Alert archive / South Dakota / Mesoscale Discussions in 2007

Mesoscale Discussion 1782

August 17, 20074 states

The Storm Prediction Center issued this mesoscale discussion at Aug 17, 2007, 3:47 PM MDT for 4 states. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued: Aug 17, 2007, 3:47 PM MDT (21:47 UTC)
Expired: Aug 17, 2007, 5:45 PM MDT
In force: 118 min
Issued by: the Storm Prediction Center

Counties Carter County, MT, Adams County, ND, Bowman County, ND, Butte County, SD, Corson County, SD, Custer County, SD, Dewey County, SD, Haakon County, SD, Harding County, SD, Jackson County, SD, Jones County, SD, Lawrence County, SD, Meade County, SD, Oglala Lakota County, SD, Pennington County, SD, Perkins County, SD, Stanley County, SD, Ziebach County, SD, Crook County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 65 km from the middle of the area, began a volume at 21:47 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.

Tornado Watch 613Aug 17, 4:20 PM MDT

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 9.8 hours before the alert went out and 71 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: 1026 J/kg
Mixed-layer CIN: -203 J/kg
Mixed-layer LCL: 1565 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 48 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
Aug 17, 4:21 PM MDT	Tornado Watch	SPC	Carter	8 hr
Aug 17, 5:39 PM MDT	Mesoscale Discussion	SPC	Beaverhead, Broadwater, Gallatin, Jefferson, Madison, Silver Bow	2 hr

Nearby

Mesoscale Discussions in South Dakota, 2007 Mesoscale Discussions in North Dakota, 2007 Mesoscale Discussions in Wyoming, 2007 Every mesoscale discussion in 2007

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.