Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 1806
The Storm Prediction Center issued this mesoscale discussion at Oct 6, 2021, 5:25 PM CDT for 18 counties in Alabama; 13 counties in Georgia; 20 counties in Tennessee. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- Oct 6, 2021, 5:25 PM CDT (22:25 UTC)
- Expired
- Oct 6, 2021, 7:00 PM CDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 513
All 51 counties
Blount County, AL, Calhoun County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Jackson County, AL, Jefferson County, AL, Limestone County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Bartow County, GA, Carroll County, GA, Catoosa County, GA, Chattooga County, GA, Dade County, GA, Floyd County, GA, Gordon County, GA, Haralson County, GA, Murray County, GA, Paulding County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA, Bedford County, TN, Bledsoe County, TN, Bradley County, TN, Cannon County, TN, Coffee County, TN, Franklin County, TN, Giles County, TN, Grundy County, TN, Hamilton County, TN, Lincoln County, TN, Marion County, TN, Marshall County, TN, Maury County, TN, Meigs County, TN, Moore County, TN, Rhea County, TN, Rutherford County, TN, Sequatchie County, TN, Van Buren County, TN, Warren County, TN
The radar
The Northeast Alabama radar (KHTX), 44 km from the middle of the area, began a volume at 22:27 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
Birmingham, AL (KBMX), launched 12:00Z, 10.4 hours before the alert went out and 165 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
- 683 J/kg
- Mixed-layer CIN
- -31 J/kg
- Mixed-layer LCL
- 559 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 111 m²/s²
- 0-3 km storm-relative helicity
- 119 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.8
The text
As transmitted.
251
ACUS11 KWNS 062225
SWOMCD
SPC MCD 062225
GAZ000-TNZ000-ALZ000-070000-
Mesoscale Discussion 1806
NWS Storm Prediction Center Norman OK
0525 PM CDT Wed Oct 06 2021
Areas affected...Northern Alabama...northwest Georgia...southern
Tennessee.
Concerning...Tornado Watch 513...
Valid 062225Z - 070000Z
The severe weather threat for Tornado Watch 513 continues.
SUMMARY...The severe weather threat continues in watch 315.
DISCUSSION...Loosely organized storms continue across northern
Alabama and northwest Georgia into southern Tennessee. Storms have
mostly been below severe limits, but a report of 1 inch hail was
recently received in Cullman County, Alabama. Low-level rotation has
been mostly weak, likely due to a very weak wind field in the lowest
4-5 km per BMX/HTX VWP. However, the KMRX does show stronger
low-level flow and 0-1 SRH in excess of 100 m2/s2. It appears at
least one storm in the area has realized this more favorable
low-level shear environment as a storm which recently moved into
Cumberland County, TN has shown consistent rotation for the last 30
minutes. Therefore, the highest tornado threat (albeit still modest)
will likely be in this region for the next hour. As this storm moves
north, the airmass becomes increasingly rain cooled and stable and
therefore, the tornado threat should diminish with northward extent.
..Bentley/Thompson.. 10/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...FFC...OHX...BMX...HUN...
LAT...LON 33548708 34748730 35578723 35888658 35908580 35828511
35618478 34998449 33978456 33288539 33048634 33048692
33548708SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 6, 1:26 PM CDT | Mesoscale Discussion | SPC | Calhoun, Cherokee, Cleburne, DeKalb, Etowah, Jackson and 4 more | 3 hr |
| Oct 6, 2:53 PM CDT | Tornado Watch | SPC | Blount, Calhoun, Cherokee, Clay, Cleburne, Cullman and 12 more | 7 hr |
Nearby
Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Georgia, 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.