Hurricane Henri Poses Risk of Inland Flooding

Forecasters say the storm could stall over the mountains of the Northeast, causing flooding similar to Hurricane Irene in 2011.,

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The approaching storm brings the risk of inland flooding.

Flooded streets in Brooklyn from rain dropped by Hurricane Irene in 2011.
Flooded streets in Brooklyn from rain dropped by Hurricane Irene in 2011.Credit…Hiroko Masuike/The New York Times

By Adam Sobel

  • Aug. 21, 2021, 4:02 p.m. ET

Adam Sobel is a professor and director of the Initiative on Extreme Weather and Climate at Columbia University. He is an atmospheric scientist and host of the “Deep Convection” podcast.

As the forecast for Hurricane Henri has evolved over the past few days, attention has focused on where the storm will make landfall and the risks from wind and storm surge on the coast. But the latest forecasts point to a substantial and perhaps underappreciated risk from inland flooding.

For New York State in particular, the threat is shaping up to resemble not so much Hurricane Sandy in 2012, but Hurricane Irene the previous year. That storm devastated the mountainous eastern parts of the state, as well as much of New England. Its slow motion allowed rainfall totals to escalate, filling small tributaries and then larger rivers past their banks.

Henri, too, is expected to move slowly after landfall, but its predicted path has shifted west with time. Saturday morning’s forecasts showed potential rainfall of five inches or more, not just in parts of Long Island, Connecticut and Western Massachusetts, but also in a swath of southeastern New York that includes some of the same areas hit by Irene, including the Catskill and southern Adirondack Mountains.

Some of those areas have seen a wet summer already, compounded recently by substantial rain from the remnants of Tropical Storm Fred.

Soils will be moist and unable to absorb much more water, so new rain will produce flooding sooner. Wet soils also make trees more prone to uprooting in high winds, so widespread power outages are a possibility, as is flash flooding.

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