Alert archive / Mississippi / Tornado Watches in 2007

Tornado Watch 742

December 20, 20075 counties in Alabama; 12 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Dec 20, 2007, 10:01 AM CST for 5 counties in Alabama; 12 counties in Mississippi. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Dec 20, 2007, 10:01 AM CST (16:01 UTC)
Expired: Dec 20, 2007, 3:24 PM CST
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

Counties Baldwin County, AL, Choctaw County, AL, Clarke County, AL, Mobile County, AL, Washington County, AL, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Jasper County, MS, Jones County, MS, Lamar County, MS, Perry County, MS, Smith County, MS, Stone County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 126 km from the middle of the area, began a volume at 16:00 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: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 20%
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: 50%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Dec 20, 10:05 AM CST	Severe Thunderstorm Warning	JAN	Simpson, Smith	40 min
Dec 20, 10:13 AM CST	Severe Thunderstorm Warning	JAN	Jones	47 min
Dec 20, 10:35 AM CST	Severe Thunderstorm Warning	MOB	Greene, Perry, Wayne	40 min
Dec 20, 11:12 AM CST	Severe Thunderstorm Warning	MOB	Washington	48 min
Dec 20, 11:57 AM CST	Severe Thunderstorm Warning	MOB	Choctaw, Clarke, Monroe, Washington	63 min
Dec 20, 1:35 PM CST	Severe Thunderstorm Warning	MOB	Baldwin, Escambia	55 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, 4.0 hours before the alert went out and 148 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: 186 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 606 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 70 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.

999 
WWUS20 KWNS 201602
SEL2  
SPC WW 201602
ALZ000-MSZ000-202200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 742
NWS STORM PREDICTION CENTER NORMAN OK
1005 AM CST THU DEC 20 2007

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

       SOUTHWESTERN ALABAMA
       SOUTHEASTERN MISSISSIPPI

EFFECTIVE THIS THURSDAY MORNING AND AFTERNOON FROM 1005 AM UNTIL
400 PM CST.

TORNADOES...HAIL TO 1 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 40 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 20 MILES NORTH OF PINE BELT
MISSISSIPPI TO 100 MILES EAST OF PINE BELT MISSISSIPPI.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU2).

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...CONTINUE...WW 741...

DISCUSSION...DESPITE WEAK INSTABILITY AND SLIGHTLY ELEVATED STORM
UPDRAFT ROOTS ...TORNADO POTENTIAL WILL EXIST INTO THE AFTERNOON
HOURS WITH MESOLOW THAT WILL TRACK EWD FROM SERN MS INTO SWRN AL.

AVIATION...TORNADOES AND 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 400.
MEAN STORM MOTION VECTOR 25045.


...IMY

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 20, 11:21 AM CST	Mesoscale Discussion	SPC	Baldwin, Choctaw, Clarke, Mobile, Washington	84 min
Dec 20, 11:50 AM CST	Tornado Watch	SPC	Butler, Conecuh, Covington, Escambia, Monroe	5 hr
Dec 20, 1:03 PM CST	Mesoscale Discussion	SPC	Baldwin, Conecuh, Escambia, Mobile, Monroe	57 min
Dec 20, 8:48 AM CST	Mesoscale Discussion	SPC	Amite, Pike, Wilkinson	57 min
Dec 20, 9:15 AM CST	Tornado Watch	SPC	Amite, Hancock, Harrison, Jackson, Pearl River, Pike and 2 more	7 hr
Dec 20, 1:06 PM CST	Mesoscale Discussion	SPC	Amite, Hancock, Harrison, Jackson, Pearl River, Pike and 2 more	84 min

Nearby

Tornado Watches in Mississippi, 2007 Tornado Watches in Alabama, 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.