Alert archive / Iowa / Mesoscale Discussions in 2013

Mesoscale Discussion 582

April 30, 201315 counties in Iowa; 4 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2013, 1:05 AM CDT for 15 counties in Iowa; 4 counties in Wisconsin. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2013, 1:05 AM CDT (06:05 UTC)
Expired: Apr 30, 2013, 2:00 AM CDT
In force: 55 min
Issued by: the Storm Prediction Center

Counties Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Chickasaw County, IA, Clayton County, IA, Delaware County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hardin County, IA, Winneshiek County, IA, Wright County, IA, Crawford County, WI, Grant County, WI, Iowa County, WI, Richland County, WI

The radar

The La Crosse radar (KARX), 102 km from the middle of the area, began a volume at 06:07 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

Davenport, (KDVN), launched 00:00Z, 6.1 hours before the alert went out and 155 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: 733 J/kg
Mixed-layer CIN: -96 J/kg
Mixed-layer LCL: 1784 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 130 m²/s²
0-3 km storm-relative helicity: 254 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 10.3

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
Apr 29, 7:26 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 39 more	3 hr
Apr 29, 9:00 PM CDT	Mesoscale Discussion	SPC	Allamakee, Buchanan, Clayton, Clinton, Delaware, Dubuque and 4 more	2 hr
Apr 29, 10:21 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Allamakee, Audubon, Benton, Black Hawk and 62 more	5 hr
Apr 30, 4:01 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Cass, Dallas, Fremont, Guthrie and 7 more	119 min

Nearby

Mesoscale Discussions in Iowa, 2013 Mesoscale Discussions in Wisconsin, 2013 Every mesoscale discussion in 2013

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.