Officials warned travel conditions were treacherous, and with schools, businesses and government offices shuttered, many people stayed home. Forecasters said parts of the state's eastern half would eventually get a foot or more of fresh powder, while an icy mix was in the cards for the far southeast.
After last week's ice storm left hundreds of thousands without power, the piling snow and high winds expected later in the day were a concern for utility companies. PECO said early Thursday about 2,500 were without power in Philadelphia and its surrounding counties, a fraction of its 1.7 million customers.
At a convenience store just off Interstate 83 in Lemoyne, a suburb of Harrisburg, mechanic Joe Mayes was filling the tank of his pickup truck and heading home for some sleep after working all night at Harrisburg International Airport.
"I don't mind the snow - I like the snow, actually," Mayes said. "I'm just sick of the cold."
Philadelphian Ricardo Perez got an early start on shoveling in front of a downtown row house.
"I'm probably going to be here all day," Perez said. "Because we don't even know what time it's going to stop."
The storm system was likely to remain in central and eastern Pennsylvania for most of the day, and the snowfall was expected to continue into the evening. Philadelphia had nearly 9 inches by 7 a.m., making it the fourth 6-inch storm of the season - the first time that's happened in the city's history. Harrisburg had 8 inches by midmorning.
Airlines canceled hundreds of flights at Philadelphia International Airport while speed limit and vehicle restrictions were imposed on interstates throughout the region. The Southeastern Pennsylvania Transportation Authority suspended all bus service as of 10 a.m., and put other lines on delays.
"We have too many buses that are getting stuck and they are impeding the ability of the city to clear streets," said SEPTA manager Jeffrey Knueppel.
Pennsylvania Emergency Management Agency spokesman Cory Angell said Gov. Tom Corbett was getting a morning briefing in the emergency operations center that went into action last night. The state put 450 National Guardsmen on duty.
"There's no incidents to report, but we're just kind of looking at the weather overall," Angell said. "Everybody's just in preparedness posture."
PennDOT spokeswoman Erin Waters-Transatt said the highway agency was moving equipment from Erie, one of the nation's snowiest cities, and other western areas to Lancaster, Reading and the Lehigh Valley.
Waters-Transatt said PennDOT has used 926,000 tons of salt so far this season, compared to 748,000 tons at this point, on average, in recent years.
"Statewide, we do have enough for a handful of more storms," she said.
Lebanon City Mayor Sherry Capello declared a snow emergency early to give people time to get their vehicles off snow emergency routes. She said the winter season, with some 26 days of snowfall so far, has been tough on her maintenance workers.
"The guys are not getting a break," Capello said. "It's like every week and sometimes several times a week they are doing something related to a winter event."
Philadelphia Mayor Michael Nutter said the city had received 43 inches before the latest storm even hit, nearly twice a normal year.
"This is highly unusual weather and weather patterns, not just here in Philadelphia, but in talking with other mayors and government officials up and down the East Coast," Nutter said.
At Cantelmi's Hardware Store in Bethlehem, manager Tom Marks said he was doing a brisk business in heaters, shovels, snow blowers and just about everything storm-related except ice melt. That item was sold out.
"We should have a load coming next week," he said. "It's been delayed because it's just a high demand right now."
Scolforo reported from Lemoyne. AP writer Kathy Matheson contributed to this story.