Alert archive / Iowa / Severe Thunderstorm Watches in 2014

Severe Thunderstorm Watch 161

May 20, 201423 counties in Illinois; 51 counties in Iowa; 9 counties in Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at May 20, 2014, 3:55 PM CDT for 23 counties in Illinois; 51 counties in Iowa; 9 counties in Wisconsin. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: May 20, 2014, 3:55 PM CDT (20:55 UTC)
Expired: May 20, 2014, 11:00 PM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 83 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Buchanan County, IA, Carroll County, IA, Cass County, IA, Cedar County, IA, Clarke County, IA, Clinton County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Delaware County, IA, Dubuque County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Ringgold County, IA, Scott County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Mercer County, IL, Ogle County, IL, Putnam County, IL, Rock Island County, IL, Stephenson County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Green County, WI, Jefferson County, WI, Kenosha County, WI, Lafayette County, WI, Milwaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Waukesha County, WI

The radar

The Quad Cities radar (KDVN), 60 km from the middle of the area, began a volume at 20:59 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: 2%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 90%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 20, 4:19 PM CDT	Severe Thunderstorm Warning	DVN	Jo Daviess	56 min
May 20, 4:22 PM CDT	Severe Thunderstorm Warning	DMX	Audubon, Carroll, Guthrie	38 min
May 20, 4:36 PM CDT	Severe Thunderstorm Warning	DVN	Benton, Linn	54 min
May 20, 5:05 PM CDT	Severe Thunderstorm Warning	DVN	Jo Daviess	55 min
May 20, 5:09 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque, Jones, Linn	66 min
May 20, 5:25 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Dallas, Greene	35 min
May 20, 5:30 PM CDT	Severe Thunderstorm Warning	DVN	Dubuque, Jackson, Jones	45 min
May 20, 5:33 PM CDT	Severe Thunderstorm Warning	DVN	Jo Daviess, Stephenson	42 min
May 20, 5:54 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Hardin, Marshall, Story	36 min
May 20, 6:02 PM CDT	Severe Thunderstorm Warning	DMX	Tama	28 min
May 20, 6:04 PM CDT	Severe Thunderstorm Warning	LOT	Ogle	56 min
May 20, 6:20 PM CDT	Severe Thunderstorm Warning	DVN	Jones	40 min
May 20, 6:23 PM CDT	Severe Thunderstorm Warning	DVN	Stephenson	37 min
May 20, 6:25 PM CDT	Severe Thunderstorm Warning	DMX	Grundy, Hardin, Marshall, Story	50 min
May 20, 6:28 PM CDT	Severe Thunderstorm Warning	DMX	Tama	32 min
May 20, 6:33 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Ogle	42 min
May 20, 6:34 PM CDT	Severe Thunderstorm Warning	LOT	Winnebago	41 min
May 20, 6:40 PM CDT	Severe Thunderstorm Warning	LOT	DuPage, Kane	50 min
May 20, 6:44 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Dallas, Polk, Story	31 min
May 20, 6:57 PM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle	63 min
May 20, 6:58 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Jasper, Polk, Story	47 min
May 20, 7:14 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Kendall	46 min
May 20, 7:15 PM CDT	Severe Thunderstorm Warning	DMX	Marshall, Tama	45 min
May 20, 7:20 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	55 min
May 20, 7:22 PM CDT	Severe Thunderstorm Warning	DVN	Benton, Jones, Linn	53 min
May 20, 7:23 PM CDT	Severe Thunderstorm Warning	LOT	Lake, McHenry	52 min
May 20, 7:39 PM CDT	Severe Thunderstorm Warning	DVN	Carroll, Jo Daviess	66 min
May 20, 7:40 PM CDT	Severe Thunderstorm Warning	LOT	DuPage, Kane, Kendall, Will	50 min
May 20, 7:45 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Polk, Story	45 min
May 20, 7:59 PM CDT	Severe Thunderstorm Warning	DVN	Carroll	61 min
May 20, 8:08 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Story	52 min
May 20, 8:10 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Will	65 min
May 20, 8:10 PM CDT	Severe Thunderstorm Warning	DVN	Cedar, Jones, Linn	65 min
May 20, 8:25 PM CDT	Flash Flood Warning	DMX	Story	3 hr
May 20, 8:32 PM CDT	Flash Flood Warning	LOT	Cook, DuPage	3 hr
May 20, 8:59 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Tama	31 min
May 20, 9:05 PM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle	55 min
May 20, 9:10 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Polk, Story	35 min
May 20, 9:11 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Will	79 min
May 20, 9:33 PM CDT	Flash Flood Warning	LOT	Cook	6 hr
May 20, 10:13 PM CDT	Severe Thunderstorm Warning	LOT	Ogle	47 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 57 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: 203 J/kg
Mixed-layer CIN: -354 J/kg
Mixed-layer LCL: 1127 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 176 m²/s²
0-3 km storm-relative helicity: 190 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.

Issued	Product	Office	Counties	Lasted
May 20, 2:55 PM CDT	Mesoscale Discussion	SPC	Boone, Carroll, Jo Daviess, McHenry, Stephenson, Winnebago	2 hr
May 20, 5:49 PM CDT	Mesoscale Discussion	SPC	Boone, Carroll, Cook, DeKalb, DuPage, Jo Daviess and 10 more	86 min

Nearby

Severe Thunderstorm Watches in Iowa, 2014 Severe Thunderstorm Watches in Illinois, 2014 Severe Thunderstorm Watches in Wisconsin, 2014 Every severe thunderstorm watch in 2014

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.