Alert archive / Louisiana / Tornado Watches in 2007

Tornado Watch 710

October 17, 20077 counties in Arkansas; 33 parishes in Louisiana; 27 counties in Texas

The Storm Prediction Center issued this tornado watch at Oct 17, 2007, 11:13 AM CDT for 7 counties in Arkansas; 33 parishes in Louisiana; 27 counties in Texas. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Oct 17, 2007, 11:13 AM CDT (16:13 UTC)
Expired
Oct 17, 2007, 6:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 67 counties

Columbia County, AR, Hempstead County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Union County, AR, Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Iberia Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Union Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Angelina County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Franklin County, TX, Gregg County, TX, Hardin County, TX, Harrison County, TX, Jasper County, TX, Jefferson County, TX, Marion County, TX, Morris County, TX, Nacogdoches County, TX, Newton County, TX, Orange County, TX, Panola County, TX, Red River County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Smith County, TX, Titus County, TX, Tyler County, TX, Upshur County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 63 km from the middle of the area, began a volume at 16:16 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
30%
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
10%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Oct 17, 2:04 PM CDTSevere Thunderstorm WarningSHVBossier, Webster41 min
Oct 17, 2:10 PM CDTTornado WarningSHVBossier, Webster50 min
Oct 17, 2:52 PM CDTTornado WarningSHVColumbia38 min
Oct 17, 3:27 PM CDTSevere Thunderstorm WarningSHVColumbia, Union48 min
Oct 17, 3:59 PM CDTTornado WarningSHVUnion31 min
Oct 17, 4:40 PM CDTSevere Thunderstorm WarningSHVCherokee, Nacogdoches, Rusk35 min
Oct 17, 4:58 PM CDTTornado WarningSHVNacogdoches, Rusk32 min
Oct 17, 5:29 PM CDTTornado WarningSHVNacogdoches, Panola, Rusk, Shelby25 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

Shreveport, LA (KSHV), launched 12:00Z, 4.2 hours before the alert went out and 67 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-pSkew-T log-p diagram, Shreveport, LA at 12:00Z on 2007-10-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 865 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Shreveport, LA at 12:00Z on 2007-10-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 140 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
865 J/kg
Mixed-layer CIN
-37 J/kg
Mixed-layer LCL
477 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
140 m²/s²
0-3 km storm-relative helicity
170 m²/s²
Significant tornado parameter
0.6
Supercell composite
4.6

Open this sounding in Storm Lab

The text

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

000
WWUS20 KWNS 171608
SEL0  
SPC WW 171608
ARZ000-LAZ000-TXZ000-CWZ000-172300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 710
NWS STORM PREDICTION CENTER NORMAN OK
1110 AM CDT WED OCT 17 2007

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

       SOUTHWEST ARKANSAS
       MUCH OF WESTERN AND NORTHERN LOUISIANA
       PARTS OF EASTERN TEXAS
       COASTAL WATERS

EFFECTIVE THIS WEDNESDAY MORNING AND EVENING FROM 1110 AM UNTIL
600 PM CDT.

TORNADOES...HAIL TO 1.5 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 85 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF TEXARKANA
ARKANSAS TO 65 MILES SOUTHWEST OF INTRACOASTAL CITY LOUISIANA. 
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 708...WW 709...

DISCUSSION...VERY MOIST AIRMASS ALONG WITH FAVORABLE LOW LEVEL SHEAR
PROFILES WILL SUPPORT INCREASING TORNADIC SUPERCELL POTENTIAL
THROUGH THE AFTERNOON.  STORMS WILL INCREASE NWD THRU WATCH AREA AS
AIR MASS CONTINUES TO DESTABILIZE.

AVIATION...TORNADOES AND 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
550. MEAN STORM MOTION VECTOR 23025.


...HALES

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 17, 9:36 AM CDTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Cleveland, Columbia, Dallas and 5 more114 min
Oct 17, 10:24 AM CDTMesoscale DiscussionSPCBenton, Washington96 min
Oct 17, 10:43 AM CDTTornado WatchSPCBenton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more7 hr
Oct 17, 2:36 PM CDTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Clark, Cleveland, Columbia and 14 more114 min
Oct 17, 4:31 PM CDTTornado WatchSPCArkansas, Baxter, Benton, Boone, Bradley, Calhoun and 55 more7 hr
Oct 17, 5:15 PM CDTMesoscale DiscussionSPCArkansas, Ashley, Chicot, Crittenden, Cross, Desha and 7 more2 hr
Oct 16, 10:36 PM CDTMesoscale DiscussionSPCArmstrong, Briscoe, Carson, Castro, Childress, Collingsworth and 27 more114 min
Oct 16, 11:45 PM CDTSevere Thunderstorm WatchSPCArmstrong, Carson, Collingsworth, Donley, Gray, Hansford and 10 more2 hr
Oct 17, 1:12 AM CDTMesoscale DiscussionSPCArmstrong, Briscoe, Carson, Castro, Childress, Collingsworth and 24 more93 min
Oct 17, 1:36 AM CDTTornado WatchSPCArmstrong, Briscoe, Carson, Childress, Collingsworth, Cottle and 18 more7 hr
Oct 17, 1:44 AM CDTSevere Thunderstorm WatchSPCHansford, Hutchinson, Lipscomb, Moore, Ochiltree, Potter and 3 more7 hr
Oct 17, 4:41 AM CDTMesoscale DiscussionSPCArcher, Baylor, Borden, Brown, Callahan, Coke and 32 more2 hr
Oct 17, 6:07 AM CDTMesoscale DiscussionSPCArmstrong, Briscoe, Childress, Collingsworth, Cottle, Crosby and 19 more113 min
Oct 17, 6:50 AM CDTMesoscale DiscussionSPCHansford, Hutchinson, Lipscomb, Moore, Ochiltree, Potter and 2 more100 min
Oct 17, 7:43 AM CDTTornado WatchSPCArcher, Baylor, Clay, Foard, Hardeman, Knox and 2 more7 hr
Oct 17, 1:20 PM CDTMesoscale DiscussionSPCCollin, Delta, Fannin, Grayson, Hunt, Lamar and 1 more85 min

Nearby

Tornado Watches in Louisiana, 2007Tornado Watches in Texas, 2007Tornado Watches in Arkansas, 2007Every 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.