As rivers and lakes in the Midwest temporarily began to thaw from a long, frosty winter, some residents have been asked to evacuate as ice jams encroach on their lives.
According to NOAA, an ice jam occurs when pieces of floating ice are carried downstream and build up behind any obstruction. Water gets held back by the impediment, and if the ice jam suddenly breaks free, the rush of water can lead to flooding downstream.
Late last week, mild temperatures allowed ice to wriggle free and flow downstream in multiple states. Southwest of Chicago, ice jams on the Kankakee River forced water over the river banks, NBC Chicago reports. Along this river, ice jams are an annual occurrence, but conditions have gotten so bad this year that a bridge near Kankakee River State Park had to be closed after ice jams piled up and may have caused structural damage to the bridge.
The swollen river drew dozens of onlookers who stood on bridges to take pictures of the massive ice chunks, according to a WGN-TV report. There's little that can be done about these ice jams, the U.S. Army Corps of Engineers told WGN, but last week, warm water was pumped from a Will County nuclear plant to melt some of the ice chunks.
Not every Northern town threatened by flooding has that option, and there's plenty more ice jams on the way as temperatures rise on the long trek toward spring. In Vermilion, Ohio, the Vermilion River, which flows into nearby Lake Erie, is so jammed with ice that some residents had to be evacuated, according to a Cleveland.com report. To the east, an ice jam along Rocky River broke free, providing good news for nearby towns on edge.
In western Pennsylvania, flood warnings have been issued for Armstrong and Clarion counties due to an ice jam that is blocking the Allegheny River, creating a backflow of water into Parker, according to an Associated Press report. State Route 268 has been flooded and at least two people have been rescued from the floodwaters in Parker.
find this story at: http://www.weather.com/news/commuter-conditions/ice-jams-midwest-20140224
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