May 28 2012 Severe Weather Summary for Southcentral and Southeast Wisconsin (Updated 6/1)

What - severe thunderstorms.

Impact - scattered reports of damaging, straight-line winds of 60 to 75 mph, large hail up to golfball size (1.75 inches), one gustnado and brief periods of heavy rains that led to minor urban-street ponding of water.

There were many reports of large tree branches snapped, or large trees uprooted.  Probably at least a couple dozen homes sustained shingle or siding of soffet damage, several cars damaged or totaled by fallen trees, roof shingles off a barn roof, one tree on a car, and pushed-over fencing.  Scattered power outages were noted as branches or trees fell on power-lines.  Some roads were blocked by tree debris.  Some windows in buildings in or near Wisconsin Dells were broken by the large hail.

When - 344 pm to 730 pm CDT - time span of all storms.

Where - southcentral and southeast Wiscosnin.  Counties affteced include Marquette, Green Lake, Sauk, Columbia, Washington, Ozaukee, Dane, Waukesha, Milwaukee, Green, and Rock.  All other counties in southcentral and southeast Wisconsin experienced sub-severe thunderstorms with gusty winds and brief heavy rains.

Why - a cold front with a band of thunderstorms rolled west to east across the area.

Below are three graphics showing the progression of line of thunderstorms during the time period of 606 pm CDt to 701 pm CDT.

radar 606 pm   radar 629 pm  radar 701 pm


Gustnado Event

Where - about 3/8 mile east of Lake Five on the border of Waukesha and Washington counties.

When - 637 pm CDT.

Impact - dirt/dust picked up along with some tree branches.  Knocked down a 28-foot section of a fence and some soffit damage to a home.

Discussion - many people saw this event.  A fire-fighter (a trained severe weather spotter) saw the gustnado form over a farm field southwest of the intersection of STH 164 and Q in extreme north-central Waukesha County.  It left a "burn-mark" where it picked up dirt from the field.  It traveled east-northeast  and knocked down a 28-foot section of a fence, damaged a home's soffit, overturned an empty, above-ground swimming pool, and knocked some branches out of trees.  Within its shallow circulation, which only extended upward about a couple hundred feet, dirt and some tree branches were rotating.

Skip Voros, President of the Milwaukee Area Skywarn Association (MASA), and an advanced severe weather spotter, conducted a damage survey early Tuesday afternoon, May 29th, on behalf of the National Weather Service.  He confirmed other eyewitness reports of a "burn-mark" in the farm field where the gustnado initially developed, and confirmedfencing and soffit damage to a residential home.

Below, in the image Skip Voros annotated the locations of damage as well as the gustnado "burn-mark" location.  Click on image for larger version

  MASA graphic

Below are a couple damage pictures taken by Tom Edwards who lives in the southeast quadrant of the intersection of STH 164 & CTH Q.  His property sustained damage to his home's soffit and fencing, and his pool was flipped over.

fence down  soffit down

Additional Gustnado Information - type in the word "gustnado" in your favorite search engine to obtain numerous on-line web pages/sites that have gusnado information.


Wind Damage & Large Hail Reports

Below is a graphic showing locations of large hail reports (green numbers) and wind gust values (blue numbers).  Click on image for a  larger size.  The "W" represents locations of wind damage.  The green arrows show probable locations (swath) of large hail stones.  If you live under or near one of the green arrows, feel free to e-mail your report to us with your estimate on hail size (diameter in inches, or use an object like nickels, ping-pong balls, golf balls, baseballs, softballs, CDs).  Send your reports to rusty.kapela@noaa.gov

reprot plot

To view a text product with specific severe weather reports, click here

Below is a brief listing of damage reports from Wisconsin Emergency Management.

Marquette County: Monday's storms caused some downed trees and minor roof damage in the Briggsville area.  Hams reported golf ball size hail in Briggsville. 

Columbia County: Columbia County officials report about $12,000 in damage and debris removal mainly in the Wisconsin Dells area following Monday's severe storms. 

Dane County: Dane County reported some minor street flooding that occurred on Monday as well as some minor structural fires caused by lightning. 

Green County: Strong storms caused numerous down trees. In the Juda area, strong winds and storm debris damaged a home and two barns (see pictures below). In New Glarus, downed trees also brought down some electrical lines. Officials say power has been restored. Minor storm damage was also reported in Brodhead. Some homes between Belleville and Dayton had rooftop shingle damage.

Below are a couple pictures of damage to the Burke property about 3.5 miles southwest of Brodhead near the intersection of STH 11/81 and CTH G. They experienced an intense microburst. Two barns/sheds were damaged, some siding was removed, several windows were broken by wind-driven debris, a toilet seat in a bathroom was ripped off, a pool cover was removed and a door was blown in.  Once the wind was able to penetrate the house through broken windows, funky minor damage occurred inside the house.  Click on images for larger version.

Barn damage  house damage

Rock County: Hail and heavy winds were reported in the Evansville area. Officials say lightning caused a fire at a senior center in Edgerton that displaced 40 people. No one was injured and the Red Cross and the Southern Wisconsin Emergency Preparedness Team provided assistance.  

 

Below is a picture of damage to an apartmente building after lightning ignited a fire.  The building is in the northeast part of Edgerton.  Dan Starker, a MidWest SSTRC severe weather spotter, took the picture.

Edgerton Ltg Damage

Ozaukee County: Cedarburg was hit yesterday afternoon with hail and strong winds that downed trees and power lines. Some streets were closed until public works could remove debris.

Washington County: South of Highway 60 received the brunt of the storm on Monday with downed trees and power lines. A few small fires were started from the downed lines but were quickly extinguished. 

Waukesha County: Strong winds of over 65 mph were reported at the town of Lisbon yesterday. Officials originally thought it was a weak tornado but have confirmed it as a gustnado, which is a short-lived, low level rotating cloud. Damage reported was minimal. 

Kapela, WFO Milwaukee



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