A mix of snow and ice bore down on the U.S. Northeast early on Saturday, disrupting post-holiday weekend airline traffic and prompting officials in New York and New Jersey to issue weather emergency declarations even as the storm ebbed by mid-morning.

A winter storm is now dumping heavy snow and treacherous ice on parts of the Great Lakes and Northeast Friday evening after snarling travel and knocking out power in parts of the region. Hundreds of flights have been delayed or canceled at New York’s three major airports along with Philadelphia International Airport,