By Ian Simpson
WASHINGTON, Jan 2 (Reuters) - The first major winter storm of 2014 bore down on the northeastern United States on Thursday, packing heavy snow, Arctic temperatures and strong winds for returning holiday travelers, forecasters said.
The double-barreled storm system stretching from the lower Mississippi Valley to the Atlantic coast could dump more than 12 inches (30.5 cm) of snow in some areas, especially southern New England, by Friday morning, the National Weather Service said.
"Heavy snow, strong winds, frigid temperatures and dangerous wind chills are in forecast for much of the region," it said in a statement.
The storm is expected to snarl traffic on the I-95 highway corridor between New York and Boston, the weather service said. At the southern edge of the storm, Washington is expected to receive less than one inch (2.5 cm) of snow.
The powerful storm forced about 1,000 U.S. flights to be canceled and about 250 delayed, with the worst-affected airport Chicago's O'Hare International, according to FlightAware, a website which tracks air travel.
More than 94 million people were estimated to be traveling during the holiday season through Jan. 1, the automotive group AAA said, although many people may not be planning to head home until later this week or over the weekend.
In Boston, public schools were told to close on Friday, extending students' holiday break by a day.
"What a New Year's gift, to receive one last snowstorm as mayor," said Mayor Thomas Menino, whose 20-year run as the city's top executive will end on Monday.
The storm will provide an early challenge to New York Mayor Bill de Blasio even as he tries to enact a progressive agenda. Problems from digging out from snowstorms have been political havoc for mayors in the United States' biggest city for decades.
The weather service said the mass of Arctic air would drop temperatures from 20 to 30 degrees below normal, with record lows possible on Friday.
The low temperature in the contiguous United States on Wednesday was -43 Fahrenheit (-42 Celsius) at Embarrass, Minnesota, the weather service said.
(Additional reporting by Scott Malone in Boston; Editing by Nick Zieminski)