A powerful winter storm has plunged U.S. holiday travel into chaos, grounding flights and paralyzing major airports during one of the busiest travel periods of the year. Ice and snow slammed the Northeast and Great Lakes, triggering mass cancellations and delays across key hubs including New York’s JFK, LaGuardia, and Newark airports. Millions were placed under winter weather advisories as officials urged people to stay off roads. As the East struggles to dig out, attention is shifting west, where a series of intense storms and atmospheric rivers threaten California with flooding, mudslides, and dangerous travel conditions — extending the disruption coast to coast.