An Arctic blast gripping much of the nation caused more than 11,000 flights to be delayed or canceled Monday, and with another storm looming, the number was expected to grow. New York was spared most of the delays at the outset, but that was poised to change as a snowstorm descended across the Northeast. As of Monday evening, there had been 8,478 delays within, into or out of the U.S. and 3,028 cancellations, according to Flight Aware. Worldwide, delays totaled 25,419 and there were 4,150 cancellations. Southwest Airlines led the pack in the U.S. with 761 cancellations, or 19% of its flights. …