Alert archive / Iowa / Mesoscale Discussions in 2015

Mesoscale Discussion 1765

September 6, 20154 states

The Storm Prediction Center issued this mesoscale discussion at Sep 6, 2015, 5:26 PM CDT for 4 states. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Sep 6, 2015, 5:26 PM CDT (22:26 UTC)
Expired: Sep 6, 2015, 7:00 PM CDT
In force: 94 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 64 counties

Audubon County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Emmet County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Hancock County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, O'Brien County, IA, Osceola County, IA, Page County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Wright County, IA, Blue Earth County, MN, Cottonwood County, MN, Faribault County, MN, Freeborn County, MN, Jackson County, MN, Martin County, MN, Steele County, MN, Waseca County, MN, Watonwan County, MN, Atchison County, MO, Burt County, NE, Butler County, NE, Cass County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Gage County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Thayer County, NE, Thurston County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 96 km from the middle of the area, began a volume at 22:28 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 504Sep 6, 6:00 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.4 hours before the alert went out and 96 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: 648 J/kg
Mixed-layer CIN: -347 J/kg
Mixed-layer LCL: 1274 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 387 m²/s²
0-3 km storm-relative helicity: 389 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
Sep 6, 2:31 PM CDT	Mesoscale Discussion	SPC	Dickinson, Lyon, O'Brien, Osceola, Sioux	119 min
Sep 6, 5:12 PM CDT	Mesoscale Discussion	SPC	Allamakee, Chickasaw, Howard, Winneshiek	2 hr
Sep 6, 6:02 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Allamakee, Audubon, Black Hawk, Boone and 47 more	7 hr
Sep 5, 7:34 PM CDT	Mesoscale Discussion	SPC	Aitkin, Cass, Crow Wing, Douglas, Hubbard, Itasca and 6 more	86 min
Sep 6, 3:42 PM CDT	Severe Thunderstorm Watch	SPC	Aitkin, Anoka, Benton, Carlton, Carver, Cass and 33 more	6 hr
Sep 6, 6:29 PM CDT	Mesoscale Discussion	SPC	Aitkin, Anoka, Benton, Carlton, Carver, Chippewa and 24 more	2 hr

Nearby

Mesoscale Discussions in Iowa, 2015 Mesoscale Discussions in Nebraska, 2015 Mesoscale Discussions in Minnesota, 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.