FlightAware has reported that airlines have cancelled 226 flights so far for Wednesday with the expectation of reduced capacity at airports due to the winter storm. Hardest hit are New York City-area airports (EWR, LGA, JFK, HPN), which add up to 180 of the cancellations so far today. Most impacted are regional carriers operating "express" flights for major airlines, JetBlue (which has a major presence in New York), and the Delta Shuttle between Boston and LaGuardia. This is not a huge number of cancellations, but due to the holiday, flights will be more full and there will be fewer available seats to accommodate displaced passengers from cancelled flights.
“Although this is not a major weather event, we expect thousands of delays that will cause moderate disruption to Thanksgiving travellers. The delays will begin accumulating early afternoon as the worst of the weather impacts the Northeast and will continue to cascade through the evening. Traveling earlier in the day is recommend, if possible, or changing to an early flight Thursday if arriving late is preferable over delays this evening,” advised FlightAware.