Alert archive / Illinois / Tornado Watches in 2024
Tornado Watch 282
The Storm Prediction Center issued this tornado watch at May 21, 2024, 7:13 PM CDT for 12 counties in Illinois. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- May 21, 2024, 7:13 PM CDT (00:13 UTC)
- Expired
- May 22, 2024, 12:00 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 65 kt
Counties Boone County, IL, Bureau County, IL, DeKalb County, IL, Kane County, IL, Kendall County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Putnam County, IL, Stephenson County, IL, Winnebago County, IL
The radar
The Chicago radar (KLOT), 93 km from the middle of the area, began a volume at 00:13 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
- 20%
- Ten or more severe wind reports
- 60%
- 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
- 5%
- Six or more combined severe hail and wind reports
- 80%
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 |
|---|---|---|---|---|
| May 21, 7:27 PM CDT | Severe Thunderstorm Warning | DVN | Carroll, Jo Daviess, Stephenson, Whiteside | 48 min |
| May 21, 7:45 PM CDT | Severe Thunderstorm Warning | DVN | Bureau, Henry, Whiteside | 28 min |
| May 21, 7:53 PM CDT | Severe Thunderstorm Warning | LOT | Lee, Ogle | 45 min |
| May 21, 8:14 PM CDT | Severe Thunderstorm Warning | DVN | Stephenson | 34 min |
| May 21, 8:31 PM CDT | Severe Thunderstorm Warning | DVN | Carroll, Jo Daviess, Stephenson | 44 min |
| May 21, 8:36 PM CDT | Severe Thunderstorm Warning | LOT | Boone, Winnebago | 20 min |
| May 21, 9:58 PM CDT | Severe Thunderstorm Warning | DVN | Stephenson | 47 min |
| May 21, 10:28 PM CDT | Severe Thunderstorm Warning | LOT | Winnebago | 47 min |
| May 21, 10:53 PM CDT | Severe Thunderstorm Warning | LOT | Lee | 67 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 00:00Z, 0.2 hours before the alert went out and 123 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
- 1821 J/kg
- Mixed-layer CIN
- -33 J/kg
- Mixed-layer LCL
- 1656 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 18 m²/s²
- 0-3 km storm-relative helicity
- 56 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.9
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 7:55 PM CDT | Mesoscale Discussion | SPC | Adams | 2 hr |
| May 21, 7:56 PM CDT | Mesoscale Discussion | SPC | Boone, McHenry, Stephenson, Winnebago | 64 min |
Nearby
Tornado Watches in Illinois, 2024Every tornado watch in 2024
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.