Alert archive / South Dakota / Mesoscale Discussions in 2017

Mesoscale Discussion 1577

August 26, 201712 counties in Nebraska; 17 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 26, 2017, 3:24 PM MDT for 12 counties in Nebraska; 17 counties in South Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 26, 2017, 3:24 PM MDT (21:24 UTC)
Expired: Aug 26, 2017, 5:30 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 29 counties

Arthur County, NE, Blaine County, NE, Box Butte County, NE, Cherry County, NE, Dawes County, NE, Garden County, NE, Grant County, NE, Hooker County, NE, McPherson County, NE, Morrill County, NE, Sheridan County, NE, Thomas County, NE, Bennett County, SD, Butte County, SD, Custer County, SD, Dewey County, SD, Fall River County, SD, Haakon County, SD, Jackson County, SD, Jones County, SD, Lawrence County, SD, Meade County, SD, Mellette County, SD, Oglala Lakota County, SD, Pennington County, SD, Perkins County, SD, Stanley County, SD, Todd County, SD, Ziebach County, SD

The radar

The Rapid City radar (KUDX), 152 km from the middle of the area, began a volume at 21:27 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 nearest sounding before it

Rapid City, SD (KRAP), launched 12:00Z, 9.4 hours before the alert went out and 150 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: 69 J/kg
Mixed-layer CIN: -227 J/kg
Mixed-layer LCL: 2080 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 110 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 26, 1:13 PM MDT	Mesoscale Discussion	SPC	Arthur, Box Butte, Cherry, Dawes, Garden, Grant and 3 more	3 hr
Aug 26, 2:04 PM MDT	Severe Thunderstorm Watch	SPC	Box Butte, Cherry, Dawes, Garden, Grant, Hooker and 3 more	7 hr
Aug 26, 3:46 PM MDT	Mesoscale Discussion	SPC	Furnas, Hitchcock, Red Willow	2 hr

Nearby

Mesoscale Discussions in South Dakota, 2017 Mesoscale Discussions in Nebraska, 2017 Every mesoscale discussion in 2017

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.