Alert archive / Iowa / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 528

July 17, 20074 states

The Storm Prediction Center issued this severe thunderstorm watch at Jul 17, 2007, 9:31 PM CDT for 4 states. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 17, 2007, 9:31 PM CDT (02:31 UTC)
Expired: Jul 18, 2007, 4:00 AM CDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 50 counties

Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Chickasaw County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Howard County, IA, Jackson County, IA, Jones County, IA, Linn County, IA, Mitchell County, IA, Winneshiek County, IA, Boone County, IL, Carroll County, IL, DeKalb County, IL, Jo Daviess County, IL, Lee County, IL, Ogle County, IL, Stephenson County, IL, Whiteside County, IL, Winnebago County, IL, Dodge County, MN, Fillmore County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Wabasha County, MN, Winona County, MN, Buffalo County, WI, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Jackson County, WI, La Crosse County, WI, Lafayette County, WI, Monroe County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Trempealeau County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 67 km from the middle of the area, began a volume at 02:31 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 30%
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: 30%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 17, 9:39 PM CDT	Severe Thunderstorm Warning	MKX	Lafayette	66 min
Jul 17, 10:52 PM CDT	Severe Thunderstorm Warning	MKX	Lafayette	23 min
Jul 17, 11:53 PM CDT	Severe Thunderstorm Warning	ARX	Clayton	37 min
Jul 17, 11:57 PM CDT	Severe Thunderstorm Warning	DVN	Dubuque	63 min
Jul 18, 12:11 AM CDT	Flash Flood Warning	DVN	Jo Daviess, Stephenson	6 hr
Jul 18, 12:13 AM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle	62 min
Jul 18, 12:18 AM CDT	Flash Flood Warning	ARX	Allamakee, Clayton	6 hr
Jul 18, 12:18 AM CDT	Flash Flood Warning	ARX	Allamakee	6 hr
Jul 18, 12:49 AM CDT	Flash Flood Warning	LOT	Lee	6 hr
Jul 18, 1:10 AM CDT	Severe Thunderstorm Warning	ARX	Clayton	50 min
Jul 18, 1:11 AM CDT	Flash Flood Warning	DVN	Dubuque	6 hr

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, 2.5 hours before the alert went out and 206 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 78 J/kg
Mixed-layer CIN: -337 J/kg
Mixed-layer LCL: 1823 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 236 m²/s²
0-3 km storm-relative helicity: 388 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 17, 11:24 PM CDT	Mesoscale Discussion	SPC	Bureau, Carroll, DeKalb, Henderson, Henry, Jo Daviess and 15 more	96 min
Jul 18, 3:35 AM CDT	Mesoscale Discussion	SPC	Boone, Carroll, DeKalb, Jo Daviess, Kane, Lee and 5 more	85 min
Jul 18, 4:21 AM CDT	Mesoscale Discussion	SPC	Clark, Clay, Coles, Crawford, Cumberland, Douglas and 10 more	54 min
Jul 18, 4:59 PM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, Champaign, Cook, DeKalb and 32 more	91 min
Jul 18, 5:35 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Bureau, Carroll, DeKalb, DeWitt, Fulton and 25 more	6 hr
Jul 18, 6:38 PM CDT	Mesoscale Discussion	SPC	Champaign, Cook, Douglas, DuPage, Edgar, Ford and 11 more	97 min
Jul 18, 6:50 PM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, DeKalb, Henderson, Henry and 18 more	85 min
Jul 18, 12:47 PM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Bremer, Buchanan, Buena Vista and 37 more	2 hr
Jul 18, 2:09 PM CDT	Severe Thunderstorm Watch	SPC	Black Hawk, Boone, Bremer, Buena Vista, Butler, Calhoun and 33 more	4 hr
Jul 18, 12:17 PM CDT	Mesoscale Discussion	SPC	Anoka, Chisago, Isanti, Ramsey, Washington	118 min
Jul 18, 3:42 PM CDT	Mesoscale Discussion	SPC	Anoka, Dakota, Goodhue, Hennepin, Olmsted, Ramsey and 4 more	63 min
Jul 18, 3:59 PM CDT	Severe Thunderstorm Watch	SPC	Anoka, Carver, Dakota, Dodge, Fillmore, Goodhue and 14 more	5 hr
Jul 18, 6:44 PM CDT	Mesoscale Discussion	SPC	Houston, Winona	2 hr
Jul 18, 1:37 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Calumet, Dodge, Door, Fond du Lac, Green Lake and 18 more	7 hr
Jul 18, 5:46 PM CDT	Mesoscale Discussion	SPC	Brown, Calumet, Dodge, Fond du Lac, Green Lake, Manitowoc and 11 more	119 min

Nearby

Severe Thunderstorm Watches in Iowa, 2007 Severe Thunderstorm Watches in Wisconsin, 2007 Severe Thunderstorm Watches in Illinois, 2007 Every 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.