AccuWeather.com

By Alex Sosnowski, Expert Senior Meteorologist

May 16, 2011; 11:10 AM ET

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"If tropical moisture gets drawn into the storm, there's the potential for some serious problems."

AccuWeather.com meteorologists are concerned about the risk of flooding problems in the Northeast as a rainy weather pattern persists through the balance of the week.

A very slow-moving, upper-level storm will continue to pull moisture from the Atlantic Ocean over the mid-Atlantic, New England and neighboring Canada.

Heating from the strengthening sun, though absent from view much of the time, will also help to turn the atmosphere over, creating areas of torrential downpours, especially during the afternoon and early evening hours.

This could set the stage for some feisty thunderstorms in the southern mid-Atlantic this afternoon. On top of flooding downpours, these storms could produce damaging winds and hail.

Chief Meteorologists Elliot Abrams and Evan Myers are two of many worried about the situation.

"There is a band of moisture extending all the way into the tropics just off the Atlantic Seaboard," according to Abrams.

"If that tropical moisture gets drawn into the storm, there's the potential for some serious problems," Abrams added.

Expected rainfall amounts could double in that case.

Fortunately, nearly a week of rain-free weather helped many streams and rivers return to normal last week.

That dry weather could be critical for rivers if tropical moisture gets involved.

"Parts of the Northeast have already received from 1 to 3 inches of rain since the start of the weekend, as of Monday morning," according to Myers.

Due to the almost daily rounds of rain and the potential for training-effect downpours, with and without thunderstorms, at the very least there is concern for flash and urban flooding.

It is possible storm drains could be overwhelmed at times. As a result, developed areas would be the most susceptible to heavy rainfall first.

As long as tropical moisture stays away, few problems are anticipated, other than the inconvenience of foiled outdoor activities and slow travel.

As we said last week, trying to time when to cut the grass could be difficult this week.

Flooding continues to be a problem on Lake Champlain, which borders New York, Vermont and Ouebec, Canada.

A couple of weeks ago, record lake levels occurred.

Due to the slow drainage of the lake, waters continue to run well above flood stage and were hovering above record levels set in 1993.

According to Senior Meteorologist Jim Andrews, "Enough rain could fall this week over the Lake Champlain tributaries to lead to a new record flood."

Melting snow combined with the heavy rain from this spring and runoff from Lake Champlain has had the Richeliue River out of its banks for weeks.

The Richeliue flows northward into southern Ouebec.

Lake Champlain, like the lower Mississippi River, could be facing flooding problems well into the summer, due to the slow pace at which these two waterways rise and fall.

In addition, the weather pattern appears as though it does not want to cut these areas much of a break.