Alert archive / South Dakota / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 384, NWS Rapid City, SD

August 17, 2011Tripp County, South Dakota

NWS Rapid City, SD issued this severe thunderstorm warning at Aug 17, 2011, 8:58 PM CDT for Tripp County, South Dakota. It was in force for 44 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 17, 2011, 8:58 PM CDT (01:58 UTC)
Expired: Aug 17, 2011, 9:42 PM CDT
In force: 44 min
Issued by: NWS Rapid City, SD
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Tripp County, SD

The radar

The North Platte radar (KLNX), 164 km from the middle of the area, began a volume at 02:01 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 17, 3:37 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 2.0 hours before the alert went out and 253 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1270 J/kg
Mixed-layer CIN: -74 J/kg
Mixed-layer LCL: 1399 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 180 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 7.5

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Rapid City, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 17, 8:45 PM CDT, 13 minutes earlier.

Area forecast discussion, Aug 17, 8:45 PM CDT, 13 minutes before

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Hazardous weather outlook, Aug 17, 7:47 AM CDT, 13 hours 11 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
647 AM MDT WED AUG 17 2011

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-181300-
BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON-
HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK-
NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-
SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS-
SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH-
647 AM MDT (747 AM CDT) WED AUG 17 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND INTO TONIGHT ACROSS
MUCH OF WESTERN AND SOUTH CENTRAL SOUTH DAKOTA. THERE IS A SLIGHT
RISK FOR SEVERE STORMS ACROSS SOUTHWESTERN SOUTH DAKOTA THIS
AFTERNOON...AND EASTWARD INTO SOUTH CENTRAL SOUTH DAKOTA THIS
EVENING. LARGE HAIL AND STRONG WIND GUSTS WILL BE THE MAIN THREATS
FROM ANY SEVERE STORMS. AN ISOLATED TORNADO IS ALSO POSSIBLE ACROSS
FAR SOUTHERN SOUTH DAKOTA...NEAR THE NEBRASKA BORDER.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE WILL BE A DAILY CHANCE FOR THUNDERSTORMS ACROSS MUCH OF THE
AREA THROUGH SATURDAY. THERE IS A SLIGHT RISK FOR SEVERE STORMS
ACROSS PORTIONS OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA ON
THURSDAY. LARGE HAIL AND STRONG WIND GUSTS WILL BE THE MAIN THREATS
FROM ANY SEVERE STORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY.

In the hours before

Local storm report, Aug 17, 8:30 PM CDT, 28 minutes before

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Local storm report, Aug 17, 8:31 PM CDT, 27 minutes before

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Local storm report, Aug 17, 8:33 PM CDT, 25 minutes before

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Local storm report, Aug 17, 8:43 PM CDT, 15 minutes before

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Local storm report, Aug 17, 8:45 PM CDT, 13 minutes before

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Local storm report, Aug 17, 8:49 PM CDT, 9 minutes before

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The office that day

Everything else NWS Rapid City, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 17, 7:06 PM CDT	Severe Thunderstorm Warning	UNR	Mellette, Todd, Tripp	54 min
Aug 17, 7:11 PM CDT	Severe Thunderstorm Warning	UNR	Mellette	49 min
Aug 17, 7:34 PM CDT	Tornado Warning	UNR	Todd, Tripp	32 min
Aug 17, 7:55 PM CDT	Severe Thunderstorm Warning	UNR	Mellette, Todd	65 min
Aug 17, 8:01 PM CDT	Severe Thunderstorm Warning	UNR	Todd, Tripp	59 min
Aug 17, 8:31 PM CDT	Severe Thunderstorm Warning	UNR	Todd, Tripp	59 min
Aug 18, 4:34 PM CDT	Severe Thunderstorm Warning	UNR	Meade, Perkins	56 min
Aug 18, 4:40 PM CDT	Severe Thunderstorm Warning	UNR	Pennington	65 min
Aug 18, 4:55 PM CDT	Severe Thunderstorm Warning	UNR	Meade	38 min
Aug 18, 5:06 PM CDT	Severe Thunderstorm Warning	UNR	Meade, Perkins, Ziebach	54 min
Aug 18, 5:20 PM CDT	Severe Thunderstorm Warning	UNR	Bennett, Jackson	55 min
Aug 18, 6:07 PM CDT	Severe Thunderstorm Warning	UNR	Bennett	53 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 2011 Every severe thunderstorm warning 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.