Today is the 24th anniversary of the famous “derecho” thunderstorm outbreak of 1998. A derecho (Spanish for “straight”) is a fast-moving line of severe thunderstorms that produces a wide and long swath of significant wind damage.  Around 5 AM that Sunday morning, the storms blasted through West Michigan with winds estimated as high as 130 mph in Grand Haven, Spring Lake and Walker. According to the Storm Prediction Center, this episode ranks as one of the top thunderstorm events in world history!

From the Storm Prediction Center: “The leading edge of the derecho reached the eastern shores of Lake Michigan around 4:45 a.m. EDT Sunday and blasted across Lower Michigan at a speed of about 70 mph. It reached the “Thumb” area in a little over 2 hours (Figure 1). Winds of 60 to 90 mph were common; in some areas, winds were estimated to have reached 130 mph. Of all the regions affected by the derecho, the greatest damage and the greatest number of casualties occurred in Lower Michigan. In this region four people were killed and 146 were injured. Total damage was estimated to be $172 million (1998 U.S. dollars). Approximately 250 homes and 34 businesses were totally destroyed, and over 12,000 homes and 800 businesses were damaged. About 860,000 customers lost electrical power. This was a new historical record, slightly exceeding the number of customers that lost power during the Southern Great Lakes Derecho of 1991. In some locations power was not restored for up to 10 days. For Consumers Energy, the utility company that serves much of western and middle Lower Michigan, this derecho was the most destructive weather event in the company’s history. Besides the loss of hundreds of power poles and lines, five of the company’s 345-kilovolt transmission towers were blown down between Ludington and Grand Rapids. These massive towers were designed to withstand continuous winds up to 90 mph and gusts to 110 mph.”

A large area of significant wind damage occurred from South Dakota all the way to the East Coast. At one point, not a single stoplight was working between Grand Rapids and Baldwin. The toll would have been much higher if the storms came in the afternoon instead of in the early morning when most people were asleep in their homes.

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The supercells eventually formed the line that raced from eastern S.D. to Massachusetts and out into the Atlantic Ocean. Twenty years later you could still identify swaths where most of the trees were blown over (White Lake exit on US 31 – the Spring Lake Cemetery). Here’s a radar loop from S. Dakota to Michigan. Read more here, here, and here. Storm Reports here (pages 2 – 8). The 1998 storm was a “once in a lifetime event”. The storm line formed in S. Dakota and the line went 400 miles out into the Atlantic Ocean before the storms dissipated.

I went out to visit Spencer, S.D. where the worst tornado occurred as the supercells first formed. That small town was pretty much wiped out. Only two blocks in the entire town were spared significant tornado damage. The tornado was an EF4 and was the most destructive tornado in the history of the state. The tornado occurred at sunset and afterward it was soon dark. It was mid-morning before some of the victims were found. A portable Doppler radar indicated winds of 220 mph with that tornado. In a town of 315, there were six fatalities and nearly half the town residents who where there that night were injured. The population of the town dropped to 145 after the tornado.

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Wind damage reports from May 31, 1998

Area of Lower Michigan affected by the worst damage from the May 31, 1998 derecho. Red numbers are maximum measured wind gusts in mph. Orange/tan numbers are estimated maximum gusts in mph, based on a damage survey by Grand Rapids NWS Forecast Office meteorologists. Thirteen Michigan counties (noted in black lettering and within light blue border) together were declared a Federal Disaster Area by the Federal Emergency Managers Association. The purple “S” represents where a “seiche” took place on the eastern shore of Lake Michigan.

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Radar of the derecho crossing Lower Michigan

I talked with Robert Johns, who was a lead forecaster at the Storm Prediction Center. He said they issued Tornado Watches instead of Severe Thunderstorm Watches for Wisconsin and Michigan, anticipating tornado-like damage from the derecho.

Actual record wind gusts in red – estimated in tan.

The numbers on this map are wind gusts from the storm…in red those were measured gusts, in tan, they were estimated wind gust speeds. I would be surprised if we saw an event of that intensity (130 mph wind gusts in Grand Haven and Walker) and widespread area again in my lifetime. Here’s pictures from Grand Haven after the storm.

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Damage to condominiums in Spring Lake
Frequency of Derechoes in the United Sates

Here’s a summary of fatalities and injuries from the Iowa derecho of August 10, 2020. This does not include injuries that occurred after the event (there are sometimes more injuries after a derecho than during the storm).

A final note…. In 1998, there were four major derechos across the Great Lakes states…this one was the worst. Storm Team 8 will be tracking storms this summer. We’ve had a pretty quiet spring for severe weather in West Michigan so far. Let’s hope that continues.