Alert archive / Tennessee / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 331
The Storm Prediction Center issued this severe thunderstorm watch at May 31, 2012, 6:00 PM CDT for 7 counties in Alabama; 29 counties in Tennessee. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- May 31, 2012, 6:00 PM CDT (23:00 UTC)
- Expired
- May 31, 2012, 9:32 PM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 36 counties
Colbert County, AL, Franklin County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Morgan County, AL, Bedford County, TN, Benton County, TN, Cheatham County, TN, Clay County, TN, Davidson County, TN, Dickson County, TN, Giles County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Jackson County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Macon County, TN, Marshall County, TN, Maury County, TN, Montgomery County, TN, Moore County, TN, Perry County, TN, Robertson County, TN, Rutherford County, TN, Smith County, TN, Stewart County, TN, Sumner County, TN, Trousdale County, TN, Wayne County, TN, Williamson County, TN, Wilson County, TN
The radar
The Nashville radar (KOHX), 101 km from the middle of the area, began a volume at 23:00 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
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 5%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
2 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 31, 8:49 PM CDT | Severe Thunderstorm Warning | OHX | Macon, Smith, Trousdale, Wilson | 26 min |
| May 31, 8:57 PM CDT | Severe Thunderstorm Warning | OHX | Macon, Sumner, Trousdale | 20 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, 11.0 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1645 m above ground
- 0-6 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 24 m²/s²
- 0-3 km storm-relative helicity
- 126 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
190
WWUS20 KWNS 312303
SEL1
SPC WW 312303
ALZ000-TNZ000-010400-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 331
NWS STORM PREDICTION CENTER NORMAN OK
600 PM CDT THU MAY 31 2012
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
NORTHERN ALABAMA
MIDDLE TENNESSEE
EFFECTIVE THIS THURSDAY EVENING FROM 600 PM UNTIL 1100 PM CDT.
HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH
NORTHWEST OF NASHVILLE TENNESSEE TO 25 MILES SOUTH OF MUSCLE
SHOALS ALABAMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).
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...CONTINUE...WW 328...WW 329...WW 330...
DISCUSSION...TSTM BAND IN NE MS/W TN MAY INCREASE IN STRENGTH THIS
EVE AS IT CONTINUES ENE INTO RELATIVELY UNDISTURBED ENVIRONMENT
ACROSS NRN AL/MIDDLE TN. OTHER STORMS MAY FORM AHEAD OF THE BAND AS
LARGE SCALE ASCENT INCREASES WITH THE APPROACH OF UPR VORT NOW
NEARING MEMPHIS. 20-25 KT WSWLY DEEP SHEAR MAY SUPPORT A FEW
SUSTAINED STORMS WITH LOCALLY DMGG WIND/MARGINALLY SVR HAIL.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 24025.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 31, 2:38 PM CDT | Mesoscale Discussion | SPC | Lamar | 67 min |
| May 31, 5:21 PM CDT | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 18 more | 84 min |
| May 31, 5:30 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Lauderdale, Lawrence, Limestone | 2 hr |
| May 31, 10:41 AM CDT | Severe Thunderstorm Watch | SPC | Adams, Amite, Claiborne, Copiah, Franklin, Issaquena and 5 more | 6 hr |
| May 31, 11:59 AM CDT | Mesoscale Discussion | SPC | Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 32 more | 61 min |
| May 31, 12:59 PM CDT | Severe Thunderstorm Watch | SPC | Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 41 more | 6 hr |
| May 31, 1:53 PM CDT | Mesoscale Discussion | SPC | Adams, Amite, Attala, Choctaw, Claiborne, Clarke and 36 more | 67 min |
| May 31, 2:53 PM CDT | Severe Thunderstorm Watch | SPC | Clarke, Covington, Forrest, George, Greene, Hancock and 18 more | 5 hr |
| May 31, 1:56 PM CDT | Mesoscale Discussion | SPC | Lake | 64 min |
Nearby
Severe Thunderstorm Watches in Tennessee, 2012Severe Thunderstorm Watches in Alabama, 2012Every severe thunderstorm watch in 2012
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.