Alert archive / Iowa / Mesoscale Discussions in 2011

Mesoscale Discussion 1877

August 6, 201151 counties in Iowa; 14 counties in Missouri; 29 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Aug 6, 2011, 8:10 PM CDT for 51 counties in Iowa; 14 counties in Missouri; 29 counties in Nebraska. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 6, 2011, 8:10 PM CDT (01:10 UTC)
Expired
Aug 6, 2011, 10:15 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 94 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Crawford County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Fremont County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Harrison County, IA, Ida County, IA, Iowa County, IA, Jasper County, IA, Keokuk County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monona County, IA, Monroe County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Wayne County, IA, Webster County, IA, Woodbury County, IA, Andrew County, MO, Atchison County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Mercer County, MO, Nodaway County, MO, Putnam County, MO, Schuyler County, MO, Sullivan County, MO, Worth County, MO, Boone County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Colfax County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Gage County, NE, Johnson County, NE, Lancaster County, NE, Madison County, NE, Nance County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Richardson County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, York County, NE

The radar

The Des Moines radar (KDMX), 112 km from the middle of the area, began a volume at 01:12 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.2 hours before the alert went out and 126 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, Omaha, NE at 00:00Z on 2011-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3454 joules per kilogram.LCLEL10008507005003002001001 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, Omaha, NE at 00:00Z on 2011-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 49 square meters per square second.19395878Sfc1 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
3454 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
1012 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
49 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
1.9
Supercell composite
13.5

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
Aug 6, 10:14 PM CDTSevere Thunderstorm WatchSPCAppanoose, Cedar, Davis, Des Moines, Henry, Iowa and 16 more5 hr
Aug 6, 11:06 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Cass, Clarke, Davis and 25 more114 min
Aug 7, 10:48 AM CDTMesoscale DiscussionSPCPlatte117 min
Aug 7, 12:55 PM CDTSevere Thunderstorm WatchSPCBates, Buchanan, Caldwell, Carroll, Cass, Clay and 11 more5 hr
Aug 7, 3:16 PM CDTMesoscale DiscussionSPCBarton, Bates, Benton, Camden, Carroll, Cass and 24 more119 min
Aug 7, 3:29 PM CDTSevere Thunderstorm WatchSPCBarton, Benton, Boone, Callaway, Camden, Cedar and 18 more6 hr
Aug 7, 5:20 PM CDTMesoscale DiscussionSPCBarry, Barton, Benton, Bollinger, Boone, Callaway and 48 more115 min
Aug 7, 5:41 PM CDTSevere Thunderstorm WatchSPCBollinger, Butler, Cape Girardeau, Carter, Franklin, Iron and 17 more6 hr
Aug 7, 6:07 PM CDTSevere Thunderstorm WatchSPCBarry, Christian, Douglas, Greene, Howell, Jasper and 11 more5 hr
Aug 7, 1:23 PM CDTMesoscale DiscussionSPCArthur, Blaine, Brown, Cherry, Custer, Grant and 5 more67 min
Aug 7, 2:58 PM CDTSevere Thunderstorm WatchSPCArthur, Blaine, Brown, Buffalo, Cherry, Custer and 21 more8 hr
Aug 7, 6:35 PM CDTMesoscale DiscussionSPCAdams, Arthur, Blaine, Boyd, Brown, Buffalo and 25 more115 min

Nearby

Mesoscale Discussions in Iowa, 2011Mesoscale Discussions in Nebraska, 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.