HUDSON — Dozens of schools in eastern New York had canceled classes or dismissed early by Thursday afternoon as the region braced for a wintry mix of snow, sleet and freezing rain.

The National Weather Service has issued winter and ice storm warnings for Thursday and continuing into Friday for a region stretching from the mid Hudson Valley to the Adirondacks. Forecasters said some northern areas could get up to a foot of snow while parts of the Hudson Valley and the Catskills could have significant ice accumulations.

Heavy snow was also possible in central New York and the Southern Tier as a storm moved up the East Coast. Four departing flights had been canceled at Albany International Airport by noon Thursday.

A dispatcher with the sheriff’s department in Columbia County, south of Albany, said driving conditions were very icy Thursday morning.

Meteorologist George Maglaras said the weather service had issued a winter storm warning for eastern New York through 1 p.m. Friday due to expected freezing rain and sleet. Maglaras said freezing rain is forecast to get heavier into Thursday night, and could result in significant icing by Friday morning.

Ice accumulations of as much as an inch could cause power outages and there may also be some sleet accumulation, Maglaras said.