Alert archive / Texas / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 266

May 7, 20127 parishes in Louisiana; 11 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at May 7, 2012, 7:39 PM CDT for 7 parishes in Louisiana; 11 counties in Texas. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
May 7, 2012, 7:39 PM CDT (00:39 UTC)
Expired
May 8, 2012, 12:00 AM CDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt

Counties Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Red River Parish, LA, Webster Parish, LA, Camp County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Morris County, TX, Panola County, TX, Rusk County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 49 km from the middle of the area, began a volume at 00:40 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
10%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 7, 7:42 PM CDTSevere Thunderstorm WarningSHVBowie, Camp, Morris, Red River, Titus33 min
May 7, 7:49 PM CDTSevere Thunderstorm WarningSHVBossier, Claiborne, Webster56 min
May 7, 8:17 PM CDTSevere Thunderstorm WarningSHVCamp, Cass, Morris, Titus, Upshur43 min
May 7, 8:29 PM CDTSevere Thunderstorm WarningSHVSmith, Wood46 min
May 7, 8:31 PM CDTSevere Thunderstorm WarningSHVClaiborne, Webster44 min
May 7, 8:50 PM CDTSevere Thunderstorm WarningSHVCass, Harrison, Marion, Morris, Upshur55 min
May 7, 9:12 PM CDTSevere Thunderstorm WarningSHVBienville48 min
May 7, 9:27 PM CDTSevere Thunderstorm WarningSHVGregg, Harrison, Upshur48 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 00:00Z, 0.7 hours before the alert went out and 57 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 00:00Z on 2012-05-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 891 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 00:00Z on 2012-05-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.1939Sfc1 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
891 J/kg
Mixed-layer CIN
-79 J/kg
Mixed-layer LCL
1717 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
72 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 7, 7:21 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 3 more54 min
May 7, 9:15 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Red River and 1 more60 min
May 7, 7:54 PM CDTMesoscale DiscussionSPCAtascosa, Bandera, Bastrop, Bee, Bexar, Brazos and 40 more66 min
May 7, 9:46 PM CDTMesoscale DiscussionSPCAndrews, Borden, Crane, Crockett, Dawson, Ector and 15 more89 min
May 8, 1:42 AM CDTMesoscale DiscussionSPCAtascosa, Bandera, Bexar, Comal, Dimmit, Edwards and 13 more93 min
May 8, 10:44 AM CDTMesoscale DiscussionSPCBee, Brooks, Duval, Frio, Goliad, Jim Hogg and 11 more61 min
May 8, 10:58 AM CDTSevere Thunderstorm WatchSPCAransas, Atascosa, Bee, Brooks, Calhoun, Cameron and 28 more8 hr
May 8, 1:37 PM CDTMesoscale DiscussionSPCBrewster, Culberson, El Paso, Hudspeth, Jeff Davis, Presidio and 1 more113 min
May 8, 2:07 PM CDTSevere Thunderstorm WatchSPCBrewster, Culberson, El Paso, Hudspeth, Jeff Davis, Presidio7 hr
May 8, 3:03 PM CDTMesoscale DiscussionSPCCameron, Hidalgo, Starr, Willacy87 min
May 8, 4:53 PM CDTMesoscale DiscussionSPCBrewster, Culberson, El Paso, Hudspeth, Jeff Davis, Presidio67 min
May 8, 5:47 PM CDTMesoscale DiscussionSPCCameron, Hidalgo, Kenedy, Willacy58 min

Nearby

Severe Thunderstorm Watches in Texas, 2012Severe Thunderstorm Watches in Louisiana, 2012Every severe thunderstorm 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.