A storm that crept across the United States bringing snow, ice and miserable road conditions is heading toward the upper Northeast as more wintry weather was expected to persist in making it hard on air travelers. Online air traffic site Flightaware.com says more than 1,000 flights are already canceled for Monday following days of icy, snowy weather from Texas to the East Coast. A winter storm warning is in effect for Baltimore and Washington, where up to a quarter inch (630-millimeter) of ice could accumulate. Heavy snow fell Sunday in the Mid-Atlantic region, with more than 8 inches (200 millimeters) reported in Philadelphia and a foot in nearby Delaware. According to AP, National Weather Service meteorologist Greg Heavener says icy precipitation could affect travel through the northeast corridor well into Monday.