AER Issues Winter Weather Outlook

Arctic predictors may impact polar vortex, leading to dramatic swings in weather for upcoming winter

FALMOUTH, MA, Dec. 09, 2020 (GLOBE NEWSWIRE) -- There’s increased possibility of severe winter weather in the second half of winter, with warming temperatures brought on by climate change potentially disrupting the polar vortex leading to dramatic swings in weather this winter season. These were some of the findings explained by Dr. Judah Cohen, Director of Seasonal Forecasting at Atmospheric and Environmental Research (AER), a Verisk™ business, for the upcoming winter.  

Each year, AER provides a winter weather outlook, and this year’s outlook predicts cold temperatures, and variable weather conditions for North America. Regionally, the U.S. can expect relatively cold temperatures in the Pacific Northwest, Upper Midwest and the Great Lakes with relatively mild temperatures in the Southern US and up the Eastern Seaboard.

AER’s outlook is based in large part on research advanced in collaboration with Woodwell Climate Research Center’s Senior Scientist Dr. Jennifer Francis. Dr. Francis is an expert on the link between Arctic warming and weather patterns around the northern hemisphere, and together she and Dr. Cohen have been working to unravel the significant role that rapid Arctic warming is having on the jetstream and shifting mid-latitude weather patterns. 

According to Dr. Cohen, while mainstream seasonal outlooks typically rely heavily on tropical predictors such as the El Niño Southern Oscillation index -- ENSO, AER’s winter weather outlook also factors in key Arctic indicators - such as sea ice variability, atmospheric blocking at high latitudes, and snow cover in Siberia - that have the potential to disrupt the polar vortex and impact temperatures and weather patterns throughout the winter months. 

Factoring in this season’s warm Arctic temperatures and record low sea ice, Dr. Cohen highlights in the 2020-2021 winter weather outlook:

  • a moderate La Niña is expected this winter, which will significantly impact winter weather. It’s important to note that  the polar vortex can have just as large an impact, yet it is not considered by most long-range forecasters; a weaker vortex increases the risk of colder weather
  • therefore, greater cold risk than currently expected, and that the cold weather could reach farther east than predicted by NOAA and other seasonal forecasts; 
  • increased possibility of severe winter weather in the second half of the winter; and
  • potential for disruption to the polar vortex, which increases the risk of more severe weather, leading to greater variability and swings in weather as the warming temperatures brought by climate change compete and clash with the cold temperatures brought by disruptions to the polar vortex.

“As the planet warms, I believe it is increasingly difficult to have sustained cold weather without a polar vortex disruption,” said Dr. Cohen. “However, changing Arctic conditions are making such disruptions more common. This year, a significant polar vortex disruption is looking increasingly likely, which could mean a colder than normal winter in parts of the Northern US.”

“Judah’s seasonal predictions incorporate cutting-edge research related to the impact of climate change that can prove beneficial on a number of fronts -- everything from how much road salt a director of transportation needs to buy, to how much snow-making equipment might be needed to support a ski operation, to how much freshwater will be stored in a snowpack for the dry summer to follow,” said Dr. Francis. “Seasonal weather forecasting is a complex and fast-moving area of meteorology. We’re proud to collaborate with Judah and AER to share unique insights about the impact of climate change to help people better plan and prepare for the winter months ahead.”

Dr. Cohen’s Winter Weather Outlook, offering a static prediction for this winter’s weather, can be found here. His blog, a more dynamic source continuously updated with key meteorological information on temperature and weather patterns throughout the winter as weather events occur, can be found here

About Woodwell Climate Research Center: 

Originally founded as Woods Hole Research Center (WHRC) by the renowned ecologist Dr. George Woodwell in 1985, Woodwell Climate Research Center is an organization of highly respected researchers who work with a worldwide network of partners to understand and combat climate change. Our experts have vast experience in the field, collecting data firsthand and generating knowledge about Earth’s most consequential ecosystems. We bring together hands-on experience and 35 years of policy impact to find societal-scale solutions that can be put into immediate action.

About Verisk 

Verisk (Nasdaq:VRSK) is a leading data analytics provider serving customers in insurance, energy and specialized markets, and financial services. Verisk offers predictive analytics and decision support solutions to customers in rating, underwriting, claims, catastrophe and weather risk, global risk analytics, natural resources intelligence, economic forecasting, and many other fields. Around the world, Verisk helps customers protect people, property, and financial assets.

Headquartered in Jersey City, N.J., Verisk operates in 30 countries and is a member of Standard & Poor's S&P 500® Index and part of the Nasdaq 100 Index. For more information, please visit


AER/Verisk Media Contact: 

Joseph Madden,

Brett Garrison, Edelman (for Verisk),

Woodwell Climate Media contact: 
Maddie Rocklin-Waltch,