Long Island and Connecticut under hurricane warning as threat from Henri grows

The slow-moving storm could bring serious coastal and inland flooding and damaging winds with conditions starting to deteriorate as soon as late Saturday night.

Recent computer model forecasts have become more locked on the likelihood of a direct hit by Henri, which is most likely to make landfall somewhere between Long Island and Rhode Island. If it strikes at hurricane strength, it would be the first storm to do so in the Northeast since Bob in 1991.

“Hurricane conditions are expected to begin late Saturday night or Sunday in portions of Long Island and Connecticut,” the National Hurricane Center wrote Saturday morning, also noting that such conditions could spread across portions of Rhode Island.

The surge, or the storm-driven rise in ocean water above normally dry land, could cause “dangerous” coastal inundation, the Hurricane Center wrote, while torrential rain may lead to “considerable” flooding farther inland. Power outages are probable due to powerful winds.

A hurricane warning has been issued for the south shore of Long Island from Fire Island Inlet to Montauk Point and the north shore from Port Jefferson Harbor to Montauk Point. To the northeast, hurricane warnings stretch from New Haven, Conn. to west of Watch Hill, R.I.

Hurricane watches remain in effect from Rhode Island to Cape Cod and the Islands, where there exists risk for hurricane force winds. The risk here is perhaps lowered compared to previous forecasts, given a continued westward shift in the track.

Storm surge warnings, for tide rises of two to five feet, have also been issued for the south shore of Long Island, from Mastic Beach to Montauk Point, and the north shore from Oyster Bay to Montauk Point. Surge warnings are also in effect for Greenwich, Conn., to Chatham, Mass., including Nantucket, Martha’s Vineyard, and Block Island.

Additionally, tropical storm warnings are in effect from Port Jefferson Harbor, N.Y., to west of New Haven, Conn., including the south shore of Long Island from west of Fire Island Inlet to East Rockaway Inlet.

Tropical storm warnings have also been expanded westward into the Big Apple, home to more than 8 million people, and northern New Jersey since tropical storm conditions are increasingly probable there. Storm surge flooding is a risk, too, but will be highly variable and depend on time of day of landfall, tides and the exact track of the storm.

According to the Associated Press, Massachusetts Gov. Charlie Baker urged vacationers on Cape Cod to leave before Henri’s arrival while Eversource, a power company in Connecticut, told customers to prepare to be without electricity for up to 5 to 10 days.

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 as the storm parallels the coast, according to the Hurricane Center.

Henri will weaken quickly as it charges north into New England, but not before delivering a substantial blow at a time of year when trees are fully leafed and beachside communities ordinarily packed with tourists.

Henri now

As of Saturday morning, the storm was centered about 200 miles southeast of the North Carolina Outer Banks, moving north-northeast at 12 mph.

Until Friday morning, wind shear, or changing wind direction with altitude, which had disrupted Henri’s development. But, as the shear eased on Friday, Henri began to intensify, its peak winds increasing to 70 mph, just 4 mph shy of hurricane strength. Additional intensification is predicted Saturday.

"[S]atellite imagery shows that the convection is beginning to wrap around the northeastern and eastern portions of the circulation suggesting that the anticipated decrease in shear is occuring, and that Henri may be on the verge of strengthening.,” the Hurricane Center wrote Saturday morning.

The storm has about 12 to 18 hours to intensify as it careens northward. It is forecast to be an 80 mph hurricane by late Saturday or early Sunday while offshore well east of the Mid-Atlantic.

Henri’s approach

Of initial uncertainty in Henri’s track was whether it would be captured by a trough, or low-pressure system nestled within a dip in the jet stream, to the west over the Appalachians, or if it would escape out to sea ahead of the approaching high-altitude disturbance. It’s now clear that Henri will be yanked westward toward the United States; the question is to what extent.

The key time frame for the Northeast is from late Saturday night, when tropical storm conditions could begin from northern New Jersey to Long Island, into early Monday morning.

Models still offer a wide range of possibilities that project landfall locations anywhere between northern New Jersey and Cape Cod; some of the new and most reliable models suggest the storm will come ashore over eastern Long Island late Sunday morning. Typically, the most severe conditions, included the strongest winds and maximum storm surge, occur near and just to the east of where the storm comes inland. Slight shifts in the projected locationand timing of landfall are to be expected through Saturday.

Landfall intensity simulations have consistently shown a high-end tropical storm to hurricane-strength storm upon arrival, yet depict a rapid weakening of the storm’s wind field as the storm penetrates inland. However, as the storm unwinds some, while the harshest winds will ease, the area affected by tropical-storm-force winds will expand.

“We encourage everyone in southern New England to begin preparations now for the possibility of an impactful tropical storm or hurricane Sunday into Monday,” the National Weather Service office serving the region wrote.

What to expect

Tropical Storm Henri will probably make landfall with a narrow corridor of winds sustained around 60 to 70 mph and gusts over 75 mph.

Long Island and New England are locations highly accustomed to serious windstorms, receiving annual buffets from nor’easters and coastal storms. Wind is nothing new there and the infrastructure can usually handle it. What’s different this time is that the trees are fully leafed, something that’s not a factor during a cold-season storm. That means tree damage will be more widespread, and power outages could be considerable.

Storm surge flooding will be problematic, particularly east of Henri’s center, where a fetch of onshore winds will pile water up against the coast. Up to 3 to 5 feet of coastal inundation is possible, which could flood roads, homes and businesses.

Buzzards Bay near the west end of the Cape Cod Canal, Narragansett Bay and Long Island Sound are particularly susceptible to coastal flooding. Even though Henri will be quickly weakening during its landfall, it will be slowing, meaning a greater duration of winds that will help stir up the seas. If Henri takes a path near New York City, significant storm surge flooding would be likely along the west end of Long Island Sound, with water funneled west into the East River.

A broad 3 to 6 inches of rainfall with localized totals to 10 inches is expected, too, which could cause inland flooding and, given the urban nature of the Northeast, pockets of flash flooding. These predicted amounts could be conservative as some computer models show the storm stalling over interior New England which could prolong heavy rain and increase the flooding potential from the Catskills northward.

Complicating factors

Making matters worst is the fact that Sunday marks this month’s full moon, meaning tides will be running anomalously high.

Inland flooding will be more significant than ordinary thanks to saturated soils from heavy rain in recent weeks. Boston has seen 14.4 inches of rain since July 1 and had its wettest July on record. Worcester saw their wettest July on record, with nearly 14 inches in four weeks’ time! A whopping 18.71 inches has been measured there since July 1.

Most of southern New England is running very wet; flash flood warnings were even issued in the Boston metro Thursday due to flooding from the remnants of Tropical Depression Fred. The saturated soils will also increase the possibility of falling trees.

Henri may free New England from is grasp by very early Monday morning, but impacts will remain. Choppy seas and rip currents near the coast are likely, along with lingering power outages that could last into next week. And, if the storm stalls, problematic rainfall could also linger in some areas.

Ian Livingston contributed to this article.