English: Lock and Dam Number 2 on the Allegheny River at Aspinwall, Pennsylvania, USA (part of the Pittsburgh metropolitian area). The lock and dam were built by the U.S. Army Corps of Engineers as a part of an extensive system of locks and dams to improve navigation along the Allegheny River. The Highland Park bridge crosses the river just above the dam. (Photo credit: Wikipedia)
The Allegheny River is poised to see its largest river ice jam in almost 20 years, according to the National Weather Service.
“The last time we had a major ice event was January 1996,” said Lee Hendricks, a meteorologist at the National Weather Service in Moon. “There was a lot of ice, primarily on the Allegheny River, and a decent snowpack.” A snowpack forms when snow from the surrounding countryside melts and runs into creeks, rivers and lakes.
“Rain covered the top (of the ice) and we had decently high temperatures,” he said. “It caused the ice to break loose and caused a lot of problems, including flooding in a lot of locations and river navigation headaches.”
Hendricks said the region’s extremely cold temperatures won’t break for at least another 10 days, so conditions will be ideal for the same situation to occur.
Read more: http://triblive.com/neighborhoods/yourallekiskivalley/yourallekiskivalleymore/5469537-74/ice-river-allegheny#ixzz2rKs8N291
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Roy's Rants - For Your Information 
What most “green weenies” don’t understand is that we are in a natural weather cycle.This is not “climate change”.I remember growing up in the 70’s we had winters that froze up the rivers here in the Pittsburgh area. This winter reminds me of the winters I seen growing up as a kid.
Freezing rivers is not new to Pittsburgh.We have had the coldest weather in 20 years.
Spring can’t come soon enough for me.