Alert archive / Illinois / Tornado Watches in 2023
Tornado Watch 477
The Storm Prediction Center issued this tornado watch at Jul 12, 2023, 3:53 PM CDT for 16 counties in Illinois; 4 counties in Indiana. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 12, 2023, 3:53 PM CDT (20:53 UTC)
- Expired
- Jul 12, 2023, 9:07 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
Counties Boone County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Will County, IL, Winnebago County, IL, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN
The radar
The Chicago radar (KLOT), 46 km from the middle of the area, began a volume at 20:54 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
- 50%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- 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
- 70%
Warnings issued inside it
9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 12, 5:37 PM CDT | Tornado Warning | LOT | DuPage, Kane, Kendall, Will | 23 min |
| Jul 12, 6:10 PM CDT | Tornado Warning | LOT | Cook | 20 min |
| Jul 12, 6:13 PM CDT | Tornado Warning | LOT | McHenry | 32 min |
| Jul 12, 6:18 PM CDT | Tornado Warning | LOT | Kane | 27 min |
| Jul 12, 6:20 PM CDT | Tornado Warning | LOT | Cook | 23 min |
| Jul 12, 6:31 PM CDT | Tornado Warning | LOT | Cook, DuPage | 29 min |
| Jul 12, 6:35 PM CDT | Tornado Warning | LOT | Lake | 25 min |
| Jul 12, 6:51 PM CDT | Tornado Warning | LOT | Cook, DuPage | 24 min |
| Jul 12, 7:00 PM CDT | Tornado Warning | LOT | Cook | 32 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 167 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
- 9 J/kg
- Mixed-layer CIN
- -301 J/kg
- Mixed-layer LCL
- 936 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 48 m²/s²
- 0-3 km storm-relative helicity
- 252 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 12, 5:15 AM CDT | Severe Thunderstorm Watch | SPC | Rock Island | 6 hr |
| Jul 12, 8:44 AM CDT | Mesoscale Discussion | SPC | Carroll, Henry, Lee, Ogle, Rock Island, Whiteside | 91 min |
| Jul 12, 3:05 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 12 more | 85 min |
| Jul 12, 4:59 PM CDT | Mesoscale Discussion | SPC | Calhoun, Monroe, Saint Clair | 91 min |
Nearby
Tornado Watches in Illinois, 2023Tornado Watches in Indiana, 2023Every tornado watch in 2023
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.