Alert archive / South Dakota / Mesoscale Discussions in 2008

Mesoscale Discussion 794

May 6, 20084 states

The Storm Prediction Center issued this mesoscale discussion at May 6, 2008, 10:56 AM CDT for 4 states. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: May 6, 2008, 10:56 AM CDT (15:56 UTC)
Expired: May 6, 2008, 12:30 PM CDT
In force: 94 min
Issued by: the Storm Prediction Center

All 42 counties

Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Ida County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sac County, IA, Sioux County, IA, Woodbury County, IA, Nobles County, MN, Rock County, MN, Boyd County, NE, Cedar County, NE, Dakota County, NE, Dixon County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Pierce County, NE, Thurston County, NE, Wayne County, NE, Aurora County, SD, Bon Homme County, SD, Brule County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Todd County, SD, Tripp County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 114 km from the middle of the area, began a volume at 15:55 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.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 3.9 hours before the alert went out and 204 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: 60 J/kg
Mixed-layer CIN: -206 J/kg
Mixed-layer LCL: 1232 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: -37 m²/s²
0-3 km storm-relative helicity: -3 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

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
May 6, 12:03 PM CDT	Severe Thunderstorm Watch	SPC	Buena Vista, Calhoun, Carroll, Cherokee, Clay, Crawford and 15 more	7 hr
May 6, 2:22 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more	113 min
May 6, 2:50 PM CDT	Severe Thunderstorm Watch	SPC	Harrison, Monona, Pottawattamie, Shelby	7 hr
May 6, 6:23 PM CDT	Mesoscale Discussion	SPC	Audubon, Cass, Crawford, Fremont, Harrison, Mills and 4 more	2 hr
May 6, 1:58 PM CDT	Mesoscale Discussion	SPC	Arthur, Blaine, Boone, Brown, Chase, Cherry and 21 more	92 min
May 6, 3:46 PM CDT	Severe Thunderstorm Watch	SPC	Dundy, Hitchcock, Red Willow	6 hr

Nearby

Mesoscale Discussions in South Dakota, 2008 Mesoscale Discussions in Iowa, 2008 Mesoscale Discussions in Nebraska, 2008 Every mesoscale discussion in 2008

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.