Strong northeast winds and giant waves battered Lake Superior’s north and south shores Wednesday, strewing rocks and debris, flooding low-lying areas and forcing officials to close roads and beaches.

Winds frequently gusted near 50 miles an hour or more near Duluth and some waves measured 20 feet, according to the National Weather Service. A Canadian freighter measured an 86 mph wind gust off the shore near Castle Danger about 12:30 a.m.

Duluth, sitting at the westernmost point of the lake, was believed to have taken the biggest brunt of the waves. Standing water forced the city to close much of Canal Park, the popular tourism area near the iconic lift bridge. Only residents of Park Point and those with business in the area were allowed past Buchanan Street, police said. Officials warned of rocks and debris on flooded streets and the popular Lakewalk.

Harbor Drive behind the Duluth Entertainment Convention Center was also deemed inaccessible, and the city closed Brighton Beach farther up the shore.

But flooding and damage extended up the North Shore and into Wisconsin, too. Roads were closed in Ashland County, Wis. In Minnesota’s Cook County, near the Canadian border, officials closed County Road 69 in Hovland because of flooding. In downtown Grand Marais, waves crashed into the parking lots at Artists’ Point, carrying rocks with them, according to Mayor Jay Arrowsmith DeCoux.

In Duluth, the strong winds pushed the lake level up about 10 inches.

Strong storms are not unusual on the lake in the fall season, weather service meteorologist Greg Frosig said.

“It’s just that it’s a long-lasting one,” he said. “It’s been affecting us for a couple of days.”

Assessing damage

The storm, which started early Monday, was expected to clear by Thursday morning.

City officials in Duluth said in an afternoon briefing that they likely wouldn’t be able to start assessing damage until then. The storm came just as workers were beginning to rebuild a portion of the Lakewalk after a storm last year inflicted millions of dollars in damage.

A city official said a Lakewalk inspection Wednesday morning near the Fitger’s Complex revealed new damage including land erosion, caved-in asphalt and flipped boardwalk panels.

Authorities asked wave watchers to stay away from the flooded areas.

“Yes, it is an interesting thing to see the power of Lake Superior,” said Keith Hamre, acting chief administrative officer for the city. “But ... we need to be respectful of that power of Lake Superior. It can be very deadly very quickly.”

Instead, officials suggested sightseers stay cozy and watch waves on one of many webcams set up along the lake.

Owners and employees of Vikre Distillery, near the foot of the lift bridge, decided to leave around noon on Wednesday, feeling it might not be safe to stick around their business. Water had flooded the street in front of the distillery and was coming into the small bar area on the ground floor, co-owner Joel Vikre said. Most of the business is up a few steps, however, so Vikre said he was hopeful the damage would be minimal.

“I’m sure there will be some things that need to be fixed and obviously cleaned up,” Vikre said. Cement floors in the business would make things easier, he added. “This is where being rustic comes to your advantage.”

The storm brought an unusual gift for Park Point resident Paul Kellner and his family.

A blue canoe that disappeared last year — one they assumed had been stolen — reappeared after waves battered sand dunes on their property.

“That is just the weirdest,” Kellner said, explaining that a storm must have buried it last year. “The lake taketh and then the lake giveth back, I guess.”

As if the wind and water weren’t enough, northern Minnesota residents were bracing for an early dose of winter Thursday.

One to 6 inches of snow is expected to fall in northern Minnesota, with heaviest amounts north and west of the Iron Range, according to the National Weather Service. Four to 6 inches is expected in the International Falls area. To the south, an inch or 2 is possible across much of central Minnesota.

Roads in those areas will be slippery Thursday morning and visibility may be reduced, the Weather Service cautioned.

Light rain will fall again in the Twin Cities and in the southern third of Minnesota on Thursday, the Weather Service said.