Change in Arctic Oscillation Chills North America and Warms Arctic

This NASA satellite map shows how a major change in Arctic air currents has led to topsy-turvy weather across North America, with temperatures far below normal in the U.S. and western Canada and extreme warmth affecting many Arctic regions. The red and blue colors represent to what degree recent temperatures have been above or below the norm, as measured by instruments aboard NASA’s Aqua satellite. The bizarre weather has occurred because a climate pattern known as the Arctic Oscillation, which occurs because of differences in air pressure between the Arctic and mid-latitudes, has shifted into a negative phase. That means the pressure gradient has weakened, enabling Arctic air to pour south and warm air to slip north. The NASA map shows that large swaths of Alaska and Canada have experienced temperatures as much as 18 degrees C (32 F) above normal, while much of the U.S. has experienced unusually cold temperatures and frequent snowstorms. While residents of the eastern seaboard have faced a battery of winter storms, residents in Iqualit, capital of the Canadian territory of Nunavut, were forced to cancel their New Year’s snowmobile parade.