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July 7, 1991 Southern Wisconsin Derecho

Jul 07, 2010
This blog will fully detail my memorable experience with the July 7, 1991 squall line/derecho that plowed through much of Southern Wisconsin. Not only was this storm unique with its structure, but produced many uprooted trees, downed power lines across a wide area and destroyed a popular city landmark.

I was 11 years old at the time watching a baseball tournament at Banting Elementary School with my parents in Waukesha. The morning started off hot and humid with not a single cloud in the sky. Soon around the early afternoon, the skies started to become gray with anvil clouds streaming from the west. I remember sitting watching the game when someone shouted in the stands that the National Severe Storms Forecast Center issued a Severe Thunderstorm Watch for all of Southern Wisconsin. As the game was wrapping up the final outcome, it started to rain with some cloud to ground lightning to the west. I knew there was a storm coming, but it didn't look to ominous as it was approaching.

Storm Structure

I remember vividly my parents driving through the south side of Waukesha to get home. The leading edge of the storm had a light gray color with moderate rain and some lightning that occurred for 5 to 10 minutes. In general, the storm structure wasn't threatening at all. That all changed as we drove further west as the sky had a darker appearance of gray with a bright white area following behind. Interestingly, there was no monster shelf cloud racing out ahead of the storm or anything really threatening. The dark gray clouds got closer and the trees in the distance were swaying violently signaling strong winds. We soon were overtaken as I became frightened sitting in the back seat. Damage was occurring everywhere from small branches to large trees snapping and being blown over as we took refuge at a gas station until the storm passed.


The storm moved on to the east quickly and we proceeded to go home. We found many trees damaged with the loss of power at stop lights and commercial stores. We discovered our house had the front door wide open and the attic panel located on the upstairs ceiling was half way open. Our patio table shattered glass everywhere and our umbrella was nowhere to be found. Due to the loss of power, we stayed at the Country Springs Hotel for the night.

The storms originated in eastern South Dakota and made the journey through, Iowa, Wisconsin, Michigan, Ohio, New York and died out in Pennsylvania. This storm system would be classified as a derecho (long-lived wind storm).

Dun Bar Oak Tree - Waukesha, Wisconsin

This storm also caused havoc to the famous Dun Bar Oak Tree located in Waukesha, Wisconsin. Story has it; Richard Dunbar was cured by drinking water at a spring at Bethesda Park. His diabetes and kidney ailments were cured when drinking the water from the spring sitting underneath the oak tree.

Unfortunately the July 7, 1991 derecho damaged the oak tree severely. Even though it wasn't uprooted like many others, it had been badly damaged and the city had no choice but to cut it down. Today there is a landmark with the tree stump showing where the tree once existed. It had a good life, living to be nearly 300 years old.

July 7, 1991 Derecho Resources:

Storm Prediction Center July 7, 1991 Discussion

Wikipedia Discussion

Milwaukee Sentinel Newspaper - July 7, 1991 Derecho

Milwaukee Journal Newspaper - July 7, 1991 Derecho


Sam Raisor
Dec 12, 2010 - 3:06 pm
I was fourteen years old at the time. I already had a profound interest in meteorology, thanks to the May 31, 1985 tornado outbreak.

I remember that Sunday in '91 vividly, here in Beaver County, Pennsylvania. That was the third consecutive day of severe weather here in Western Pennsylvania. We were under three separate Severe Thunderstorm Watches throughout that day. The first Watch went until 5 PM, and then another Watch until midnight, but that Watch was cancelled around 9 PM that evening.

This is where the derecho comes into the picture. A Tornado Watch was issued for Eastern Ohio til 3 AM, and a Severe Thunderstorm Watch was issued for Western Pennsylvania til 5 AM. Around 10 PM that evening, I started seeing very strange-looking lightning in the northwestern part of the sky, in the direction of where the storms were coming from. The lightning was like flashbulbs going on and off nonstop. A tiny little bolt of lightning was spit out from the top of the cloud and shot across the sky. It looked like something out of a video game. To this day, I have never seen lightning like I have that night. The storms arrived here right before midnight. The strong winds came in at the onset of the storms, in the 50-60 MPH range, but after a few minutes, the lightning became the major issue. Very frequent, intense lightning and booming thunder. A huge lightning bolt struck down my neighbor's big tree right across the street. The very intense lightning and thunder continued for a couple of hours, before gradually easing up, but the thunder and lightning never completely went away that night, as it continued in a much more gentle pattern during the entire overnight, up until another storm came in right around 5 AM, and the lightning was intense enough to briefly knock out the power. The sky completely cleared up later that morning, and we had a beautiful, sunny day with lower humidity and much more comfortable conditions. The previous night's storms were the main topic of conversation for everyone around here. I did see trees down in places when I was out and about that Monday afternoon.

Hard to believe it's been over nineteen years already. In closing, that was indeed quite a storm.