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DULUTH – On Thursday's 47th anniversary of the sinking of the Edmund Fitzgerald, the waves were nearly twice as tall as the pier they toppled over behind Glensheen Mansion, which sits on the shore of Lake Superior.

A boathouse door was damaged, according to the museum's keepers, and in places there was a shift in the shape of the beach — the wear tied to the gales of November, an unofficial season in these parts made famous by Gordon Lightfoot's song "Wreck of the Edmund Fitzgerald."

A gale is a sustained wind or frequent gusts between 39 and 54 mph and its born of a difference in temperature between air masses from the north meeting air masses from the south. The wave height, according to Linda Engebretson at the National Weather Service in Duluth, is determined by how long the wind has been over the water.

"The reason we get big waves when it's out of the northeast is because it runs all the way from the northern sections of Lake Superior, all the way to the southwest arm," she said. "That long fetch distance makes for a long distance to push up waves.

"They're pretty frequent in November," said added. "We get them in October around here, too, but everyone wants to talk about the gales of November."

Massive waves crashed on the shoreline by the Split Rock Lighthouse in Two Harbors in 2019.
Massive waves crashed on the shoreline by the Split Rock Lighthouse in Two Harbors in 2019.

Alex Kormann, Star Tribune

The Edmund Fitzgerald, a freighter that sank in 1975, isn't the only ship to succumb to the phenomenon. Of the 600 shipwrecks on Lake Superior, about half have occurred at this time of the year, according to Sean Ley at the Great Lakes Shipwreck Museum in Michigan's Upper Peninsula.

Shippers "want to make those last trips when the water is warm," Ley said. "If they can avoid the storms, they're OK. They can't always avoid the storms."

Glensheen Mansion has a staff of weather hobbyists — some with office windows that offer a view of the wildest days on Lake Superior. Mike Mayou, marketing director, posted live to social media on Thursday from the roof of the estate's boathouse. He stood next to the weather station and a lake camera during a 6-minute clip — his voice distorted by the fuzz of wind against his microphone.

The weather station recorded consistent winds between 30 to 35 mph, with gusts up to 50 mph.

"It was crazy," Mayou said.

Friday was calmer along Duluth's shoreline, but Engebretson said there would likely be strong wind and waves again on Saturday. The best viewing would be along the shore in Bayfield, Wis., and into the Upper Peninsula. She advised lake watchers to be careful — the waves can sweep a person right off a structure.