LANSING, Mich. (AP) — As Thanksgiving approaches, residents in the Great Lakes region should brace themselves for a snowy holiday. A weather system is delivering significant precipitation across the area, especially impacting Michigan’s Upper Peninsula.

Snowfall, which began on Wednesday, continued through Thursday, driven by winds from the north and northwest. Alger County, located east of Marquette, Michigan, is under a blizzard warning until 7 p.m. on Thursday.

The National Weather Service forecasts that the most substantial snowfall will occur west of Munising, with the potential for up to 13 inches (33 centimeters) of additional accumulation. As the day wears on, snow bands are expected to diminish, starting with the western areas of the Upper Peninsula.

Lily Chapman, a meteorologist at the National Weather Service in Marquette, reported that 15 inches (38 centimeters) of snow had fallen by Thursday morning at her location. Near Bessemer, Michigan, about 113 miles (182 kilometers) east of Duluth, Minnesota, there have been reports of snow depths ranging from 18 to 28 inches (46 to 71 centimeters).

“Snowfall amounts can change quickly due to factors like elevation or the alignment of stronger snow bands,” Chapman explained.

What is lake effect snow?

Lake effect snow is characterized by thin bands of clouds that can produce heavy snowfall. Some areas can see much more snow than others nearby thanks to the narrow bands.

The phenomenon occurs when cold air from Canada is blown over the warmer water of the Great Lakes: Superior, Michigan, Huron, Ontario and Erie. Warm air from the lakes pushes the moisture in the sky higher into a zone most conducive to snowfall. The clouds that form as a result can dump 2 to 3 inches (5 to 8 centimeters) per hour and sometimes more.

The weather particularly affects Michigan, Ohio and New York, but lake effect snow can also happen over other large bodies of water, like the Great Salt Lake in Utah.

About 10 miles (16 kilometers) west from Bessemer near Montreal, Wisconsin, the National Weather Service reported 33 inches (84 centimeters) of snow in one location early Thursday morning. Roy Eckberg, a meteorologist with the National Weather Service in Green Bay, said the elevation of the area creates an even better environment for clouds to create snow.

“So you not only have the lake effect, you’ve got the lift of the terrain,” he said. “So that area can get some pretty interesting snow totals like this event.”

Dangerous driving on Thanksgiving

The traveling bands of lake effect snow can cause sudden and extreme whiteouts, making driving hazardous. Travel was difficult across the Upper Peninsula on Thursday with low visibility, Chapman said.

Additionally, strong winds of up to 45 mph (72 kph) posed a threat of creating large snow drifts over roads and power outages. Over 1,000 power outages were reported near Houghton, Michigan, about 100 miles (160 kilometers) west of Marquette on Thursday morning, according to the utility provider the Upper Peninsula Power Company.

Similar power outages were reported by Consumers Energy on the coast of Lake Michigan near Holland, about 170 miles (274 kilometers) west of Detroit. The National Weather Service of Grand Rapids expected about two inches of snow Thursday with high gusts of wind of 45 mph (72 kph) near the lakeshore. The weather service warned of slick roads.

The lake effect snow is expected to ease west to east as Friday approaches. However, a different storm system is forecasted to blanket the Great Plains and Midwest regions with snow starting Friday heading into the weekend. The National Weather Service said Chicago could see six inches of accumulated snow through Sunday.

About 2 to 3 inches of snow were reported near Buffalo, New York, on Thanksgiving morning, and a lake effect snow warning was in effect until early Saturday morning.