U.S. cities dig out from storm amid bitter cold

Residents of the northeastern United States on Wednesday looked to dig themselves out from a storm that has dumped over a foot of snow in many places, snarling traffic and forcing the Philadelphia school system to shut down. The weather system packing snow and Arctic cold forced the cancellation of over 3,000 flights.
Background:
Frigid temperatures to persist as northeastern U.S. digs out from snow [Reuters]
U.S. East Coast hit with heavy snow and bitter cold [BBC]
Snow storm snarls travel on East Coast; at least one death reported [CBS News]