Alert archive / Iowa / Severe Thunderstorm Watches in 2002

Severe Thunderstorm Watch 540

July 27, 2002Jo Daviess County, Stephenson County, Illinois; 27 counties in Iowa; 10 counties in Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at Jul 27, 2002, 8:55 PM CDT for Jo Daviess County, Stephenson County, Illinois; 27 counties in Iowa; 10 counties in Wisconsin. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Jul 27, 2002, 8:55 PM CDT (01:55 UTC)
Expired
Jul 28, 2002, 2:00 AM CDT
In force
5 hr
Issued by
the Storm Prediction Center
All 39 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Clayton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Grundy County, IA, Hamilton County, IA, Hardin County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Jo Daviess County, IL, Stephenson County, IL, Columbia County, WI, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Lafayette County, WI, Richland County, WI, Rock County, WI, Sauk County, WI

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 27, 10:17 PM CDTSevere Thunderstorm WarningMKXIowa58 min
Jul 27, 11:44 PM CDTSevere Thunderstorm WarningMKXGreen, Iowa61 min
Jul 27, 11:47 PM CDTSevere Thunderstorm WarningMKXDane, Rock58 min

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.9 hours before the alert went out and 147 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 2002-07-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 7133 joules per kilogram.LCLEL10008507005003002001001 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 2002-07-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 127 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
7133 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
660 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
127 m²/s²
0-3 km storm-relative helicity
177 m²/s²
Significant tornado parameter
6.1
Supercell composite
30.5

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 28, 1:00 PM CDTSevere Thunderstorm WatchSPCCherokee, Dickinson, Lyon, O'Brien, Osceola, Plymouth and 2 more5 hr
Jul 28, 3:55 PM CDTTornado WatchSPCCerro Gordo, Chickasaw, Clay, Emmet, Floyd, Hancock and 6 more5 hr
Jul 28, 4:50 PM CDTTornado WatchSPCAudubon, Buena Vista, Calhoun, Carroll, Cherokee, Crawford and 13 more5 hr

Nearby

Severe Thunderstorm Watches in Iowa, 2002Severe Thunderstorm Watches in Wisconsin, 2002Severe Thunderstorm Watches in Illinois, 2002Every severe thunderstorm watch in 2002

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.