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Forecasters warn of potential ice jams this weekend

HARRISBURG, P.A. --- Over the last few days, warmer conditions have made the Susquehanna River less icy.

However, with forecasters predicting rain across the entire Susquehanna basin, a lot of water will be quickly flowing down stream through Saturday night into Monday.

Experts believe it will, most likely, dislodge the ice at some point in that timeframe.

"When the ice moves around say the bend of a river, maybe a little bit of a turn or a subtle change, maybe the river gets a little narrower, there are certain places where ice tends to slow down and jam up if the right conditions happen," said Charles Ross, senior service hydrologist with the National Weather Service located in State College.

Ice jams become temporary dams, blocking the flow of water downstream, potentially causing flooding.

Ross said the problem for forecasters is they can never predict where a jam might form.

"I wish I could tell you there's going to be an ice jam at this location but it just doesn't always work that way. It depends on the nature of the ice and how it moves," said Ross.

Ben Pratt, hydraulic engineer with the Susquehanna River Basin Commission, predicts the water in the Susquehanna River to rise a little above 10 feet starting Saturday night.

To put that in perspective, in Harrisburg, 11 feet calls for action and 17 feet means flooding over the banks.

But Pratt said that rise doesn't account for ice in the channel and with a significant amount of ice already in the channel, he said it creates cause for warning.
"Unfortunately, it'll happen in the dark, or could happen in the dark with the river rising overnight. Ideally, we'd like this thing to take place at noontime in broad daylight," said Pratt.

Pratt also said a myriad of factors come to play in what might happen, such as how much the river will rise? What will happen to the ice? And how much will freeze when temperatures drop tonight?

In the meantime, he said he want residents to know the river conditions could change rapidly over the weekend.

"If you have an interest along the river, you need to be aware of that risk and make appropriate decision to protect yourself and your property," said Pratt.

While experts call it a "unique" scene in nature, Pratt said to "enjoy the show from the shore."

They say don't go out onto the ice and keep your distance from the river due to risk of large amounts of ice, moving quickly.