Thaw Points To Spring Floods
Harsh winter could mean rough times ahead in watershed
In March, the Great Lakes were nearly 92 percent iced over. (Courtesy NOAA)
As warmer temperatures announce the arrival of spring, some of the most significant ice coverage on the Great Lakes in decades is finally beginning to diminish.
And while officials warn of the dangerous conditions a rapid melt can present anglers and boating enthusiasts throughout the Great Lakes Region, the potential remains for flooding farther south as well.
In early March, the overall Great Lakes ice coverage reached 92 percent, the most extensive freeze since the nearly 95 percent coverage seen in 1979, according to George Leshkevich, a physical scientist with the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory in Ann Arbor, Mich.
At that point, officials realized the dangerous conditions that awaited when the spring thaw finally did arrive.
“You could have runoff and ice jams, and any number of those could result in flooding,” Leshkevich told the Buffalo News. “Especially if you get a quick melt, you could get significant flooding in those areas.”
By the first week of April, the ice cover had dropped significantly to 54 percent, and the unpredictable situations caught some off guard.
Near Duluth, Minn., a group of more than a dozen people was trapped on a drifting ice floe before jumping to safety when the floe neared the shoreline.
In Harrison Township, Mich., four people became stranded on Lake St. Clair as ice began to break up. Due to shallow conditions, rescue crews were able to safely walk the group off the ice.
“Ice conditions are rapidly changing,” said Karl Willis of the U.S. Coast Guard’s 9th District Command Center in Cleveland. “Warmer temperatures and wind significantly affect ice strength and can lead to extremely hazardous conditions with a high probability for drifting pack ice.”
Even before the thaw, ice jams caused flooding in some areas where local streams and rivers remained flooded.
The large ice coverage could result in flooding conditions much farther south than the Great Lakes.
The NOAA’s National Hydro Logic Assessment was released on March 20 and details the spring flooding risks for the U.S. in 2014. While the report did not go as far as to predict heavy flooding, it did say a significant flood potential exists with even typical spring rainfall.
“With significant frozen ground in these areas, the flood risk is highly dependent on the amount of future rainfall and the rate of snowmelt this spring,” the report said. “Recent snowmelt has increased the near surface soil moisture and elevated the potential for rapid runoff from rain events.
“In addition, significant river ice increases the risk of flooding related to ice jams and ice jam breakups.”
Some areas of the Midwest along the Mississippi River that typically deal with spring flooding could expect it again, according to the report.
“Specific rivers at risk include the Mississippi River between Davenport, Iowa, and Burlington, Iowa, the Illinois River between Beardstown, Ill., and Henry, Ill., and many smaller rivers in the area,” it said.
Check out the complete report at http://www.nws.noaa.gov/hic/nho/