Tornadoes · United States · Wisconsin · 2011
EF0 tornado, Sherwood, Wisconsin, August 23, 2011
This EF0 tornado ran 0.5 miles across Calumet County on August 23, 2011, touching down at 9:05 PM CDT and reaching 100 yards wide. It killed nobody, and did $50,000 of property damage.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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.
The record
- Rating
- EF0
- Date
- August 23, 2011
- Touchdown
- 9:05 PM CDT (02:05 UTC)
- Lifted
- 9:06 PM CDT (02:06 UTC)
- On the ground
- 1 minutes
- Path length
- 0.5 miles (0.8 km)
- Path width
- 100 yards (91 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $50,000
- County
- Calumet County
- Touchdown point
- 44.183, -88.254
- Lift-off point
- 44.181, -88.244
- Record number
- 1108232005-01
What the Weather Service recorded
Severe thunderstorms formed as a strong upper level low pressure system moved across Wisconsin.
A tornado struck less than a mile northeast of Sherwood at 9:05 PM CDT. The EF0 tornado toppled two trees that damaged the roof of a house and snapped or uprooted six pine trees near Highway M. The tornado continued east-southeast, moving over a swamp, where swirl marks were seen in the thick swamp grass. The tornado then hit a farm on Kesler Road. Two old barns were heavily damaged (DI 1, DOD 5, 6 -- lower bound due to condition of structures). Peak winds were estimated near 85 mph. Average path width of the tornado was 75 yards.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.
The county was under a tornado watch, issued at 22:20 UTC and running to 02:58 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 22:20 UTC | 02:58 UTC | Tornado Watch | GRB |
| 01:33 UTC | 02:30 UTC | Severe Thunderstorm Warning | GRB |
| 02:15 UTC | 02:50 UTC | Severe Thunderstorm Warning | GRB |
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 forecast that day
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 01:00 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 air that afternoon
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.
Green Bay/Straub, WI (KGRB), 00:00Z
2.1 hours before the tornado, 35 km from the path. August 24, 2011.
- Mixed-layer CAPE
- 1178 J/kg
- Mixed-layer CIN
- -15 J/kg
- Surface CAPE
- 1451 J/kg
- Mixed-layer LCL
- 727 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 150 m²/s²
- 0-3 km storm-relative helicity
- 203 m²/s²
- Significant tornado parameter
- 1.0
- Supercell composite
- 4.4
- 0-3 km lapse rate
- 5.9 K/km
Green Bay/Straub, WI (KGRB), 12:00Z
9.9 hours after it, 35 km from the path. August 24, 2011.
- Mixed-layer CAPE
- 2500 J/kg
- Mixed-layer CIN
- -233 J/kg
- Surface CAPE
- 844 J/kg
- Mixed-layer LCL
- 891 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 150 m²/s²
- 0-3 km storm-relative helicity
- 237 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.7
- 0-3 km lapse rate
- 3.9 K/km
The radar
The Green Bay radar (KGRB), 37 km away, was scanning. The volume nearest the touchdown began at 02:03 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.
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 23:48 UTC | FUNNEL CLOUD | Navarino | Shawano, WI | FUNNEL CLOUD MOVING EAST. |
| 23:56 UTC | TORNADO | Sse Briarton | Shawano, WI | BRIEF EF0 TORNADO TOUCHED DOWN IN FIELD SHORTLY BEFORE 7 PM NORTH OF SHADY RD BETWEEN HERMAN CREEK RD AND ELM RD. TALL GRASS/HAY IN FIELD WAS FLATTENED IN CYCLONIC PATTERN. IN ADDITION, APPROX A DOZEN TREES HAD SNAPPED L |
| 00:25 UTC | HAIL 0.5 | Suamico | Brown, WI | WITH HEAVY RAIN. |
| 02:05 UTC | TSTM WND DMG | Sherwood | Calumet, WI | TREES DOWN |
| 02:05 UTC | TORNADO | Sherwood | Calumet, WI | EF0 TORNADO STRUCK LESS THAN A MILE NORTHEAST OF SHERWOOD. SEVERAL STRUCTURES WERE IMPACTED INCLUDING TWO BARNS THAT WERE HEAVILY DAMAGED. SEVERAL PINE TREES WERE SNAPPED ABOUT 15 FEET ABOVE THE GROUND. SWIRL MARKS SEEN |
| 02:10 UTC | HAIL 1 | Forest Junction | Calumet, WI |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2011 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are
The other tornadoes of August 23, 2011
3 more were confirmed in the United States that day.
What this means
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.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.