Alert archive / Tennessee / Severe Thunderstorm Watches in 2002

Severe Thunderstorm Watch 698

September 20, 200214 counties in Alabama; 5 counties in Georgia; 44 counties in Tennessee

The Storm Prediction Center issued this severe thunderstorm watch at Sep 20, 2002, 5:05 PM CDT for 14 counties in Alabama; 5 counties in Georgia; 44 counties in Tennessee. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Sep 20, 2002, 5:05 PM CDT (22:05 UTC)
Expired: Sep 20, 2002, 10:00 PM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 63 counties

Blount County, AL, Cherokee County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Franklin County, AL, Jackson County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Winston County, AL, Catoosa County, GA, Chattooga County, GA, Dade County, GA, Walker County, GA, Whitfield County, GA, Anderson County, TN, Bedford County, TN, Bledsoe County, TN, Bradley County, TN, Campbell County, TN, Cannon County, TN, Clay County, TN, Coffee County, TN, Cumberland County, TN, Davidson County, TN, DeKalb County, TN, Fentress County, TN, Franklin County, TN, Giles County, TN, Grundy County, TN, Hamilton County, TN, Jackson County, TN, Lawrence County, TN, Lincoln County, TN, Loudon County, TN, Macon County, TN, Marion County, TN, Marshall County, TN, Maury County, TN, McMinn County, TN, Meigs County, TN, Moore County, TN, Morgan County, TN, Overton County, TN, Pickett County, TN, Putnam County, TN, Rhea County, TN, Roane County, TN, Rutherford County, TN, Scott County, TN, Sequatchie County, TN, Smith County, TN, Sumner County, TN, Trousdale County, TN, Van Buren County, TN, Warren County, TN, White County, TN, Williamson County, TN, Wilson County, TN

The radar

The Northeast Alabama radar (KHTX), 33 km from the middle of the area, began a volume at 22:09 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 20, 6:18 PM CDT	Severe Thunderstorm Warning	OHX	Rutherford	27 min
Sep 20, 6:57 PM CDT	Severe Thunderstorm Warning	BMX	Winston	48 min
Sep 20, 9:07 PM CDT	Severe Thunderstorm Warning	MRX	Bradley	38 min

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 12:00Z, 10.1 hours before the alert went out and 124 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 719 J/kg
Mixed-layer CIN: -36 J/kg
Mixed-layer LCL: 749 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 203 m²/s²
0-3 km storm-relative helicity: 175 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WWUS20 KWNS 202206
SEL8  
SPC WW 202205
ALZ000-GAZ000-TNZ000-210300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 698
STORM PREDICTION CENTER NORMAN OK
505 PM CDT FRI SEP 20 2002

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   NORTHERN ALABAMA                            
   NORTHWEST GEORGIA                            
   MIDDLE AND EAST TENNESSEE                          

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 505 PM UNTIL 1000
PM CDT.

HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 80 STATUTE MILES
EAST AND WEST OF A LINE FROM 45 MILES WEST OF GADSDEN ALABAMA TO 45
MILES NORTH OF CROSSVILLE TENNESSEE.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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.  SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.

OTHER WATCH INFORMATION...THIS SEVERE THUNDERSTORM WATCH REPLACES
SEVERE THUNDERSTORM WATCH NUMBER 694.  WATCH NUMBER 694 WILL NOT BE
IN EFFECT AFTER 505 PM CDT.  CONTINUE...WW 693...WW 695...WW
696...WW 697...

DISCUSSION...THUNDERSTORMS/POSSIBLE SUPERCELLS EXPECTED TO PERSIST
OVER WW REGION THIS EVENING AS AREA IS GLANCED BY TAIL END OF 50+
KT SPEED MAX EJECTING NNE TOWARD THE GRT LKS.  WITH SURFACE-BASED
INSTABILITY AXIS PRESENT AHEAD OF EXISTING STORMS...POTENTIAL WILL
REMAIN FOR ORGANIZED CLUSTERS/BANDS OF STORMS WITH STRONG
WINDS/MARGINALLY SEVERE HAIL. 

AVIATION...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 500.  MEAN STORM MOTION
VECTOR 22035.

...CORFIDI

363,0833 335,0852 335,0881 363,0863

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 20, 12:10 PM CDT	Severe Thunderstorm Watch	SPC	Benton, Carroll, Cheatham, Chester, Davidson, Decatur and 24 more	5 hr

Nearby

Severe Thunderstorm Watches in Tennessee, 2002 Severe Thunderstorm Watches in Alabama, 2002 Severe Thunderstorm Watches in Georgia, 2002 Every severe thunderstorm watch in 2002

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.