Tornadoes · United States · Wisconsin · 2010

EF1 tornado, Zittau to Larsen, Wisconsin, May 4, 2010

From Zittau to Larsen, this EF1 tornado ran 0.7 miles across Winnebago County on May 4, 2010, touching down at 7:10 PM CDT and reaching 100 yards wide. It killed nobody, and did $10,000 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.

  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.

The record

Rating
EF1
Date
May 4, 2010
Touchdown
7:10 PM CDT (00:10 UTC)
Lifted
7:12 PM CDT (00:12 UTC)
On the ground
2 minutes
Path length
0.7 miles (1.1 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
Property damage
$10,000
County
Winnebago County
Touchdown point
44.195, -88.738
Lift-off point
44.196, -88.724
Record number
1005041810-01

What the Weather Service recorded

Thunderstorms, in the vicinity of a strong warm front, moved into central Wisconsin during the afternoon. These storms produced severe weather as they made their way across parts of central and east central Wisconsin, knocking down and uprooting trees and dropping hail up to penny size. Two tornadoes, one EF0 and one EF1, briefly touched down in the vicinity of Lake Poygan.

This tornado snapped numerous pine trees in a wooded area (DI 28, DOD 4) and threw a gazebo into the side of a house. The tornado also destroyed a 100 year old barn (DI 1, DOD 6). Wind speed was estimated at 95 mph.

This tornado damaged several structures. It destroyed a shed, swirling 2 by 4's in the air. The 2 by 4's struck a house, damaging the roof. It threw a trailer about 200 yards into a field and ripped siding off a garage (DI 2, DOD 2) and knocked over a small camper trailer. Winds were estimated at 80 mph.

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. One was issued for the county at another hour that day.

Issued (UTC)ExpiredProductOffice
00:14 UTC00:41 UTCTornado WarningGRB

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 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:58 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

0.2 hours before the tornado, 59 km from the path. May 5, 2010.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 00:00Z on 2010-05-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -89302, lifted condensation level 1647 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Green Bay/Straub, WI at 00:00Z on 2010-05-05The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 213 square meters per square second, 0 to 6 km bulk shear 51 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-89302 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1647 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
22 kt
0-1 km storm-relative helicity
213 m²/s²
0-3 km storm-relative helicity
477 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0
0-3 km lapse rate
6.3 K/km

Open this sounding in Storm Lab

Green Bay/Straub, WI (KGRB), 12:00Z

11.8 hours after it, 59 km from the path. May 5, 2010.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 12:00Z on 2010-05-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -85361, lifted condensation level 1356 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Green Bay/Straub, WI at 12:00Z on 2010-05-05The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -74 square meters per square second, 0 to 6 km bulk shear 92 knots.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-85361 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1356 m above ground
0-6 km bulk shear
92 kt
0-1 km bulk shear
22 kt
0-1 km storm-relative helicity
-74 m²/s²
0-3 km storm-relative helicity
66 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.2 K/km

Open this sounding in Storm Lab

The surface observations

Appleton/Outagam (ATW), 18 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:45 UTC66.246.4130° 10 kt1001.7
23:45 UTC66.246.4110° 10 kt1000.3
00:15 UTC64.446.480° 12 kt20999.7-TSRA
00:45 UTC57.251.8350° 17 kt251003.4RA
01:45 UTC57.253.610° 10 kt1003.4RA

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

The radar

The Green Bay radar (KGRB), 60 km away, was scanning. The volume nearest the touchdown began at 00:11 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)ReportWhereCountyRemark
23:40 UTCTSTM WND DMG1 E IolaWaupaca, WI1 TREE DOWN ON ROAD EAST OF IOLA
23:40 UTCHAIL 0.25New LondonWaupaca, WI0.25 INCH HAIL NORTH OF IOLA
23:55 UTCHAIL 0.25New LondonWaupaca, WI
00:04 UTCHAIL 0.252 Sw EmbarrassWaupaca, WIALSO ESTIMATED WIND GUSTS TO 40 MPH
00:12 UTCFUNNEL CLOUDLake PoyganWinnebago, WISEVERAL REPORTS OF FUNNEL CLOUDS NEAR THE BOOM BAY AREA NEAR LAKE POYGAN
00:12 UTCTORNADO4 W WinchesterWinnebago, WI
00:15 UTCTORNADOWinchesterWinnebago, WI
00:17 UTCTSTM WND GST 602 Ne WinneconneWinnebago, WIPOSSIBLE GUSTNADO ALSO SEEN
00:17 UTCTSTM WND GST 60WinneconneWinnebago, WI
00:25 UTCFUNNEL CLOUDGreenvilleOutagamie, WINEAR HIGHWAY 96 AND HIGHWAY 15
00:32 UTCHAIL 0.75WinchesterWinnebago, WIDIME SIZE HAIL NEAR APPLETON
01:06 UTCFUNNEL CLOUDPotterCalumet, WICOUNTY HWY PP
01:06 UTCHAIL 0.5BrillionCalumet, WI

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2010 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

The other tornadoes of May 4, 2010

1 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 47:13 PM CDTEF0Winnebago, WI3.4100$25,000

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.