EF1 tornado, Mt Horeb to Verona Arpt, Wisconsin, July 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 mphthis tornado

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

3. EF2111 to 135 mph

   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

EF1

Date

July 22, 2010

Touchdown

6:52 PM CDT (23:52 UTC)

Lifted

6:55 PM CDT (23:55 UTC)

On the ground

3 minutes

Path length

1.5 miles (2.3 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$5,000

County

Dane County

Touchdown point

42.975, -89.729

Lift-off point

42.980, -89.701

Record number

1007221752-01

A stalled frontal boundary combined with a moist and unstable atmosphere and strong wind shear to produce numerous tornadoes and funnel clouds over South Central and Southeast Wisconsin. A series of vorticity maxima moving west to east through the western Great Lakes enhanced isentropic lift, as a strengthening southerly low-level jet interacted with a nearly stationary west to east warm front.

An EF1 tornado developed about 2 miles south of Mt. Horeb, just east of CTH JG about 1/4 mile east of the intersection of Sand Rock Rd. and Barton Rd. The tornado caused minor home damage, knocked trees down and broke tree limbs, uplifted patio pavers, and tumbled a farm wagon along a 1.5 mile path that averaged 50 yards in width. The tornado ended about 2.5 miles southeast of Mt. Horeb, just east of STH 92, about 1 mile north of the intersection of STH 92 and Malone Rd. The EF1 estimated wind speeds of 95 to 100 mph were based on DI 2(FR12) DOD4. The exact start location is Lat 42.97497 and Lon -89.72878. The exact end location is Lat 42.97961 and Lon -89.70055.

A brief EF0 tornado developed about 1 mile southeast of Verona, just southeast of the intersection of Harvest Ln. and Whalen Rd. The tornado caused minor tree limb damage around Whalen Rd., but no structural damage was noted. The short 0.22 mile path averaged about 15 yards in width. The tornado ended just northeast of the intersection of Whalen Rd. and Gatsby Glenn Dr. The EF0 estimated wind speeds of 65 to 70 mph were based on DI 27(TH) DOD1. The exact start location is Lat 42.97827 and Lon -89.52267. The exact end location is Lat 42.98007 and Lon -89.51900.

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

12 minutes of warning. NWS MKX issued a tornado warning for this county at 23:40 UTC, 12 minutes before the tornado touched down, in force until 00:17 UTC.

The county was under a tornado watch, issued at 20:26 UTC and running to 01:21 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 21:02 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), 95 km away, was scanning. The volume nearest the touchdown began at 23:52 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 WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

16 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.