Competing Theories On Coming Winter

Competing Theories On Coming Winter

The snow in Siberia has piled up again, and according to one theory this means cold and ice are on the way for the Northeast and other parts of the eastern United States. That is, if the snow can wrestle El Nino into submission.

Before the match starts with El Nino, here’s a recap of how the whole winter outlook thing works: It all starts when a large expanse of Eurasia is covered by snow by the end of October, said Judah Cohen, the theory’s author and director of seasonal forecasting at Atmospheric and Environmental Research in Lexington, Mass.

That creates a pool of cold air and strong high pressure over Siberia. The result is a chain reaction that eventually ends up with a shift in the Arctic Oscillation, a difference in pressures over the polar region, and people in Manhattan risking frostbite if they leave their faces uncovered. At least, that’s the theory.

Last year, it didn’t exactly work out. Despite the second- largest Siberian snowcover on record for the end of October, the AO didn’t shift.

“The snow did a great job predicting the temperature but it didn’t do a good job with the AO,” Cohen said.

Todd Crawford, principal scientist at WSI in Andover, Massachusetts, thinks the theory is good, “grounded in theoretical, observational, and modeling research.”

“But the theory is based on the AO, which they missed badly last year,” he said. “They got the temps right for the wrong reason in the U.S., and missed badly in Europe and Asia. Having said that, one bad year does not disprove the theory.”

Cohen said he doesn’t accept the idea that he got the right answer for the wrong reason. Many pieces fell into place even if the Arctic Oscillation didn’t react as predicted. After looking at the details from last winter, “I feel better about what happened,” he said.

However, as he looks forward, Cohen said the winter of 2015-2016 will be different from past years for one big reason — there’s a strong El Nino in the equatorial Pacific and it’s playing havoc with weather patterns all over the world. It may even trump the Siberian snow effect.

“It’s still a huge wild card,” Cohen said.

Many forecasters believe the El Nino will mean a mild winter for the northern and eastern U.S. in particular.

The U.S. Climate Prediction Center’s outlook through January calls for a mild start to the season for the northern part of the country. The U.S. Energy Information Administration is also predicting a milder winter than 2014-2015, when record snow fell on Boston.

“In this winter’s case, the El Nino is way too strong,” said Matt Rogers, president of the Commodity Weather Group in Bethesda, Maryland. The theory “would be interesting to talk about in other winters, but not this one.”

Cohen, who hasn’t released his own forecast for the winter, keeps looking at the snow across Eurasia.

October ended with 4.89 million square miles of snow in the region, the third-most in the past 10 years, according to the Rutgers University Global Snow Lab.

So the snow is there.

Despite predictions from computer models and the human forecasters that El Nino will make the winter mild, “it could be colder than that based on the Arctic,” Cohen said.

In other words, maybe you should get that snowblower fixed after all.

Author: Brian K. Sullivan Bloomberg News

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