Image from Twin Cities NWS

A strong low pressure system produced widespread 45 to 50MPH winds which caused minor tree damage in what ended out to be a pretty significant wind event. A strong, tight low pressure over Michigan brought these very strong winds to much of the Upper Midwest. The low in this image was center near Duluth,MN, the NWS says the purple and blue colors indicated stronger low pressure and stronger winds. The strongest winds appeared to be on the southern and western side, as well as the Northeastern side of the low.
Strong winds on front yard tree September 29th 2011

For the local area, the winds started out in the morning hours, but really got very strong around 1PM in the afternoon, which is also when showers started to develop, by the 1pm hour, gusts were well over 45MPH on multiple stations across the area. One very strong gust in particular measured 56MPH from Rochester. Widespread minor damage in forms of breaking tree limbs and blown around objects occurred area wide, The good news is there was no significant damage reported. The winds were highest across Southern and western parts of the local area, in places like Rochester, Dodge Center, Austin and Preston which was more on the edge of the shower activity.

Effects from Rochester

Strong wind video from Front yard.

The NWS had wind advisories and warnings for many states across the region in preparation for this event, Much of Minnesota, all of Wisconsin and Michigan, and some of Illinois were included in these advisories or warnings, so naturally it was known there was going to be alot of wind. The winds was pretty gusty early, but it was when class was over around 1pm that the winds really picked up. During my drive home drive home winds were howling across the city, I witnessed one impressive gust of wind which sent a shower of small dead branches and leaves at the street and my car, none were of concerning size to cause damage.

2 inch Ash branch along 4th Downtown Rochester

The city will have alot of branches to clean up this weekend, especially from ash tree species, which really took beating in these winds, I seen multiple branches from ash down across the city, Trees that were especially hard hit were right along 4th street in Downtown, one block between stoplights had 5 branches of the size above laying in the boulevard. Not only was there ,many branches but there were lots of of leaves piled 3 feet deep in some of the alleys between high rise buildings!

Tree branch laying on boulevard along 4th street SW

Large 4 inch diameter ash branch snapped

This was the largest of the branches I found in Downtown, it was large enough that it made an indentation in the grass where it fell. My thinking on why the Downtown trees were some of the hardest hit is because the wind blowing between the high rise buildings, acted like wind tunnels that were aimed right at these trees.
Very large 10 inch diameter tree top snapped St Marys Park-West Downtown

This was the largest branch I found that broke off the top of a tree in St Marys Park in West Downtown. This damage occurred again from the Ash tree species. There was a large hole in the ground where the base of the branch struck the ground.

Damage from my neighborhood.

This was a fair sized Maple branch that broke off and landed in the sidewalk on my street, just up the hill slightly. These types of trees are stronger and do not typically loose branches as easily, which really showed how strong the winds were.

Damage from our yard September 29th 2011

I spent much of the time when the winds were strongest at home. They were probably some of the strongest I’ve seen, it reminded me of the October 2010 storm system in Wisconsin accept the winds were not as sustained. Some effects I saw was the tree in the front seemed to sway surprisingly vigorous back in forth, I was surprised in how flexible that tree is. At one point, I also watched as a huge box and pieces trash blow like tumbleweeds across the industrial lot west our house, the garbage then scattered into my neighborhood. it was quite an interesting experience to see, but not so much to clean up after! There was also lots of leaves flying through the air constantly all day long. There was some minor damage around the yard which included the 2 inch Silver Maple branch above, there was also lots dead branches varying in size from pretty large to small, I spent much of the afternoon Saturday picking up these branches. Wind reports from the closest wind gauge to our neighborhood said winds were 56MPH, this was from St Marys hospital 2 blocks from the house, but this gauge is located on top of the hospital where it is high above the tree line, free of obstacles. Closer to the ground around my neighborhood it was probably closer to 45MPH. The Rochester International Airport 7 miles to my south recorded a 48MPH gust!

Highest wind gusts reported.

Wind gusts were over 45MPH at most stations, The highest wind gust area wide was from a station 2 miles Southwest of Downtown Rochester a very strong 56MPH and the least windiest conditions were found in Northeastern areas.