Henri turned into a hurricane Saturday morning as the storm stormed up the east coast towards Long Island and southern New England, where it is expected to come ashore on Sunday.
Hurricane warnings cover east Long Island, the Rhode Island coast, much of the Connecticut coast, and parts of southeast Massachusetts, where harmful winds could result in hundreds of thousands of power outages. Meanwhile, the ocean tide and heavy rains from the storm could lead to dangerous flooding both along the coast and inland.
“A dangerous situation is unfolding this weekend in the northeastern United States as #Henri approaches,” tweeted Louis Uccellini, director of the National Weather Service. “A track perpendicular to the coast on landing is the worst-case scenario for wave and wind effects for [Long Island] and southern New England. “
In addition to the hurricane warnings, tropical storm warnings cover northeast New Jersey, New York City and west Long Island and extend to Martha’s Vineyard and Nantucket in the northeast. Here, the effects of Henri could be severe, but less severe than in the hurricane warning zone.
It has been 10 years since the last hurricane warnings were 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 in the northeast since Bob 1991. The residents are preparing for a possibly long period without electricity.
“Hurricane conditions are expected to start late tonight or Sunday,” warned the National Hurricane Center. “Dangerous storm surge floods are expected,” it said.
Current projections bring Henri ashore between late Sunday morning and afternoon between eastern Long Island and the coast of Connecticut and Rhode Island, although slight shifts in place and time are possible. Tropical storm conditions could hit coastal areas early Sunday morning.
“Residents should prepare for power outages and coastal flooding,” tweeted Laura Curran, executive director of Nassau County on Long Island. “Our crews will work around the clock.”
Connecticut Governor Ned Lamont, a Democrat, declared a state of emergency before the storm. “We expect heavy rains and strong winds, with coastal and urban flooding being a significant problem,” he tweeted on Friday.
The flood or storm-induced rise in seawater over normally dry land could be “life threatening” and thanks to the full moon on Sunday the tide is high anyway.
Flash floods could also be widespread, with more than half a foot of rain expected on Long Island and in areas east of the Berkshires in western New England. That comes after the wettest July on record for many cities in the northeast. The weather service warns of “moderate risk” of flash floods and excessive rainfall, “with isolated maximum totals near 10 inches” likely.
“Heavy rains can result in many evacuations and rescues,” said the weather service and uttered unusually strong words before Henri’s closest approach. “Floods can penetrate into many structures within several communities, some structures become uninhabitable or washed away.”
There is also a storm surge warning in areas such as Queens and along the East River in New York City, as well as along the coasts of Long Island, Connecticut, Rhode Island, and southeastern Massachusetts.
Though not directly affected by wind and rain, areas further south in the mid-Atlantic, from the North Carolina Outer Banks to the beaches of Maryland-Delaware, will have “life-threatening surf and rip currents” by the weekend the hurricane center.
– – –
At 5 p.m. on Saturday, Henri was about 240 miles east-northeast of Cape Hatteras, NC, and had gained some speed during the day, storming north at 18 mph. Its sustained winds were 75 mph, unchanged from the Hurricane Center’s 11 a.m. warning that upgraded it to a hurricane.
Satellite imagery showed abundant thunderstorm activity blooming around Henri’s core. The winds in the upper level have become more favorable to development, and Henri moves across the warm waters of the Gulf Stream.
“Visible satellite images and microwave data show that a tight inner core has formed in connection with Henri, but the convection pattern appears ragged in infrared images,” the Hurricane Center wrote on Saturday at 5pm. “The environment looks favorable so that Henri can strengthen himself tonight.”
Upper level drainage or the evacuation of rain-cooled air at high altitudes also improved and helped Henri become more organized. The Hurricane Center expects Henri to peak with at least 80 mph winds on Saturday night.
Henri will weaken early Sunday as he moves away from the mild waters east of the Delmarva Peninsula and approaches Long Island as a strong tropical storm or near the strength of a hurricane.
– – –
The inhabitants of the northeast are used to cool “nor’easters”, which, in addition to widespread beach erosion and rain or snow, often bring with them a stormy wind. While Henri will be of a similar magnitude in terms of wind and waves, the presence of fully leafy trees, sodden soil from previous wet conditions, and additional flood of rain will result in significantly more tree and vegetation damage, likely leading to power outages.
Even before Henri, Eversource Energy had dispatched thousands of crews to the northeast to position them for post-storm cleanup while working to mitigate the risk of the first rains.
“Trees are that [number one] Cause of power outages during a storm, ”the company tweeted.
The strongest winds are found within approximately 25 miles of the center and can blow over 65 miles per hour on Long Island, southern Connecticut, and the Rhode Island coast. A sporadic gust of over 75 km / h near the coast cannot be ruled out. The strongest winds come around sunrise on Sunday and last about six hours.
Wind will be considerably weaker further inland – 30 miles an hour or less in Boston, New York, Providence, RI, and Hartford, Conn.
East of the center the wind blows from the south, with the north wind on the left side of the storm.
– – –
The wind will back up water on the coast, potentially creating a significant storm surge that could damage property and infrastructure on the coast. A storm surge of 3 to 5 feet is possible in a worst-case scenario in Long Island Sound, depending on when Henri hits land, especially if Henri only comes by in the east. That would push seawater to the west end of the sound, which would be problematic for those along the East River in New York City.
A similar increase is expected at the southern end of Long Island but may not be realized due to Henri’s projected path. A small increase is possible in the New Jersey coast.
Narragansett Bay in Rhode Island as well as Buzzards Bay and Nantucket Sound are all prone to severe flooding during tropical systems. There, too, a 3 to 5 foot wave is possible which is more likely to occur due to the likelihood of prolonged onshore winds. Cape Cod Bay could see splashes several feet.
“The combination of a dangerous storm surge and the high tide will result in normally dry areas near the coast being flooded by rising water moving inland from the coast,” wrote the National Hurricane Center.
The severity of the tide depends on whether Henri hits land at high tide; Currently, there is a chance the landing will be closer to low tide than high tide, reducing the risk of a worst-case scenario.
– – –
Storm surges will only hit local residents near the coast, and Henri’s wind footprint will admittedly be small. The most common risk is flash floods from heavy rainfall.
Weather models agree that a significant amount of moisture is discharged from Henri, particularly near and west of the center of the system. Torrential tropical downpours, with rainfall rates greater than an inch per hour, will contribute to widespread totals of 3 to 6 inches in eastern Long Island, parts of the Connecticut River Valley, Hudson Valley, and Catskills. Localized quantities up to 10 inches are possible.
The largest totals should be concentrated primarily west of Worcester County, Massachusetts, and west of the Connecticut-Rhode Island border. Heavy rain and flooding could even invade southern Vermont and New Hampshire. But Henri is likely to be nothing in places like Boston, which struggle to see a quarter of an inch of rain.
Many areas in southwest New England have seen more than 30 inches of rain since July 1. The data shows that the soils are saturated and cannot take much additional rain.
New York City and New Jersey – which should have significantly less rain on average from Henri’s core – can still end up under sporadic downpours, enlivened by Henri’s tropical humidity. The water-saturated areas could occasionally absorb heavy rains with torrential rains of several centimeters per hour.
Henri will linger over southern New England on Monday as a holdover from rain and windy winds before completely dissolving Tuesday through Wednesday.
– – –
Ian Livingston of the Washington Post contributed to this report.