EF1 tornado, Augusta, Wisconsin, April 10, 2011

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

April 10, 2011

Touchdown

4:57 PM CDT (21:57 UTC)

Lifted

5:03 PM CDT (22:03 UTC)

On the ground

6 minutes

Path length

1.6 miles (2.5 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

Property damage

$200,000

County

Eau Claire County

Touchdown point

44.630, -91.190

Lift-off point

44.646, -91.167

Record number

1104101557-01

A strong early Spring cold front moved across eastern Minnesota during the afternoon of Sunday, April 10th. Ahead of this cold front, strong southerly winds and instability made for a moderate risk of severe weather based the Storm Prediction Center and atmospheric dynamics. After 2 pm, a few supercells developed rapidly from Red Wing, Minnesota, northward across Menomonie and Rice Lake, Wisconsin. These supercells rapidly became severe and started to produce large hail. One of the thunderstorms produced two EF-1 tornadoes near Augusta. These storms quickly moved out of west central Wisconsin by 6 pm.

An EF-1 tornado, with maximum wind speeds of 95 to 105 mph occurred from approximately 5 miles southwest of Augusta, to 3.5 miles southwest of Augusta, Wisconsin. Two farmsteads were directly impacted with severe tree damage around the homes. One farmstead had their garage completely destroyed along with a barn heavily damaged.

An EF-1 tornado, with maximum wind speeds of 90 to 100 mph, occurred along a path from northwest of Augusta to north of Augusta, Wisconsin. Numerous trees and power poles were snapped, along with an outbuilding destroyed, and three other outbuildings significantly damaged.

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

16 minutes of warning. NWS MPX issued a tornado warning for this county at 21:41 UTC, 16 minutes before the tornado touched down, in force until 22:30 UTC.

The county was under a tornado watch, issued at 20:20 UTC and running to 22:52 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 Moderate Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:54 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), 91 km away, was scanning. The volume nearest the touchdown began at 21:56 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 2011 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

15 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.