Alert archive / South Dakota / Mesoscale Discussions in 2004

Mesoscale Discussion 1728

July 18, 20048 counties in Nebraska; 14 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2004, 8:53 PM CDT for 8 counties in Nebraska; 14 counties in South Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 18, 2004, 8:53 PM CDT (01:53 UTC)
Expired: Jul 18, 2004, 11:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 22 counties

Boyd County, NE, Garfield County, NE, Holt County, NE, Keya Paha County, NE, Loup County, NE, Rock County, NE, Valley County, NE, Wheeler County, NE, Brule County, SD, Buffalo County, SD, Dewey County, SD, Gregory County, SD, Hughes County, SD, Hyde County, SD, Jones County, SD, Lyman County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Tripp County, SD, Walworth County, SD, Ziebach County, SD

The radar

The Rapid City radar (KUDX), 202 km from the middle of the area, began a volume at 01:50 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

Aberdeen, SD (KABR), launched 00:00Z, 1.9 hours before the alert went out and 180 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: 2541 J/kg
Mixed-layer CIN: -155 J/kg
Mixed-layer LCL: 1628 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 172 m²/s²
0-3 km storm-relative helicity: 230 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 5.9

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 18, 10:43 PM CDT	Mesoscale Discussion	SPC	Boyd, Garfield, Holt, Keya Paha, Loup, Rock and 2 more	62 min
Jul 19, 4:09 PM CDT	Mesoscale Discussion	SPC	Arthur, Blaine, Box Butte, Brown, Cherry, Custer and 16 more	2 hr
Jul 18, 8:00 PM CDT	Tornado Watch	SPC	Brown, Campbell, Clark, Codington, Day, Deuel and 12 more	5 hr

Nearby

Mesoscale Discussions in South Dakota, 2004 Mesoscale Discussions in Nebraska, 2004 Every mesoscale discussion in 2004

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.