Source: Sherman Publications

Warm winter explained

by Gabriel L. Ouzounian

February 15, 2012

"Better late then never" is a term many would not apply to winter's late arrival in Lake Orion, but the snowy season seems to have finally arrived.

The cause of the delay is not common knowledge. The term "global warming" has surfaced on many lips but, according to the experts at the Great Lake Environmental Research Lab in Ann Arbor, the cause involves more than just greenhouse gases.

"One of the factors is certainly global warming, but that doesn't account for all of it," said Brent Lofgren, physical scientist for the National Oceanic and Atmospheric Administration(NOAA). "We've got a positive phase in the North Atlantic Oscillation (a weather phenomena which alters the bearing and power of westerly winds.) This tends to bring in warmer air from the south, but there's always an element of chance with these factors. You combine those elements with climate change due to greenhouse gases and a few more chance occurrences and it adds up to a warm winter.

"It's not even the warmest January we've had - it's the eighth."

According to Lofgren, air pressure on the surface of the earth near Iceland is ordinarily much lower than current levels. The magnitude changes over a period of around seven years and results in stronger, warmer winds from the southwest.

Russ Stowers, an earth science teacher at Lake Orion High School, said the effect is consistent with an El Niņa winter.

"Basically our weather patterns have shifted," said Stowers. "The weather that comes our way is a result of wave-like action southwest to northeast. Those weather patterns have moved further west. Basically our weather is now too far to the west. As far as snow, we're not behind on precipitation, but we're not getting any additional snow fall."

Lofgren also commented on the lack of precipitation, adding he finds people are often puzzled by lack of snow despite cold conditions.

"One I hear a lot that confuses people about the amount snow is that many think the colder it is the more snow you get," he said. "You need two conditions - below freezing-point temperatures and moisture, with the moisture being more important."

Despite the warm weather, changes in subsequent seasons should remain minimal according to Lake Orion Life Sciences Teacher Tim Polunki, though he said noticeable changes could be seen in shoreline habitats due to lack of ice and a buggier summer due to the low number of deep freezes.

"We rely on ice covering lakes to prevent evaporation, which could change the shoreline a bit," he said. "Weeds could develop in places where they don't usually grow and, because we haven't had any deep freezes, larval survival will increase, leading to more bugs in the warmer months.

"Of course this is all temporary - last year we had one of the snowiest winters on record."

Lofgren said because of the high amount of precipitation in 2011, lake levels wouldn't change much and added they were actually higher than they were last year. He agreed the lack of ice cover would promote evaporation, but said new studies have determined the effect of evaporation on lakes may be exaggerated. Other factors could change the outcome as well, including runoff, but overall the levels remain in normal ranges.