Winter Weather
12:34 pm
Tue February 18, 2014

With High Temps Expected This Week, Melting Snow Could Bring Flooding

The National Weather Service is calling for temperatures to reach the low 50s this week, meaning the possibility of a lot of melted snow and ice — and floods.

Werner Loehlein, the chief of the water management for the Pittsburgh Army Corps of Engineers, said the Corps always worries about substantial snow and river ice when the temperature rises.

However, he said the latest forecast from the National Weather Service appears to show that Pittsburgh is safe from flooding.

“It’s a little bit delayed and it doesn’t appear to be as long a duration as originally forecasted a few days ago,” Loehlein said. “So winter’s still holding on a little bit.”

Loehlein said Pittsburgh has had 57.5 inches of snow so far this year, whereas the average snowfall is usually 42 inches for the entire year in the city.

If the forecast is correct, he said there will be about a four to six foot rise on the Monongahela River, a foot or two rise on the lower Allegheny River and a five to 10 foot rise on the Ohio River.

Loehlein said the flood stage in Pittsburgh is 25 feet.

“Though it’s a significant rise, it doesn’t look like it’s going to be anywhere near flood stage so that part is still good,” Loehlein said. “But we still have a lot of snow, we still have a lot of ice, and it’s going to get cold next week so it’s like we’ll be talking about this into the early part of March.”

According to Loehlein, if the daily high temperature is above freezing and the low temperature drops below freezing, the snow melt starts and then stops, which is ideal.

“If you have one day where it’s both above freezing, that’s okay,” Loehlein said. “It’s when you get two days or three days in a row where it happened like that, then it all can come out at one time, and for Pittsburgh that becomes a problem.”

He said that could cause the Allegheny and the Monongahela Rivers to melt and rise at the same time, creating a lot of high water in the city.

The Pittsburgh Water and Sewer Authority (PWSA) is still anticipating the melted snow to create basement flooding and drainage issues.

The PWSA suggests residents clear snow from ground drains and gutters and be careful not to cover catch basins or fire hydrants when shoveling.