Alert archive / Mississippi / Tornado Watches in 2012

Tornado Watch 689

December 20, 20124 states

The Storm Prediction Center issued this tornado watch at Dec 20, 2012, 4:23 AM CST for 4 states. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued: Dec 20, 2012, 4:23 AM CST (10:23 UTC)
Expired: Dec 20, 2012, 1:14 PM CST
In force: 9 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 65 kt

All 103 counties

Autauga County, AL, Baldwin County, AL, Barbour County, AL, Bibb County, AL, Bullock County, AL, Butler County, AL, Calhoun County, AL, Chambers County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Cleburne County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Greene County, AL, Hale County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Pike County, AL, Randolph County, AL, Russell County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Attala County, MS, Choctaw County, MS, Clarke County, MS, Clay County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Hinds County, MS, Jackson County, MS, Jasper 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, Lowndes County, MS, Madison County, MS, Marion County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Webster County, MS, Wilkinson County, MS, Winston County, MS

The radar

The Mobile radar (KMOB), 115 km from the middle of the area, began a volume at 10:24 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: 50%
One or more EF2 to EF5 tornadoes: 30%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 30%
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: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Dec 20, 4:25 AM CST	Severe Thunderstorm Warning	JAN	Carroll, Grenada, Leflore, Montgomery	80 min
Dec 20, 4:34 AM CST	Severe Thunderstorm Warning	JAN	Adams, Claiborne, Franklin, Jefferson	71 min
Dec 20, 4:42 AM CST	Tornado Warning	MOB	Mobile	36 min
Dec 20, 4:48 AM CST	Severe Thunderstorm Warning	JAN	Hinds, Madison	57 min
Dec 20, 4:49 AM CST	Tornado Warning	MOB	Choctaw	30 min
Dec 20, 5:01 AM CST	Severe Thunderstorm Warning	JAN	Copiah	59 min
Dec 20, 5:08 AM CST	Severe Thunderstorm Warning	JAN	Attala, Choctaw, Webster	67 min
Dec 20, 5:14 AM CST	Tornado Warning	MOB	Baldwin	46 min
Dec 20, 5:16 AM CST	Severe Thunderstorm Warning	JAN	Leake, Rankin, Scott	74 min
Dec 20, 5:24 AM CST	Severe Thunderstorm Warning	JAN	Lincoln	66 min
Dec 20, 5:26 AM CST	Severe Thunderstorm Warning	JAN	Jasper, Smith	34 min
Dec 20, 5:27 AM CST	Severe Thunderstorm Warning	JAN	Marion	48 min
Dec 20, 5:29 AM CST	Tornado Warning	MOB	Washington	46 min
Dec 20, 5:31 AM CST	Tornado Warning	LIX	Washington	29 min
Dec 20, 5:37 AM CST	Severe Thunderstorm Warning	LIX	Saint Tammany, Tangipahoa, Washington	38 min
Dec 20, 5:38 AM CST	Tornado Warning	MOB	Choctaw, Clarke, Washington	52 min
Dec 20, 5:38 AM CST	Tornado Warning	JAN	Marion	37 min
Dec 20, 5:44 AM CST	Severe Thunderstorm Warning	JAN	Jefferson Davis, Lawrence, Simpson	76 min
Dec 20, 5:44 AM CST	Tornado Warning	LIX	Pearl River	16 min
Dec 20, 5:45 AM CST	Tornado Warning	MOB	Baldwin, Mobile	39 min
Dec 20, 5:53 AM CST	Severe Thunderstorm Warning	JAN	Clay, Oktibbeha, Winston	52 min
Dec 20, 5:56 AM CST	Severe Thunderstorm Warning	LIX	Livingston, Saint Tammany, Tangipahoa, Washington	64 min
Dec 20, 5:58 AM CST	Severe Thunderstorm Warning	JAN	Neshoba, Newton	62 min
Dec 20, 5:59 AM CST	Severe Thunderstorm Warning	JAN	Covington, Lamar	46 min
Dec 20, 6:00 AM CST	Severe Thunderstorm Warning	JAN	Jasper, Smith	75 min
Dec 20, 6:03 AM CST	Tornado Warning	MOB	Clarke	28 min
