Tornadoes · United States · Wisconsin · 2011
EF1 tornado, Askeaton to Greenleaf, Wisconsin, April 10, 2011
From Askeaton to Greenleaf, this EF1 tornado ran 1.2 miles across Brown County on April 10, 2011, touching down at 8:53 PM CDT and reaching 75 yards wide. It killed nobody, and did $15,000 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 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
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
- EF1
- Date
- April 10, 2011
- Touchdown
- 8:53 PM CDT (01:53 UTC)
- Lifted
- 8:55 PM CDT (01:55 UTC)
- On the ground
- 2 minutes
- Path length
- 1.2 miles (1.9 km)
- Path width
- 75 yards (69 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $15,000
- County
- Brown County
- Touchdown point
- 44.285, -88.110
- Lift-off point
- 44.300, -88.096
- Record number
- 1104101953-01
What the Weather Service recorded
Thunderstorms developed along and ahead of a cold front as it encountered moist and unstable air across Wisconsin.||A record number of tornadoes for April struck Wisconsin on April 10. Fifteen twisters affected the state as a strong spring storm moved across the western Great Lakes. In the National Weather Service Green Bay service area of northeast Wisconsin, ten tornadoes were reported, a record single-day outbreak for any month of the year.||In addition to the tornadoes, the lines of thunderstorms that developed produced plenty of straight line wind damage and large hail. Wind gusts, some estimated in the 80 mph to 100 mph range, downed numerous trees, damaged a small building, caused an injury and damage to two homes, toppled an 80-foot tall radio tower, threw a carport two houses away, and caused major damage to two industrial buildings. The largest hail reported was baseball size near Winneconne in Winnebago County.
A brief tornado touched down about a mile and a half south of Greenleaf. The tornado damaged the tops of two silos then ripped the roof off a barn (DI 1, DOD 5). Average path width was 75 yards.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The forecast that day
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 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.
What forecasters said that day
The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Green Bay, WI wrote its last area forecast discussion before the tornado touched down at Apr 10, 2:40 PM CDT, 6 hours 13 minutes earlier.
Area forecast discussion, Apr 10, 2:40 PM CDT, 6 hours 13 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 240 PM CDT SUN APR 10 2011 .SHORT TERM...TNGT AND MON. MAIN FCST FOCUS TO BE ON SEVERE POTENTIAL LATE THIS AFTERNOON INTO THE EVENING HOURS. POTENTIAL EXISTS FOR SIGNIFICANT THUNDERSTORMS WITH DAMAGING WINDS...LARGE HAIL AND SEVERAL TORNADOES. THE 19Z MSAS SFC ANALYSIS SHOWED A STG AREA OF LOW PRES SITUATED OVER E-CNTRL MN WITH A WRMFNT EXTENDED EWD THRU CNTRL WI. A CDFNT STRETCHED SOUTH FROM THE LOW THRU CNTRL SECTIONS IA. AIR MASS ACROSS SRN WI HAS BECOME VERY UNSTABLE WITH DEW PTS RISING INTO THE LWR 60S...CAPES APPROACHING 2K J/KG AND LI'S AS LOW AS -8. RADAR MOSAIC/SATL IMAGERY INDICATED ACCAS CLDS/SCT SHWRS DEVELOPING OVER NE IA AND MOVING NEWD INTO CNTRL WI. NONE OF THESE STORMS ARE SVR AS OF YET. OUTBREAK OF SVR STORMS IS STILL EXPECTED LATE THIS AFTERNOON INTO THE EVENING HOURS OVER MUCH OF NE WI. THUNDERSTORMS ARE FCST TO DVLP FROM ERN MN/NE IA AHD OF THE CDFNT THIS AFTERNOON AND THEN MOVE RAPIDLY EAST (40 TO 50 MPH) THRU WI. THERMODYNAMICS ALL APR FAVORABLE FOR THESE STORMS TO QUICKLY TURN SEVERE AS JET ENERGY LIFTS NE THRU THE MIDWEST AHD OF THE MAIN UPR TROF. THESE SVR STORMS WL REACH CNTRL WI BETWEEN 5 AND 7 PM...ERN WI BETWEEN 7 AND 9 PM. LARGEST HODOGRAPHS ARE FCST TO RESIDE NEAR THE WRMFNT WHICH SHOULD BE LOCATED