Alert archive / Arkansas / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 296

May 12, 201132 counties in Arkansas; 8 counties in Missouri; 4 counties in Oklahoma

The Storm Prediction Center issued this severe thunderstorm watch at May 12, 2011, 10:03 PM CDT for 32 counties in Arkansas; 8 counties in Missouri; 4 counties in Oklahoma. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
May 12, 2011, 10:03 PM CDT (03:03 UTC)
Expired
May 13, 2011, 5:00 AM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 44 counties

Baxter County, AR, Cleburne County, AR, Conway County, AR, Crawford County, AR, Faulkner County, AR, Franklin County, AR, Fulton County, AR, Garland County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Johnson County, AR, Logan County, AR, Lonoke County, AR, Monroe County, AR, Montgomery County, AR, Newton County, AR, Perry County, AR, Polk County, AR, Pope County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Sharp County, AR, Stone County, AR, Van Buren County, AR, White County, AR, Woodruff County, AR, Yell County, AR, Dent County, MO, Howell County, MO, Maries County, MO, Oregon County, MO, Phelps County, MO, Pulaski County, MO, Shannon County, MO, Texas County, MO, Latimer County, OK, LeFlore County, OK, Pittsburg County, OK, Pushmataha County, OK

The radar

The Little Rock radar (KLZK), 117 km from the middle of the area, began a volume at 03:06 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
5%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
50%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 12, 10:52 PM CDTSevere Thunderstorm WarningLZKFulton, Sharp38 min
May 12, 11:48 PM CDTSevere Thunderstorm WarningLZKArkansas, Lonoke, Monroe, Prairie, Woodruff42 min
May 13, 12:23 AM CDTSevere Thunderstorm WarningLZKArkansas, Jefferson, Lonoke, Monroe, Prairie52 min
May 13, 12:31 AM CDTSevere Thunderstorm WarningLZKMonroe, Prairie, Woodruff44 min
May 13, 1:23 AM CDTSevere Thunderstorm WarningLZKArkansas, Monroe, Woodruff23 min
May 13, 1:40 AM CDTSevere Thunderstorm WarningLZKArkansas, Jefferson, Lincoln, Monroe50 min
May 13, 2:27 AM CDTSevere Thunderstorm WarningLZKArkansas, Monroe33 min
May 13, 3:27 AM CDTSevere Thunderstorm WarningLZKMonroe, Woodruff32 min
May 13, 4:09 AM CDTFlash Flood WarningLZKArkansas, Jefferson, Lonoke, Monroe, Prairie3 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

Springfield, MO (KSGF), launched 00:00Z, 3.1 hours before the alert went out and 155 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, Springfield, MO at 00:00Z on 2011-05-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1521 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, Springfield, MO at 00:00Z on 2011-05-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 84 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
1521 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
1233 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
84 m²/s²
0-3 km storm-relative helicity
153 m²/s²
Significant tornado parameter
0.7
Supercell composite
6.8

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 12, 9:41 PM CDTMesoscale DiscussionSPCBaxter, Boone, Cleburne, Conway, Crawford, Faulkner and 22 more64 min
May 12, 10:09 PM CDTMesoscale DiscussionSPCClay66 min
May 13, 12:01 PM CDTMesoscale DiscussionSPCArkansas, Clay, Craighead, Crittenden, Cross, Greene and 13 more89 min
May 13, 12:31 PM CDTSevere Thunderstorm WatchSPCClay, Craighead, Crittenden, Cross, Greene, Lawrence and 6 more6 hr
May 13, 2:44 PM CDTMesoscale DiscussionSPCCrittenden, Mississippi2 hr
May 12, 9:16 PM CDTMesoscale DiscussionSPCAtchison59 min
May 13, 4:40 PM CDTMesoscale DiscussionSPCLincoln, Saint Charles, Saint Louis, City of Saint Louis95 min

Nearby

Severe Thunderstorm Watches in Arkansas, 2011Severe Thunderstorm Watches in Missouri, 2011Severe Thunderstorm Watches in Oklahoma, 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.