Alert archive / Mississippi / Tornado Watches in 2007

Tornado Watch 744

December 22, 2007Ashley County, Chicot County, Arkansas; 17 parishes in Louisiana; 26 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Dec 22, 2007, 2:38 PM CST for Ashley County, Chicot County, Arkansas; 17 parishes in Louisiana; 26 counties in Mississippi. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Dec 22, 2007, 2:38 PM CST (20:38 UTC)
Expired: Dec 22, 2007, 8:00 PM CST
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

All 45 counties

Ashley County, AR, Chicot County, AR, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Franklin Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Pointe Coupee Parish, LA, Richland Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Tensas Parish, LA, West Baton Rouge Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Bolivar County, MS, Carroll County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Lawrence County, MS, Leflore County, MS, Lincoln County, MS, Madison County, MS, Pike County, MS, Rankin County, MS, Sharkey County, MS, Sunflower County, MS, Walthall County, MS, Warren County, MS, Washington County, MS, Wilkinson County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 110 km from the middle of the area, began a volume at 20:40 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: 20%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 5%
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: 30%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Dec 22, 4:32 PM CST	Severe Thunderstorm Warning	JAN	East Carroll	13 min
Dec 22, 5:29 PM CST	Severe Thunderstorm Warning	JAN	Franklin, Jefferson, Lincoln	46 min
Dec 22, 5:46 PM CST	Severe Thunderstorm Warning	JAN	Holmes, Yazoo	29 min
Dec 22, 5:59 PM CST	Severe Thunderstorm Warning	LIX	East Feliciana, Saint Helena	31 min
Dec 22, 6:17 PM CST	Severe Thunderstorm Warning	JAN	Claiborne, Copiah, Jefferson	28 min
Dec 22, 6:35 PM CST	Severe Thunderstorm Warning	LIX	Pike	25 min
Dec 22, 6:38 PM CST	Severe Thunderstorm Warning	LIX	East Baton Rouge, Livingston	37 min
Dec 22, 7:00 PM CST	Severe Thunderstorm Warning	LIX	Walthall	30 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, 8.6 hours before the alert went out and 101 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 582 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 265 m²/s²
0-3 km storm-relative helicity: 311 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.

534 
WWUS20 KWNS 222042
SEL4  
SPC WW 222042
ARZ000-LAZ000-MSZ000-230200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 744
NWS STORM PREDICTION CENTER NORMAN OK
240 PM CST SAT DEC 22 2007

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

       SOUTHEAST ARKANSAS
       EASTERN LOUISIANA
       WESTERN MISSISSIPPI

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 240 PM UNTIL
800 PM CST.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHWEST OF
GREENWOOD MISSISSIPPI TO 35 MILES WEST OF BATON ROUGE LOUISIANA. 
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU4).

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.

DISCUSSION...SCTD SLIGHTLY ELEVATED STORMS THAT FORMED EARLIER TODAY
ALONG WIND SHIFT LINE/SHALLOW COLD FRONT OVER THE SABINE RVR VLY
HAVE PROGRESSED ENE INTO AREA THAT EXPERIENCED MODEST SFC HEATING
ALONG THE LS/MS BORDER THIS AFTN.  WHILE STORMS MAY REMAIN VERY
SLIGHTLY ELEVATED...GIVEN STRENGTH OF WIND FIELD AND LOW-LVL
DIRECTIONAL SHEAR...POTENTIAL WILL EXIST FOR EMBEDDED AREAS OF
LOW-LVL STORM ROTATION.  THESE MAY POSE A THREAT FOR ISOLATED
TORNADOES/LOCALLY DAMAGING WIND BEFORE THE STORMS MOVE E BEYOND
NARROW AXIS OF INSTABILITY.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 23045.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 22, 12:38 PM CST	Mesoscale Discussion	SPC	Arkansas, Ashley, Chicot, Clay, Craighead, Crittenden and 10 more	97 min
Dec 22, 3:51 PM CST	Mesoscale Discussion	SPC	Chicot	54 min

Nearby

Tornado Watches in Mississippi, 2007 Tornado Watches in Louisiana, 2007 Tornado Watches in Arkansas, 2007 Every tornado watch in 2007

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.