Alert archive / Oklahoma / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 218

April 26, 201126 counties in Oklahoma; 8 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Apr 26, 2011, 3:43 PM CDT for 26 counties in Oklahoma; 8 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Apr 26, 2011, 3:43 PM CDT (20:43 UTC)
Expired
Apr 26, 2011, 10:00 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 34 counties

Atoka County, OK, Beckham County, OK, Bryan County, OK, Caddo County, OK, Carter County, OK, Coal County, OK, Comanche County, OK, Cotton County, OK, Custer County, OK, Garvin County, OK, Grady County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Jefferson County, OK, Johnston County, OK, Kiowa County, OK, Love County, OK, Marshall County, OK, McClain County, OK, Murray County, OK, Pontotoc County, OK, Roger Mills County, OK, Stephens County, OK, Tillman County, OK, Washita County, OK, Archer County, TX, Baylor County, TX, Clay County, TX, Foard County, TX, Hardeman County, TX, Knox County, TX, Wichita County, TX, Wilbarger County, TX

The radar

The Altus AFB radar (KFDR), 54 km from the middle of the area, began a volume at 20:46 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
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
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
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 26, 4:25 PM CDTSevere Thunderstorm WarningOUNAtoka10 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

Norman, OK (KOUN), launched 12:00Z, 8.7 hours before the alert went out and 119 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, Norman, OK at 12:00Z on 2011-04-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Norman, OK at 12:00Z on 2011-04-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -58 square meters per square second.1939587897117Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
882 m above ground
0-6 km bulk shear
69 kt
0-1 km storm-relative helicity
-58 m²/s²
0-3 km storm-relative helicity
119 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
Apr 26, 1:11 PM CDTMesoscale DiscussionSPCBryan, Choctaw, McCurtain2 hr
Apr 26, 1:44 PM CDTTornado Watch PDSSPCMcCurtain10 hr
Apr 26, 3:15 PM CDTMesoscale DiscussionSPCBeckham, Caddo, Canadian, Cleveland, Comanche, Cotton and 15 more90 min
Apr 26, 3:59 PM CDTMesoscale DiscussionSPCMcCurtain91 min
Apr 26, 5:00 PM CDTMesoscale DiscussionSPCHaskell, Latimer, LeFlore, McIntosh, Pushmataha, Sequoyah30 min
Apr 26, 5:08 PM CDTTornado WatchSPCChoctaw, Haskell, Latimer, LeFlore, Pittsburg, Pushmataha and 1 more5 hr
Apr 26, 6:17 PM CDTMesoscale DiscussionSPCAdair, Cherokee, Craig, Delaware, LeFlore, McCurtain and 6 more118 min
Apr 25, 7:34 PM CDTMesoscale DiscussionSPCCamp, Cass, Marion, Morris116 min
Apr 25, 9:37 PM CDTMesoscale DiscussionSPCAnderson, Angelina, Cherokee, Ellis, Freestone, Gregg and 26 more83 min
Apr 25, 10:47 PM CDTTornado WatchSPCHardin, Jasper, Newton, Tyler5 hr
Apr 26, 1:34 AM CDTMesoscale DiscussionSPCHardin, Jasper, Newton, San Jacinto, Tyler86 min
Apr 26, 1:52 AM CDTSevere Thunderstorm WatchSPCChambers, Hardin, Harris, Jasper, Jefferson, Liberty and 4 more5 hr
Apr 26, 3:01 PM CDTMesoscale DiscussionSPCAtascosa, Austin, Bastrop, Bee, Bexar, Blanco and 22 more89 min
Apr 26, 4:56 PM CDTTornado WatchSPCAngelina, Austin, Bastrop, Brazos, Burleson, Fayette and 23 more5 hr
Apr 26, 6:43 PM CDTMesoscale DiscussionSPCAnderson, Angelina, Austin, Bastrop, Bell, Bowie and 64 more2 hr

Nearby

Severe Thunderstorm Watches in Oklahoma, 2011Severe Thunderstorm Watches in Texas, 2011Every severe thunderstorm 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.