NEWS

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February 17, 2006

Unseasonably warm weather is met with mixed campus response

After a pattern of warm weather in January, followed closely by rain in February, it seems this year that Chicago has lost one of its most infamous traits: freezing cold winter weather.

Gidon Eshel, assistant professor of physical oceanography and climate in the department of geophysical sciences, said that Chicago’s warm spell is not unusual.

“Almost every square inch of the country has experienced positive deviation from average temperatures for this time of the year,” Eshel said.

So far this year, cities nationwide have all had above-normal temperatures. While many onlookers attribute the phenomenon to global warming, Eshel said that there are more factors at play in this winter’s abnormally warm weather in America.

Climate is dependent on what scientists call the Planetary Wave Pattern (PWP), a model that describes the planet’s means of equalizing heat from solar radiation over the earth. Landmasses and water bodies interact to disturb the fluidity of the PWP. Many other factors have also contributed to agitate the consistency of the PWP, thus resulting in fluctuations in the global weather system.

The North Atlantic Oscillation (NAO), a seesaw in atmospheric mass between the polar low and subtropical high, is the dominant mode of winter climate variability in the North Atlantic region affecting North America, Europe, and a large sector of northern Asia.

The climate pattern in Europe is consistent with the NAO explanation: As North America experiences abnormally warm temperatures, northern Europe is experiencing abnormally cold temperatures.

The NAO has two phases. In the positive phase, it shifts jet streams north of its usual position resulting in warm days in the U.S., and in the negative phase it shifts jet streams south, usually producing bursts of cold air and snowstorms. While NAO phases change weekly, January saw a long period of the positive phase which is still continuing, according to the National Weather Service’s Climate Prediction Centre.

The climate aberrations of this year have been felt by students on a number of levels.

“It seems like Chicago winters get milder every year—less snow and fewer sub-zero temperature days,” said Amy Winans, a third-year in the College and Chicago native. “I can’t say I miss the windchill but I do miss the snow.”

While most students agree that the warm weather has been a nice change, some students actually miss the seemingly unpopular cold Chicago winters.

“One of the reasons I chose the U of C is because I heard that Chicago winters are just like winters in Russia,” said Igor Sitnikov, a fourth-year in the College from Moscow. “In the past three years the Chicago winters have met my standards, but this year I’ve been really disappointed.”

Students who miss the bitter Chicago winters need not worry, as the NAO could change its phase within a week, creating the cold icy winters Chicagoans are use to. However, whether it will continue to be warm or take a turn to the cold is unpredictable, as the phase of the NAO is difficult to anticipate more than one to two weeks in advance.

“Weather changes week by week, and there are so many factors affecting it,” Eshel said. “We are not a 100 percent sure what’s going on right now, so it is even harder to say what will happen.”