Dec 20, 6:06 AM CST	Tornado Warning	MOB	Washington	22 min
Dec 20, 6:08 AM CST	Tornado Warning	MOB	Baldwin	21 min
Dec 20, 6:11 AM CST	Tornado Warning	MOB	Conecuh, Escambia, Monroe	49 min
Dec 20, 6:16 AM CST	Severe Thunderstorm Warning	LIX	Washington	29 min
Dec 20, 6:17 AM CST	Severe Thunderstorm Warning	JAN	Lauderdale	43 min
Dec 20, 6:18 AM CST	Severe Thunderstorm Warning	JAN	Lamar, Marion	42 min
Dec 20, 6:20 AM CST	Severe Thunderstorm Warning	JAN	Lowndes, Noxubee	40 min
Dec 20, 6:23 AM CST	Severe Thunderstorm Warning	JAN	Covington, Jones	82 min
Dec 20, 6:31 AM CST	Severe Thunderstorm Warning	LIX	Saint Tammany, Washington	44 min
Dec 20, 6:33 AM CST	Severe Thunderstorm Warning	JAN	Kemper, Lauderdale	57 min
Dec 20, 6:38 AM CST	Severe Thunderstorm Warning	JAN	Forrest	37 min
Dec 20, 6:39 AM CST	Tornado Warning	MOB	Conecuh, Monroe	35 min
Dec 20, 6:40 AM CST	Tornado Warning	MOB	Washington	50 min
Dec 20, 6:47 AM CST	Severe Thunderstorm Warning	LIX	Ascension, Livingston, Saint John the Baptist, Saint Tammany, Tangipahoa, Washington	43 min
Dec 20, 6:48 AM CST	Severe Thunderstorm Warning	JAN	Lamar, Marion	57 min
Dec 20, 6:51 AM CST	Severe Thunderstorm Warning	JAN	Clarke, Lauderdale	54 min
Dec 20, 6:56 AM CST	Tornado Warning	MOB	Baldwin, Mobile	34 min
Dec 20, 6:59 AM CST	Severe Thunderstorm Warning	LIX	Ascension, Jefferson, Lafourche, Saint Charles, Saint James, Saint John the Baptist and 1 more	46 min
Dec 20, 6:59 AM CST	Severe Thunderstorm Warning	JAN	Lowndes, Noxubee	19 min
Dec 20, 7:02 AM CST	Tornado Warning	MOB	Baldwin, Mobile	58 min
Dec 20, 7:03 AM CST	Severe Thunderstorm Warning	BMX	Greene, Pickens, Sumter	57 min
Dec 20, 7:12 AM CST	Severe Thunderstorm Warning	JAN	Forrest	48 min
Dec 20, 7:12 AM CST	Severe Thunderstorm Warning	MOB	Wayne	63 min
Dec 20, 7:18 AM CST	Tornado Warning	MOB	Clarke, Washington	42 min
Dec 20, 7:19 AM CST	Tornado Warning	MOB	Conecuh, Escambia, Monroe	56 min
Dec 20, 7:25 AM CST	Tornado Warning	MOB	Clarke, Wilcox	50 min
Dec 20, 7:31 AM CST	Severe Thunderstorm Warning	LIX	Saint Tammany, Tangipahoa, Washington	33 min
Dec 20, 7:34 AM CST	Tornado Warning	LIX	Hancock, Harrison	26 min
Dec 20, 7:36 AM CST	Tornado Warning	MOB	Baldwin, Clarke, Monroe	42 min
Dec 20, 7:42 AM CST	Severe Thunderstorm Warning	MOB	George, Greene, Perry, Stone	63 min
Dec 20, 7:52 AM CST	Tornado Warning	MOB	Baldwin	53 min
Dec 20, 8:03 AM CST	Severe Thunderstorm Warning	LIX	Harrison	27 min
Dec 20, 8:10 AM CST	Tornado Warning	MOB	Wilcox	32 min
Dec 20, 8:14 AM CST	Tornado Warning	MOB	Conecuh, Monroe	33 min
Dec 20, 8:15 AM CST	Severe Thunderstorm Warning	MOB	Choctaw, Clarke	17 min
Dec 20, 8:21 AM CST	Severe Thunderstorm Warning	BMX	Autauga, Dallas	24 min
Dec 20, 8:27 AM CST	Tornado Warning	MOB	Escambia	63 min
Dec 20, 8:29 AM CST	Tornado Warning	MOB	Escambia	46 min
Dec 20, 8:41 AM CST	Tornado Warning	MOB	Escambia, Okaloosa, Santa Rosa	64 min
Dec 20, 9:00 AM CST	Tornado Warning	MOB	Escambia, Santa Rosa	60 min
Dec 20, 9:11 AM CST	Tornado Warning	MOB	Escambia	25 min
Dec 20, 9:13 AM CST	Severe Thunderstorm Warning	LIX	Harrison, Jackson	47 min
Dec 20, 9:25 AM CST	Tornado Warning	MOB	Covington	55 min
Dec 20, 9:28 AM CST	Severe Thunderstorm Warning	MOB	Wilcox	15 min
Dec 20, 9:43 AM CST	Tornado Warning	MOB	Okaloosa, Santa Rosa	62 min
Dec 20, 9:49 AM CST	Severe Thunderstorm Warning	MOB	Wilcox	26 min
Dec 20, 9:50 AM CST	Tornado Warning	MOB	Covington, Crenshaw	16 min
Dec 20, 10:35 AM CST	Severe Thunderstorm Warning	BMX	Autauga, Elmore, Lowndes, Montgomery	40 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