OVER NRN WI WHEN THE STORMS ARRIVE. THIS AREA WOULD HAVE THE BEST CHC OF SEEING TORNADO ACTIVITY WITH THE POSSIBILITY OF LONG-TRACKED TORNADOES. ANTICIPATE A WEATHER WATCH TO BE ISSUED SHORTLY. THE SFC LOW TO CONT MOVING NE THRU THE WRN GREAT LKS TNGT AND SWEEP THE CDFNT THRU THE FCST AREA THIS EVENING. ONGOING CONVECTION SHOULD ALREADY BE IN THE PROCESS OF EXITING WI AROUND THE MIDNGT HOUR WITH ONLY LGT STRATIFORM RAIN IN SCT FASHION FOR THE OVERNIGHT PERIOD. WINDS WL VEER WEST AND INCREASE THRU THE NGT WITH GUST APPROACHING 30 MPH TOWARD DAYBREAK. HAVE LOWERED MIN TEMPS A FEW DEGS AS COOLER AIR QUICKLY MOVES IN BEHIND THE DEPARTED CDFNT. WRAP-AROUND MSTR/SECONDARY SFC TROF/PASSAGE OF THE UPR TROF TO MOVE THRU WI MON MORNING AND MAY BE ABLE TO KICK OFF A FEW LGT SHWRS. BY MON AFTERNOON...A RDG OF HI PRES IS FCST TO MOVE INTO THE UPR MS VALLEY AND BEGIN TO ADVECT DRIER AIR INTO WI. HAVE LEFT A TOKEN SLGT CHC POP FOR THE AFTERNOON...BUT THESE MAY BE ABLE TO GET DROPPED IF MDLS PERSIST ON AMT OF DRYING. MAX TEMPS BACK TO NORMAL ON MON WITH LWR 50S NORTH...MID-UPR 50S ELSEWHERE. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY. UPPER RIDGE BUILDS INTO THE AREA MONDAY NIGHT AND REMAINS ACROSS WISCONSIN BEFORE FLATTENING TUESDAY NIGHT. THIS SHOULD PROVIDE FOR DRY AND SEASONABLE WEATHER THROUGH EARLY WEDNESDAY. CLIPPER LIKE SYSTEM APPROACHES WEDNESDAY WITH A SURFACE COLD FRONT THAT DROPS ACROSS WISCONSIN BEFORE STALLING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT THROUGH THURSDAY. THEN MODELS SUGGEST THAT AN INVERTED TROUGH WILL FORM FROM THE SOUTHERN PLAINS TO IOWA...WITH OVERRUNNING PRECIPITATION TO IT/S NORTH. UPPER JET ENERGY MOVING INTO THE SOUTHERN PLAINS FROM THE WESTERN UNITED STATES IS EXPECTED TO PRODUCE A CLOSED LOW OVER THE MID MISSISSIPPI VALLEY THURSDAY NIGHT WHICH THEN MOVES VERY SLOWLY EAST TO THE OHIO VALLEY BY SATURDAY. THE GFS IS FURTHER SOUTH THAN THE ECMWF AT FIRST BUT THEN THE TWO MODELS COME TOGETHER WITH A LOW OVER ILLINOIS ON SATURDAY. THIS COULD MAKE FOR AN EXTENDED PERIOD OF CLOUDS AND COOLER WEATHER THURSDAY THROUGH SATURDAY WITH PERIODS OF RAIN AND POSSIBLY SOME SNOW. ACCUMULATING SNOW POSSIBLE FRIDAY NIGHT AND SATURDAY IF THE BOUNDARY LAYER TEMPERATURES ARE COLD ENOUGH. && .AVIATION...VFR CONDITIONS TO ONLY LAST INTO THE EVENING HOURS BEFORE A CDFNT SWEEPS THRU THE RGN AND BRING SVR TSTMS TO MUCH OF THE AREA. SOUTH WNDS TO VEER WEST AND INCREASE INTO THE 15 TO 25 KT RANGE WITH GUSTS APPROACHING 30 KTS. A LARGE AREA OF LOW STRATUS CLDS TO THEN OVERSPREAD THE TAF SITES AFTER MIDNIGHT WITH CIGS/VSBYS IN THE IFR/MVFR RANGE. AS A RDG OF HI PRES BEGINS TO BUILD INTO THE WRN GREAT LKS MON AFTERNOON...EXPECT CIGS TO RETURN TO VFR CONDITIONS. && .GRB WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH UNTIL 1 AM CDT MONDAY FOR WIZ018>021-030-031-035>040- 045-048>050-074. && KALLAS/RDM
Hazardous weather outlook, Apr 10, 11:54 AM CDT, 8 hours 59 minutes before
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 1154 AM CDT SUN APR 10 2011 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-111700- VILAS-ONEIDA-FOREST-FLORENCE-NORTHERN MARINETTE-LINCOLN-LANGLADE- MENOMINEE-NORTHERN OCONTO-DOOR-MARATHON-SHAWANO-WOOD-PORTAGE- WAUPACA-OUTAGAMIE-BROWN-KEWAUNEE-WAUSHARA-WINNEBAGO-CALUMET- MANITOWOC-SOUTHERN MARINETTE-SOUTHERN OCONTO- 1154 AM CDT SUN APR 10 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST WISCONSIN. .DAY ONE...THIS AFTERNOON AND TONIGHT THERE IS A MODERATE RISK FOR SEVERE WEATHER OVER ALL OF NORTH CENTRAL AND NORTHEAST WISCONSIN THIS AFTERNOON AND EVENING. A MAJOR SEVERE WEATHER OUTBREAK STILL LOOKS LIKELY FOR LATE THIS AFTERNOON AND EVENING AS A STRONG LOW PRESSURE SYSTEM AND COLD FRONT MOVE INTO THE REGION. THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN WISCONSIN AND NORTHEAST IOWA BY MID-AFTERNOON AND QUICKLY BECOME SEVERE. THESE SEVERE STORMS WILL RAPIDLY SWEEP EAST AT 40 TO 50 MPH ACROSS CENTRAL AND EASTERN WISCONSIN BETWEEN 5 AND 9 PM WITH THE PRIMARY THREAT BEING DAMAGING WINDS...LARGE HAIL AND TORNADOES. RAINFALL AMOUNTS FROM THE STORMS IS ALSO EXPECTED TO BE HEAVY AT TIMES. THAT WILL RESULT IN AN INCREASED RISK OF FLOODING... ESPECIALLY NEAR RIVERS AND STREAMS. