People treat snowstorms differently in her native Serbia, Vesna Cirica said Saturday as she loaded groceries into her car outside a Hannaford store in South Portland.

“It’s not like here,” said Cirica, noting that there was no big build-up to a storm and the snowfall was ignored as much as possible. “Schools are working, people are working.” But in her 20 years in the U.S., Cirica said, she’s adopted some American customs. And that meant that early Saturday afternoon, she was out grocery shopping to prepare for the biggest snowstorm of the winter so far.

The National Weather Service expected the snow to move into Maine on Saturday night and is forecasting that between 12 and 18 inches will fall in Portland and coastal southern Maine before the storm winds down Sunday night. The snow is expected to ramp up quickly, with a half-foot on the ground in Portland by 7 a.m. Sunday, meteorologist William Watson said, and some sleet or freezing rain may mix in near the end. A winter storm warning is in effect from 7 p.m. Saturday until 1 a.m. Monday for southern Maine and from 11 p.m. Saturday until 1 p.m. Monday in northern Maine.

IMPACT ON TRAVEL

In northern Maine, including the cities of Presque Isle and Caribou, heavier snow – 18 to 24 inches – is expected. The forecast for Bangor and Brewer calls for 12 to 20 inches of snow and ice of up to half an inch.

The storm will then usher in bitter cold, with high temperatures Monday in the low teens and lows Monday night around zero in Portland and below zero in northern Maine.

By Saturday afternoon, the impending storm had started to affect travel in Maine. Portland International Jetport and Bangor International Airport continued to get flights from cities along the East Coast until early afternoon, but flights after 5 p.m. were canceled. That meant early Sunday morning departures were canceled as well because the planes for those flights weren’t going to be in Maine overnight.

Greater Portland Metro announced late Saturday afternoon that it was suspending service Sunday because of the storm. Regular service will resume Monday, the bus service said.

Cirica, who lives in Boston but was visiting her son in South Portland, said she stocked up so she could cook a big family dinner Sunday and also wanted to have enough on hand so that she won’t have to go out Monday.

She wasn’t alone.

Connie Henderson of South Portland said she wanted to make sure that her cat – along with her daughter’s six cats – would have plenty of food to ride out the storm. She also picked up some soda, cereal and bread so the people who take care of all those cats would be well-fed.

Henderson said she avoided the Hannaford store near where she lives in Mill Creek, knowing that it would be jammed in advance of a snowstorm, and opted for a store near the Maine Mall, which was busy as well.

SLOW GOING EXPECTED

Another shopper, Brittney Russell of Portland, said Saturday was her normal grocery shopping day, but she did buy more of some items to make sure her family had enough to get through the storm.

Russell said she was already nervous about having to work an 8 a.m. to 4 p.m. Sunday shift at a sub shop. Even though she lives only a short distance from the shop, Russell said she would leave early in anticipation of slow going on the way in.

PARKING BANS

Most towns and cities in southern Maine, including Brunswick, Westbrook and Scarborough, issued bans for on-street parking starting Saturday night and running through to Monday because of the storm. Portland issued a parking ban from 10 p.m. Sunday through 6 a.m. Monday and city officials urged residents to move into snow parking ban lots Saturday night, earlier than the ban, to avoid having to drive Sunday. Cars will need to be moved out of the lots by 8 a.m. Monday, an hour later than normal because schools will be closed for the Martin Luther King Jr. holiday.

Watson of the weather service said the storm will bring in a short shot of very cold air. But it will ease by Wednesday, he said, when the high temperature might be near 40 and a storm arriving could bring mixed precipitation or rain.