Alert archive / Texas / Tornado Watches in 2011

Tornado Watch 872

November 7, 201130 counties in Texas

The Storm Prediction Center issued this tornado watch at Nov 7, 2011, 6:44 PM CST for 30 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Nov 7, 2011, 6:44 PM CST (00:44 UTC)
Expired
Nov 7, 2011, 8:58 PM CST
In force
2 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.8 in
Strongest gust expected
60 kt
All 30 counties

Bosque County, TX, Camp County, TX, Collin County, TX, Cooke County, TX, Coryell County, TX, Dallas County, TX, Delta County, TX, Denton County, TX, Ellis County, TX, Fannin County, TX, Franklin County, TX, Grayson County, TX, Hamilton County, TX, Henderson County, TX, Hill County, TX, Hopkins County, TX, Hunt County, TX, Johnson County, TX, Kaufman County, TX, Lamar County, TX, McLennan County, TX, Navarro County, TX, Rains County, TX, Red River County, TX, Rockwall County, TX, Smith County, TX, Tarrant County, TX, Titus County, TX, Van Zandt County, TX, Wood County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 45 km from the middle of the area, began a volume at 00:47 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
10%
Ten or more severe hail reports
10%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
70%

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Fort Worth, TX (KFWD), launched 00:00Z, 0.7 hours before the alert went out and 68 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, Fort Worth, TX at 00:00Z on 2011-11-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1725 joules per kilogram.LCLEL10008507005003002001001 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, Fort Worth, TX at 00:00Z on 2011-11-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 236 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
1725 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
615 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
236 m²/s²
0-3 km storm-relative helicity
303 m²/s²
Significant tornado parameter
2.9
Supercell composite
10.8

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Nov 7, 7:43 PM CSTMesoscale DiscussionSPCArcher, Baylor, Clay, Foard, Haskell, Knox and 3 more62 min
Nov 7, 8:28 PM CSTTornado WatchSPCArcher, Baylor, Clay, Foard, Hardeman, Knox and 2 more8 hr
Nov 7, 8:53 PM CSTMesoscale DiscussionSPCBorden, Coke, Fisher, Glasscock, Haskell, Howard and 9 more2 hr
Nov 7, 9:16 PM CSTTornado WatchSPCBorden, Callahan, Coke, Coleman, Concho, Crane and 31 more8 hr
Nov 7, 11:20 PM CSTMesoscale DiscussionSPCArcher, Baylor, Clay, Knox, Wichita85 min
Nov 8, 2:12 AM CSTMesoscale DiscussionSPCArcher, Baylor, Brown, Callahan, Clay, Coleman and 28 more93 min
Nov 8, 10:31 AM CSTMesoscale DiscussionSPCBowie, Camp, Cass, Franklin, Gregg, Harrison and 12 more29 min
Nov 8, 10:49 AM CSTTornado WatchSPCAnderson, Angelina, Bowie, Camp, Cass, Cherokee and 30 more7 hr
Nov 8, 1:03 PM CSTMesoscale DiscussionSPCAnderson, Angelina, Bowie, Camp, Cass, Cherokee and 24 more57 min
Nov 8, 1:44 PM CSTMesoscale DiscussionSPCAustin, Chambers, Grimes, Hardin, Harris, Jasper and 10 more61 min
Nov 8, 1:59 PM CSTTornado WatchSPCChambers, Grimes, Hardin, Harris, Houston, Jasper and 12 more6 hr
Nov 8, 3:48 PM CSTMesoscale DiscussionSPCAngelina, Bowie, Camp, Cass, Cherokee, Gregg and 11 more87 min
Nov 8, 3:53 PM CSTMesoscale DiscussionSPCAngelina, Grimes, Hardin, Harris, Jasper, Liberty and 7 more2 hr
Nov 8, 5:09 PM CSTMesoscale DiscussionSPCHardin, Jasper, Newton, Orange, Sabine, San Augustine and 2 more66 min
Nov 8, 5:30 PM CSTTornado WatchSPCAngelina, Hardin, Jasper, Jefferson, Nacogdoches, Newton and 6 more7 hr

Nearby

Tornado Watches in Texas, 2011Every tornado watch in 2011

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.