What happened to winter? Jet stream science explains unseasonable warmth in U.S.

The lack of snow in Russia led Moscow to bring in fake snow for its New Year festivities and pushed one lawmaker to accuse the United States of using a "climate weapon" against his country.If the mild conditions in the U.S. persist through February, this could be the country’s warmest winter in recorded history, according to the National Oceanic and Atmospheric Administration (NOAA).Though it may seem like another symptom of global warming, the warmer-than-usual conditions are more directly caused by an Arctic weather pattern that is trapping cold air in the polar region. "What we’re seeing is the polar front jet stream shifted north and that Arctic air is just trapped at high latitudes."Scientists are studying whether climate change is affecting the Arctic Oscillation, but for now, any concrete links are tough to pin down, according to Serreze.Studies have suggested that as global warming minimizes temperature differences between the Arctic and regions further south, the jet stream could become wavier than usual."We’re already seeing the Arctic warming at an outsize rate compared to the rest of the planet," he said.