Alert archive / South Dakota / Mesoscale Discussions in 2015

Mesoscale Discussion 1559

July 27, 2015Boyd County, Nebraska; 5 counties in North Dakota; 33 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 27, 2015, 9:41 PM CDT for Boyd County, Nebraska; 5 counties in North Dakota; 33 counties in South Dakota. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jul 27, 2015, 9:41 PM CDT (02:41 UTC)
Expired: Jul 28, 2015, 12:15 AM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 39 counties

Dickey County, ND, LaMoure County, ND, McIntosh County, ND, Ransom County, ND, Sargent County, ND, Boyd County, NE, Aurora County, SD, Beadle County, SD, Brookings County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Clark County, SD, Codington County, SD, Davison County, SD, Day County, SD, Deuel County, SD, Douglas County, SD, Edmunds County, SD, Faulk County, SD, Grant County, SD, Gregory County, SD, Hamlin County, SD, Hand County, SD, Hanson County, SD, Hutchinson County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Marshall County, SD, McCook County, SD, McPherson County, SD, Miner County, SD, Minnehaha County, SD, Roberts County, SD, Sanborn County, SD, Spink County, SD, Turner County, SD

The radar

The Aberdeen radar (KABR), 137 km from the middle of the area, began a volume at 02:42 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.

Severe Thunderstorm Watch 458Jul 27, 10:50 PM CDT

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 2.7 hours before the alert went out and 76 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: 2357 J/kg
Mixed-layer CIN: -33 J/kg
Mixed-layer LCL: 1333 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: -10 m²/s²
0-3 km storm-relative helicity: 11 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -0.7

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 28, 12:38 AM CDT	Mesoscale Discussion	SPC	Arthur, Blaine, Brown, Custer, Garfield, Grant and 8 more	3 hr
Jul 28, 3:37 AM CDT	Mesoscale Discussion	SPC	Cedar, Dixon	2 hr
Jul 28, 3:40 PM CDT	Mesoscale Discussion	SPC	Cass, Douglas, Gage, Johnson, Lancaster, Nemaha and 4 more	2 hr
Jul 28, 5:46 PM CDT	Severe Thunderstorm Watch	SPC	Johnson, Nemaha, Otoe, Pawnee, Richardson	6 hr
Jul 27, 7:31 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Billings, Bowman, Burke, Burleigh, Divide and 17 more	7 hr
Jul 27, 9:19 PM CDT	Mesoscale Discussion	SPC	Adams, Billings, Bowman, Divide, Dunn, Golden Valley and 12 more	116 min
Jul 27, 10:49 PM CDT	Severe Thunderstorm Watch	SPC	Barnes, Benson, Bottineau, Cavalier, Dickey, Eddy and 17 more	5 hr
Jul 28, 1:57 AM CDT	Mesoscale Discussion	SPC	Barnes, Cass, Dickey, LaMoure, Ransom, Richland and 3 more	2 hr

Nearby

Mesoscale Discussions in South Dakota, 2015 Mesoscale Discussions in North Dakota, 2015 Mesoscale Discussions in Nebraska, 2015 Every mesoscale discussion in 2015

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.