A winter storm that changed course on short notice was set to hit the Philadelphia region around dawn and create near-blizzard conditions by Sunday afternoon. Forecasters expected as much as a foot of snow by the time the storm ends midday Monday, with gusty winds that could push windchill readings into the single digits.

"It's going to be pretty wintry out there," National Weather Service meteorologist Jim Hayes said.

Hundreds of flights were canceled or delayed Saturday, especially in hard-hit Southern states, and airlines were warning of additional cancellations Sunday.

In Philadelphia, snow was expected to begin falling around 7 a.m., with total accumulation between 8 and 12 inches. The Jersey Shore may see as much as 18 inches.

Though it won't likely be as strong as the walloping that dumped nearly two feet on the city just before Christmas last year, the storm may bring with it memories of last season's never-ending snow.

Gusts as high as 35 m.p.h. could push snow into drifts, create even trickier driving conditions, and cause headaches for utility crews. They also could complicate tailgating plans for Eagles fans headed to the game at 8 p.m., which was still on as of Saturday night.

Mayor Nutter said the city was preparing for a significant storm. To help the Streets Department, "We're asking Philadelphians to take care of the shopping necessities and other activities Sunday morning and then stay off the roads during the afternoon."

He said city residents are asked to clear a sidewalk path of 36 inches within six hours of the storm's end.

Peco's emergency operations center was open and tracking the storm Saturday. The forecast for high winds was especially concerning, spokeswoman Karen Muldoon Geus said.

"Everybody's on standby right now," she said.

Pennsylvania Department of Transportation crews had begun spraying salt brine on the expressways. Spokesman Gene Blaum expected all 410 state and contracted plow trucks to be working Sunday in Philadelphia and its suburban counties.

"It looks like this will be what we call a 'full call-out,' " he said.

The storm already has shown its might elsewhere.

The system came from the West Coast and is the same one that brought heavy rain and mud slides to parts of California this month. It weakened as it moved east across Texas but picked up power again over the Gulf of Mexico, Hayes said. It didn't go out to sea, as had been predicted.

It brought snow and rain to the Southeast on Saturday and prompted hundreds of flights along the East Coast to be delayed or canceled.

Holiday travelers should get out early Sunday or "be prepared to wait it out," said Joe Dee, spokesman for the New Jersey Department of Transportation. "Let our crews do what they need to do."