AER Winter Forecast Predicts Cold in the Northern and Eastern U.S., Mild in the Southwestern U.S.

Publish Date: November 16, 2017
Article Source: AER / National Science Foundation
Article Link:

The Atmospheric and Environmental Research (AER) winter temperature forecast has been made available publicly and can also be found on the website of the National Science Foundation, which funds AER scientist Judah Cohen’s atmospheric and polar research. 

The 2017–18 winter forecast shows below-normal temperatures for the northern and eastern United States, with above-normal temperatures in the southwestern and southcentral U.S. The winter precipitation forecast shows above-normal precipitation across the northern part of the country and below-normal precipitation across the South. The combination of cold and wet could result in an above-normal snow season for parts of the northern U.S., including the large population centers of the Northeast.

The predictors that contribute to AER’s forecast include the El Niño/Southern Oscillation (ENSO), October Eurasian snow cover extent, Arctic sea ice concentration, and an index that measures high-latitude blocking. October Eurasian snow cover extent was above-normal, Arctic sea ice extent is below-normal, and active blocking at high latitudes has occurred this fall. All three indicators favor a cold winter in the eastern U.S. A La Niña is also happening this winter, which favors a cold winter in the northwestern U.S.

“ENSO is the traditional and ubiquitous predictor of weather on seasonal timescales, which we include as well. But seasonal predictions based solely on ENSO are sometimes off-target,” says Cohen, director of seasonal forecasting at AER, a Verisk business. AER has tried to improve on seasonal forecasts that rely exclusively on ENSO by including information from high latitudes, an area of active research and the subject of many scientific articles at AER.

“The climate and forecast communities are realizing the importance of the polar vortex on winter weather, and we believe that snow cover, sea ice, and high-latitude blocking are very good predictors of the behavior of the polar vortex,” continues Cohen. All three indicators suggest that the polar vortex will break down later this winter, potentially unleashing an extended period of severe winter weather.