EF2 tornado, Rock Cut State Park to Capron, Illinois, November 22, 2010

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mphthis tornado

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF2

Date

November 22, 2010

Touchdown

3:00 PM CST (21:00 UTC)

Lifted

3:25 PM CST (21:25 UTC)

On the ground

25 minutes

Path length

18.1 miles (29.1 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

6

Property damage

$5.0 million

Counties

Boone, Winnebago and McHenry counties

Touchdown point

42.331, -88.970

Lift-off point

42.445, -88.651

Record number

1011221500-01

3 damage points were recorded along this path by NWS LOT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.

• Roof, multiple walls collapsed on barn.
• Roof and at least one exterior wall collapsed on portion of house.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

Strong to severe thunderstorms moved across parts of northern Illinois during the afternoon hours of November 22nd. These storms produced two tornadoes, hail, heavy rain and some flooding.

Based on an eyewitness report, a tornado touched down in the backyard of a home just west of Interstate 39, on the eastern edge of a subdivision. The tornado then blew over a school bus near the intersection of Argyle and Harlem Roads. There were six people on the bus, the driver and five children. All six people were taken to the hospital but none of the injuries were serious. The tornado then knocked down eleven electrical high tension towers just southwest of the same intersection. The tornado was likely at EF2 intensity at this time and as it crossed into Boone County.

A tornado which touched down in eastern Winnebago County, crossed into western Boone County and moved across largely open rural fields towards the town of Caledonia. Significant damage occurred to at least six buildings in Caledonia, with approximately 20 additional buildings sustaining minor damage. Several large trees were snapped or uprooted, and a grain bin partially collapsed. The tornado was again likely at EF2 intensity at this time. The tornado then continued northeast from Caledonia, downing several power poles and causing damage ranging from blown off roofs to completely destroying at least three farm outbuildings. One of these buildings, located two miles northwest of Capron, had also been damaged during the January 2008 tornado. The tornado then crossed into McHenry County.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

The county was under a tornado watch, issued at 17:25 UTC and running to 21:56 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:48 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Milwaukee radar (KMKX), 68 km away, was scanning. The volume nearest the touchdown began at 21:00 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2010 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

3 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.