Henri intensified into a hurricane Saturday morning, as the storm charged up the East Coast toward Long Island and southern New England, where it is expected to come ashore Sunday.
Hurricane warnings are in effect for eastern Long Island, coastal Rhode Island, much of coastal Connecticut and parts of southeast Massachusetts, where damaging winds could bring hundreds of thousands of power outages. Meanwhile, the storm’s ocean surge and heavy rainfall could yield dangerous flooding both along the coast and inland.
“A dangerous situation unfolding across the NE U.S. this weekend as #Henri approaches,” tweeted Louis Uccellini, director of the National Weather Service. “A track perpendicular to coast at landfall is worst case scenario for surge & wind impacts for [Long Island] and southern New England.”
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Flanking the hurricane warnings, tropical storm warnings cover northeast New Jersey, New York City and western Long Island and extend into Martha’s Vineyard and Nantucket to the northeast. Here, Henri’s impacts could be serious but less severe than in the hurricane warning zone.
Downpours surging northward ahead of the storm triggered flash flood warnings around New York City, unloading up to 3 to 4 inches of rain Saturday evening.
It’s been 10 years since hurricane warnings were last issued for the Northeast, where Irene came ashore as a tropical storm in August 2011. And if Henri strikes at hurricane strength, it would be the first storm to do so in the Northeast since Bob in 1991. Residents are preparing for what could be an extended duration without electricity.
“Hurricane conditions are expected to begin late tonight or Sunday,” warned the National Hurricane Center. “Dangerous storm surge inundation is expected,” it wrote.
Current projections bring Henri ashore between eastern Long Island and the coast of Connecticut and Rhode Island between late Sunday morning and afternoon, although slight shifts in the location and timing are possible. Tropical storm conditions could reach coastal areas early Sunday morning.
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“Residents should start preparing for power outages and coastal flooding,” tweeted Laura Curran, executive for Nassau County on Long Island. “Our crews will be working around the clock.”
Connecticut Gov. Ned Lamont (D) declared a state of emergency ahead of the storm. “We’re anticipating heavy rainfall and high winds, with coastal and urban flooding a significant concern,” he tweeted Friday.
The surge, or storm-driven rise in ocean water above normally dry land, could be “life-threatening,” and tides are running high anyway thanks to Sunday’s full moon.
Flash flooding could also be widespread, with more than half a foot of rain expected in Long Island and areas east of the Berkshires in western New England. That comes following what was the wettest July on record for many cities in the Northeast. The Weather Service cautions of a “moderate risk” of flash flooding and excessive rainfall, “with isolated maximum totals near 10 inches” probable.
“Major rainfall flooding may prompt many evacuations and rescues,” stated the Weather Service, breaking out unusually strong language ahead of Henri’s closest approach. “Floodwaters can enter many structures within multiple communities, some structures becoming uninhabitable or washed away.”
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There’s also a storm surge warning in effect in areas including Queens and along the East River in New York City, as well as along the shoreline of Long Island, Connecticut, Rhode Island and southeast Massachusetts.
While they won’t be directly affected by wind and rain, areas farther south in the Mid-Atlantic from the North Carolina Outer Banks to the Maryland-Delaware beaches will have “life-threatening surf and rip currents” through the weekend, according to the Hurricane Center.
The latest on Henri
As of 11 p.m. Saturday, Henri was about 180 miles south-southeast of Long Island and had gained some speed during the day, charging north at 21 mph. Its sustained winds were 75 mph, unchanged from the Hurricane Center’s 11 a.m. advisory that upgraded it to a hurricane.
The Hurricane Center said its satellite appearance was less ragged than earlier in the day but that the storm had not strengthened significantly even as it passed over the warm waters of the Gulf Stream. “Henri is almost out of time to strengthen, as the center will be moving north of the north wall of the Gulf Stream during the next several hours,” it wrote.
Henri will begin to weaken early Sunday as it becomes removed from the mild waters east of the Delmarva Peninsula, approaching Long Island as a strong tropical storm or near hurricane strength.
