La Niña expected to bring changingweather patterns

By Michael Grass
Daily Staff Reporter

University students battled high winds, sheets of rain and temperamental umbrellas as bad weather moved into Ann Arbor yesterday.

"The weather was very depressing," said LSA senior Angela Moore. "I've been here for four years and I know that you have to buy a secure umbrella."

The worst weather, however, may be yet to come.

"It's been a relatively dry fall so far, but the weather is beginning to pick up," said Peter Sousounis, assistant professor for atmospheric, oceanic and space sciences.

The weather is expected to get more interesting in the upcoming months since meteorologists have predicted this winter will be affected by La Niña, a weather phenomenon that cools equatorial Pacific Ocean waters and has far-reaching effects.

Last winter, which saw periods of below normal precipitation and warmer temperatures, was influenced by La Niña's brother El Niño, which significantly warms Pacific Ocean waters.

Many people have heard that La Niña will bring a colder, harsher winter to the Great Lakes region, Sousounis said.

But the science behind how La Niña will affect regional weather is more complex. The winter jet stream is forecasted to cross North America, south of Michigan, steering most severe winter storms away from the area, Sousounis said.

"We will be under a more cold, dry air mass ... and we will experience more frequent periods of light snow," Sousounis said.

La Niña is expected to affect local weather by February and March, but "we could start feeling the effects by late December or January," Sousounis said.

"Actually, it could start snowing from tomorrow onward - the air is getting cold enough now ... we're ready for it," Sousounis said.

But are University students ready for winter?

"For graduate school, I want to move to a warmer climate," Moore said. "I don't particularly like the cold."

Last winter, El Niño brought warmer weather and very little snow to the Great Lakes region in January and February, creating poor conditions for skiing and other outdoor sports, Sousounis said.

In terms of precipitation, last year's El Niño winter was not too different from a normal winter. Detroit saw near normal precipitation, Sousounis said.

"It all depends on the timing," he said.

Sousounis said that last winter it was difficult to predict the weather. Forecast models would be totally different from the actual weather.

"But this winter, students should be able to trust the forecasts more," Sousounis said.

The last La Niña event, hitting the Great Lakes region during the winter of 1995-96, saw record amounts of lake effect snow. Brought on by colder winds crossing the warmer waters of the Great Lakes, lake effect snow normally pummels areas in West Michigan and the Upper Peninsula.

Students and faculty in the atmospheric, oceanic and space sciences department will be studying data related to precipitation in Michigan as La Niña approaches. In the study, made possible by a Great Lakes Environmental Research Lab grant, weather data dating from 1931 will be analyzed for possible relationships between the El Niño and La Niña weather patterns, lake effect snow and precipitation in Michigan, Sousounis said.

11-11-98