Alert archive / Iowa / Severe Thunderstorm Watches in 2004

Severe Thunderstorm Watch 76

April 16, 200417 counties in Iowa

The Storm Prediction Center issued this severe thunderstorm watch at Apr 16, 2004, 9:45 PM CDT for 17 counties in Iowa. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Apr 16, 2004, 9:45 PM CDT (02:45 UTC)
Expired
Apr 17, 2004, 2:00 AM CDT
In force
4 hr
Issued by
the Storm Prediction Center

Counties Benton County, IA, Black Hawk County, IA, Buchanan County, IA, Cedar County, IA, Delaware County, IA, Grundy County, IA, Iowa County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Mahaska County, IA, Marshall County, IA, Poweshiek County, IA, Tama County, IA, Washington County, IA

The radar

The Des Moines radar (KDMX), 123 km from the middle of the area, began a volume at 02:45 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

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

IssuedProductOfficeCountiesLasted
Apr 16, 10:28 PM CDTSevere Thunderstorm WarningDMXGrundy32 min
Apr 16, 10:45 PM CDTSevere Thunderstorm WarningDMXPoweshiek45 min
Apr 16, 11:18 PM CDTSevere Thunderstorm WarningDVNIowa, Keokuk42 min
Apr 17, 12:40 AM CDTSevere Thunderstorm WarningDMXPoweshiek50 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

Davenport, (KDVN), launched 00:00Z, 2.8 hours before the alert went out and 145 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 2004-04-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 428 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 2004-04-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 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
428 J/kg
Mixed-layer CIN
-47 J/kg
Mixed-layer LCL
2694 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
35 m²/s²
0-3 km storm-relative helicity
62 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 16, 7:17 PM CDTMesoscale DiscussionSPCAudubon, Black Hawk, Boone, Bremer, Buena Vista, Butler and 29 more88 min
Apr 17, 5:03 PM CDTMesoscale DiscussionSPCBoone, Buena Vista, Butler, Calhoun, Carroll, Cerro Gordo and 30 more2 hr

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.