PITTSBURGH (KDKA) — Flooding caused some major damage in the Pittsburgh area last weekend, and Allegheny County Emergency Services says there may be even more this weekend.
A heavy white crust frozen in place hides the flowing water of the Allegheny River. Make no mistake the river is flowing, and that’s just what people who live along its banks want it to continue to do.
The flow is being fed by the snow pack throughout the region rapidly melting under a brilliant winter sun. National Weather Service Hydrologist Lee Hendricks says most of the snow will be gone by Sunday.
“You’re going to have runoff going into the streams which will help weaken and help erode some of the thinner ice,” Hendricks said.
The runoff will add to the flow and start eroding the ice from below while the sun and rain coming Sunday will work on it from above. Hendricks says that will cause a rise in the river levels.
“Usually it takes about three feet of movement to get stable ice to break loose and start moving on the rivers,” he said.
Moving is not necessarily good because the ice is anywhere from six inches to feet thick, and it only takes a bend in the river or a bridge to cause an ice jam. Hendricks says when a jam occurs, the river behind the jam will rise rapidly.
“It can go up a couple feet an hour,” he said.
There is already some ice prompted flooding on the Kiski River.
“If we do get an ice jam just below Freeport or above Natrona, you could have backwater flooding into the mouth of the Kiski and farther on up as far as Vandergrift,” Hendricks said.
So far things look pretty good on the Mon although Hendricks says there is some ice.
“There is some ice down around Charleroi and Maxwell, but it’s not really obstructing flow,” he said.
The Yough is showing a lot of ice especially, according to Hendricks, “up around Connellsville and farther upstream towards Ohiopyle.”
On the Ohio River, there is quite a bit of ice in the Dashields Dam area, but the biggest concern is more ice coming out of the Allegheny and Mon and piling up at the Emsworth Dam. Crews there are still trying to get to the barges that broke loose and lodged against the dam last weekend.
“They’ve got ice that’s at least ten feet thick right now that is up against Emsworth [Dam] that they are trying to dig out,” Hendricks said.
Hendricks says while the Kiski is under a flood warning going into the weekend, for the rest of the rivers, “the greatest likelihood of any problems would probably be Monday or into Tuesday.”