Traffic was light on Congress Street in Portland Thursday as heavy snow and sleet fell in the city.
PORTLAND — Southern Maine can expect at least 6 inches of snow, and a foot or more in many places, from a storm that arrived late Wednesday and is expected to last until late Thursday.
The National Weather Service upgraded its winter storm watch to a warning for all parts of the state except Down East. Andy Pohl, a meteorologist with the weather service, said 6 to 10 inches are expected along the coast, with wide variations.
For instance, he said Cape Elizabeth should get about 4½ inches of snow, because its proximity to the ocean and the expected wind direction will produce a longer period of rain in the middle of the storm.
Portland, most of which is slightly more inland, can expect about 9½ inches of snow, Pohl said.
Farther inland, 12 to 18 inches are expected, and even heavier snow could fall in pockets in the foothills, in communities such as Fryeburg, Lewiston, Auburn and Augusta, he said.
"Somebody's going to come in with some incredible snow totals," Pohl said.
The storm had already disrupted holiday travel as it moved east, knocking out power to thousands of homes and causing at least six deaths in the Midwest.
Hundreds of flights were canceled or delayed, scores of motorists got stuck on icy roads or slid into drifts, and blizzard warnings were issued with snowy gusts of 30 mph.
"The way I've been describing it is as a low-end blizzard, but that's sort of like saying a small Tyrannosaurus rex," John Kwiatkowski, a meteorologist with the National Weather Service in Indianapolis, told The Associated Press.
The system, which spawned tornadoes along the Gulf Coast on Christmas Day and a historic amount of snow in Arkansas, pushed through the Upper Ohio Valley and headed toward the Northeast on Wednesday.
Forecasts called for 12 to 18 inches of snow inland from western New York to Maine starting late Wednesday and into Thursday, tapering off into a mix of rain and snow closer to the coast. Little accumulation was expected in such cities as New York and Boston.
Forecasters said parts of the Southeast from Virginia to Florida would also see severe thunderstorms.
Snow was blamed for scores of traffic accidents as far east as Maryland, and about two dozen counties in Indiana and Ohio issued snow emergency travel alerts, according to the AP.
Two passengers in a car on a sleet-slickened Arkansas highway were killed Wednesday in a head-on collision, and two people, including a 76-year-old Milwaukee woman, were killed Tuesday on Oklahoma highways.
In Maine, the snow was expected to start falling in York County just before midnight Wednesday, Pohl said, and then spread over southern Maine.
He said the worst of the storm, which will also pack strong winds, was expected to hit between 9 a.m. and 3 p.m.
Rain could mix in along the coast in the late morning to early afternoon, Pohl said, then change back to snow.
Significant accumulations should begin to taper off by 6 p.m, he said, but snow will continue until late Thursday night.
Scott Carr, deputy director of the Portland International Jetport, said flights were still "reasonably" on time Wednesday afternoon, and the airport expected most of the late-night flights to arrive as scheduled.
More than 1,200 flights nationally were canceled by midday Wednesday, according to FlightAware.com, and some airlines said they would waive change fees. Delays of more than an hour were reported Wednesday at the three New York City-area airports, the Federal Aviation Administration said.
Carr suggested that people planning to fly out Thursday morning check with their airline before heading out and plan to get to the airport at least 90 minutes before the scheduled departure. Travelers can check arrival and departure information on the airport's website, www.portlandjetport.org.
Several communities had already announced on-street parking bans Wednesday:
• Sanford/Springvale: 11 p.m. Wednesday until 11 a.m. Friday.
• Windham: 11 p.m. Wednesday until 7 p.m. Friday.
• Old Orchard Beach: 10 p.m. Wednesday until noon Friday.
• Gorham: midnight Wednesday until 6 a.m. Friday.
• Scarborough: midnight Wednesday until 6 a.m. Friday.
Portland will decide by midday Thursday whether to ban on-street parking, said Nicole Clegg, the city's spokeswoman. Any ban would be in effect from 10 p.m. Thursday through 6 a.m. Friday, she said.
Staff Writer Edward D. Murphy can be reached at 791-6465 or at:
A city plow clears a sidewalk near Monument Square in Portland early Thursday morning, Dec. 27, 2012.