PORTLAND – The snow that started falling shortly after sunset tonight should wrap up by late Sunday morning, but the storm will dump 6 to 10 inches in the meantime, forecasters say.

Eric Schwibs, a meteorologist with the National Weather Service, said the precipitation changed over to snow much faster than anticipated. The forecast had called for rain through midnight before the change to snow, but the transition began right after the precipitation started to fall.

Police said they started to see an increase in cars sliding off roads after the snow had been falling for several hours.

State police said more than a dozen cars had slid off by about 9:30 p.m., most of them south of Portland on the Maine Turnpike. The Cumberland County Sheriff’s Office said one car slid off the road and flipped over in Windham, and York County officials said a handful of cars slid off local roads. No one was reported hurt in any of the incidents.

Schwibs said some rain may still mix in overnight, especially along the coast, if the wind shifts from the north to northeast. That will draw in slightly warmer air that’s over the water, he said.

Inland, the precipitation should be all snow, he said, and that’s where accumulations are mostly likely to be near 10 inches.

Schwibs said temperatures will rise into the mid-40s Sunday, melting some of the snow, and into the low 50s by midweek.

Power failures are likely because many trees still have not shed their leaves. That means branches will be weighed down with more snow, increasing the likelihood they will snap and take down power lines.

Central Maine Power Co. said it only scattered power outages as of 8 p.m.Fewer than 300 customers said they had lost power, all in York County, the utility said.