Alert archive / Louisiana / Tornado Watches in 2008

Tornado Watch 945

December 9, 20086 counties in Arkansas; 33 parishes in Louisiana; 28 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Dec 9, 2008, 9:32 AM CST for 6 counties in Arkansas; 33 parishes in Louisiana; 28 counties in Mississippi. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Dec 9, 2008, 9:32 AM CST (15:32 UTC)
Expired: Dec 9, 2008, 3:55 PM CST
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 67 counties

Ashley County, AR, Bradley County, AR, Chicot County, AR, Desha County, AR, Drew County, AR, Union County, AR, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Attala County, MS, Bolivar County, MS, Carroll County, MS, Claiborne County, MS, Coahoma 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, Leflore County, MS, Lincoln County, MS, Madison County, MS, Montgomery County, MS, Quitman County, MS, Rankin County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Warren County, MS, Washington County, MS, Wilkinson County, MS, Yalobusha County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 170 km from the middle of the area, began a volume at 15:34 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: 60%
One or more EF2 to EF5 tornadoes: 30%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 40%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Dec 9, 9:46 AM CST	Severe Thunderstorm Warning	LCH	Rapides	16 min
Dec 9, 9:57 AM CST	Tornado Warning	LCH	Rapides	33 min
Dec 9, 10:28 AM CST	Tornado Warning	LCH	Rapides	32 min
Dec 9, 10:59 AM CST	Severe Thunderstorm Warning	LCH	Rapides	31 min
Dec 9, 11:08 AM CST	Severe Thunderstorm Warning	SHV	Grant, LaSalle	37 min
Dec 9, 11:12 AM CST	Tornado Warning	LCH	Rapides	33 min
Dec 9, 11:20 AM CST	Severe Thunderstorm Warning	SHV	Bienville, Claiborne, Lincoln, Union, Webster	40 min
Dec 9, 11:33 AM CST	Tornado Warning	SHV	Grant, LaSalle	42 min
Dec 9, 11:35 AM CST	Severe Thunderstorm Warning	LZK	Arkansas, Desha, Drew	55 min
Dec 9, 12:17 PM CST	Tornado Warning	SHV	Caldwell, LaSalle	28 min
Dec 9, 12:19 PM CST	Tornado Warning	SHV	Natchitoches, Sabine	41 min
Dec 9, 12:22 PM CST	Severe Thunderstorm Warning	JAN	Bolivar	53 min
Dec 9, 12:33 PM CST	Tornado Warning	JAN	Catahoula, Franklin, Richland	57 min
Dec 9, 12:45 PM CST	Tornado Warning	SHV	Caldwell, LaSalle	30 min
Dec 9, 1:01 PM CST	Severe Thunderstorm Warning	LZK	Desha	28 min
Dec 9, 1:08 PM CST	Severe Thunderstorm Warning	JAN	Bolivar, Sunflower	52 min
Dec 9, 1:19 PM CST	Tornado Warning	SHV	Natchitoches, Sabine	41 min
Dec 9, 1:31 PM CST	Tornado Warning	JAN	Franklin, Richland	28 min
Dec 9, 1:37 PM CST	Tornado Warning	JAN	Bolivar, Leflore, Sunflower	38 min
Dec 9, 1:39 PM CST	Severe Thunderstorm Warning	MEG	Panola, Quitman	36 min
Dec 9, 1:40 PM CST	Tornado Warning	SHV	Natchitoches, Winn	35 min
Dec 9, 1:52 PM CST	Severe Thunderstorm Warning	JAN	Franklin, Madison, Richland	38 min
Dec 9, 1:54 PM CST	Tornado Warning	JAN	Franklin	34 min
Dec 9, 1:57 PM CST	Tornado Warning	SHV	Grant, Natchitoches, Winn	36 min
Dec 9, 2:15 PM CST	Tornado Warning	JAN	East Carroll, Madison, Richland	45 min
Dec 9, 2:27 PM CST	Severe Thunderstorm Warning	SHV	Natchitoches, Winn	20 min
Dec 9, 2:34 PM CST	Flash Flood Warning	MEG	Coahoma, Marshall, Panola, Quitman, Tate, Tunica	3 hr
Dec 9, 2:46 PM CST	Tornado Warning	JAN	Issaquena, Sharkey	44 min
Dec 9, 3:08 PM CST	Tornado Warning	SHV	Caldwell, Winn	37 min
Dec 9, 3:26 PM CST	Tornado Warning	JAN	Sharkey, Yazoo	49 min
Dec 9, 3:32 PM CST	Tornado Warning	JAN	East Carroll, Madison	43 min
Dec 9, 3:45 PM CST	Severe Thunderstorm Warning	SHV	Caldwell, Grant, Jackson, LaSalle, Winn	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, 3.5 hours before the alert went out and 161 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: 587 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 445 m²/s²
0-3 km storm-relative helicity: 522 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.

