Alert archive / South Dakota / Mesoscale Discussions in 2004

Mesoscale Discussion 804

May 21, 20048 counties in Nebraska; 17 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 21, 2004, 4:57 PM CDT for 8 counties in Nebraska; 17 counties in South Dakota. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: May 21, 2004, 4:57 PM CDT (21:57 UTC)
Expired: May 21, 2004, 6:30 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center

All 25 counties

Blaine County, NE, Brown County, NE, Cherry County, NE, Hooker County, NE, Keya Paha County, NE, Logan County, NE, McPherson County, NE, Thomas County, NE, Campbell County, SD, Corson County, SD, Dewey County, SD, Haakon County, SD, Hughes County, SD, Hyde County, SD, Jackson County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Walworth County, SD, Ziebach County, SD

The radar

The North Platte radar (KLNX), 153 km from the middle of the area, began a volume at 21:58 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 (KUNR), launched 12:00Z, 10.0 hours before the alert went out and 194 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 641 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 145 m²/s²
0-3 km storm-relative helicity: 127 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 20, 10:03 PM CDT	Mesoscale Discussion	SPC	Adams, Buffalo, Burt, Butler, Cass, Chase and 44 more	87 min
May 20, 10:30 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Buffalo, Butler, Chase, Clay, Colfax and 32 more	6 hr
May 21, 1:11 AM CDT	Mesoscale Discussion	SPC	Antelope, Arthur, Blaine, Boone, Boyd, Brown and 29 more	34 min
May 21, 1:20 AM CDT	Severe Thunderstorm Watch	SPC	Antelope, Boone, Boyd, Burt, Cedar, Colfax and 18 more	6 hr
May 21, 2:22 AM CDT	Mesoscale Discussion	SPC	Antelope, Boone, Boyd, Burt, Cedar, Cuming and 11 more	23 min
May 21, 2:22 PM CDT	Mesoscale Discussion	SPC	Banner, Box Butte, Cheyenne, Dawes, Kimball, Morrill and 3 more	113 min
May 21, 3:05 PM CDT	Severe Thunderstorm Watch	SPC	Arthur, Banner, Box Butte, Cheyenne, Dawes, Deuel and 8 more	5 hr
May 21, 5:35 PM CDT	Mesoscale Discussion	SPC	Adams, Antelope, Boone, Buffalo, Burt, Butler and 35 more	115 min
May 21, 6:33 PM CDT	Mesoscale Discussion	SPC	Adams, Antelope, Boone, Boyd, Buffalo, Burt and 44 more	57 min

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.