Winter’s cold grasp finally wrapped itself around Colgate this week, with fresh snowfall and glacial temperatures greeting students each morning. Despite the fierce chill, though, many on campus could not forget the balmy breezes that crossed the same space just a few weeks earlier. Extreme as they may appear, this year’s odd weather patterns seem to be the result of several common atmospheric phenomena that have the power to affect weather across the hemisphere.

“The hot thing on everybody’s mind is global warming,” Associate Dean of the Faculty and Professor of Geography Adam Burnett said. “But the conditions we have at any one time are the result of multiple inputs.”

The lack of snowfall observed this year was disconcerting to some, but was not the lowest on record. Despite an overall upward trend in lake-effect snow totals over the last century, the year-to-year measurements are variable.

“When you look at the data I think people are amazed how variable it is,” Burnett said.

Burnett explained that two common weather phenomena in place this fall – an El Ni?no and a positive North Atlantic Oscillation – seem to have resulted in Hamilton’s mild early winter.

“These things, by themselves, can produce odd weather,” Burnett said, explaining that the combination correlates with bizarre conditions.

El Ni?no patterns, often cited as a cause of extreme weather in the United States, are the result of warm ocean surface temperatures in the equatorial Pacific Ocean. According to Burnett, warmer ocean surface temperatures alter the dynamics of energy transfer between sea and atmosphere, thus affecting the weather.

“We’ve been in an El Ni?no state since last spring,” Burnett said. “What we’ve seen are warmer temperatures across the entire northern U.S., more rain in the south and a drier west.”

Burnett noted that, while snowfall was low, this fall and early winter were still rather wet.

“The low snow that people noted was probably related to higher temperatures,” Burnett said.

Compounding the current El Ni?no was a second phenomenon called a positive North Atlantic Oscillation. When a strong center of high pressure establishes itself off the southeast coast of the United States and a strong low-pressure center sets up farther to the north, the pressure gradient formed causes a shift in the jet stream winds that drive large storms.

The jet stream winds that would normally draw polar air down over the east coast instead pull that air into the intermountain west, which in turn keeps most large storms away from the east coast, and central New York.

“Our winter weather was basically parked over the west coast,” Burnett said, alluding to the massive storms in Colorado and Wyoming this December and January.

“The thing I try to convey to people is that climate is a variable creature,” he said. “Though it was an unusual December, I thought it was only a matter of time before things [got back to normal].”

Now that the snow has returned, this statement seems to have proven true.

However, despite less-calamitous explanations as to the immediate causes of this year’s bizarre weather, the possible impact of global warming is not far from Burnett’s mind.

“One has to begin to ask if global warming will contribute to these patterns,” he said.