Alert archive / South Dakota / Mesoscale Discussions in 2011

Mesoscale Discussion 1501

July 4, 201123 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 4, 2011, 2:51 PM MDT for 23 counties in South Dakota. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: Jul 4, 2011, 2:51 PM MDT (20:51 UTC)
Expired: Jul 4, 2011, 3:45 PM MDT
In force: 54 min
Issued by: the Storm Prediction Center

All 23 counties

Bennett County, SD, Campbell County, SD, Corson County, SD, Custer County, SD, Dewey County, SD, Edmunds County, SD, Fall River County, SD, Faulk County, SD, Haakon County, SD, Hughes County, SD, Hyde County, SD, Jackson County, SD, Jones County, SD, Lyman County, SD, McPherson County, SD, Mellette County, SD, Oglala Lakota County, SD, Pennington County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Walworth County, SD, Ziebach County, SD

The radar

The Rapid City radar (KUDX), 159 km from the middle of the area, began a volume at 20:52 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 597Jul 4, 3:45 PM MDT

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 8.9 hours before the alert went out and 165 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: 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

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 3, 10:30 PM MDT	Mesoscale Discussion	SPC	Harding	90 min
Jul 4, 3:45 PM MDT	Severe Thunderstorm Watch	SPC	Beadle, Bennett, Brown, Brule, Buffalo, Campbell and 30 more	8 hr

Nearby

Mesoscale Discussions in South Dakota, 2011 Every mesoscale discussion 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.