Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 791

May 21, 20044 states

The Storm Prediction Center issued this mesoscale discussion at May 21, 2004, 4:34 AM CDT for 4 states. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued
May 21, 2004, 4:34 AM CDT (09:34 UTC)
Expired
May 21, 2004, 5:30 AM CDT
In force
56 min
Issued by
the Storm Prediction Center
All 88 counties

Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Cerro Gordo County, IA, Cherokee County, IA, Chickasaw County, IA, Clay County, IA, Clayton County, IA, Delaware County, IA, Dickinson County, IA, Dubuque County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Lyon County, IA, Mitchell County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Jo Daviess County, IL, Blue Earth County, MN, Brown County, MN, Cottonwood County, MN, Dodge County, MN, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Houston County, MN, Jackson County, MN, Le Sueur County, MN, Martin County, MN, Mower County, MN, Murray County, MN, Nicollet County, MN, Nobles County, MN, Olmsted County, MN, Pipestone County, MN, Rice County, MN, Rock County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Watonwan County, MN, Winona County, MN, Adams County, WI, Buffalo County, WI, Columbia County, WI, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Jackson County, WI, Juneau County, WI, La Crosse County, WI, Lafayette County, WI, Marquette County, WI, Monroe County, WI, Portage County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Trempealeau County, WI, Vernon County, WI, Wood County, WI

The radar

The La Crosse radar (KARX), 165 km from the middle of the area, began a volume at 09:36 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

Minneapolis, MN (KMPX), launched 00:00Z, 9.6 hours before the alert went out and 194 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, Minneapolis, MN at 00:00Z on 2004-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Minneapolis, MN at 00:00Z on 2004-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -46 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1738 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
-46 m²/s²
0-3 km storm-relative helicity
121 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.

IssuedProductOfficeCountiesLasted
May 20, 7:32 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 21 more88 min
May 20, 9:05 PM CDTSevere Thunderstorm WatchSPCBureau, Cook, DeKalb, DuPage, Ford, Fulton and 20 more5 hr
May 21, 9:40 AM CDTMesoscale DiscussionSPCCook, DuPage, Kane, Kankakee, Lake, Will2 hr
May 21, 10:25 AM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Carroll, DeKalb, Henry, Jo Daviess and 8 more6 hr
May 21, 2:45 PM CDTTornado WatchSPCRock Island7 hr
May 21, 5:35 PM CDTTornado WatchSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 21 more5 hr
May 20, 10:03 PM CDTMesoscale DiscussionSPCFremont, Harrison, Mills, Pottawattamie87 min
May 21, 1:11 AM CDTMesoscale DiscussionSPCAudubon, Boone, Buena Vista, Calhoun, Carroll, Cherokee and 27 more34 min
May 21, 1:20 AM CDTSevere Thunderstorm WatchSPCAudubon, Boone, Buena Vista, Calhoun, Carroll, Cherokee and 19 more6 hr
May 21, 2:22 AM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 47 more23 min
May 21, 2:35 AM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 22 more4 hr
May 21, 6:23 AM CDTMesoscale DiscussionSPCAllamakee, Bremer, Butler, Cerro Gordo, Chickasaw, Clay and 20 more67 min
May 21, 9:44 AM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Buena Vista and 38 more3 hr
May 21, 1:59 PM CDTMesoscale DiscussionSPCBenton, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 9 more2 hr
May 21, 6:33 PM CDTMesoscale DiscussionSPCLyon, Plymouth, Sioux, Woodbury57 min
May 21, 2:20 AM CDTSevere Thunderstorm WatchSPCBlue Earth, Brown, Cottonwood, Dodge, Faribault, Fillmore and 20 more5 hr
May 21, 3:00 PM CDTSevere Thunderstorm WatchSPCAdams, Calumet, Columbia, Dane, Dodge, Fond du Lac and 19 more7 hr

Nearby

Mesoscale Discussions in Iowa, 2004Mesoscale Discussions in Minnesota, 2004Mesoscale Discussions in Wisconsin, 2004Every mesoscale discussion in 2004

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.