Great Lakes mostly frozen over; big thaw to replenish water levels

Harsh winter of snow, ice drawing tourists and researchers

Lake Michigan’s frozen waters and snow draw photographers to the shore of northern Leelanau County between Northport and Leland. The ice ridges were several hundred feet from shore.

ASSOCIATED PRESS

Lake Michigan’s frozen waters and snow draw photographers to the shore of northern Leelanau County between Northport and Leland. The ice ridges were several hundred feet from shore.

The 2014 version of the Great Lakes region’s incredible spectacle of ice — one of the most dazzling displays of frozen art provided by nature in years — is slowly fading.

Despite the forecast for a heavy, late-season snowstorm today and for temperatures in the 20s on Thursday, the great thaw is gradually settling in as daily highs are expected to climb back into the 40s on Friday.

Expect another curve thrown our way this weekend, with the forecast calling for freezing daytime temperatures on Sunday and Monday after being in the high 30s on Saturday, which is the usual March zigzag.

But while this throwback of a winter has included its fair number of surprises and memorable bone-chilling events, the calendar suggests spring is on the way, meaning the days of icy splendor between Duluth and Montreal will be melting into a more familiar, watery vista over the next several weeks.

Thousands of people have visited western Lake Superior ice caves in Wisconsin’s Apostle Islands and in northern Lake Michigan’s Leelanau Peninsula.

While many of the Great Lakes region’s 30 million U.S. and 10 million Canadian residents are fed up with winter, many others have braved subzero temperatures to go out on the ice.

They’ve flocked in such crowds up and down the Lake Michigan shoreline that sheriff’s offices and local police have gone out to control Super Bowl-like traffic jams at times.

Ice balls the size of boulders have been found along the Sleeping Bear shores of Lake Michigan. Images have appeared of wolves venturing out on Isle Royale’s frozen cliffs.

False stories even spread that the cold had frozen Niagara Falls solid — talk generated by some crafty photographs circulated across the Internet that had been taken at strategic angles. The American and Canadian falls have indeed had more ice than usual.

Amazing winter ice formations are nothing new for the Great Lakes region, but many agree they’ve been more dramatic this winter because of the sheer volume of ice.

Ice covered 92.2 percent of the Great Lakes last Thursday, according to the National Oceanic and Atmospheric Administration.

That’s the most since 94.7 percent of the Great Lakes surface area was frozen over in early 1979. As of Monday, less than 84 percent of the ice cover remained, according to NOAA. 

Flood concerns

Contrary to what many wonder — if this winter will ever end — the question isn’t if that ice will melt. It’s how fast.

Heavy rain or rapid melting could play havoc with the region’s storm sewers and result in flooding.

“We’re certainly paying very close attention to the weather in the next few weeks,” said Keith Kompoltowicz, hydrology branch chief of the Army Corps of Engineers district office in Detroit.

The corps and NOAA are the two federal agencies that predict and monitor Great Lakes water levels.

Late last fall, the corps said it expected a winter robust enough to help restore some of the long-suppressed Great Lakes water levels.

The region got that and more. In addition to thick ice holding in more water, lakes Superior, Michigan, and Huron have had their best snowpack in a decade. The upper lakes’ water levels greatly influence the levels of Erie and Ontario because of how the water flows down to them.

Ice also has sealed off a lot of winter evaporation.

Although scientists are learning evaporation in the fall has been somewhat underrated, winter evaporation continues to be among the most dramatic.

The lakes are under great stress — and expend a lot of energy — just because they freeze over because of the differences between air and water temperatures.

“By a long shot, this is the most ice we’ve had on Lake Superior in 20 years,” Jay Austin, associate professor at the Large Lakes Observatory in Duluth, Minn., told Accuweather.com. 

Low water expensive

The low-water era has cost the region in many ways — including higher shipping costs because less cargo could be hauled on ships transiting shallower channels, and more dredging to keep those channels open at all.

George Leshkevich, a physical scientist at NOAA’s Great Lakes Environmental Research Laboratory in Ann Arbor, said there’s no question all the ice has reduced evaporation and will boost water levels.

He said it’ll be especially helpful if this spring’s melt is slow and gradual, allowing ice to remain in the water longer and keep the water cool as summer arrives. That also would help combat evaporation, Mr. Leshkevich said.

The corps is projecting near-normal levels for the lakes this summer.

Lakes Michigan and Huron are expected to regain 9 to 14 inches, yet still could be as much as a foot below their long-term average.

Lake Superior, which holds more water than the other four Great Lakes combined, might edge above its long-term average this month for the first time since 1998. 

Ontario freezes last

Many might be surprised to learn the lake bringing down the region’s ice-cover average is Lake Ontario. Its surface, even now, is less than 60 percent frozen. The others were as much as 91 to 96 percent frozen.

Lake Ontario is last to freeze for a number of reasons: It has one of the region’s warmer climates — though residents of upstate New York might disagree — and gets warmth from two hydroelectric plants. But, perhaps more importantly, it has some of the fastest-moving water and relatively little surface area for its depth.

By being a deep and more confined body of water, it retains more warmth, Mr. Leshkevich said.

While Lake Superior is much deeper than Lake Ontario, it has considerably more surface area, which allows for more rapid heat loss and, thus, freezing. It also is in the most frigid climate.

“Certainly, the depth vs. surface area has to be a factor,” Mr. Leshkevich said. 

Niagara Falls flow

Internet chatter of Niagara Falls freezing over solid appears to be a result of photography that was more visually stunning than usual.

A solid ice bridge formed at the falls’ base, as has happened before. More than a century ago, people were allowed to walk out onto those ice bridges to view the falls from below. But after three tourists died when caught beneath the falls when an ice bridge broke up on Feb. 4, 1912, such access has been denied.

There was a partial freezing, mostly spray mist that formed ice on rocks and became thicker along the shoreline as winter progressed.

But the flow of the Niagara River between Lake Erie and Lake Ontario never came to a standstill, including in the U.S. and Canadian areas collectively known as Niagara Falls.

One news crew’s video that has been circulated among several Web sites shows tourists showing up this winter, disappointed to learn the falls were still flowing.

According to Niagara Falls State Park, water flows over the falls at a rate of 3,160 tons per second.

That also can be expressed as 75,750 gallons per second over the American and Bridal Veil Falls and 681,750 gallons per second over Canada’s Horseshoe Falls, a park fact sheet states.

“It’s just the volume of the water and the speed,” Mr. Leshkevich said. “It’s got to be the Ice Age to get Niagara Falls to completely freeze.”

Although the more powerful Horseshoe Falls on the Canadian side have never frozen over, a promotional guide for the region said the American Falls have frozen over six times, most recently in 1949, because of ice jams.

An ice boom installed at the mouth of Lake Erie, plus the construction of a dam jointly operated by the United States and Canada have “all but eliminated the possibility of the American Falls ever completely freezing over in modern times,” the guide said.

Information from The Blade’s news services was used in this report.

Contact Tom Henry at: thenry@theblade.com or 419-724-6079.