Slidell Radar S, LA (KSIL), launched 00:00Z, 10.4 hours before the alert went out and 136 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: 673 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 242 m²/s²
0-3 km storm-relative helicity: 277 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.

540 
WWUS20 KWNS 201023
SEL9
SPC WW 201023
ALZ000-FLZ000-LAZ000-MSZ000-CWZ000-201800-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 689
NWS STORM PREDICTION CENTER NORMAN OK
425 AM CST THU DEC 20 2012

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

       CENTRAL AND SOUTHERN ALABAMA
       WESTERN PANHANDLE OF FLORIDA
       SOUTHEASTERN LOUISIANA
       CENTRAL AND SOUTHERN MISSISSIPPI
       COASTAL WATERS

EFFECTIVE THIS THURSDAY MORNING FROM 425 AM UNTIL NOON CST.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 140 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTHWEST OF GULFPORT
MISSISSIPPI TO TUSCALOOSA ALABAMA.  FOR A COMPLETE DEPICTION OF
THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS
WOU9).

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 688...

DISCUSSION...CONVECTION IS INCREASING IN INTENSITY AND COVERAGE
WITHIN FAVORABLE ENVIRONMENT THAT IS SPREADING INLAND ACROSS WW
AREA.  EXPECT FAVORABLE JUXTAPOSITION OF NEWD-SPREADING WARM SECTOR
-- CHARACTERIZED BY 60S F SFC DEW POINTS AND LOW 70S NEAR COAST --
WITH STG KINEMATIC REGIME CHARACTERIZED BY 45-55 KT EFFECTIVE SHEAR
AND 250-450 J/KG EFFECTIVE SRH.  THIS WILL SUPPORT STORM-SCALE
ROTATION AND TORNADO POTENTIAL WITH DISCRETE CELLS...AS WELL AS
DAMAGING WIND AND SPORADIC TORNADO RISK WITH QLCS BOW/LEWP FEATURES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 24035.


...EDWARDS

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 20, 4:08 AM CST	Mesoscale Discussion	SPC	Choctaw, Colbert, Fayette, Franklin, Greene, Lamar and 5 more	67 min
Dec 20, 7:09 AM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 22 more	96 min
Dec 20, 8:49 AM CST	Mesoscale Discussion	SPC	Dale, Geneva, Henry, Houston	56 min
Dec 20, 9:19 AM CST	Tornado Watch	SPC	Coffee, Dale, Geneva, Henry, Houston	9 hr
Dec 20, 9:56 AM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Bibb, Butler, Chambers, Chilton and 22 more	64 min
Dec 20, 1:31 PM CST	Mesoscale Discussion	SPC	Barbour, Coffee, Dale, Geneva, Henry, Houston and 1 more	59 min
Dec 20, 5:22 PM CST	Mesoscale Discussion	SPC	Alachua, Baker, Bradford, Clay, Columbia, Dixie and 7 more	53 min
Dec 19, 9:56 PM CST	Severe Thunderstorm Watch	SPC	Bossier, Caddo, De Soto	5 hr
Dec 19, 11:55 PM CST	Mesoscale Discussion	SPC	Allen, Avoyelles, Beauregard, Bienville, Bossier, Caddo and 28 more	95 min
Dec 20, 12:50 AM CST	Mesoscale Discussion	SPC	Bienville, Caldwell, Claiborne, East Carroll, Franklin, Jackson and 10 more	55 min
Dec 20, 1:07 AM CST	Severe Thunderstorm Watch	SPC	Avoyelles, Bienville, Caldwell, Catahoula, Claiborne, Concordia and 20 more	5 hr

Nearby

Tornado Watches in Mississippi, 2012 Tornado Watches in Alabama, 2012 Tornado Watches in Louisiana, 2012 Every tornado 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.