Alert archive / Texas / Tornado Watches in 2008

Tornado Watch 131

March 18, 2008Union County, Arkansas; 20 parishes in Louisiana; 51 counties in Texas

The Storm Prediction Center issued this tornado watch at Mar 18, 2008, 10:59 AM CDT for Union County, Arkansas; 20 parishes in Louisiana; 51 counties in Texas. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Mar 18, 2008, 10:59 AM CDT (15:59 UTC)
Expired
Mar 18, 2008, 7:00 PM CDT
In force
8 hr
Issued by
the Storm Prediction Center
Particularly dangerous situation
Yes
Largest hail expected
2 in
Strongest gust expected
70 kt
All 72 counties

Union County, AR, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Anderson County, TX, Angelina County, TX, Austin County, TX, Bastrop County, TX, Bell County, TX, Brazoria County, TX, Brazos County, TX, Burleson County, TX, Chambers County, TX, Cherokee County, TX, Colorado County, TX, Coryell County, TX, Falls County, TX, Fayette County, TX, Fort Bend County, TX, Freestone County, TX, Galveston County, TX, Grimes County, TX, Hardin County, TX, Harris County, TX, Hill County, TX, Houston County, TX, Jackson County, TX, Jasper County, TX, Jefferson County, TX, Lee County, TX, Leon County, TX, Liberty County, TX, Limestone County, TX, Madison County, TX, Matagorda County, TX, McLennan County, TX, Milam County, TX, Montgomery County, TX, Nacogdoches County, TX, Navarro County, TX, Newton County, TX, Orange County, TX, Panola County, TX, Polk County, TX, Robertson County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX

The radar

The Shreveport radar (KSHV), 177 km from the middle of the area, began a volume at 16:01 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
90%
One or more EF2 to EF5 tornadoes
60%
Ten or more severe wind reports
80%
One or more gusts of 65 knots or more
60%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
40%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Mar 18, 12:45 PM CDTSevere Thunderstorm WarningHGXAustin, Brazos, Grimes, Waller, Washington45 min
Mar 18, 12:59 PM CDTFlash Flood WarningFWDHill3 hr
Mar 18, 2:04 PM CDTSevere Thunderstorm WarningFWDBosque, Hill, McLennan35 min
Mar 18, 2:31 PM CDTFlash Flood WarningFWDBell, Coryell3 hr
Mar 18, 3:01 PM CDTSevere Thunderstorm WarningFWDAnderson, Henderson44 min
Mar 18, 3:55 PM CDTFlash Flood WarningFWDHill3 hr

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, 4.0 hours before the alert went out and 186 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 2008-03-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 682 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Shreveport, LA at 12:00Z on 2008-03-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 356 square meters per square second.1939587897Sfc1 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
682 J/kg
Mixed-layer CIN
-38 J/kg
Mixed-layer LCL
741 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
356 m²/s²
0-3 km storm-relative helicity
487 m²/s²
Significant tornado parameter
1.7
Supercell composite
6.7

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 17, 7:34 PM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Crawford, Franklin and 11 more56 min
Mar 17, 9:36 PM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Cleburne, Conway and 20 more114 min
Mar 17, 10:16 PM CDTTornado WatchSPCBaxter, Benton, Boone, Carroll, Cleburne, Conway and 31 more8 hr
Mar 18, 1:13 AM CDTMesoscale DiscussionSPCWashington62 min
Mar 18, 2:23 AM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Fulton, Madison and 2 more2 hr
Mar 18, 2:46 AM CDTMesoscale DiscussionSPCBaxter, Cleburne, Conway, Crawford, Faulkner, Franklin and 27 more89 min
Mar 18, 5:54 AM CDTMesoscale DiscussionSPCBenton, Boone, Carroll, Crawford, Madison, Washington2 hr
Mar 18, 9:26 AM CDTMesoscale DiscussionSPCCalhoun, Clark, Columbia, Conway, Dallas, Garland and 19 more2 hr
Mar 18, 10:16 AM CDTTornado Watch PDSSPCArkansas, Clark, Clay, Cleburne, Cleveland, Columbia and 48 more7 hr
Mar 18, 11:54 AM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Crawford, Franklin and 6 more3 hr
Mar 18, 12:10 PM CDTMesoscale DiscussionSPCArkansas, Clark, Cleburne, Cleveland, Conway, Craighead and 47 more2 hr
Mar 18, 1:51 PM CDTMesoscale DiscussionSPCPolk, Sevier3 hr
Mar 18, 3:54 PM CDTMesoscale DiscussionSPCClark, Cleburne, Columbia, Dallas, Faulkner, Garland and 21 more2 hr
Mar 18, 4:46 PM CDTMesoscale DiscussionSPCArkansas, Clark, Clay, Craighead, Crittenden, Cross and 19 more59 min
Mar 18, 5:19 PM CDTTornado WatchSPCArkansas, Bradley, Calhoun, Clark, Clay, Cleburne and 43 more11 hr
Mar 18, 6:06 PM CDTMesoscale DiscussionSPCClark, Clay, Cleburne, Conway, Craighead, Cross and 20 more3 hr
Mar 18, 6:47 PM CDTTornado WatchSPCUnion9 hr
Mar 18, 6:19 PM CDTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Bienville, Bossier and 22 more56 min
Mar 17, 7:09 PM CDTSevere Thunderstorm WatchSPCArcher, Baylor, Clay, Wichita, Wilbarger7 hr
Mar 17, 9:17 PM CDTMesoscale DiscussionSPCBandera, Blanco, Bosque, Brown, Burnet, Callahan and 53 more58 min
Mar 17, 10:21 PM CDTMesoscale DiscussionSPCArcher, Baylor, Clay, Wichita, Wilbarger54 min
Mar 17, 11:06 PM CDTMesoscale DiscussionSPCBandera, Blanco, Bosque, Brown, Burnet, Callahan and 53 more54 min
Mar 18, 1:32 AM CDTMesoscale DiscussionSPCBrown, Callahan, Coke, Coleman, Concho, Crockett and 9 more58 min
Mar 18, 1:43 AM CDTMesoscale DiscussionSPCBrown, Callahan, Coke, Coleman, Concho, Crockett and 9 more32 min
Mar 18, 1:52 AM CDTTornado WatchSPCBandera, Blanco, Bosque, Brown, Burnet, Callahan and 34 more7 hr
Mar 18, 4:57 AM CDTMesoscale DiscussionSPCBandera, Blanco, Burnet, Coryell, Gillespie, Hamilton and 7 more93 min
Mar 18, 7:22 AM CDTMesoscale DiscussionSPCAnderson, Austin, Bastrop, Bell, Brazoria, Brazos and 40 more113 min
Mar 18, 7:50 AM CDTMesoscale DiscussionSPCBandera, Bosque, Brown, Burnet, Coleman, Comanche and 19 more55 min
Mar 18, 1:19 PM CDTMesoscale DiscussionSPCAnderson, Austin, Bastrop, Bell, Brazos, Burleson and 37 more116 min

Nearby

Tornado Watches in Texas, 2008Tornado Watches in Louisiana, 2008Tornado Watches in Arkansas, 2008Every 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.