Robert McClure shovels the sidewalk in front of Blaze in West Market Square as a two-part storm started on Thursday morning. Heavy snow is predicted across much of Maine heading into the weekend. Credit: Linda Coan O'Kresik

A two-part storm will dump heavy snow across much of Maine as we head into the weekend.

The National Weather Service has issued a winter storm warning for much of northern Maine and the western mountains, as well as a winter weather advisory for the Penobscot Valley and the coast. Both are in effect through 4 a.m. Saturday.

“Travel could be very difficult today and tonight and extremely dangerous on Friday. Patchy blowing snow Friday could significantly reduce visibilities and cause hazardous travel,” the weather service said in a Thursday morning advisory.

Heaviest snow will arrive Friday, bringing as much as an additional foot in places as the storm gathers steam. Thursday will see mostly light snow, with a wintry mix of sleet and ice before becoming all snow, according to the weather service.

From 5 a.m. to 10:20 a.m., there were five crashes due to weather, according to Bangor Police Department spokesman Sgt. Wade Betters. Police also received two calls from stranded drivers.

Greater Bangor could see up to 10 inches of fresh snow by Saturday morning, according to the weather service’s Caribou office. For Thursday, the likely accumulation is 4 inches, with an additional 6 inches in the forecast for Friday.

The immediate coast will be spared the brunt of the snow, with up to 5 inches expected to fall over an area stretching from Bar Harbor to Eastport, the weather service reports.

Snowfall will become heavier further inland, where up to 15 inches are forecast for Greenville in Piscataquis County and 15 inches for Millinocket and 13 inches for Lincoln in Penobscot County, according to the weather service’s Caribou office.

That accumulation will only get heavier toward the Canadian border, where as much as 20 inches could fall in Fort Kent and 19 inches apiece in Madawaska and Van Buren. Other Aroostook County communities, including Caribou and Presque Isle, could see up to 19 inches, while Houlton is forecast to get up to 17 inches of snow, the weather service’s Caribou office reports.

Up to 2 inches of sleet and two-tenths of an inch of ice could accompany the snow in places, according to a weather service advisory.

Meanwhile to the south, snowfall will be marginal along the immediate coastline, where up to 3 inches could fall from Portland to Rockland and 4 to 6 inches in the Belfast area, according to the weather service’s Gray office.

Inland toward the western mountains snowfall will get heavier, with up to 11 to 16 inches forecast for an area stretching from Rangeley to Jackman near the border, the weather service reports.

The storm will give way Saturday to mostly sunny skies, with temperatures ranging from the teens to the high 20s from north to south.

BDN writer Eesha Pendharkar contributed to this report.

Watch: Take a trip inside a Bangor plow truck