More Storm Reports & Dry Days Ahead

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Thank you for stopping by the Weather Watch 12 Blog!  More information and storm reports were gathered on Saturday to help us get an even better picture of the damaging storms that hit the area on Friday evening.  This blog will focus on an update to those storms, and also breakdown what should be a very nice stretch of weather that begins on Sunday!

Let’s start by going over a few pieces of information from Friday’s storms that was not contained in the previous blog entry.

North Milwaukee/Whitefish Bay Heavy Rain

  • Between 10 p.m. and Midnight Friday, an isolated thunderstorm sat over parts of these areas and produced around 2.00″ of rain.  Areas that were devastated by the July 22 flood reported more water and sewage in basements.

Green Lake Microburst – Winds of 100 mph

  • A small, intense microburst hammered the northeast corner of the Green Lake shoreline (Green Lake County) about 5:40 pm on Friday, August 20, 2010, and then moved northeast for about 1.8 miles. 
  • Maximum wind speeds were an estimated 100 mph.  One shoreline home with a partially sheltered wind anemometer had a measured wind gust of 90 mph.

The National Weather Service conducted a damage survey in Green Lake on Saturday.  This was to determine if the damage was from a tornado or microburst.  Here is how the determination is made.  Below is a NEXRAD radar image from Green Bay at 5:40 p.m. Friday.  The dark blue is high winds that were all moving towad the radar site.     

The result of the 90-100 mph winds were numerous downed trees, and siding/roof damage to homes.  The picture below tells me many things.  Let’s look at it first…and then discuss.  The picture is from the NWS, just click to enlarge.

 The picture above tells me a few things.  First, the trees that we see are all laying in the same direction.  This is a good indication the wind was blowing in one direction.  Often tornadoes will scatter trees or they may be criss-crossed.  Second, the strength of the wind was incredible, this may have been due to the lack of friction once the air descended from the cloud.  Once it hit the water there were no trees, buildings, etc. to slow its momentum until it hit the land.

Third, combining the information from the picture with the radar image above helps to put the puzzle together that this was a microburst.  Obviously the survey crews put a lot of time into getting all the facts together before making a call as to whether or not the damage was the result of a tornado or microburst.  But this is the very simplified version of how you can tell the difference between a tornado and a microburst.

Brown County EF-1 Tornado

  • EF-1 tornado with winds estimated at 95 mph occurred near Greenleaf in southern Brown County.  Tornado touched down at 4:20 p.m. Friday.  Greenleaf is south of Green Bay. 
  • This is the 39th documented tornado of 2010 for the state of Wisconsin.  This is the 3rd highest tornado count for a single year in state history.


That is a quick recap of the new information that was gathered on Saturday.  If you have any questions or reports of your own please post them to the comments section of the blog.  Several of our bloggers shared their experiences with the storms in yesterday’s entry…check it out in the comments section!

Finally, some quiet weather back in the forecast for Sunday and Monday.  Both days will have a breeze off Lake Michigan, so that will mean cooler temperatures near the shore, and warmer inland.  I would say some areas near the lake will see highs in the upper 70s the next couple of days.  Also very welcomed will be a slight drop in dew points.

Below is a surface map for Sunday afternoon.  Notice the wind barbs showing a northeast wind. 

Along with the nice breeze there will be lots of sunshine!  The next chance of a shower or t-storm will hold off until later Tuesday.  Until then, make sure to watch WISN 12 News for the latest updates!

Have a great weekend!

Jeremy Nelson


2 Responses

  1. Nice recap.

    First – that velocity scan is a mess. It is hard to tell what is what.

    Second – the velocity scan at that distance likely is about 2-3K into the clouds. Hard to tell what was at the ground. I learned that the hard way this last weekend down here. The NWS site radar was showing about 5okt winds at about 1500 feet. Switching to TDWR, it showed nearly 100 mph at about 2oo ft.

    Three – good explanation of the damage survey. Often with winds that high, much of the observational queues can point to either, but the damage indicators do indeed point to straight line winds.

  2. I think that up here in NE Dodge County (Lomira) we experienced one of those microburss as well. I lost siding and fascia trim off of my house. I spent a good portion of Saturday picking up limbs and tree branches. The neighbor’s soybean field was flattened. The wind was horrendous for about 5-7 minutes. I actually thought it was a tornado at first because of the “freight train” sound. I know now it wasn’t a tornado.

    When the garage door started bowing inward I headed to the basement. I’m not sure how strong the wind was here but there were some trees down in the area and siding was blown off the houses.

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