Alert archive / Iowa / Mesoscale Discussions in 2011

Mesoscale Discussion 729

May 11, 201138 counties in Iowa; 10 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at May 11, 2011, 8:09 AM CDT for 38 counties in Iowa; 10 counties in Missouri. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued
May 11, 2011, 8:09 AM CDT (13:09 UTC)
Expired
May 11, 2011, 9:15 AM CDT
In force
66 min
Issued by
the Storm Prediction Center
All 48 counties

Allamakee County, IA, Appanoose County, IA, Benton County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Chickasaw County, IA, Clarke County, IA, Clayton County, IA, Davis County, IA, Decatur County, IA, Delaware County, IA, Fayette County, IA, Grundy County, IA, Hardin County, IA, Howard County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Linn County, IA, Lucas County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Winneshiek County, IA, Adair County, MO, Grundy County, MO, Knox County, MO, Linn County, MO, Macon County, MO, Mercer County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Sullivan County, MO

The radar

The Des Moines radar (KDMX), 100 km from the middle of the area, began a volume at 13:12 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 12:00Z, 1.2 hours before the alert went out and 189 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-pSkew-T log-p diagram, Davenport, at 12:00Z on 2011-05-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2842 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 12:00Z on 2011-05-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -17 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2842 J/kg
Mixed-layer CIN
-105 J/kg
Mixed-layer LCL
931 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
-17 m²/s²
0-3 km storm-relative helicity
93 m²/s²
Significant tornado parameter
0.3
Supercell composite
2.6

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.

IssuedProductOfficeCountiesLasted
May 10, 8:45 PM CDTMesoscale DiscussionSPCAllamakee, Howard, Mitchell, Winneshiek, Worth90 min
May 11, 1:23 PM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 17 more6 hr
May 11, 2:31 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Carroll, Cass, Crawford and 13 more59 min
May 11, 2:53 PM CDTTornado WatchSPCAdair, Adams, Appanoose, Audubon, Boone, Carroll and 33 more6 hr
May 11, 3:38 PM CDTMesoscale DiscussionSPCAllamakee, Appanoose, Benton, Black Hawk, Buchanan, Cedar and 26 more2 hr
May 11, 5:03 PM CDTMesoscale DiscussionSPCBuena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 6 more57 min
May 11, 6:17 PM CDTMesoscale DiscussionSPCAppanoose, Clarke, Davis, Decatur, Jasper, Lucas and 9 more28 min
May 11, 2:18 PM CDTMesoscale DiscussionSPCLincoln, Pike, Saint Charles, Saint Louis, City of Saint Louis57 min
May 11, 3:57 PM CDTMesoscale DiscussionSPCAndrew, Atchison, Barton, Bates, Benton, Buchanan and 27 more48 min
May 11, 4:00 PM CDTSevere Thunderstorm WatchSPCAndrew, Atchison, Barry, Barton, Bates, Buchanan and 35 more8 hr
May 11, 6:35 PM CDTMesoscale DiscussionSPCBarry, Christian, Dade, Greene, Jasper, Lawrence and 4 more55 min

Nearby

Mesoscale Discussions in Iowa, 2011Mesoscale Discussions in Missouri, 2011Every mesoscale discussion in 2011

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.