The major winter storm we've been tracking all week is now blanketing much of the eastern half of the U.S., with snow falling from Oklahoma through Louisville, Cleveland, Washington, DC, Baltimore, and Philadelphia, and now reaching Boston.

Impacts are already significant, with the largest surge in flight cancellations and delays since the Covid era: Airlines have canceled more than 10,00 U.S. flights for Sunday, according to the flight-tracking site FlightAware. Most in single day since Covid era.