EF1 tornado, Watermill to Wyeville, Wisconsin, August 27, 2018

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

August 27, 2018

Touchdown

8:23 PM CDT (01:23 UTC)

Lifted

8:29 PM CDT (01:29 UTC)

On the ground

6 minutes

Path length

5.1 miles (8.2 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$25,000

County

Monroe County

Touchdown point

44.029, -90.479

Lift-off point

44.023, -90.376

Record number

1808271923-01

2 damage points were recorded along this path by NWS ARX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

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

A line of severe thunderstorms moved across western Wisconsin during the evening of August 27th. A brief tornado touched down and had an intermittent damage path between Tomah and Wyeville (Monroe County). The damage was limited to trees and power poles. These storms blew down trees and caused roof damage in Sparta (Monroe County), rolled a camper and damaged several signs near Tomah (Monroe County) and downed trees around Hixton (Jackson County) and in the Town of Cleveland (Jackson County). The storms then became oriented in an east to west line and dumped copious amounts of rain from southern La Crosse County and northern Vernon County east across the southern sections of Monroe, Juneau and Adams Counties. Numerous roads were closed because of flooding or mudslides, homes had to be evacuated with several water rescues were performed. Towns that were hit hard by the flooding included Coon Valley, Ontario (Vernon County), Elroy and Wonewoc (Juneau County). The eastbound Amtrak Empire Builder had to be halted near Tomah because of a washout on the rail line near Mauston (Juneau County). In Monroe and Vernon Counties, four earthen flood control dams failed and seven others sustained damage. Rainfall totals of 6 to 10 inches were common in this heavy rain band with the highest reported totals being 9.14 inches in Union Center (Juneau County) and 9.98 inches near Westby (Vernon County). The runoff later produced historic flooding on the Kickapoo River with several record flood crests established. Damages in Juneau County exceeded $22 million of which $6.5 million was from Elroy. The State of Wisconsin Governor declared a state of emergency for the entire state. A federal disaster declaration was made for La Crosse, Monroe, Juneau, Adams, Vernon, Crawford and Richland Counties.

An EF1 tornado caused an intermittent damage path along and south of State Highway 21 between Tomah and Wyeville. The damage was limited to trees and a few power poles.

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.

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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 00:56 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 La Crosse radar (KARX), 65 km away, was scanning. The volume nearest the touchdown began at 01:22 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 2018 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

2 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.