With monster storms repeatedly battering the East Coast, extreme drought still lingering over much of the country and the holidays just around the corner, many weather-watchers are wondering what Mother Nature will bring in the coming months.
And while long-term weather forecasts are notoriously hard to pin down, meteorologists have begun to release their best guesses for how this coming winter will stack up to seasons past.
By comparing current conditions with the same measurements taken at this time over the decades and extrapolating the future based on what happened in the past, at least one long-range forecast is calling for a harsh winter in the Northeast, a mild West Coast, and a cold but not too snowy winter in the Midwest.
Of course, jet streams and other conditions can change without warning. Good records only go back 60 years or so for some measurements, making it hard to come up with reliable patterns. Even with more data, statistics are not fortune-tellers.
With so many factors involved in determining weather, long-range forecasts need to be taken with liberal grains of salt.
"It's like asking your banker what your interest rats are going to be in the middle of 2013," said meteorologist Paul Douglas, founder of Weather Nation, a weather outsourcing company in the Twin Cities, Minn. "Good luck with that. There are billions of variables."
"The future is wonderfully unknowable," he added. "Anybody who pretends to have an answer key for the winter to come is trying to sell you something, and I can't stress enough, "Buyer beware.'"
When predicting winter weather, one of the first things many weather experts look to is the temperature of surface waters in the tropical Pacific Ocean. When waters off the West Coast of the United States are warmer than average, it's called an El Niño pattern. Colder than average ocean temperatures, on the other hand, make an El Niña.
Together, the overall cycle is called The El Niño–Southern Oscillation, and it can have major effects on temperature and precipitation readings across the country.
Earlier this fall, it looked like an El Niño was setting up, Douglas said, but the chances of that happening have now dropped to 53 percent. El Niño's, when they happen, tend to push the jet stream southward, upping the chances of wet weather in the south-central and southeastern U.S. and mild, dry conditions in the northern states.
But those trends are far from a sure thing. Last year's La Niña, for example, led many meteorologists to call for a cold and snowy winter up north. Instead, much of the country saw record-breaking warmth.
To fine-tune his predictions each fall, meteorologist Larry Cosgrove considers the ENSO alongside other weather-influencing conditions, including sunspot number, wind speeds in the upper atmosphere and the severity of recent droughts.
He then looks back through decades worth of data to find analogous years for each condition. Finally, he throws these parallel seasons together, using what he calls his own "whirring blender technology" to come up with predictions for the coming months. His method, he says, is accurate about 60 to 70 percent of the time.
This year for example, the drought and hot temperatures of summer mirrored Dust Bowl conditions during the winters of 1933-34 and 1936-37. Meanwhile, the best analog for current jet-stream conditions at about 15,000 and 30,000 feet happened in the winter of 1993-94. And the closest scenario Cosgrove could find to current sunspot conditions happened in 1926-27. As for the ENSO, the winter of 2006-7 looks like a decent analog.
After a lot of number crunching and data analysis, Cosgrove is calling for a tough winter in New England and the Northeast, with cold and wet weather through January and February. He also expects plenty of snow and ice in the middle of the country from Colorado to Ohio and south to Oklahoma and Arkansas. Further north, Minnesota and Wisconsin will likely be cold but not extremely snowy as the storm-track stays further south. The west, he says, will probably be mild.
By March, Cosgrove is predicting "a quick exit to spring, and a very warm spring at that," said Cosgrove, of the forecasting company WEATHERAmerica in Hockly, Texas. "If I had to zero in on one period where snow and ice-lovers would really like, it would be the week of Christmas and New Year's through January up to Valentine's Day. That's the strike zone."
The Farmer's Almanac, for its part, is going with mild and dry for the upper Midwest, cold and dry for New England, and cold and snowy for the mid-Atlantic and Ohio valley into the Carolinas. The Almanac, Douglas pointed out, is right about half the time.
The National Weather Service's Climate Prediction Center, meanwhile, is projecting warmer-than-normal temperatures for much of the west over the next three months. It also calls for below-average precipitation in the northwest and Midwest and extra-wet conditions in the southeast through February.
One of the big wildcards is what's happening in the Arctic, Douglas said. Record-low amounts of ice in the far north have put into motion a sequence of unprecedented events with unknown consequences. One possibility is that the melting will cause a high-pressure bubble over the Arctic, which could displace cold air from the North Pole, causing bitter cold fronts to stray further south than usual.
Despite all the speculations, there's no way to know for sure what this winter will bring.
"My confidence level is very low for any long-range forecast," Douglas said. "People want to know, but that doesn't mean we have the science to back it up."