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY ON MONDAY AFTERNOON...STRONG NORTHWEST WINDS OF 20 TO 30 MPH ARE FORECAST TO OVERSPREAD THE REGION. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING. LMZ521-522-541>543-111700- THE BAY OF GREEN BAY SOUTH OF A LINE FROM CEDAR RIVER MI TO ROCK ISLAND PASSAGE-LAKE MICHIGAN FROM WASHINGTON ISLAND TO SHEBOYGAN- 1154 AM CDT SUN APR 10 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST LAKE MICHIGAN AND THE WATERS OF GREEN BAY. .DAY ONE...THIS AFTERNOON AND TONIGHT MOIST AIR MOVING NORTH OVER THE COLD WATERS OF LAKE MICHIGAN WILL BRING AREAS OF DENSE FOG FROM TIME TO TIME. THUNDERSTORMS ARE ALSO EXPECTED LATE THIS AFTERNOON AND EVENING. SOME OF THESE STORMS MAY BE ABLE TO PRODUCE DAMAGING WINDS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THE PROBABILITY FOR WIDESPREAD SEVERE WEATHER IS LOW. AK
In the hours before
Local storm report, Apr 10, 7:52 PM CDT, 1 hour 1 minute before
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</html>Local storm report, Apr 10, 8:46 PM CDT, 7 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREEN BAY WI
846 PM CDT SUN APR 10 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0846 PM TSTM WND GST 2 N DARBOY 44.26N 88.38W
04/10/2011 M60 MPH OUTAGAMIE WI AMATEUR RADIO
&&
THThe 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
1.9 hours before the tornado, 21 km from the path. April 11, 2011.
- Mixed-layer CAPE
- 1647 J/kg
- Mixed-layer CIN
- -38 J/kg
- Surface CAPE
- 1592 J/kg
- Mixed-layer LCL
- 1073 m above ground
- 0-6 km bulk shear
- 74 kt
- 0-1 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 399 m²/s²
- 0-3 km storm-relative helicity
- 397 m²/s²
- Significant tornado parameter
- 4.2
- Supercell composite
- 11.4
- 0-3 km lapse rate
- 5.5 K/km
The surface observations
Ashwaubenon (GRB), 21 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Green Bay radar (KGRB), 23 km away, was scanning. The volume nearest the touchdown began at 01:52 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.
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 April 10, 2011
15 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| April 10 | 4:57 PM CDT | EF1 | Eau Claire, WI | 1.6 | 200 | $200,000 | ||
| April 10 | 5:04 PM CDT | EF1 | Eau Claire, WI | 0.7 | 150 | $250,000 | ||
| April 10 | 6:08 PM CDT | EF3 | Marathon, WI | 21.1 | 1,050 | 2 | $11 million | |
| April 10 | 6:12 PM CDT | EF2 | Adams, WI | 17.1 | 800 | $3.3 million | ||
| April 10 | 6:14 PM CDT | EF1 | Juneau, WI | 4.4 | 150 | $30,000 | ||
| April 10 | 6:30 PM CDT | EF1 | Adams, WI | 11.7 | 140 | $601,000 | ||
| April 10 | 6:50 PM CDT | EF1 | Langlade, WI | 5.3 | 400 | $1.0 million | ||
| April 10 | 7:06 PM CDT | EF1 | Waushara, WI | 27.7 | 200 | |||
| April 10 | 7:30 PM CDT | EF2 | Forest, WI | 12.0 | 600 | $215,000 | ||
| April 10 | 7:53 PM CDT | EF1 | Waushara, WI | 14.9 | 150 | $1.5 million | ||
| April 10 | 8:03 PM CDT | EF1 | Forest, WI | 3.3 | 250 | $50,000 | ||
| April 10 | 8:27 PM CDT | EF0 | Green Lake, WI | 1.8 | 50 | $300 | ||
| April 10 | 8:43 PM CDT | EF2 | Outagamie, WI | 1.5 | 175 | $6.7 million | ||
| April 10 | 8:59 PM CDT | EF1 | Calumet, WI | 1.7 | 100 | $100,000 | ||
| April 10 | 10:55 PM CDT | EF0 | Webster, MO | 6.7 | 100 | $10,000 |
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.