A fast-moving but moderate winter storm moved into southern Maine late Saturday afternoon and was expected to drop another 4-6 inches of snow on most of the state by Sunday morning.

National Weather Service meteorologist James Brown said the storm was born out of warm air traveling north and combining with a cold air mass that has settled over the Northeast.

The weather service issued a winter weather advisory for most of the state, except northwestern regions. Some extreme coastal areas could see less if the precipitation shifts to rain, Brown said.

Light snow began falling about 5 p.m. Saturday and began sticking to the roads an hour or so later, making travel conditions slippery.

Maine Turnpike officials closed the northbound exit ramp in Scarborough shortly after 7 p.m. because of a weather-related accident.

According to officials, a vehicle slid off the road between the ramp at Exit 44 and the northbound lanes. Maine State Police troopers responded and called a tow truck to remove the vehicle, but traffic was slowed. No one was injured. The ramp was reopened after about 15 minutes.

Some Cumberland County communities, such as Falmouth, Brunswick and Westbrook, issued parking bans through Sunday morning. Westbrook’s ends at 7 a.m., Brunswick’s at 8 a.m. and Falmouth’s is in effect through noon.

The city of Portland did not issue a ban, but officials asked residents and visitors to park off the street if possible.

Portland also offered the $3 winter ban discount rate Saturday night at the city-owned Spring Street parking garage, where vehicles must be removed by noon Sunday to take advantage of the rate.

Crews were out again Saturday evening to clear snow and dangerous snowbanks from city streets.

Portland has seen nearly 86 inches of snow so far this season, double the normal amount of 43 inches for this date.

City officials said they may still declare a parking ban for Sunday night if the storm is severe enough.

Once the snow ends Sunday, temperatures will warm into the 30s for the first time in weeks, but that won’t last long.

By Sunday night, temperatures will drop back into the teens and stay there through the early part of next week, Brown said.