Alert archive / Iowa / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 436

June 21, 20074 counties in Illinois; 32 counties in Iowa

The Storm Prediction Center issued this severe thunderstorm watch at Jun 21, 2007, 3:55 PM CDT for 4 counties in Illinois; 32 counties in Iowa. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jun 21, 2007, 3:55 PM CDT (20:55 UTC)
Expired
Jun 21, 2007, 6:56 PM CDT
In force
3 hr
Issued by
the Storm Prediction Center
Largest hail expected
3 in
Strongest gust expected
60 kt
All 36 counties

Adair County, IA, Adams County, IA, Audubon County, IA, Cass County, IA, Cedar County, IA, Clarke County, IA, Clinton County, IA, Dallas County, IA, Des Moines 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, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Scott County, IA, Union County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Henderson County, IL, Mercer County, IL, Rock Island County, IL, Warren County, IL

The radar

The Des Moines radar (KDMX), 52 km from the middle of the area, began a volume at 20:55 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
10%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
50%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
50%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jun 21, 4:13 PM CDTSevere Thunderstorm WarningDMXBoone, Dallas47 min
Jun 21, 4:22 PM CDTSevere Thunderstorm WarningDMXAdair53 min
Jun 21, 4:36 PM CDTSevere Thunderstorm WarningDMXDallas, Polk54 min
Jun 21, 4:56 PM CDTSevere Thunderstorm WarningDMXPolk, Story49 min
Jun 21, 5:01 PM CDTSevere Thunderstorm WarningDMXMadison, Warren44 min
Jun 21, 5:17 PM CDTSevere Thunderstorm WarningDMXJasper43 min
Jun 21, 5:23 PM CDTTornado WarningDMXMadison, Warren37 min
Jun 21, 5:43 PM CDTSevere Thunderstorm WarningDMXClarke, Lucas47 min
Jun 21, 5:49 PM CDTSevere Thunderstorm WarningDMXMarion, Warren41 min
Jun 21, 5:57 PM CDTSevere Thunderstorm WarningDMXJasper, Poweshiek63 min
Jun 21, 6:11 PM CDTSevere Thunderstorm WarningDMXClarke, Decatur49 min
Jun 21, 6:33 PM CDTSevere Thunderstorm WarningDVNIowa57 min
Jun 21, 6:44 PM CDTSevere Thunderstorm WarningDMXMonroe26 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 12:00Z, 8.9 hours before the alert went out and 222 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 2007-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 683 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 2007-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 64 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
683 J/kg
Mixed-layer CIN
-148 J/kg
Mixed-layer LCL
1072 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
64 m²/s²
0-3 km storm-relative helicity
23 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 21, 9:57 AM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, Champaign, Cook, DeKalb and 42 more33 min
Jun 21, 12:27 PM CDTMesoscale DiscussionSPCBoone, Carroll, DeKalb, Jo Daviess, Kane, McHenry and 3 more63 min
Jun 21, 3:25 PM CDTMesoscale DiscussionSPCJo Daviess35 min
Jun 21, 5:42 PM CDTMesoscale DiscussionSPCBureau, Carroll, Fulton, Henderson, Henry, Jo Daviess and 15 more93 min
Jun 21, 6:47 PM CDTSevere Thunderstorm WatchSPCCarroll, Hancock, Henderson, Henry, Jo Daviess, Knox and 6 more4 hr
Jun 20, 11:30 PM CDTMesoscale DiscussionSPCHoward, Mitchell, Winnebago, Worth90 min
Jun 21, 4:27 AM CDTSevere Thunderstorm WatchSPCAllamakee, Howard, Mitchell, Winneshiek8 hr
Jun 21, 9:10 AM CDTMesoscale DiscussionSPCClay, Dickinson, Lyon, O'Brien, Osceola, Sioux35 min
Jun 21, 9:38 AM CDTSevere Thunderstorm WatchSPCBuena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more6 hr
Jun 21, 11:55 AM CDTMesoscale DiscussionSPCAllamakee, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 16 more50 min
Jun 21, 11:59 AM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 36 more8 hr
Jun 21, 2:13 PM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 50 more62 min
Jun 21, 3:15 PM CDTMesoscale DiscussionSPCCherokee, Clay, Dickinson, Ida, Lyon, O'Brien and 4 more30 min

Nearby

Severe Thunderstorm Watches in Iowa, 2007Severe Thunderstorm Watches in Illinois, 2007Every severe thunderstorm watch in 2007

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.