Alert archive / Illinois / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 535
The Storm Prediction Center issued this severe thunderstorm watch at Jun 21, 2011, 5:42 PM CDT for 29 counties in Illinois; 5 counties in Indiana; 7 counties in Wisconsin. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2011, 5:42 PM CDT (22:42 UTC)
- Expired
- Jun 21, 2011, 9:41 PM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 41 counties
Boone County, IL, Bureau County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Fulton County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, McHenry County, IL, McLean County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN, Green County, WI, Kenosha County, WI, Milwaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Waukesha County, WI
The radar
The Chicago radar (KLOT), 86 km from the middle of the area, began a volume at 22:44 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
- 60%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
21 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 5:51 PM CDT | Flash Flood Warning | ILX | Fulton, Peoria | 5 hr |
| Jun 21, 6:15 PM CDT | Severe Thunderstorm Warning | ILX | Tazewell, Woodford | 60 min |
| Jun 21, 6:19 PM CDT | Severe Thunderstorm Warning | ILX | DeWitt, Logan, McLean, Piatt | 56 min |
| Jun 21, 6:30 PM CDT | Severe Thunderstorm Warning | ILX | Marshall | 30 min |
| Jun 21, 6:34 PM CDT | Severe Thunderstorm Warning | DVN | Bureau, Putnam | 45 min |
| Jun 21, 6:37 PM CDT | Severe Thunderstorm Warning | LOT | DeKalb, Grundy, LaSalle, Lee, Livingston | 68 min |
| Jun 21, 6:57 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine | 33 min |
| Jun 21, 6:59 PM CDT | Severe Thunderstorm Warning | ILX | Woodford | 40 min |
| Jun 21, 7:06 PM CDT | Flash Flood Warning | ILX | Tazewell, Woodford | 6 hr |
| Jun 21, 7:09 PM CDT | Severe Thunderstorm Warning | ILX | McLean, Tazewell, Woodford | 50 min |
| Jun 21, 7:22 PM CDT | Severe Thunderstorm Warning | LOT | McHenry | 23 min |
| Jun 21, 7:22 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine, Walworth | 38 min |
| Jun 21, 7:27 PM CDT | Tornado Warning | LOT | LaSalle, Livingston | 33 min |
| Jun 21, 7:31 PM CDT | Severe Thunderstorm Warning | LOT | DeKalb, DuPage, Grundy, Kane, Kendall, LaSalle and 2 more | 37 min |
| Jun 21, 7:50 PM CDT | Flash Flood Warning | ILX | Woodford | 5 hr |
| Jun 21, 7:53 PM CDT | Severe Thunderstorm Warning | MKX | Milwaukee, Racine, Waukesha | 12 min |
| Jun 21, 7:57 PM CDT | Tornado Warning | LOT | Cook, DeKalb, DuPage, Grundy, Kane, Kendall and 1 more | 63 min |
| Jun 21, 7:57 PM CDT | Flash Flood Warning | MKX | Milwaukee, Waukesha | 4 hr |
| Jun 21, 8:22 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage, Kane, Lake, McHenry, Will | 53 min |
| Jun 21, 8:38 PM CDT | Tornado Warning | LOT | Cook, DuPage, Lake | 52 min |
| Jun 21, 8:51 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine, Walworth | 24 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, 10.7 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
- 12 J/kg
- Mixed-layer CIN
- -422 J/kg
- Mixed-layer LCL
- 1767 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- -64 m²/s²
- 0-3 km storm-relative helicity
- -114 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 11:45 AM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DeWitt and 32 more | 3 hr |
| Jun 21, 12:56 PM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Calhoun, Christian, Clay, Clinton and 40 more | 64 min |
| Jun 21, 1:22 PM CDT | Tornado Watch | SPC | Alexander, Bond, Calhoun, Cass, Champaign, Christian and 49 more | 9 hr |
| Jun 21, 3:31 PM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Calhoun, Cass, Champaign, Christian and 46 more | 89 min |
| Jun 21, 4:56 PM CDT | Mesoscale Discussion | SPC | Bond, Brown, Bureau, Cass, Champaign, Christian and 68 more | 94 min |
| Jun 21, 2:11 PM CDT | Tornado Watch | SPC | Adams, Barron, Buffalo, Chippewa, Clark, Columbia and 22 more | 7 hr |
Nearby
Severe Thunderstorm Watches in Illinois, 2011Severe Thunderstorm Watches in Wisconsin, 2011Severe Thunderstorm Watches in Indiana, 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.