snap saves Lake Erie from further declines Tom Henry
The Toledo Blade
The cold snap has been a blessing to the Great Lakes, because
it has frozen much of the water south of Lake Superior and
has sealed off the lower lakes from further evaporation
at a critical time of year.
But officials are leery about the summer outlook, predicting
an eight-inch decline in Lake Erieís water level this June
and proportionate declines elsewhere.
They blame roller-coaster temperatures that led up to the
recent blast of arctic-like weather, plus a long drought
in the upper lakes that replenish Erie. The Great Lakes
region had a relatively dry fall. Those in the region may
have shoveled a fair amount of snow this winter, but, in
some parts, much of whatís fallen is viewed by hydrologists
as a mirage because it was lake-effect.
That is snow formed by cold air masses that rob moisture
from the lakes before they freeze over, Cynthia Sellinger,
a National Oceanic and Atmospheric Administration hydrologist
in Ann Arbor, explained. The lakes do not get that water
back in a quick snow-and-melt cycle: Unless it is part of
a snow-pack that thaws gradually, the stuff usually evaporates
before it can replenish a water body, she said.
The good news to her and other Great Lakes watchers is that
the evaporation cycle has been broken by the cold snap.
"Absolutely," Ms. Sellinger said. "[Having Lake Erie freeze]
is the best thing that could have happened."
The bad news: The National Weather Service is predicting
above-average temperatures and below-average precipitation
in the coming months. If that proves to be true, she said,
lake levels will invariably be lower than they were last
summer - the only questions will be by how much and what
effect that will have on recreational boaters and the shipping
industry, both vital cogs to the regionís economy.
"There could be a tremendous amount of boat repairs from
boaters hitting old hot-water tanks and other debris that
all of a sudden are in propeller range because the water
level dropped," predicted Macomb County marina owner George
Chuck Brockman, a Lake St. Clair boater for 50 years, said
he copes with changing levels by reading charts more carefully
and avoiding unfamiliar spots. "Experienced boaters will
be OK. The newer boater will have to learn," he said.
Shippers must haul lighter loads when lake levels decline,
which increases costs.
The driving force of the Great Lakes is Lake Superior, by
far the deepest lake. It is so deep that its temperature
fluctuates only a few degrees, despite its northern latitude.
Ray Assel, a NOAA physical scientist who has spent years
studying Great Lakes ice patterns, said he cannot cite a
single year in which Superior has formed a thick block of
ice across the lake. "I would hesitate to say it ever freezes
over completely," he said.
A lot of what happens to Lake Erie this summer depends on
how much ice forms and snow falls in the upper Great Lakes
the rest of the winter, he said.
"Itís been very dry in the Michigan-Huron [lakes] basin
the past six months," said Marie Strum, water resources
engineer with the U.S. Army Corps of Engineers in Detroit.
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