It’s important to note that the Saffir-Simpson hurricane wind scale only describes storms based on their estimated wind speeds and doesn’t take into consideration any of the frequently more high-impact attributes associated with a landfalling system, such as inland flooding.
Wind threat
Residents in the Northeast are accustomed to cool-season “nor’easters,” which often bring a buffeting wind in addition to widespread beach erosion and rain or snow. While Henri will be similar in magnitude from a wind and surge standpoint, the presence of fully leafed trees, a sodden ground from earlier wet conditions and an additional deluge of rainfall will make for significantly more tree and vegetation damage, rendering power outages all the more likely.
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Eversource Energy had already dispatched thousands of crews to the Northeast ahead of Henri, positioning them for post-storm cleanup while also working to mitigate risk before the first drops of rainfall.
“Trees are the [number one] cause of power outages during a storm,” the company tweeted.
Different locations will face different hazards.
The left side of the storm will be more rainy, and the right side more windy.
There are lots of alerts and lots of sources of info with #Henri. Here's a simple graphic of what folks should reasonably be preparing for. pic.twitter.com/UodGy7KLNi
— Matthew Cappucci (@MatthewCappucci) August 21, 2021The strongest winds will be found within about 25 miles of the center and could gust over 65 mph on Long Island, southern Connecticut and coastal Rhode Island. A sporadic 75-plus mph gust near the shoreline can’t be ruled out. The strongest winds arrive around sunrise Sunday and last about six hours.
Winds will be considerably weaker farther inland — 30 mph or less in Boston, New York, Providence, R.I., and Hartford, Conn.
East of the center, winds will be from the south, with northerly winds on the left side of the storm.
Storm surge
The wind will pile water up against the coastline, potentially resulting in a significant storm surge that could cause damage to coastal property and infrastructure. A 3-to-5-foot storm surge is possible in a worst case-scenario situation in Long Island Sound, depending on when Henri makes landfall, especially if Henri passes just to the east. That would push seawater to the western end of the sound, which would be problematic for those along the East River in New York City.
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A similar surge is expected on the southern end of Long Island, but may not be realized due to the projected path of Henri. A minor surge is possible in coastal New Jersey.
Narragansett Bay in Rhode Island, as well as Buzzards Bay and Nantucket Sound, are all prone to serious flooding during tropical systems. A 3-to-5-foot surge is possible there too and has a greater chance of occurring due to the likelihood of prolonged onshore winds. Cape Cod Bay could see a few feet of splashover.
“The combination of a dangerous storm surge and the tide will cause normally-dry areas near the coast to be flooded by rising waters moving inland from the shoreline,” wrote the National Hurricane Center.
The severity of the surge will depend on whether Henri makes landfall around high tide; right now there is some possibility that landfall occurs closer to low tide than high tide, which lowers the risk of a worst-case scenario.
Heavy rainfall
Storm surge will only affect residents near the coast, and Henri’s wind footprint will admittedly be small. The most widespread risk is flash flooding due to heavy rainfall.
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Weather models are in good agreement that a serious amount of moisture will be unloaded from Henri, particularly near and west of the system’s center. Torrential tropical downpours with rainfall rates topping an inch per hour will contribute to widespread totals of 3 to 6 inches on eastern Long Island, parts of the Connecticut River Valley, the Hudson Valley and Catskills. Localized amounts up to 10 inches are possible.
The heaviest totals should mostly focus west of Worcester County in Massachusetts and west of the Connecticut-Rhode Island border. Heavy rain and flooding could even creep into southern Vermont and New Hampshire. But Henri is probably a nonevent in places such as Boston, which may struggle to see a quarter inch of rain.
Many areas in southwestern New England have seen over a foot of rain since July 1. Data indicates that soils are saturated and can’t handle much additional rainfall.
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New York City and New Jersey — which should see, on the average, significantly lesser rainfall from Henri’s core — may still wind up beneath sporadic pop-up downpours invigorated by Henri’s tropical moisture. The waterlogged areas could pick up isolated heavy downpours with torrential rainfall rates of several inches per hour.
Henri will linger over southern New England as a leftover swirl of rain and breezy winds Monday before dissipating altogether on Tuesday into Wednesday.
Ian Livingston contributed to this article.
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