Tornadoes · United States · Wisconsin · 2012

EF0 tornado, Marathon, Wisconsin, May 24, 2012

This EF0 tornado ran 5.9 miles across Marathon County on May 24, 2012, touching down at 7:01 PM CDT and reaching 75 yards wide. It killed nobody.

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 mphthis tornado

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

  2. EF186 to 110 mph

    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
EF0
Date
May 24, 2012
Touchdown
7:01 PM CDT (00:01 UTC)
Lifted
7:07 PM CDT (00:07 UTC)
On the ground
6 minutes
Path length
5.9 miles (9.6 km)
Path width
75 yards (69 m)
Deaths
0
Injuries
0
County
Marathon County
Touchdown point
44.869, -89.805
Lift-off point
44.939, -89.736
Record number
1205241801-01

What the Weather Service recorded

A strong low pressure system moved across northwest Wisconsin. Thunderstorms formed along a trailing cold front. The storms moved quickly and some produced high winds that downed trees and tree limbs. One of the storms produced a brief tornado southwest of Wausau in Marathon County.

A tornado formed southwest of Wausau and rapidly moved northeast just after 7:00 pm CDT. About 100 trees sustained large broken branches or were snapped by the tornado (DI 28, DOD 2, 4). No structures were damaged. Average path width was 50 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. One was issued for the county at another hour that day.

The county was under a tornado watch, issued at 19:25 UTC and running to 00:36 UTC.

Issued (UTC)ExpiredProductOffice
17:00 UTC02:17 UTCWind AdvisoryGRB
19:25 UTC00:36 UTCTornado WatchGRB
23:36 UTC00:00 UTCSevere Thunderstorm WarningGRB
23:59 UTC00:34 UTCSevere Thunderstorm WarningGRB
00:03 UTC00:30 UTCTornado WarningGRB
00:36 UTC02:14 UTCSevere Thunderstorm WatchGRB
00:49 UTC01:30 UTCSevere Thunderstorm 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 Moderate Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:46 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

0.0 hours before the tornado, 140 km from the path. May 25, 2012.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 00:00Z on 2012-05-25Temperature 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 -74499, lifted condensation level 2474 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 2012-05-25The 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 313 square meters per square second, 0 to 6 km bulk shear 42 knots.19395878Sfc1 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
-74499 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
2474 m above ground
0-6 km bulk shear
42 kt
0-1 km bulk shear
33 kt
0-1 km storm-relative helicity
313 m²/s²
0-3 km storm-relative helicity
468 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.6 K/km

Open this sounding in Storm Lab

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

12.0 hours after it, 140 km from the path. May 25, 2012.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 12:00Z on 2012-05-25Temperature 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 -66029, lifted condensation level 1030 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 2012-05-25The 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 -110 square meters per square second, 0 to 6 km bulk shear 94 knots.1939587897117136Sfc1 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
-66029 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1030 m above ground
0-6 km bulk shear
94 kt
0-1 km bulk shear
30 kt
0-1 km storm-relative helicity
-110 m²/s²
0-3 km storm-relative helicity
7 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.5 K/km

Open this sounding in Storm Lab

The surface observations

Wausau (AUW), 12 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:54 UTC8651170° 29 kt39993.9HZ
23:13 UTC84.251.8180° 19 kt28994.2HZ
23:54 UTC8452170° 19 kt32993.9HZ
00:21 UTC69.862.6240° 16 kt34995.9-RA
00:54 UTC6663270° 17 kt28997.3+RA BR
01:39 UTC64.462.6230° 8 kt16998.6+RA BR
01:46 UTC62.662.6230° 9 kt998.3RA BR
01:49 UTC62.660.8240° 9 kt998.3RA BR
01:54 UTC6361220° 7 kt998.3-RA BR

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

The radar

The Green Bay radar (KGRB), 139 km away, was scanning. The volume nearest the touchdown began at 00:01 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
23:15 UTCTSTM WND GST 601 Ne SpencerMarathon, WIHEAVY RAINFALL AND SMALL HAIL ALSO REPORTED.
23:20 UTCTSTM WND DMG4 E LongwoodClark, WITREE DOWN ON ROAD AT COUNTY P AND COUNTY N. APPROXIMATE TIME VIA RADAR. SHERIFF REPORT RECEIVED FROM PUBLIC AT 651 PM.
23:30 UTCTSTM WND DMG2 S DorchesterClark, WITREE DOWN ON PINE ROAD AND HILINE ROAD. APPROXIMATE TIME VIA RADAR. SHERIFF REPORT RECEIVED FROM PUBLIC AT 655 PM.
23:45 UTCTSTM WND DMGStratfordMarathon, WI12 INCH DIAMETER TREES DOWN
23:48 UTCTSTM WND DMG2 Wnw HalderMarathon, WITREES AND BRANCHES BLOWN DOWN NEAR STRATFORD
00:07 UTCTORNADORib MountainMarathon, WICONFIRMED TORNADO BY LAW ENFORCEMENT.
00:32 UTCTSTM WND DMGPloverPortage, WISEVERAL TREES DOWN-RELAYED FROM PORTAGE SHERRIF DEPT.
01:05 UTCTSTM WND DMGPloverPortage, WISEVERAL TREES DOWN-RELAYED FROM PORTAGE SHERRIF DEPT.

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

This ground now

The live radar over the trackEvery 2012 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

The other tornadoes of May 24, 2012

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 244:56 PM CDTEF1Fayette, IA3.030$30,000
May 245:36 PM CDTEF2Platte, NE0.8100$100,000

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.