000
WWUS20 KWNS 091533
SEL5  
SPC WW 091533
ARZ000-LAZ000-MSZ000-092300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 945
NWS STORM PREDICTION CENTER NORMAN OK
935 AM CST TUE DEC 9 2008

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

       SOUTHEAST ARKANSAS
       NORTHERN AND CENTRAL LOUISIANA
       WESTERN AND CENTRAL MISSISSIPPI

EFFECTIVE THIS TUESDAY MORNING AND AFTERNOON FROM 935 AM UNTIL
500 PM CST.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH NORTHWEST OF
GREENWOOD MISSISSIPPI TO 25 MILES SOUTH SOUTHEAST OF FORT POLK
LOUISIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).

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 944...

DISCUSSION...THUNDERSTORMS CONTINUE TO INTENSIFY ACROSS PARTS OF
CENTRAL LA...AND ALONG CONVECTIVE LINE FROM NORTHEAST TX INTO
EASTERN AR.  INCREASING SOUTHERLY LOW LEVEL WINDS ACROSS THIS REGION
WILL HELP ESTABLISH A MOIST AND MARGINALLY UNSTABLE AIRMASS THROUGH
THE DAY...WHILE STRONG VERTICAL SHEAR IS MAINTAINED.  POTENTIAL FOR
ISOLATED TORNADOES AND DAMAGING WINDS WILL BE PRESENT THROUGH MUCH
OF THE DAY.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 24035.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 8, 11:31 PM CST	Tornado Watch	SPC	Little River, Miller	7 hr
Dec 9, 12:10 AM CST	Mesoscale Discussion	SPC	Benton, Boone, Carroll, Madison, Marion, Newton and 1 more	35 min
Dec 9, 12:22 AM CST	Severe Thunderstorm Watch	SPC	Baxter, Benton, Boone, Carroll, Cleburne, Conway and 24 more	4 hr
Dec 9, 1:20 AM CST	Mesoscale Discussion	SPC	Baxter, Benton, Boone, Carroll, Cleburne, Conway and 25 more	25 min
Dec 9, 2:17 AM CST	Mesoscale Discussion	SPC	Little River, Miller	58 min
Dec 9, 3:41 AM CST	Mesoscale Discussion	SPC	Ashley, Bradley, Calhoun, Clark, Cleveland, Columbia and 36 more	64 min
Dec 9, 4:11 AM CST	Tornado Watch	SPC	Arkansas, Bradley, Calhoun, Clark, Cleveland, Columbia and 25 more	7 hr
Dec 9, 7:41 AM CST	Mesoscale Discussion	SPC	Arkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 21 more	64 min
Dec 9, 10:12 AM CST	Mesoscale Discussion	SPC	Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 10 more	93 min
Dec 9, 2:18 PM CST	Mesoscale Discussion	SPC	Chicot	87 min
Dec 9, 3:51 PM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 35 more	9 hr
Dec 9, 5:52 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Avoyelles, Catahoula, Concordia and 18 more	83 min
Dec 8, 7:10 PM CST	Mesoscale Discussion	SPC	Bosque, Collin, Comanche, Cooke, Dallas, Denton and 14 more	2 hr
Dec 8, 9:37 PM CST	Severe Thunderstorm Watch	SPC	Anderson, Bosque, Camp, Cherokee, Collin, Cooke and 36 more	5 hr
Dec 8, 11:14 PM CST	Mesoscale Discussion	SPC	Anderson, Camp, Delta, Franklin, Freestone, Henderson and 16 more	91 min
Dec 9, 2:30 AM CST	Mesoscale Discussion	SPC	Bosque, Collin, Dallas, Grayson	30 min

Nearby

Tornado Watches in Louisiana, 2008 Tornado Watches in Mississippi, 2008 Tornado Watches in Arkansas, 2008 Every tornado watch in 2008

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.