Alert archive / Iowa / Mesoscale Discussions in 2013

Mesoscale Discussion 585

April 30, 20134 states

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2013, 4:01 PM CDT for 4 states. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2013, 4:01 PM CDT (21:01 UTC)
Expired: Apr 30, 2013, 6:00 PM CDT
In force: 119 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 27 counties

Adair County, IA, Adams County, IA, Cass County, IA, Dallas County, IA, Fremont County, IA, Guthrie County, IA, Madison County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Clay County, KS, Cloud County, KS, Marshall County, KS, Mitchell County, KS, Republic County, KS, Washington County, KS, Atchison County, MO, Gage County, NE, Jefferson County, NE, Johnson County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE

The radar

The Omaha radar (KOAX), 125 km from the middle of the area, began a volume at 21:02 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

Omaha, NE (KOAX), launched 12:00Z, 9.0 hours before the alert went out and 125 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: 2469 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 304 m²/s²
0-3 km storm-relative helicity: 338 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
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, 1:05 AM CDT	Mesoscale Discussion	SPC	Allamakee, Black Hawk, Bremer, Buchanan, Butler, Chickasaw and 9 more	55 min

Nearby

Mesoscale Discussions in Iowa, 2013 Mesoscale Discussions in Nebraska, 2013 Mesoscale Discussions in Kansas, 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.