F1 tornado, Wisconsin Dells to Portage, Wisconsin, June 6, 2006

1. F040 to 72 mph

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

2. F173 to 112 mphthis tornado

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

3. F2113 to 157 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. F3158 to 206 mph

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

5. F4207 to 260 mph

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

6. F5261 to 318 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

F1

Date

June 6, 2006

Touchdown

6:54 PM CDT (23:54 UTC)

Path length

16.9 miles (27.2 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

Property damage

$1.0 million

Counties

Sauk and Columbia counties

Touchdown point

43.630, -89.700

Lift-off point

43.450, -89.480

Record number

603

Several supercell thunderstorms developed along a cold front across southwest Wisconsin and pushed east southeast into south-central Wisconsin during the late afternoon and early evening. Six tornadoes resulted from these storms (listed with details above) of the F0 to F1 variety across the counties of Sauk, Columbia, and Iowa. A couple funnel clouds were reported in Green and Columbia counties, as well as large hail in Green Lake and Columbia counties, and thunderstorm wind damage in Dane and Columbia counties. Synoptically, with temperatures in the low or mid 70s and dewpoints in the mid 60s with cold air aloft, high instability resulted. Vertical wind shear, in addition to lift with the cold front, allowed supercell thunderstorms to develop. Sufficient low-level shear allowed tornadic development with two of the supercells.

The first segment of a multi-county-segmented tornado spun up 3.0 miles east of Wisconsin Dells at 1754CST about 0.6 mile east-northeast of the intersection of Broadway Rd. and CTH Q. It headed southeast and crossed STH 16 at Lewiston, and then crossed the Wisconsin River into Sauk County about 1.5 miles southeast of Lewiston at 1813CST. In this first Columbia County stretch, around 10 houses were damaged or destroyed, along with a couple pole sheds and many trees and power lines. An estimated 400,000 dollars in property damage occurred. The tornado was rated F1 with winds of 64 to 97 knots (73-112 mph). After a short track through Sauk County, this tornado re-entered Columbia County about 7 miles west of Portage, crossed Interstate 90/94, and then crossed the Wisconsin River again before dissipating at 1840CST.

This tornado segment is the 2nd of a three-segment tornado (Columbia-Sauk-Columbia). The first segment started in Columbia County about 3.0 miles east of Wisconsin Dells. This second segment entered Sauk County about 8.5 miles east-southeast of Lake Delton at 1813CST (or about 0.6 mile northeast of the intersection of N Hein Rd. and Levee Rd.) and headed southeast. It exited Sauk County about 10.1 miles east-southeast of Lake Delton at 1817CST where Levee Rd. goes east into Columiba County. The tornado caused a tree to fall onto a home which caused 1000 dollars in property damage. The tornado during this second county segment had weakened a bit down to the F0 rating with winds of 35-63 knots (40-72 mph). Overall, this three-segment tornado path length was 16.9 miles with a time span of 1754CST to 1840CST.

This tornado segment is a third, county-segment, continuation of a tornado that initially spun up in far northwestern Columbia County about 3.0 miles east of Wisconsin Dells at 1754CST and then crossed into Sauk County about 1.5 miles southeast of Lewiston at 1813CST. This tornado re-entered Columbia County about 7.0 miles west of Portage at 1817CST where Levee Rd. on the south side of the Wisconsin River exits Columbia County going west. The heading of this tornado was southeast, and it crossed Interstate 90/94 near Tritz Road where a vehicle swerved and caused a semitrailer to roll onto its side. It eventually passed through a residential trailer complex/camp ground south of the Cascade Ski Resort. It crossed Interstate 90/94 where Ziehmke Rd approached the Interstate from the east. At this point, the tornado caused a semitrailer to be blown off the road. The tornado then tracked over the extreme eastern edge of Pickerel Lake, crossed over the Wisconsin River for the second time, and dissipated about 1.0 mile southwest of Dekorra at 1840CST, just short of CTH V. Around 10 houses were damaged, along with a barn, a couple pole sheds, and many trees and power lines. The tornado caused about 600,000 dollars in property damage, and was rated F1 with winds of 64-97 knots (73-112 mph). The tornado was well-photographed and filmed. Overall, this F1 Columbia-Sauk-Columbia County tornado path length was 16.9 miles with a beginning time of 1754CST and an ending time of 1840CST.

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

15 minutes of warning. NWS MKX issued a tornado warning for this county at 23:39 UTC, 15 minutes before the tornado touched down, in force until 00:45 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 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:55 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.

Dells/Baraboo (DLL), 15 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Milwaukee radar (KMKX), 106 km away, was scanning. The volume nearest the touchdown began at 23:54 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 2006 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

6 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.