Alert archive / Illinois / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 427
The Storm Prediction Center issued this severe thunderstorm watch at Jun 4, 2011, 4:53 PM CDT for 31 counties in Illinois; 5 counties in Iowa; Clark County, Scotland County, Missouri. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 4, 2011, 4:53 PM CDT (21:53 UTC)
- Expired
- Jun 4, 2011, 10:31 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 38 counties
Des Moines County, IA, Henry County, IA, Jefferson County, IA, Lee County, IA, Van Buren County, IA, Cass County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Coles County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Knox County, IL, Logan County, IL, Macon County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Moultrie County, IL, Peoria County, IL, Piatt County, IL, Sangamon County, IL, Schuyler County, IL, Shelby County, IL, Stark County, IL, Tazewell County, IL, Vermilion County, IL, Warren County, IL, Woodford County, IL, Clark County, MO, Scotland County, MO
The radar
The Quad Cities radar (KDVN), 81 km from the middle of the area, began a volume at 21:56 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
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 4, 5:14 PM CDT | Severe Thunderstorm Warning | DVN | Hancock | 61 min |
| Jun 4, 5:39 PM CDT | Severe Thunderstorm Warning | DVN | Hancock | 21 min |
| Jun 4, 5:41 PM CDT | Severe Thunderstorm Warning | ILX | Schuyler | 64 min |
| Jun 4, 6:24 PM CDT | Severe Thunderstorm Warning | ILX | Cass, Fulton, Mason, Schuyler | 66 min |
| Jun 4, 6:58 PM CDT | Severe Thunderstorm Warning | ILX | Cass, Logan, Mason, Menard, Sangamon | 62 min |
| Jun 4, 7:51 PM CDT | Severe Thunderstorm Warning | ILX | Christian, DeWitt, Logan, Macon, Piatt, Sangamon and 1 more | 54 min |
| Jun 4, 8:33 PM CDT | Severe Thunderstorm Warning | ILX | Champaign, Vermilion | 57 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, 9.9 hours before the alert went out and 84 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
- 2541 J/kg
- Mixed-layer CIN
- -116 J/kg
- Mixed-layer LCL
- 1175 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- -128 m²/s²
- 0-3 km storm-relative helicity
- -36 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 4, 1:27 PM CDT | Mesoscale Discussion | SPC | Bureau, Cook, DeKalb, DuPage, Grundy, Iroquois and 8 more | 63 min |
| Jun 4, 2:08 PM CDT | Severe Thunderstorm Watch | SPC | Cook, DeKalb, DuPage, Ford, Grundy, Iroquois and 6 more | 7 hr |
| Jun 4, 4:47 PM CDT | Mesoscale Discussion | SPC | DeWitt, Fulton, Hancock, Henderson, Knox, Logan and 10 more | 28 min |
| Jun 4, 5:42 PM CDT | Mesoscale Discussion | SPC | Andrew, Buchanan, Caldwell, Carroll, Clay, Clinton and 10 more | 63 min |
Nearby
Severe Thunderstorm Watches in Illinois, 2011Severe Thunderstorm Watches in Iowa, 2011Severe Thunderstorm Watches in Missouri, 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.