Millions under flood watch in Northeast, Mid-Atlantic due to heavy rain from plume of tropical moisture

A stream of tropical moisture and a slow-moving frontal boundary are expected to produce periods of heavy rainfall from South Carolina into the Northeast through the first half of the weekend.

The National Hurricane Center had been tracking an area of low pressure as it swirled off the southeastern U.S. coast for possible tropical development.

It never organized into a tropical system but is still packing plenty of rain.

Meanwhile, a strong, but stalled front is acting as a source for atmospheric lift, constantly providing a focus for the storms to develop.

The tropical plume is then set to ride north along the front, dropping a train of torrential rain along its journey.

Flood Watches have been issued for 45 million along the Interstate 95 coastal areas from Boston through New York City and Philadelphia and into the Carolinas through at least the first half of the weekend.

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“I don’t think it’s a washout, I think each community will have part of their weekend to get out and enjoy,” said FOX Weather Meteorologist Britta Merwin.

“But also part of their weekend will feature board games, a movie, (and) kinda sticking inside.”

Most of the rainfall Friday will be focused along eastern Virginia and North Carolina, with a few stronger storms extending north along the I-95 corridor between Philadelphia and New York, according to the FOX Forecast Center.

With the setup remaining relatively static, those areas can expect multiple rounds of storms training northeastward along the front Friday into Friday night.

Widespread rainfall totals of 2-3 inches are likely along coastal Virginia and North Carolina, with isolated areas seeing up to 5 inches, according to NOAA’s Weather Prediction Center (WPC).

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Some storms could bring rainfall at rates of 2 inches per hour.

“The moisture is coming from the tropics,” Merwin said.

“And that means the thunderstorms and the showers will really drop a lot of rain… and that’s why we have some flooding potential.”

Parts of the Southeast have been rather dry of late, but isolated to scattered urbanized flooding will be possible where heavier rainfall totals are expected.

By Friday night, the focus for the heaviest rain shifts to northeastern Maryland, northern Delaware, far southeastern Pennsylvania, and southwest New Jersey.

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The flood threat may be greatest here as drought conditions are not as strong as areas to the south.

Overall, the WPC has placed communities such as Raleigh, New York, Baltimore and Washington, D.C. in a Level 2 of 4 flood risk through Saturday morning with hints that an upgrade to Level 3 may be coming for some in the region later Friday.

Saturday will see the deepest area of moisture shift to the northeast, and the storms will go along with it , the FOX Forecast Center said.

Expect another unsettled day featuring multiple chances for downpours from the Mid-Atlantic to southern New England.

The flood threat will be across parts of New England where storms are expected to move very slowly over nearly saturated ground.

Widespread sunny conditions will return on Sunday.

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