Alert archive / Illinois / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 281
The Storm Prediction Center issued this severe thunderstorm watch at May 11, 2011, 1:23 PM CDT for 39 counties in Illinois; 23 counties in Iowa; 32 counties in Wisconsin. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- May 11, 2011, 1:23 PM CDT (18:23 UTC)
- Expired
- May 11, 2011, 7:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 94 counties
Allamakee County, IA, Benton County, IA, Buchanan County, IA, Cedar County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cass County, IL, DeKalb County, IL, DeWitt County, IL, Fulton County, IL, Grundy County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McHenry County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Morgan County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Winnebago County, IL, Woodford County, IL, Adams County, WI, Calumet County, WI, Clark County, WI, Columbia County, WI, Crawford County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Grant County, WI, Green County, WI, Green Lake County, WI, Iowa County, WI, Jackson County, WI, Jefferson County, WI, Juneau County, WI, La Crosse County, WI, Lafayette County, WI, Marquette County, WI, Monroe County, WI, Outagamie County, WI, Portage County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Vernon County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI
The radar
The La Crosse radar (KARX), 123 km from the middle of the area, began a volume at 18:23 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
- 40%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
31 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 1:38 PM CDT | Severe Thunderstorm Warning | ARX | Juneau, Monroe | 52 min |
| May 11, 1:39 PM CDT | Severe Thunderstorm Warning | MKX | Dane | 36 min |
| May 11, 1:43 PM CDT | Severe Thunderstorm Warning | MKX | Columbia, Dane | 32 min |
| May 11, 1:50 PM CDT | Severe Thunderstorm Warning | ARX | Adams, Juneau | 40 min |
| May 11, 2:03 PM CDT | Severe Thunderstorm Warning | MKX | Dane, Dodge, Jefferson | 42 min |
| May 11, 2:21 PM CDT | Severe Thunderstorm Warning | MKX | Columbia, Dane, Dodge | 24 min |
| May 11, 2:27 PM CDT | Severe Thunderstorm Warning | MKX | Jefferson, Rock, Walworth | 48 min |
| May 11, 2:51 PM CDT | Severe Thunderstorm Warning | ARX | Monroe | 39 min |
| May 11, 2:54 PM CDT | Severe Thunderstorm Warning | MKX | Jefferson, Racine, Walworth, Waukesha | 36 min |
| May 11, 3:10 PM CDT | Severe Thunderstorm Warning | MKX | Jefferson, Waukesha | 35 min |
| May 11, 3:19 PM CDT | Severe Thunderstorm Warning | LOT | Lake, McHenry | 56 min |
| May 11, 3:22 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine, Walworth | 38 min |
| May 11, 3:53 PM CDT | Severe Thunderstorm Warning | MKX | Dane | 52 min |
| May 11, 3:58 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine, Walworth | 32 min |
| May 11, 4:06 PM CDT | Severe Thunderstorm Warning | LOT | Cook, Kane, Lake, McHenry | 54 min |
| May 11, 4:28 PM CDT | Severe Thunderstorm Warning | MKX | Waukesha | 47 min |
| May 11, 4:36 PM CDT | Severe Thunderstorm Warning | MKX | Green, Rock | 39 min |
| May 11, 4:39 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage, Kane, Lake | 36 min |
| May 11, 4:42 PM CDT | Severe Thunderstorm Warning | MKX | Dane | 48 min |
| May 11, 4:48 PM CDT | Severe Thunderstorm Warning | ILX | Logan, McLean, Mason, Menard, Tazewell | 57 min |
| May 11, 4:51 PM CDT | Severe Thunderstorm Warning | LOT | Lake, McHenry | 54 min |
| May 11, 5:02 PM CDT | Flash Flood Warning | LOT | Cook, Kane, Lake, McHenry | 4 hr |
| May 11, 5:10 PM CDT | Severe Thunderstorm Warning | LOT | Winnebago | 10 min |
| May 11, 5:11 PM CDT | Severe Thunderstorm Warning | LOT | Cook, Kane, Lake, McHenry | 49 min |
| May 11, 5:11 PM CDT | Severe Thunderstorm Warning | MKX | Green, Rock | 49 min |
| May 11, 5:13 PM CDT | Severe Thunderstorm Warning | MKX | Dane, Green, Rock | 37 min |
| May 11, 5:33 PM CDT | Severe Thunderstorm Warning | DVN | Putnam | 27 min |
| May 11, 5:38 PM CDT | Severe Thunderstorm Warning | LOT | Lake, McHenry | 33 min |
| May 11, 5:43 PM CDT | Severe Thunderstorm Warning | LOT | Grundy, Kendall, LaSalle, Livingston | 62 min |
| May 11, 5:55 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine, Walworth | 29 min |
| May 11, 6:44 PM CDT | Severe Thunderstorm Warning | LOT | Grundy, Kankakee, Kendall, Will | 46 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, 6.4 hours before the alert went out and 138 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.
- Mixed-layer CAPE
- 2842 J/kg
- Mixed-layer CIN
- -105 J/kg
- Mixed-layer LCL
- 931 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- -17 m²/s²
- 0-3 km storm-relative helicity
- 93 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 2.6
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 12:55 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, DeKalb, DuPage, Jo Daviess, Kane and 7 more | 65 min |
| May 11, 2:18 PM CDT | Mesoscale Discussion | SPC | Adams, Bond, Brown, Calhoun, Cass, Champaign and 30 more | 57 min |
| May 11, 3:38 PM CDT | Mesoscale Discussion | SPC | Boone, Brown, Bureau, Carroll, Cass, Christian and 40 more | 2 hr |
| May 11, 5:56 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more | 5 hr |
| May 10, 8:45 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Mitchell, Winneshiek, Worth | 90 min |
| May 11, 8:09 AM CDT | Mesoscale Discussion | SPC | Allamakee, Appanoose, Benton, Black Hawk, Bremer, Buchanan and 32 more | 66 min |
| May 11, 2:31 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Carroll, Cass, Crawford and 13 more | 59 min |
| May 11, 2:53 PM CDT | Tornado Watch | SPC | Adair, Adams, Appanoose, Audubon, Boone, Carroll and 33 more | 6 hr |
| May 11, 5:03 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 6 more | 57 min |
| May 11, 6:17 PM CDT | Mesoscale Discussion | SPC | Appanoose, Clarke, Davis, Decatur, Jasper, Lucas and 9 more | 28 min |
| May 11, 3:57 PM CDT | Mesoscale Discussion | SPC | Andrew, Atchison, Barton, Bates, Benton, Buchanan and 27 more | 48 min |
| May 11, 4:00 PM CDT | Severe Thunderstorm Watch | SPC | Andrew, Atchison, Barry, Barton, Bates, Buchanan and 35 more | 8 hr |
| May 11, 6:35 PM CDT | Mesoscale Discussion | SPC | Barry, Christian, Dade, Greene, Jasper, Lawrence and 4 more | 55 min |
| May 11, 3:19 AM CDT | Mesoscale Discussion | SPC | Door, Florence, Forest, Kewaunee, Langlade, Marinette and 2 more | 56 min |
| May 11, 1:16 PM CDT | Mesoscale Discussion | SPC | Brown, Door, Forest, Kewaunee, Langlade, Lincoln and 10 more | 119 min |
Nearby
Severe Thunderstorm Watches in Illinois, 2011Severe Thunderstorm Watches in Wisconsin, 2011Severe Thunderstorm Watches in Iowa, 2011Every severe thunderstorm watch in 2011
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.