AccuWeather.com

By Alex Sosnowski, Expert Senior Meteorologist

Mar 10, 2010; 9:55 AM ET

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A rainstorm spanning Friday into Sunday combined with melting snow threatens the Northeast with urban, stream and river flooding problems this weekend into next week.

Why

A storm rolling in from the southern Plains will reorganize, strengthen and linger over the Northeast this weekend.

A general 1 to 3 inches of rain combined with climbing temperatures, moist air and strong winds will eat through the snow like crazy, releasing a half a foot of water some areas.

Where

The effects will not be immediate. However, increasing runoff in the Alleghenies, Endless, Poconos, Catskills, Adirondacks, Green, White and Longfellow mountains spanning this weekend into early next week will be enough to trigger minor to moderate flooding.

There is increasing concern that a rapid meltdown and major to severe flooding could occur on some slopes of these mountains and watersheds. A situation like this occurred during January of 1996 much of the region.

Small streams will rise first during this runoff, followed by progressively larger rivers including the Allegheny, Androscoggin, Connecticut, Delaware, Ohio, Mohawk, Monongahela, Susquehanna, Youghiogheny and the upper Hudson rivers.

While the risks of small stream flooding spans hours, the concerns of flooding along rivers will span days.

Coastal Flooding Too

Along the coast, a period of strong onshore winds may lead to flooding at times of high tide and beach erosion Saturday into Sunday.

Heavy rainfall alone may be enough to lead to street flooding along the Interstate 95 corridor from Washington, D.C., to New York City, Boston and Portland, Maine.

Get Prepared

If you are prone to flooding in the spring or during any episodes of heavy rain, now is the time to take precautionary action. Move valuables out of your basement. Have a plan of action in place in case floodwaters arrive quickly.

Officials in some areas have begun to take action. According to the Pittsburgh Post-Gazette this past Tuesday, the Army Corps of Engineers have drawn down 16 reservoirs in southwestern Pennsylvania.

Ongoing Flooding Concerns

Dangers of flooding will remain well after this storm departs next week. Rivers left running high, combined with saturated ground will be like a loaded gun as additional March storms roll in.