Great Lakes Article:

Cold winter may aid lakes

Ice cap would prevent evaporation and might stabilize water levels

December 4, 2001

BY DAN SHINE
Article courtesy of Detroit Free Press

A winter forecast for below-normal temperatures and average precipitation for the Great Lakes basin may mean an end to declining lake levels come spring.

Meteorologists at the National Oceanic and Atmospheric Administration predict temperatures will be 5 degrees below normal this winter, which would provide an ice cap over the Great Lakes and Lake St. Clair.

The cap would prevent evaporation, one of the main reasons for declining lake levels during the past four years. The forecast covers the entire Great Lakes drainage basin.

"The last three to four years, we haven't had sufficient ice cover," said Cynthia Sellinger, an NOAA hydrologist. "Last year, the lakes got to their lowest points from seasonal decline -- and then got lower because of evaporation."

Lakes can lose 1 to 2 inches of water a week from evaporation during fall and winter, when the water is much warmer than the air moving across the lakes. Predictions of average precipitation for this winter do not mean that the lakes will return to the levels they were before the decline began. That would take several winters of heavy snowfall and cold temperatures.

But an ice cap combined with average precipitation would mean the lakes won't decline further and could possibly rise in the spring, Sellinger said.

Lake levels have declined steadily during the past four years, affecting shipping and pleasure boaters.

Lake Superior is 7 inches below its long-term average; lakes Michigan and Huron are 16 inches below their average; Lake St. Clair is 10 inches below its average; Lake Erie is 8 inches below, and Lake Ontario is 2 inches below.