Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 2037

August 18, 20044 states

The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2004, 4:17 PM CDT for 4 states. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued
Aug 18, 2004, 4:17 PM CDT (21:17 UTC)
Expired
Aug 18, 2004, 6:15 PM CDT
In force
118 min
Issued by
the Storm Prediction Center
All 66 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Cass County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Des Moines County, IA, Fremont County, IA, Guthrie County, IA, Henry County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Monroe County, IA, Montgomery County, IA, Muscatine County, IA, Page County, IA, Polk County, IA, Poweshiek 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, Hancock County, IL, Henderson County, IL, Mercer County, IL, Rock Island County, IL, Warren County, IL, Adair County, MO, Atchison County, MO, Clark County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Knox County, MO, Lewis County, MO, Mercer County, MO, Nodaway County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Sullivan County, MO, Worth County, MO, Gage County, NE, Jefferson County, NE, Johnson County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Thayer County, NE

The radar

The Des Moines radar (KDMX), 99 km from the middle of the area, began a volume at 21:20 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 12:00Z, 9.3 hours before the alert went out and 267 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 2004-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3 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 2004-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 47 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
3 J/kg
Mixed-layer CIN
-230 J/kg
Mixed-layer LCL
1075 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
47 m²/s²
0-3 km storm-relative helicity
139 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
Aug 17, 7:48 PM CDTMesoscale DiscussionSPCFord, Grundy, Iroquois, Kankakee, Livingston, Will117 min
Aug 18, 1:39 PM CDTMesoscale DiscussionSPCAdams, Brown, Cass, Champaign, Christian, Clark and 28 more96 min
Aug 18, 5:17 PM CDTMesoscale DiscussionSPCAdams, Bond, Brown, Cass, Champaign, Christian and 48 more88 min
Aug 18, 5:35 PM CDTSevere Thunderstorm WatchSPCAdams, Brown, Cass, Champaign, Christian, Clark and 28 more5 hr
Aug 18, 12:27 PM CDTMesoscale DiscussionSPCAllamakee, Howard, Winneshiek63 min
Aug 18, 1:10 PM CDTSevere Thunderstorm WatchSPCAllamakee, Bremer, Chickasaw, Clayton, Fayette, Floyd and 2 more7 hr
Aug 18, 3:46 PM CDTMesoscale DiscussionSPCAllamakee, Bremer, Butler, Chickasaw, Clayton, Fayette and 3 more59 min
Aug 18, 4:50 PM CDTSevere Thunderstorm WatchSPCAppanoose, Davis, Decatur, Henry, Jefferson, Lee and 7 more6 hr
Aug 18, 5:52 PM CDTMesoscale DiscussionSPCClayton, Fayette113 min

Nearby

Mesoscale Discussions in Iowa, 2004Mesoscale Discussions in Missouri, 2004Mesoscale Discussions in Nebraska, 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.