Alert archive / Iowa / Mesoscale Discussions in 2011

Mesoscale Discussion 1878

August 6, 201110 counties in Illinois; 31 counties in Iowa; 17 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Aug 6, 2011, 11:06 PM CDT for 10 counties in Illinois; 31 counties in Iowa; 17 counties in Missouri. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Aug 6, 2011, 11:06 PM CDT (04:06 UTC)
Expired
Aug 7, 2011, 1:00 AM CDT
In force
114 min
Issued by
the Storm Prediction Center
All 58 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Cass County, IA, Clarke County, IA, Davis County, IA, Decatur County, IA, Des Moines County, IA, Fremont County, IA, Henry County, IA, Jefferson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Mills County, IA, Monroe County, IA, Montgomery County, IA, Muscatine County, IA, Page County, IA, Ringgold County, IA, Taylor County, IA, Union County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Adams County, IL, Brown County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, McDonough County, IL, Mercer County, IL, Pike County, IL, Schuyler County, IL, Warren County, IL, Adair County, MO, Clark County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Knox County, MO, Lewis County, MO, Macon County, MO, Marion County, MO, Mercer County, MO, Nodaway County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Shelby County, MO, Sullivan County, MO, Worth County, MO

The radar

The Des Moines radar (KDMX), 150 km from the middle of the area, began a volume at 04:09 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, 4.1 hours before the alert went out and 215 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 00:00Z on 2011-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1118 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 00:00Z on 2011-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 41 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
1118 J/kg
Mixed-layer CIN
-22 J/kg
Mixed-layer LCL
1057 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
41 m²/s²
0-3 km storm-relative helicity
108 m²/s²
Significant tornado parameter
0.5
Supercell composite
5.1

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 WatchSPCAdams, Brown, Hancock, Henderson, McDonough, Mercer and 3 more5 hr
Aug 7, 11:14 AM CDTMesoscale DiscussionSPCChampaign, Clark, Coles, Crawford, Cumberland, Douglas and 8 more2 hr
Aug 7, 5:20 PM CDTMesoscale DiscussionSPCBond, Calhoun, Clinton, Franklin, Jackson, Jefferson and 10 more115 min
Aug 7, 5:41 PM CDTSevere Thunderstorm WatchSPCAlexander, Bond, Calhoun, Clinton, Edwards, Franklin and 23 more6 hr
Aug 6, 8:10 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Benton, Black Hawk and 45 more2 hr
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, 6:07 PM CDTSevere Thunderstorm WatchSPCBarry, Christian, Douglas, Greene, Howell, Jasper and 11 more5 hr

Nearby

Mesoscale Discussions in Iowa, 2011Mesoscale Discussions in Missouri, 2011Mesoscale Discussions in Illinois, 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.