Flash flooding, severe storms may interfere with travel in NYC, Philly and DC

Have outdoor activities or travel plans in store into Monday in the eastern United States? If so, get ready to dodge downpours, flooded roads and locally severe thunderstorms.

Into Monday night, drenching rain and thunderstorms crawling across the East will continue to interfere with commutes and outdoor plans before the much-needed arrival of cooler, less humid and drier weather.

A slow-moving storm and trailing front are currently tapping into a zone of warm and moist air from near the Appalachians to the Atlantic coast, leading to drenching showers and thunderstorms across the region. As evidenced over the weekend, some of the storms in this atmospheric setup can turn feisty with damaging wind gusts, as well as heavy rain and flash flooding concerns.

Slow-moving thunderstorms recently unloaded 6-10 inches of rain on portions of Connecticut and southeastern New York in 24 hours. The rounds of repeating downpours unleashed flash flooding of small streams and sent water flowing across low-lying roads.

Motorists and airline passengers should anticipate major travel delays as downpours linger and severe storms approach.

Metro areas like New York City, Hartford, Connecticut, Philadelphia, Washington, D.C., Richmond, Virginia, and Raleigh, North Carolina, will be within the corridor where potent storms can fire into Monday evening. There will also be some pockets of severe thunderstorms and flooding downpours in central and eastern New England, including Boston, Providence, Rhode Island, and Portland, Maine.

"There can still be flash flooding of small streams and urban areas where it manages to pour for a couple of hours," AccuWeather Senior Meteorologist Dan Pydynowski said.

Areas that sustained infrastructure damage to drainage systems and roadways during Debby's deluge and downpours this past weekend may be most vulnerable to the quick runoff from downpours into Monday evening.

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The main reason that the Northeast did not experience widespread major river flooding from Debby was that intense rain fell in a narrow zone that affected mainly rural communities in the Appalachians rather than widespread heavy rainfall over the entire watershed of the large rivers, AccuWeather Senior Director of Forecasting Operations Dan DePodwin explained.

Farther south, Debby was not so kind to the Carolinas and part of Georgia. This zone was swamped by torrential rainfall over a broad area encompassing many major river systems. Rivers in the lowlands continued to run at moderate to high flood levels, with some not forecast to crest until late in the weekend or later this week.

Even though the bulk of the rain will focus on the Northeast into Monday night, enough downpours may occur along the Southeast coast to trigger flash urban and small stream flooding in some areas. As the rain runs off into the larger rivers, water levels may rise again in some locations, but not to the extent that Debby triggered.

Meanwhile, those at the beaches may face another dangerous problem. AccuWeather meteorologists continue to warn of the risk of frequent and strong rip currents due to Hurricane Ernesto, which was spinning over the North Atlantic and will pass near Newfoundland early this week.

By Tuesday, much of the Northeast will trend drier than what has been the theme the last few days.

Forecasters say that there may be a few stubborn showers in New England and along the mid-Atlantic coast, but a building zone of high pressure tracking eastward from the Great Lakes will promote dry conditions across the rest of the Northeast for the middle of the week.

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