Major Severe Weather Outbreak
June 21, 2010

Click here for Tornado Pictures

Summary, 5 Tornadoes, 1 downburst:

EF2 Tornado (Enhanced Fujita Scale) in the Eagle area of Waukesha County, 30 miles west southwest of downtown Milwaukee.  The EF2 scale runs from 111-135 mph, this tornado is rated at 125-130 mph, which is on the high end of the EF2 scale.  

  • Tornado path was about 4.8 miles in length 
  • Max width 1/2 mile
  • 125-130 MPH winds
  • Started at 911 PM - 1.6 miles WSW of Eagle
  • Ended at 918-919 PM - 1.4 NE of Eagleville
  • Waukesha Sheriff reported about 5 homes heavily damaged. 75 to 100 homes damaged. 

EF1 Tornado (Enhanced Fujita Scale) in the Big Bend Muskego area, Waukesha county, 17 miles southwest of downtown Milwaukee.

  • Tornado path was about 6 miles in length
  • Max width 200 yards, mostly 100 yards
  • 105 MPH winds
  • Started at intersection of I-43 and Highway 164
  • Ended at intersection of Woods Rd and Durham Rd. 
  • Mostly major tree damage and shingle damage to structures. 

EF1 Tornado in Cross Plains, Dane County, 13 miles west of the State Capitol, Madison. 

  • Tornado was about 0.3 miles in length
  • Max width 40 yards wide
  • 90 MPH winds
  • Began between Julius St. and Sylvia Pine Way.
  • Ended at Caesar St. and Woodside Dr. 
  • Major tree damage.  Shingle damage to some homes.

EF1 Tornado in Busseyville, southwest Jefferson county, 55 miles west of downtown Milwaukee

  • Tornado was about 1 mile in length
  • Max width 50-100 yards
  • 90-100 MPH winds
  • Began near Bussey Rd and Hwy 106 at 815 PM
  • Ended at the intersection of Hwy 106 and Carcajou Rd

EF1 Tornado in central Lafayette county, about 55 miles southwest of the State Capitol, Madison

  • Tornado was about 3 Miles in length
  • Max width 25 to 75 yards
  • 90-95 MPH winds
  • Began 4.5 miles SE of Darlington, just southwest of the intersection of Walnut Rd. and Pecatonica Rd at 739 PM
  • It lifted 2 miles WNW of Wiota, just north of Walnut Rd, 1/2 mile east of Tish Rd at 745 PM
  • On the ground for 1 mile, lifted then several brief touchdowns for the next 2 miles

Downburst with straightline winds of 70 to 90 mph running from Genesee Depot to Big Bend, Waukesha county, about 20 miles southwest of downtown Milwaukee. 

  • About 11 miles in length
  • Roughly 1 mile wide
  • 70 to 90 MPH winds
  • Began in the vicinity of Genesee Depot
  • Ended in the vicinity of Big Bend
  • Major tree damage. 

National Weather Service Milwaukee/Sullivan staffing during the event:  7 Meteorologists with a combined 124 years of experience.
Normal staffing during an evening shift:  2 Meteorologists.


Wiota Tornado Location Cross Plains Tornado Location Busseyville Tornado Location Eagle Tornado Location Muskego Tornado Location

 Here is a link to the latest storm reports and a graphic storm report map:

Storm Report Summary

Storm report map 

 Thunderstorms developed across much of south central and southeast Wisconsin during the evening of June 21, 2010. There was a convergence of favorable severe weather parameters very late in the afternoon and early in the evening. The most significant feature was a vigorous upper level disturbance, or short wave in meteorology speak, that helped to support deep vertical motions in the atmosphere. This acted on a warm and very moist atmosphere that contained high amounts of wind shear. This resulted in powerful thunderstorms that contained lots of rotation. The rotation makes storms very intense, often leading to damaging straight line winds, large hail, and in this case 5 tornadoes.

Below are animations of these severe weather parameters with the accompanying radar imagery from the evening.  Click images to retrieve the animation. 

Visible satellite image
Visible Satellite Image
500 mb heights and vorticity
500mb Height/Vorticity
0-6km wind shear
0-6km Wind Shear
mixed layer cape
Mixed Layer Cape
supercell composite
Supercell Composite Index
significant tornado
Significant Tornado Index

Radar Imagery:

This animation is a combination of Storm Relative Velocity and Reflectivity at the time of the Eagle tornado, around 911 PM. The storm relative velocity clearly shows the rotation. Red colors indicate movement away from the radar, green is toward the radar.  In this case, the radar indicated winds of 88 mph moving away from the radar, right next to winds of 64 mph moving toward the radar.  When they are right next to each other, this is serious spin.  The reflectivity shows a distinct Debris Ball.  These occur when debris from the damage gets ingested into the storm.   

radar image of eagle tornado

The image below shows the strength of the Downburst that moved from the Genesee Depot area, southeast toward Big Bend and Muskego. 

radar image of downburst

This loop of radar reflectivity covers the period from 704 PM through 1011 PM.  Click image for the animation. 

radar loop



 Eagle Tornado:

A mesonet reporting station located near the path of the tornado was able to depict the approach and departure of the tornado in the barometric pressure reading, as seen in the image below. Note the steep drop in pressure right after 9 pm, followed quickly with a sharp increase. The report is courtesy of P. Jensen, who operates this reporting station for the Eagle Springs Lake Management District. The station is situated on the east side of Eagle Springs Lake, approximately 2.5 miles southeast of the town of Eagle, and about 1.5 miles directly south of the tornado path. 

Below is a photograph of the tree damage at Old World Wisconsin taken by Mark Was, with John Malan in company. If you look close enough you'll see how the trees were pushed over by the tornado as it moved along with cyclonic, converging winds.  We've added red lines that are parallel to the direction that the trees were pushed over.  Note that we see a convergence of tree debris toward the center of the tornado as it moved along the thick red arrow line toward the residental section of Eagle.  We can't quite tell which directions the trees are pushed over in the top of the image, but the tornado moved through the forested area at the top of the photograph. Obviouisly the tornado quickly intensified when it reached Old World Wisconsin.

       Old World Red Arrows

 Eagle Damage Eagle Tornado Eagle Tornado

Above aerial photos courtesy of Sharon and Rick Martin

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Above Images Courtesy of Craig Koplein - TMJ4    

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Eagle Damage    
Above Images Courtesy of Jerad Albracht - WI Emergency Management    

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Big Bend/Muskego Area
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Cross Plains

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Cross Plains    


 Wiota tornado  Wiota tornado  Wiota tornado
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Looking northeast from just north of the intersection of Ames Road and Salty Hollow Road in Lafayette County, about the time the tornado caused its initial damage at 739 pm CDT. Tornado located about 3 miles to the northeast. Above Photos Courtesy of Brenda Whalen  
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 Wiota Damage    

 Below is a lightning photograph taken by Heather Lindert near intersection of Highways 14 and 51 in Janesville in the evening of June 21st.  Sort of close, isn't it?  

Lightning near Janesville is the U.S. government's official web portal to all federal, state and local government web resources and services.