Alert archive / Iowa / Severe Thunderstorm Watches in 2004

Severe Thunderstorm Watch 230

May 21, 200428 counties in Iowa

The Storm Prediction Center issued this severe thunderstorm watch at May 21, 2004, 2:35 AM CDT for 28 counties in Iowa. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
May 21, 2004, 2:35 AM CDT (07:35 UTC)
Expired
May 21, 2004, 7:00 AM CDT
In force
4 hr
Issued by
the Storm Prediction Center
All 28 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Delaware 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, Jones County, IA, Linn County, IA, Marshall County, IA, Mitchell County, IA, Story County, IA, Tama County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA

The radar

The Des Moines radar (KDMX), 152 km from the middle of the area, began a volume at 07:38 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.

Warnings issued inside it

6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
May 21, 2:55 AM CDTSevere Thunderstorm WarningARXFloyd35 min
May 21, 4:32 AM CDTSevere Thunderstorm WarningDMXFranklin28 min
May 21, 4:51 AM CDTSevere Thunderstorm WarningARXWinneshiek24 min
May 21, 5:23 AM CDTSevere Thunderstorm WarningDMXBremer37 min
May 21, 6:11 AM CDTSevere Thunderstorm WarningARXClayton, Fayette34 min
May 21, 6:28 AM CDTSevere Thunderstorm WarningDVNBuchanan, Delaware62 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 7.6 hours before the alert went out and 227 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

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 20, 7:32 PM CDTMesoscale DiscussionSPCCedar, Clinton, Des Moines, Henry, Jefferson, Keokuk and 5 more88 min
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, 4:34 AM CDTMesoscale DiscussionSPCAllamakee, Black Hawk, Bremer, Buchanan, Buena Vista, Butler and 35 more56 min
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, 10:25 AM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 37 more6 hr
May 21, 1:59 PM CDTMesoscale DiscussionSPCBenton, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 9 more2 hr
May 21, 2:45 PM CDTTornado WatchSPCAllamakee, Audubon, Benton, Black Hawk, Boone, Bremer and 59 more7 hr
May 21, 6:33 PM CDTMesoscale DiscussionSPCLyon, Plymouth, Sioux, Woodbury57 min

Nearby

Severe Thunderstorm Watches in Iowa, 2004Every severe thunderstorm watch 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.