties in Tennessee. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 29, 2021, 7:27 PM CST (01:27 UTC)
- Expired
- Dec 29, 2021, 9:30 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 570
All 40 counties
Bibb County, AL, Blount County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Fayette County, AL, Greene County, AL, Jackson County, AL, Jefferson County, AL, Marshall County, AL, Pickens County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Bartow County, GA, Catoosa County, GA, Chattooga County, GA, Dade County, GA, Floyd County, GA, Gilmer County, GA, Gordon County, GA, Murray County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA, Bledsoe County, TN, Bradley County, TN, Hamilton County, TN, Marion County, TN, McMinn County, TN, Meigs County, TN, Polk County, TN, Sequatchie County, TN
The radar
The Birmingham radar (KBMX), 91 km from the middle of the area, began a volume at 01:29 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
Birmingham, AL (KBMX), launched 00:00Z, 1.5 hours before the alert went out and 91 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
- 179 J/kg
- Mixed-layer CIN
- -40 J/kg
- Mixed-layer LCL
- 1065 m above ground
- 0-6 km bulk shear
- 57 kt
- 0-1 km storm-relative helicity
- 230 m²/s²
- 0-3 km storm-relative helicity
- 292 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.2
The text
As transmitted.
218
ACUS11 KWNS 300128
SWOMCD
SPC MCD 300127
TNZ000-GAZ000-ALZ000-MSZ000-300330-
Mesoscale Discussion 2080
NWS Storm Prediction Center Norman OK
0727 PM CST Wed Dec 29 2021
Areas affected...central and northern Alabama into northwest Georgia
Concerning...Tornado Watch 570...
Valid 300127Z - 300330Z
The severe weather threat for Tornado Watch 570 continues.
SUMMARY...Isolated tornado or damaging wind threat remains across
the region. Convective trends are being closely monitored across
central Alabama.
DISCUSSION...A line of storms continues to push east across TN into
northern AL and east-central MS, primarily displaying a solid gust
front but with periodic surges of wind and rotation in QLCS fashion.
A lone supercell was noted near the MS/AL border southwest of TCL,
and this storm will cross into AL shortly.
The environment ahead of the squall line continues to favor a rapid
eastward motion given strong west/southwest flow aloft. Instability
becomes quite marginal to support severe toward the TN area, but a
bit of warm advection may yet support isolated reports into northern
GA and southeast TN.
Some moistening may aid minor destabilization across central AL this
evening given the veered nature of the 850 mb winds, and modest
effective SRH conditionally favors a supercell threat. As such, the
area from central AL into western GA will need to be monitored for
potential watch extension or new issuance.
..Jewell.. 12/30/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...FFC...OHX...BMX...HUN...JAN...
LAT...LON 32768764 32788845 32858863 33058856 33608828 33908751
34548648 35078598 35548542 35608519 35538462 35168433
34648446 33728532 33168590 32838674 32768764SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 29, 8:44 PM CST | Mesoscale Discussion | SPC | Calhoun, Cherokee, Etowah | 2 hr |
| Dec 29, 9:16 PM CST | Tornado Watch | SPC | Calhoun, Chambers, Chilton, Clay, Cleburne, Coosa and 4 more | 7 hr |
| Dec 29, 10:56 PM CST | Mesoscale Discussion | SPC | Clay, Randolph | 2 hr |
| Dec 30, 1:15 AM CST | Mesoscale Discussion | SPC | Bibb, Chambers, Chilton, Clay, Coosa, Randolph and 3 more | 90 min |
| Dec 30, 4:02 AM CST | Mesoscale Discussion | SPC | Bibb, Chambers, Chilton, Clay, Coosa, Greene and 10 more | 2 hr |
| Dec 30, 10:34 AM CST | Mesoscale Discussion | SPC | Autauga, Bullock, Chambers, Chilton, Coosa, Dallas and 9 more | 116 min |
| Dec 30, 1:05 PM CST | Severe Thunderstorm Watch | SPC | Autauga, Barbour, Bullock, Butler, Chambers, Clarke and 13 more | 7 hr |
| Dec 30, 2:54 PM CST | Mesoscale Discussion | SPC | Barbour, Bullock, Crenshaw, Lee, Lowndes, Macon and 3 more | 2 hr |
| Dec 30, 1:00 PM CST | Mesoscale Discussion | SPC | Appling, Atkinson, Bacon, Baker, Ben Hill, Berrien and 29 more | 2 hr |
| Dec 30, 5:35 PM CST | Mesoscale Discussion | SPC | Appling, Atkinson, Bacon, Ben Hill, Berrien, Brantley and 32 more | 115 min |
Nearby
Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Georgia, 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.