Alert archive / Iowa / Mesoscale Discussions in 2013

Mesoscale Discussion 871

May 29, 201312 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at May 29, 2013, 9:36 PM CDT for 12 counties in Iowa. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: May 29, 2013, 9:36 PM CDT (02:36 UTC)
Expired: May 29, 2013, 10:30 PM CDT
In force: 54 min
Issued by: the Storm Prediction Center

Counties Adair County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Clay County, IA, Emmet County, IA, Greene County, IA, Guthrie County, IA, Humboldt County, IA, Palo Alto County, IA, Pocahontas County, IA, Webster County, IA

The radar

The Des Moines radar (KDMX), 94 km from the middle of the area, began a volume at 02:40 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 00:00Z, 2.6 hours before the alert went out and 165 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: 1667 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 572 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 249 m²/s²
0-3 km storm-relative helicity: 249 m²/s²
Significant tornado parameter: 1.9
Supercell composite: 9.0

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 29, 9:00 PM CDT	Mesoscale Discussion	SPC	Allamakee, Appanoose, Benton, Buchanan, Clayton, Davis and 16 more	60 min
May 30, 11:20 AM CDT	Mesoscale Discussion	SPC	Allamakee, Buchanan, Clayton, Delaware, Dubuque, Fayette and 2 more	115 min
May 30, 11:29 AM CDT	Mesoscale Discussion	SPC	Des Moines, Henry, Lee, Louisa, Muscatine, Scott	61 min
May 30, 11:56 AM CDT	Tornado Watch	SPC	Allamakee, Clayton, Fayette, Winneshiek	7 hr
May 30, 12:32 PM CDT	Tornado Watch	SPC	Benton, Buchanan, Cedar, Clinton, Delaware, Des Moines and 15 more	7 hr
May 30, 1:33 PM CDT	Mesoscale Discussion	SPC	Allamakee, Clayton, Fayette, Winneshiek	57 min
May 30, 2:16 PM CDT	Mesoscale Discussion	SPC	Buchanan, Cedar, Clinton, Delaware, Des Moines, Dubuque and 12 more	59 min
May 30, 3:34 PM CDT	Mesoscale Discussion	SPC	Allamakee, Clayton, Fayette, Winneshiek	116 min
May 30, 3:52 PM CDT	Mesoscale Discussion	SPC	Buchanan, Cedar, Clinton, Delaware, Des Moines, Dubuque and 12 more	113 min
May 30, 5:58 PM CDT	Mesoscale Discussion	SPC	Clayton	62 min

Nearby

Mesoscale Discussions in Iowa, 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.