Alert archive / South Dakota / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 597

July 4, 201136 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Jul 4, 2011, 4:45 PM CDT for 36 counties in South Dakota. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Jul 4, 2011, 4:45 PM CDT (21:45 UTC)
Expired
Jul 5, 2011, 1:00 AM CDT
In force
8 hr
Issued by
the Storm Prediction Center
Largest hail expected
3 in
Strongest gust expected
60 kt
All 36 counties

Beadle County, SD, Bennett County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Campbell County, SD, Clark County, SD, Corson County, SD, Custer County, SD, Day County, SD, Dewey County, SD, Edmunds County, SD, Fall River County, SD, Faulk County, SD, Haakon County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jackson County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Marshall County, SD, McPherson County, SD, Meade County, SD, Mellette County, SD, Pennington County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Walworth County, SD, Ziebach County, SD

The radar

The Aberdeen radar (KABR), 183 km from the middle of the area, began a volume at 21:45 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
10%
Ten or more severe wind reports
80%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
80%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 4, 4:58 PM CDTFlash Flood WarningUNRCuster5 hr
Jul 4, 7:46 PM CDTSevere Thunderstorm WarningUNRFall River33 min
Jul 4, 9:10 PM CDTSevere Thunderstorm WarningABRBrown, Edmunds, McPherson50 min
Jul 4, 9:35 PM CDTSevere Thunderstorm WarningABRBrown, Edmunds, McPherson55 min
Jul 4, 9:39 PM CDTSevere Thunderstorm WarningUNRBennett, Mellette, Todd81 min
Jul 4, 10:00 PM CDTFlash Flood WarningABRBrown, McPherson3 hr
Jul 4, 10:12 PM CDTSevere Thunderstorm WarningABRHughes, Stanley, Sully63 min
Jul 4, 10:17 PM CDTSevere Thunderstorm WarningUNRMellette, Todd, Tripp88 min
Jul 4, 10:23 PM CDTSevere Thunderstorm WarningABRBrown, Edmunds, McPherson67 min
Jul 4, 10:56 PM CDTFlash Flood WarningABRDewey, Hughes, Potter, Stanley, Sully6 hr
Jul 4, 10:57 PM CDTSevere Thunderstorm WarningABRDewey, Potter, Stanley, Sully63 min
Jul 4, 11:02 PM CDTSevere Thunderstorm WarningUNRTripp58 min
Jul 4, 11:06 PM CDTSevere Thunderstorm WarningABRJones, Lyman54 min
Jul 4, 11:14 PM CDTFlash Flood WarningABRBrown3 hr
Jul 4, 11:17 PM CDTSevere Thunderstorm WarningABRBrown, Day, Spink45 min
Jul 4, 11:45 PM CDTFlash Flood WarningUNRMellette, Tripp6 hr
Jul 4, 11:58 PM CDTSevere Thunderstorm WarningABREdmunds, Faulk, Hand, Hyde, Potter, Sully and 1 more62 min
Jul 5, 12:24 AM CDTFlash Flood WarningABRJones, Lyman, Stanley5 hr
Jul 5, 12:49 AM CDTSevere Thunderstorm WarningABRGrant, Roberts41 min
Jul 5, 12:50 AM CDTSevere Thunderstorm WarningABRBrown55 min
Jul 5, 12:57 AM CDTSevere Thunderstorm WarningABRGrant, Roberts40 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

Rapid City, SD (KUNR), launched 12:00Z, 9.8 hours before the alert went out and 202 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, Rapid City, SD at 12:00Z on 2011-07-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1069 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, Rapid City, SD at 12:00Z on 2011-07-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 square meters per square second.193958Sfc1 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
1069 J/kg
Mixed-layer CIN
-380 J/kg
Mixed-layer LCL
1605 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
252 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 3, 11:30 PM CDTMesoscale DiscussionSPCHarding90 min
Jul 4, 3:51 PM CDTMesoscale DiscussionSPCBennett, Campbell, Corson, Custer, Dewey, Edmunds and 17 more54 min

Nearby

Severe Thunderstorm Watches in South Dakota, 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.