December 1 marks the start of the meteorological winter in the U.S. and neighboring countries. However, there has been an increase in temperatures at high altitudes above the North Pole, which is expected to affect winter weather patterns not only in the United States but also in Europe. Here are a few weather patterns you can expect to see this winter. 

Blasts of Arctic air: This winter, the cold Arctic air is expected to move past the south of Canada, thus causing a drop in temperature in the U.S. Cold air is expected to blow into the country from Canada, causing even sub-zero temperatures in some places this year. 

Nor’easter snowstorm: The Nor’easter snowstorm is expected to bring heavy snowfall to the East Coast of the United States. 

Atmospheric river: Oregon, Washington, and California may witness the effect of the atmospheric river, which is when moisture travels from the subtropics and tropics and causes heavy snowfall and rain. From October 2019 to March 2020, about 40 atmospheric river events were documented. Seven of these atmospheric river events were classified as strong. 

Lake-effect snow: The lake-effect snow pattern occurs when cold air travels from Canada into the U.S., and causes severe snowfall. Given the unusual stratospheric warming event, weather forecasters expect the polar vortex (which happens when air circulation around low-pressure areas acts as a repository for extremely cold air) to be affected. If the polar vortex remains strong and stable, the mid-Atlantic and northeast may receive less snow. However, if the polar vortex happens to weaken, it could cause extremely cold weather. 

Ice storms: Parts of the U.S. can expect to witness hailstorms this winter, as a result of jet streams fighting to separate warm, moist air from cold air. These ice storms can travel great distances (up to a hundred miles).