New forecasts suggest milder winter than predicted

Not too many suburbanites expected that come January their sleds, skis and snow shoes would continue collecting dust, considering the ominous predictions that Chicago's winter would be the nation's nastiest.

But many forecasters are now singing a more upbeat tune. Predictions of a warmer and wetter season are replacing the grimmer cries of cold and snow.

Another bit of good news — at least to those who don't mind more mild weather — is that unseasonably warm temperatures in December don't necessarily mean spring will be pushed back.

“It's not a good gauge to look at December temperatures, because historically they don't show one way or the other what the rest of winter will be like,” National Weather Service Chicago meteorologist Jamie Enderlen said.

Meteorologists at the agency's Romeoville office looked at the 15 warmest Decembers on record, and found that unseasonably warm temperatures don't serve as a good predictor of the coming months.

In Chicago, where 1877 was the warmest December on record, the average temperatures in the following January and February were 7.9 and 8.8 degrees above average, respectively.

But in Rockford, where the warmest December on record took place in 1923, the next two months were 7.3 and 0.3 degrees cooler than average.

Meteorologists say that in looking at the 15 warmest Decembers, many winter seasons remained mild while others abruptly switched to unseasonably cold weather.

With an average temperature of 35.2 degrees, December 2011 will go down in the record books as the 15th warmest in Chicago's history.

It likely would rank even higher, but 10 of those warmer months were back when the official temperature reading was taken downtown, where it tends to be warmer. Beginning in July 1942, the city's official station was moved to O'Hare and Midway airports.

Looking ahead, Enderlen said that it's difficult to predict temperatures beyond a week or two due to changing weather patterns.

However, she said that according to the Climate Prediction Center, a warmer and wetter than normal January is predicted.

And above-average precipitation is expected through March. Temperatures also are predicted to be higher than normal, though less significantly than what the region has experienced so far.

Even the Farmers' Almanac's long-range predictions for the Midwest and Great Lakes regions — limited to flurries and light snow through February — don't seem nearly as severe as the August 2011 winter outlook its official forecaster originally dubbed “crime and punishment.”

One reason, according to Enderlen and the National Weather Service, is that the region currently is experiencing positive phases of a large-scale phenomenon known as the North Atlantic Oscillation and the Arctic Oscillation.

The positive phases cause stronger westerly upper level jet streams, which blocks cold air from spilling southward along the central and eastern U.S. Any cold air that does move into the region can exit quickly off to the east.

Compare that to the past two winters, when those atmospheric pressure trends were mostly in the negative phase, leading to fairly cold and snowy winters.

“That's essentially why it's warmer in our neck of the woods now,” Enderlen said.

Still, Enderlen said we can't rule out a significant snow event like the Feb. 2, 2011, blizzard that dumped more than 20 inches on the suburbs.

That news may not thrill some, but at least the sleds, skis and snow shoes could finally make an appearance.