Alert archive / Illinois / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 23
The Storm Prediction Center issued this severe thunderstorm watch at Feb 27, 2011, 5:33 PM CST for 18 counties in Illinois; 9 counties in Missouri. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 27, 2011, 5:33 PM CST (23:33 UTC)
- Expired
- Feb 27, 2011, 10:00 PM CST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 50 kt
All 27 counties
Adams County, IL, Brown County, IL, Cass County, IL, DeWitt County, IL, Fulton County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Tazewell County, IL, Woodford County, IL, Audrain County, MO, Boone County, MO, Knox County, MO, Lewis County, MO, Marion County, MO, Monroe County, MO, Pike County, MO, Ralls County, MO, Shelby County, MO
The radar
The St Louis radar (KLSX), 140 km from the middle of the area, began a volume at 23:33 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
- 10%
- One or more gusts of 65 knots or more
- 5%
- 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
- 60%
Warnings issued inside it
15 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 27, 5:42 PM CST | Severe Thunderstorm Warning | LSX | Marion, Monroe, Shelby | 48 min |
| Feb 27, 6:26 PM CST | Severe Thunderstorm Warning | LSX | Adams, Brown, Pike | 49 min |
| Feb 27, 6:52 PM CST | Severe Thunderstorm Warning | ILX | Fulton, Schuyler | 38 min |
| Feb 27, 6:57 PM CST | Severe Thunderstorm Warning | LSX | Lewis, Marion | 15 min |
| Feb 27, 7:19 PM CST | Severe Thunderstorm Warning | ILX | Fulton, Mason, Tazewell | 41 min |
| Feb 27, 7:38 PM CST | Severe Thunderstorm Warning | LSX | Adams, Brown, Pike | 37 min |
| Feb 27, 8:02 PM CST | Tornado Warning | LSX | Pike | 28 min |
| Feb 27, 8:14 PM CST | Severe Thunderstorm Warning | ILX | Logan, McLean, Tazewell | 31 min |
| Feb 27, 8:14 PM CST | Severe Thunderstorm Warning | LSX | Brown | 16 min |
| Feb 27, 8:25 PM CST | Severe Thunderstorm Warning | ILX | Cass, Fulton, Mason, Schuyler | 35 min |
| Feb 27, 8:25 PM CST | Severe Thunderstorm Warning | LSX | Calhoun, Pike | 35 min |
| Feb 27, 8:33 PM CST | Severe Thunderstorm Warning | ILX | Fulton, Peoria, Tazewell | 32 min |
| Feb 27, 8:44 PM CST | Severe Thunderstorm Warning | ILX | McLean | 46 min |
| Feb 27, 9:17 PM CST | Severe Thunderstorm Warning | ILX | Christian, Logan, Menard, Sangamon | 28 min |
| Feb 27, 9:50 PM CST | Severe Thunderstorm Warning | LSX | Adams, Pike | 40 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, 11.6 hours before the alert went out and 218 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 680 m above ground
- 0-6 km bulk shear
- 77 kt
- 0-1 km storm-relative helicity
- 106 m²/s²
- 0-3 km storm-relative helicity
- 172 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 |
|---|---|---|---|---|
| Feb 27, 4:57 PM CST | Mesoscale Discussion | SPC | Alexander, Franklin, Hardin, Jackson, Jefferson, Johnson and 11 more | 2 hr |
| Feb 27, 5:10 PM CST | Mesoscale Discussion | SPC | Adams, Pike | 35 min |
| Feb 27, 5:50 PM CST | Mesoscale Discussion | SPC | Bureau, Carroll, DeKalb, Henry, Lee, Mercer and 3 more | 6 hr |
| Feb 27, 12:44 PM CST | Mesoscale Discussion | SPC | Pemiscot | 91 min |
| Feb 27, 12:46 PM CST | Mesoscale Discussion | SPC | Caldwell, Carroll, Cass, Chariton, Clay, Clinton and 7 more | 59 min |
| Feb 27, 1:12 PM CST | Severe Thunderstorm Watch | SPC | Bates, Caldwell, Carroll, Cass, Chariton, Clay and 15 more | 9 hr |
| Feb 27, 2:12 PM CST | Mesoscale Discussion | SPC | Barton, Dade, Jasper, Lawrence, Newton | 93 min |
| Feb 27, 3:24 PM CST | Mesoscale Discussion | SPC | Bates, Carroll, Cass, Chariton, Clay, Cooper and 10 more | 66 min |
Nearby
Severe Thunderstorm Watches in Illinois, 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.