Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 1869

August 3, 20048 counties in Illinois; 39 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Aug 3, 2004, 8:19 PM CDT for 8 counties in Illinois; 39 counties in Iowa. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued
Aug 3, 2004, 8:19 PM CDT (01:19 UTC)
Expired
Aug 3, 2004, 9:15 PM CDT
In force
56 min
Issued by
the Storm Prediction Center
All 47 counties

Appanoose County, IA, Benton County, IA, Boone County, IA, Cedar County, IA, Clarke County, IA, Clinton County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Scott County, IA, Story County, IA, Tama County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Carroll County, IL, Henry County, IL, Jo Daviess County, IL, Knox County, IL, Mercer County, IL, Rock Island County, IL, Stark County, IL, Whiteside County, IL

The radar

The Quad Cities radar (KDVN), 114 km from the middle of the area, began a volume at 01:22 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

Davenport, (KDVN), launched 00:00Z, 1.3 hours before the alert went out and 121 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 2004-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2771 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 2004-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 54 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
2771 J/kg
Mixed-layer CIN
-73 J/kg
Mixed-layer LCL
1163 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
54 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
1.6
Supercell composite
16.5

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 3, 7:38 PM CDTMesoscale DiscussionSPCBureau, Cook, DeKalb, DuPage, Ford, Grundy and 14 more67 min
Aug 3, 7:55 PM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Cook, DeKalb, DuPage, Ford and 21 more5 hr
Aug 3, 9:45 PM CDTSevere Thunderstorm WatchSPCFulton, Hancock, Henderson, Henry, Knox, McDonough and 3 more5 hr
Aug 3, 9:52 PM CDTMesoscale DiscussionSPCCook, DuPage, Grundy, Kane, Kendall, Lake and 3 more53 min
Aug 3, 10:38 PM CDTMesoscale DiscussionSPCAdams, Brown, Calhoun, Cass, Greene, Jersey and 3 more67 min
Aug 3, 11:30 PM CDTSevere Thunderstorm WatchSPCAdams, Brown, Calhoun, Cass, Champaign, Christian and 32 more6 hr
Aug 4, 1:42 AM CDTMesoscale DiscussionSPCFulton, Henderson, Jersey, Livingston, McDonough, Mason and 5 more2 hr
Aug 4, 3:52 AM CDTMesoscale DiscussionSPCAdams, Brown, Calhoun, Cass, Champaign, Christian and 32 more53 min
Aug 4, 3:39 PM CDTMesoscale DiscussionSPCHardin, Massac, Pope96 min
Aug 3, 9:16 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Cass, Fremont, Guthrie and 9 more59 min
Aug 3, 11:34 PM CDTMesoscale DiscussionSPCAppanoose, Davis, Lee86 min

Nearby

Mesoscale Discussions in Iowa, 2004Mesoscale Discussions in Illinois, 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.