DALLAS—Hundreds of flights were canceled Wednesday at Dallas-Fort Worth International Airport as parts of Oklahoma, Missouri, and Arkansas braced for an ice storm making its way into the Southern Plains. More than half an inch of ice could accumulate in parts of the Ozarks through Friday morning, the National Weather Service said. Airlines had canceled more than 1,000 flights by Wednesday morning. More than half of them were at the Dallas-Fort Worth airport, where temperatures dipped below freezing and crews began treating runways overnight, according to airport spokesman Brian Brooks. DFW Airport is the biggest in the American Airlines network, and American had canceled 8 percent of its flights by midmorning, according to tracking service FlightAware. Meanwhile, heavy snow was expected in upstate New York and New England later this week, with more than 8 inches possible through Saturday morning. Winter took a fleeting break in the Northeast on Wednesday, …