The U.S. Coast Guard is warning island residents on the St. Marys River that connects Lake Superior and Lake Huron in the Upper Peninsula to stock up on supplies ahead of an expected deep freeze next week.

Arctic air already is beginning to move into the Great Lakes region, according to the National Weather Service in Marquette. Temperatures on Thursday night were expected to drop to zero degrees and won't improve much over the next week, with highs in the low single digits and low temperatures ranging from minus-4 degrees to minus-6 degrees through Sunday.

On top of that, large portions of the Upper Peninsula, including the cities of Grand Marais, Munising, Newberry, and Seney, were expected to get up to 10 inches of snow by Thursday night and an additional 6 inches is predicted to fall Friday.

What that means is ice buildup could disrupt ferry service to places like Sugar Island, Neebish Island and Drummond Island — the only means for islanders to travel to the mainland. Drummond Island has nearly 1,000 residents who live there year-round.

In a Facebook post, the Coast Guard said recommended preparations for islanders "include packing for overnight contingencies, stocking pantries, topping off propane and fuel oil for heating, preparing for medical needs and the inability to transport children to and from islands to attend school."

Parents need to develop contingency plans on the mainland in the event schoolchildren cannot get back to the island after the beginning of the school day, the agency said.

The Coast Guard operates cutters and ice-breaking operations but extreme weather makes it difficult to keep up.

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