Pictured: The DEC/JAN/FEB 2017-18 temperature probability forecast for North America issued by the International Research Institute for Climate and Society (left) and Climate Impact Company temperature anomaly outlook for winter (right).
Most statistical and dynamic model climate forecasts for northern hemisphere winter 2017-18 agree on evolution of a La Nina climate. Across the U.S. La Nina generally produces cold weather for the Northwest quadrant of the U.S. while the South and East are warmer than normal. Snow cover implicates the cold spots. This winter there is general agreement between Climate Impact Company and The International Research Institute for Climate and Society on above normal risk of developing arctic air in Western Canada. This cold air source region can easily drop the chill and attendant snow cover farther south to the North-Central/Midwest U.S. The Chicago area looks cold and snowy for winter 2017-18 ahead.
