Alert archive / Alabama / Tornado Watches in 2020

Tornado Watch 467

August 28, 202016 counties in Alabama; Itawamba County, Monroe County, Mississippi; 9 counties in Tennessee

The Storm Prediction Center issued this tornado watch at Aug 28, 2020, 3:46 PM CDT for 16 counties in Alabama; Itawamba County, Monroe County, Mississippi; 9 counties in Tennessee. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Aug 28, 2020, 3:46 PM CDT (20:46 UTC)
Expired
Aug 28, 2020, 8:00 PM CDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
55 kt
All 27 counties

Colbert County, AL, Cullman County, AL, DeKalb County, AL, Fayette County, AL, Franklin County, AL, Jackson County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Walker County, AL, Winston County, AL, Itawamba County, MS, Monroe County, MS, Bedford County, TN, Coffee County, TN, Franklin County, TN, Giles County, TN, Lawrence County, TN, Lincoln County, TN, Marshall County, TN, Maury County, TN, Moore County, TN

The radar

The Northeast Alabama radar (KHTX), 104 km from the middle of the area, began a volume at 20:48 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
30%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
5%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
40%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Aug 28, 3:46 PM CDTSevere Thunderstorm WarningHUNColbert, Lauderdale, Lawrence, Limestone29 min
Aug 28, 4:13 PM CDTSevere Thunderstorm WarningMEGMonroe47 min
Aug 28, 4:28 PM CDTTornado WarningHUNLawrence, Morgan32 min
Aug 28, 4:32 PM CDTSevere Thunderstorm WarningBMXFayette, Lamar, Marion43 min
Aug 28, 4:36 PM CDTTornado WarningBMXWinston39 min
Aug 28, 5:13 PM CDTSevere Thunderstorm WarningHUNCullman, Morgan47 min
Aug 28, 5:15 PM CDTSevere Thunderstorm WarningBMXWinston15 min
Aug 28, 5:21 PM CDTSevere Thunderstorm WarningBMXMarion, Walker, Winston54 min
Aug 28, 5:25 PM CDTTornado WarningHUNCullman, Morgan35 min
Aug 28, 5:27 PM CDTSevere Thunderstorm WarningBMXFayette, Lamar, Walker43 min
Aug 28, 5:49 PM CDTSevere Thunderstorm WarningHUNCullman, Madison, Marshall, Morgan41 min
Aug 28, 6:20 PM CDTSevere Thunderstorm WarningHUNJackson, Madison25 min
Aug 28, 6:28 PM CDTSevere Thunderstorm WarningHUNDeKalb, Jackson, Marshall21 min

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, 8.8 hours before the alert went out and 162 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 2020-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 598 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 12:00Z on 2020-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 152 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
598 J/kg
Mixed-layer CIN
-32 J/kg
Mixed-layer LCL
737 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
152 m²/s²
0-3 km storm-relative helicity
138 m²/s²
Significant tornado parameter
0.4
Supercell composite
3.7

Open this sounding in Storm Lab

The text

As transmitted.

657 
WWUS20 KWNS 282044
SEL7  
SPC WW 282044
ALZ000-MSZ000-TNZ000-290100-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 467
NWS Storm Prediction Center Norman OK
345 PM CDT Fri Aug 28 2020

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Northwest and north-central Alabama
  Far northeast Mississippi
  Southern middle Tennessee

* Effective this Friday afternoon and evening from 345 PM until
  800 PM CDT.

* Primary threats include...
  A couple tornadoes possible
  Isolated damaging wind gusts to 65 mph possible

SUMMARY...Lingering clusters may still pose a risk for a couple
brief tornadoes and locally damaging winds into early evening.

The tornado watch area is approximately along and 40 statute miles
east and west of a line from 60 miles north of Huntsville AL to 85
miles south southwest of Muscle Shoals AL. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU7).

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.

&&

OTHER WATCH INFORMATION...This tornado watch replaces tornado
watch number 463...tornado watch number 465. Watch number 463 465
will not be in effect after 345 PM CDT. CONTINUE...WW 464...WW
466...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1 inch. Extreme turbulence and surface wind
gusts to 55 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 23030.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 28, 10:09 AM CDTMesoscale DiscussionSPCLauderdale96 min
Aug 28, 10:31 AM CDTTornado WatchSPCColbert, Franklin, Lamar, Lauderdale, Lawrence, Limestone and 2 more5 hr
Aug 28, 5:19 PM CDTMesoscale DiscussionSPCBlount, Cullman, DeKalb, Fayette, Jackson, Lamar and 7 more116 min
Aug 27, 8:29 PM CDTMesoscale DiscussionSPCMarshall2 hr
Aug 28, 6:47 AM CDTMesoscale DiscussionSPCBenton, Lafayette, Marshall, Tippah, Union88 min
Aug 28, 1:04 PM CDTTornado WatchSPCBedford, Cannon, Clay, Coffee, Cumberland, DeKalb and 15 more3 hr
Aug 28, 1:25 PM CDTMesoscale DiscussionSPCBedford, Cannon, Coffee, DeKalb, Lincoln, Macon and 6 more65 min
Aug 28, 6:50 PM CDTMesoscale DiscussionSPCJohnson2 hr

Nearby

Tornado Watches in Alabama, 2020Tornado Watches in Tennessee, 2020Tornado Watches in Mississippi, 2020Every tornado watch in 2020

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.