Alert archive / Mississippi / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 262

May 7, 20126 parishes in Louisiana; 36 counties in Mississippi

The Storm Prediction Center issued this severe thunderstorm watch at May 7, 2012, 1:07 PM CDT for 6 parishes in Louisiana; 36 counties in Mississippi. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: May 7, 2012, 1:07 PM CDT (18:07 UTC)
Expired: May 7, 2012, 6:20 PM CDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 42 counties

Catahoula Parish, LA, Concordia Parish, LA, Franklin Parish, LA, Madison Parish, LA, Richland Parish, LA, Tensas Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Greene County, MS, Hinds County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Warren County, MS, Wayne County, MS, Wilkinson County, MS, Winston County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 63 km from the middle of the area, began a volume at 18:09 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.

What SPC expected

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

Two or more tornadoes: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 70%

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
May 7, 1:22 PM CDT	Severe Thunderstorm Warning	JAN	Madison, Tensas	38 min
May 7, 1:26 PM CDT	Severe Thunderstorm Warning	JAN	Lowndes, Noxubee, Winston	64 min
May 7, 3:53 PM CDT	Severe Thunderstorm Warning	JAN	Adams	37 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

Jackson, MS (KJAN), launched 12:00Z, 6.1 hours before the alert went out and 59 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: 2057 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 496 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: -24 m²/s²
0-3 km storm-relative helicity: -21 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

415 
WWUS20 KWNS 071807
SEL2
SPC WW 071807
LAZ000-MSZ000-080100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 262
NWS STORM PREDICTION CENTER NORMAN OK
110 PM CDT MON MAY 7 2012

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

       EASTERN LOUISIANA
       CENTRAL AND SOUTHERN MISSISSIPPI

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 110 PM UNTIL 800
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 50
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES WEST OF
NATCHEZ MISSISSIPPI TO 25 MILES SOUTHEAST OF MERIDIAN
MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).

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 261...

DISCUSSION...GUST FRONT ASSOCIATED WITH SWD-MOVING MCS WILL CONTINUE
TO INTERACT WITH A MOIST AND MODERATELY UNSTABLE AIR MASS TO FOSTER
VIGOROUS UPDRAFT GROWTH ON THE LEADING EDGE OF SYSTEM COLD POOL.
THOUGH VERTICAL SHEAR WILL REMAIN WEAK...THE PRESENCE OF STEEP LOW
TO MIDLEVEL LAPSE RATES WILL SUPPORT VIGOROUS UP/DOWNDRAFTS CAPABLE
OF DAMAGING WINDS AND 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 36025.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 7, 3:53 PM CDT	Mesoscale Discussion	SPC	Catahoula, Concordia, Franklin, Madison, Tensas	97 min
May 7, 4:38 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, Red River, Webster	67 min
May 7, 11:00 AM CDT	Mesoscale Discussion	SPC	Attala, Choctaw, Clay, Hinds, Kemper, Lauderdale and 14 more	90 min

Nearby

Severe Thunderstorm Watches in Mississippi, 2012 Severe Thunderstorm Watches in Louisiana, 2012 Every 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.