Alert archive / South Dakota / Mesoscale Discussions in 2004

Mesoscale Discussion 1753

July 21, 20048 counties in Iowa; 6 counties in Minnesota; 21 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2004, 3:43 PM CDT for 8 counties in Iowa; 6 counties in Minnesota; 21 counties in South Dakota. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: Jul 21, 2004, 3:43 PM CDT (20:43 UTC)
Expired: Jul 21, 2004, 5:15 PM CDT
In force: 92 min
Issued by: the Storm Prediction Center

All 35 counties

Cherokee County, IA, Clay County, IA, Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Cottonwood County, MN, Jackson County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, 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, Jerauld County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 41 km from the middle of the area, began a volume at 20:46 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 12:00Z, 8.7 hours before the alert went out and 190 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: 220 J/kg
Mixed-layer CIN: -217 J/kg
Mixed-layer LCL: 1834 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: -20 m²/s²
0-3 km storm-relative helicity: -6 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
Jul 20, 11:08 PM CDT	Mesoscale Discussion	SPC	Howard, Mitchell, Winnebago, Worth	97 min
Jul 21, 9:03 AM CDT	Mesoscale Discussion	SPC	Benton, Cedar, Clinton, Des Moines, Henry, Iowa and 17 more	117 min
Jul 21, 9:35 AM CDT	Severe Thunderstorm Watch	SPC	Appanoose, Benton, Cedar, Clinton, Davis, Des Moines and 24 more	5 hr
Jul 21, 1:01 PM CDT	Mesoscale Discussion	SPC	Appanoose, Benton, Cedar, Clinton, Davis, Des Moines and 22 more	89 min
Jul 21, 6:02 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Crawford, Dickinson, Emmet and 9 more	118 min
Jul 20, 9:00 PM CDT	Severe Thunderstorm Watch	SPC	Big Stone, Chippewa, Cottonwood, Jackson, Kandiyohi, Lac qui Parle and 10 more	4 hr
Jul 21, 1:30 PM CDT	Mesoscale Discussion	SPC	Big Stone, Lac qui Parle, Traverse	2 hr
Jul 21, 1:50 PM CDT	Severe Thunderstorm Watch	SPC	Big Stone, Chippewa, Douglas, Grant, Kandiyohi, Lac qui Parle and 9 more	5 hr
Jul 20, 7:20 PM CDT	Mesoscale Discussion	SPC	Campbell, Corson, Dewey, Edmunds, McPherson, Perkins and 3 more	85 min

Nearby

Mesoscale Discussions in South Dakota, 2004 Mesoscale Discussions in Iowa, 2004 Mesoscale Discussions in Minnesota, 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.