The map above shows the path of the Southern Great Lakes Derecho of July 1991. The red numbers represent measured wind gusts during the storm. Derecho is a Spanish word meaning “straight”. A derecho is a line of intense, fast-moving thunderstorms that moves across a significant area (over 400 miles) and is characterized by widespread damaging winds.
This derecho began in S. Dakota in the early morning of Sunday, July 7, 1991. The line quickly began producing damaging wind. A gust to 103 mph was measured at the airport at Sioux Center, Iowa. A roof was blown off a school in the town of Orange City – less than 10 miles southeast of Sioux Center. As the line of storms moved across Iowa, thousands of acres of corn and soybeans were flattened. There was an estimated loss of 60 million dollars (in 1991 dollars) just to the corn and soybean crops. Many farm buildings were destroyed. A woman was killed at McIntosh Woods State Park, when a tree fell on the van she had taken shelter in. A gust of 71 mph was recorded at the Mason City IA airport.
In Wisconsin, Madison had a gust to 83 mph and the National Weather Service at Sullivan (west of Milwaukee) had a gust to 81 mph. At the Madison Airport, 20 buildings and hangers were damaged or destroyed. Planes were flipped over. In Madison alone, 60,000 customers lost power and damage topped 7 million dollars. West of Milwaukee, the Waukesha Airport had a gust to 81 mph and a historic 300-year old Dunbar Oak Tree was toppled. Two planes were destroyed at the airport and the hangers were damaged. Between Madison and Milwaukee 30 farm buildings were destroyed and 250 had significant damage. There were 4 injuries. Damage in Wisconsin topped 20 million dollars (in 1991 dollars).
Sunday was my day off and I went to Hoffmaster State Park with my 3 girls. I had Saturday off, too…no cell phones, no computers to check the weather from home or the beach. I saw the sky turning gray to the west and decided to head home. Dave Whitford was working that Sunday at the station and he told me later that the storm accelerated and was moving at least 70 mph as it crossed Lake Michigan and headed into the lakeshore counties. From 1974-1995, the U.S. had a national speed limit of 55 mph (thanks to the oil “crisis” in 1973). So, the derecho is catching up to me as I drive home. The girls were only mildly disappointed that we couldn’t make our usual stop at the Whippy Dip or to play at Pamona Park in Fruitport (side note: Fruitport was hit by 85 mph winds on Aug. 9, 2009 when the WSW wind from the storm funneled up Spring Lake).
When I got to my street the storm was just coming in. I decided not to turn into my driveway. We have power lines across the front…at the time there were several trees and I didn’t want to open my garage door (which faced west). So, I turned into the dirt road going into the orchard across the street and positioned the car facing west behind the trees…so the trees couldn’t fall on the car, but would still provide a wind break. The wind hit very suddenly. If you waited for the strong wind to make a move, you were too late. I had the girls crouch down – lower center of gravity. The trees were dancing like they were possessed. I looked behind me and saw my neighbor’s tree go down. Shingles were flapping – I would up losing about 20 shingles. The power was out but the wires at our house held and my front trees had only medium-sized branches down.
A total of 853,000 customers lost power across Michigan, the most that had ever lost power up to that time. It was more than a week before power was restored. The peak wind gust in G.R. was 84 mph, Belding had 85 mph. The next day I went to tour damaged areas. We estimated the fastest wind was on Scott Road in western Ionia County, were gusts were likely in excess of 100 mph (perhaps as high as 120 mph). On the south side of the street, there was a mobile home that was intact and unmoved. The owner had done an awesome job with tie-downs…securing the home to a concrete base with steel rods. His unattached garage was destroyed and heavy objects from the garage (weed-wacker) were moved a considerable distance to the east. Across the street was a permanent home, which had significant damage. There was considerable damage to trees, power lines and other buildings along Scott Road. In Kent and Ionia Counties, two homes were completely destroyed, another 250 were significantly damaged. Nearly 50 barns were destroyed or severely damaged. Many fruit growers lost half or more of their crop.
A semi-trailer truck was blown over on I-69 near Marshall. Ten mobile homes were blown over in New Lathrop. One of the homes rolled into a nearby lake. In Durand, numerous camper trailers were blown over and one person was injured. Wind gusts ranged from 75-85 mph in Ann Arbor, Pontiac and Detroit. Thousands of trees were toppled in SE Michigan. The roof was blown off an elementary school in Swartz Creek. Two apartment building in Flint had their roofs taken off. Many cars were damaged by falling trees.
The storm continued into Ontario and the Lake Erie region, where roofs were taken off and thousands of trees and wires were toppled. The hardest hit areas in Ontario were the towns of Harrow, Chatham and Ridgetown. Kent County Michigan and Kent County Ontario were both among the hardest hit areas. The storms continued to produce severe winds and damage into Western Pennsylvania and New York.
The storms were severe for 17 continuous hours across 1,000 miles. The storm line caused at least 125 million dollars in damage (1991 dollars). One person was killed and a dozen others were transported with injuries. Over 1 million homes lost power.
In Grand Rapids the high/low temperature that day was 91°/66° – so it got hot before the storm hit. The high on Saturday, the day before was 93°. The AVERAGE wind speed that day in G.R. was just 7.5 mph – so it was a relatively calm day, except for the 10 minutes (of terror) as the storm hit. Grand Rapids got 0.46″ of rain. The storm was moving so fast, it didn’t have time to drop a large quantity of rain in any one spot. There was 73% sunshine that day…so outside of the storm, it was a sunny and rather calm day.
This is another storm that was very well warned by the National Weather Service. There was a timely watch and warnings were out as the storm move across Lake Michigan. The vast majority of people were aware of the warnings and took appropriate action, saving lives, I’m sure.