The deep and heavy blanket of fresh snow that caused widespread power outages and slowed travel Friday morning came as a surprise to many Mainers, including the forecasters who said the storm took an unexpected turn late Thursday.

Heavier-than-expected snowfall in southern Maine challenged crews trying to keep roads and highways clear, and caused delays in air and train travel. And areas that expected little, if any snow, were hit with widespread power outages when wet snow combined with strong winds to weigh down or break off tree limbs and knock down power lines.

Warm temperatures and bright sunshine Friday brought a lot of melting, but a hard freeze Friday night was expected to create icy roads into Saturday morning.

The nor’easter had been predicted to pummel the western foothills and mountains, with smaller accumulations forecast in southern inland sections and mostly rain on the coast.

That scenario mostly played out as expected Thursday afternoon, but it abruptly changed in the evening when cold air unexpectedly moved into southern and coastal areas and rain switched back into heavy snow, said James Brown, a meteorologist with the National Weather Service in Gray.

“The track was a little farther east late in the game, (and) that made a huge difference,” Brown said. “It turned fairly early. By 8 p.m. to 9 p.m. the cold air came in and it just snowed like crazy.”

That meant coastal areas such as Saco, Portland and Brunswick that were supposed to get only a few inches of snow got closer to a foot. Inland parts of Cumberland and York counties that expected 6-8 inches got double that amount, or more. Some of those towns recorded more than 20 inches of snow by Friday morning.

Naples hit the jackpot with 27 inches of snow, said Andy Pohl, a meteorologist with the National Weather Service in Gray. Snow totals varied widely across Cumberland County, where 24 inches were reported in North Sebago and 8 inches in the North Deering section of Portland.

In York County, North Waterboro got 25.6 inches of snow, while 24 inches were reported in Alfred and Acton. In Hollis, 22.5 inches fell at the home of a weather service employee, who reported as much as 5.8 inches in one hour.

“That’s a pretty crazy rate,” Pohl said. “Cumberland and York counties took the brunt of it.”

The storm’s unexpected shift left some towns and cities scrambling to keep roads clear.

“We didn’t put a full plow operation on because we didn’t expect the amount of snow we got,” Portland Public Works Operations Manager Steve Earley said. The city expected 2-4 inches overnight, Earley said. But by 11 p.m., it was clear the city would have to ramp up its operation to deal with the rapidly accumulating snow. That posed another problem, because plow truck drivers called into work were getting stuck on the way in, he said.

“By morning, we had a full plow complement, but at that point you are playing catch-up,” Earley said.

The storm also put pressure on Maine Department of Transportation crews, department spokesman Ted Talbot said.

“I think it is fair to say, we were prepared for lighter amounts in the southern region and heavier amounts in western region,” Talbot said Friday. “It wasn’t a matter of being surprised, it was us needing to do more rotations, making sure shifts are adhered to, just to be ready for a more challenging storm than what was originally forecast.”

The snow also posed problems for road crews. “The roads are still snow covered, this is a tough type of snow, very heavy, sticky,” Talbot said.

Primary roads were mainly clear by midmorning Friday and public safety dispatchers reported minor crashes during the morning commute. No serious injuries were reported.

The storm might have contributed to a fatal fire in Pownal. Barry Cain, 65, had lost power and investigators believe he was using an alternative heat source when the fire started early Friday.

Portland declared a city-wide parking ban from 10 p.m. Friday to 6 a.m. Saturday so city crews can finish clean-up in the city. Main traffic arterials were plowed Friday morning, but crews still had to get to some secondary streets.

“Residential streets are kind of a mess, some we haven’t even gotten to yet,” Earley said Friday.

In some cases, it was downed power lines and not snow that slowed travel.

A section of Route 22 in Gorham was closed early Friday while crews removed a fallen tree and repaired downed utility lines. And in Portland, downed power lines were reported on Riverton Drive.

Despite the unexpected snow, many Maine businesses reported their operations continued as usual Friday.

“We do not anticipate any major impact on shipping or deliveries,” L.L. Bean spokesman Mac McKeever said.

Bath Iron Works also reported minimal disruption as the facility observed a weeklong shutdown between Christmas and New Year’s Day, company spokesman David Hench said.

UNUM’s Portland office was open Friday, though spokeswoman Mary Fortune said the company put contingency plans in place in case some employees were unable to safely travel to work.

Gov. Paul LePage delayed the opening of state offices until 9 a.m. Friday.

Bridgton and Rumford district courts were closed.

The Portland International Jetport, where wind gusts topped out at 32 mph Thursday, reported multiple delayed and canceled flights Friday morning, but only a handful were canceled or delayed by late Friday afternoon. The Amtrak Downeaster reported that passenger trains would be delayed up to 90 minutes because of downed trees and other storm-related issues.

At the University of Maine in Orono, the combination of heavy snow and stiff winds collapsed the Mahaney Dome, an air-supported structure used for athletic training. There were no injuries and the university is assessing the extent of the damage, assistant athletic director Will Biberstein said.

Snow is back in the forecast for New Year’s Eve, with 1 to 3 inches expected to fall.

The snow will come in after dark and end in early 2017, shortly after midnight, said Chris Legro, a meteorologist with the weather service in Gray.

The cloud cover associated with the snow will keep temperatures somewhat mild, with a low around 30 expected in Portland Saturday night into Sunday morning. Skies should slowly clear New Year’s Day, Legro said, and it will be mild, with a high around 40 in southern Maine.

The next storm system is forecast to come in Tuesday, Legro said, but it will still be warm enough to produce a mix of snow and rain. Other than that, the new year’s first few days should be relatively mild and calm, he said.

Staff Writer Edward D. Murphy contributed to this report.