Alert archive / Tennessee / Tornado Watches in 2021

Tornado Watch 513

October 6, 202118 counties in Alabama; 15 counties in Georgia; 25 counties in Tennessee

The Storm Prediction Center issued this tornado watch at Oct 6, 2021, 2:53 PM CDT for 18 counties in Alabama; 15 counties in Georgia; 25 counties in Tennessee. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Oct 6, 2021, 2:53 PM CDT (19:53 UTC)
Expired
Oct 6, 2021, 10:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 58 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, Douglas County, GA, Floyd County, GA, Gordon County, GA, Haralson County, GA, Heard 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, Cumberland County, TN, DeKalb 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, Putnam County, TN, Rhea County, TN, Rutherford County, TN, Sequatchie County, TN, Van Buren County, TN, Warren County, TN, White County, TN, Williamson County, TN

The radar

The Northeast Alabama radar (KHTX), 26 km from the middle of the area, began a volume at 19:56 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
30%
One or more EF2 to EF5 tornadoes
10%
Ten or more severe wind reports
20%
One or more gusts of 65 knots or more
5%
Ten or more severe hail reports
10%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
50%

Warnings issued inside it

17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Oct 6, 3:32 PM CDTFlash Flood WarningMRXBledsoe, Sequatchie9 hr
Oct 6, 3:55 PM CDTSevere Thunderstorm WarningHUNCullman, Madison, Marshall, Morgan50 min
Oct 6, 3:56 PM CDTFlash Flood WarningOHXVan Buren6 hr
Oct 6, 4:47 PM CDTTornado WarningMRXBledsoe29 min
Oct 6, 4:54 PM CDTSevere Thunderstorm WarningHUNJackson, Madison36 min
Oct 6, 5:05 PM CDTSevere Thunderstorm WarningOHXBedford, Rutherford25 min
Oct 6, 5:09 PM CDTTornado WarningOHXCumberland36 min
Oct 6, 5:14 PM CDTFlash Flood WarningHUNMadison, Marshall8 hr
Oct 6, 5:44 PM CDTTornado WarningOHXCumberland31 min
Oct 6, 6:20 PM CDTTornado WarningOHXCumberland, Fentress25 min
Oct 6, 6:54 PM CDTFlash Flood WarningHUNJackson6 hr
Oct 6, 6:57 PM CDTFlash Flood WarningBMXBlount2 hr
Oct 6, 7:17 PM CDTFlash Flood Warning EmergencyBMXJefferson, Shelby10 hr
Oct 6, 7:20 PM CDTFlash Flood WarningMRXMarion6 hr
Oct 6, 7:48 PM CDTFlash Flood WarningOHXGiles5 hr
Oct 6, 8:36 PM CDTFlash Flood WarningHUNCullman4 hr
Oct 6, 8:52 PM CDTFlash Flood WarningOHXCumberland, Fentress, Overton, Pickett, Putnam, White3 hr

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 12:00Z, 7.9 hours before the alert went out and 164 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.

Skew-T log-pSkew-T log-p diagram, Nashville Metro, TN at 12:00Z on 2021-10-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 12:00Z on 2021-10-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -65 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1243 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
-65 m²/s²
0-3 km storm-relative helicity
-2 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

420 
WWUS20 KWNS 061950
SEL3  
SPC WW 061950
ALZ000-GAZ000-TNZ000-070300-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 513
NWS Storm Prediction Center Norman OK
250 PM CDT Wed Oct 6 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Northern and central Alabama
  Northwest Georgia
  Middle and Southeast Tennessee

* Effective this Wednesday afternoon and evening from 250 PM
  until 1000 PM CDT.

* Primary threats include...
  A couple tornadoes possible
  Isolated damaging wind gusts to 70 mph possible

SUMMARY...A very moist and increasingly unstable environment,
coincident with moderately strong shear, will support the
possibility of some severe storms/supercells as storms continue to
increase and move generally to the north through late afternoon and
evening.

The tornado watch area is approximately along and 60 statute miles
east and west of a line from 80 miles northwest of Chattanooga TN to
25 miles south of Anniston AL. For a complete depiction of the watch
see the associated watch outline update (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

&&

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1 inch. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 18020.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 6, 1:26 PM CDTMesoscale DiscussionSPCCalhoun, Cherokee, Cleburne, DeKalb, Etowah, Jackson and 4 more3 hr
Oct 6, 5:25 PM CDTMesoscale DiscussionSPCBlount, Calhoun, Cherokee, Clay, Cleburne, Cullman and 12 more95 min

Nearby

Tornado Watches in Tennessee, 2021Tornado Watches in Alabama, 2021Tornado Watches in Georgia, 2021Every tornado watch 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.