“The risks of storm surge, wind, and rain impacts in portions of southern New England and eastern Long Island are increasing,” the center said Friday morning.
A direct landfall as a hurricane means the worst winds will make it onshore.
Forecast models Friday morning are in better agreement than they were two days ago. But there is still some mystery concerning Henri’s path, intensity and effects through early next week.
“Given the still-present uncertainties in Henri’s future track and intensity and the hazards that the storm may cause, storm surge and hurricane watches are now being issued for portions of Long Island, Connecticut, Rhode Island, and southeastern Massachusetts,” the hurricane center says.
A hurricane watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical storm-force winds.
Based on the new forecast, tropical storm-force winds will be approaching the coast of southern New England in about 48 hours, the NHC said.
Wind shear — the changing of wind speed and direction with height — has been keeping Henri from strengthening the past few days. That shear is expected to end today, allowing Henri to reach hurricane status by Saturday.
Cooler waters near the coast typically weaken a hurricane, but Henri is forecast to move fast enough for these cooler waters to not have much of an effect.
As the storm makes landfall, damaging winds and storm surges are the most significant threats.
“Keep in mind tides will be astronomically high this weekend along both coasts,” says the NWS in Boston.
The full moon Sunday means higher high tides. Any storm surge on top of already higher tides could trigger enhanced coastal flooding.
“Track will ultimately tell us which coastline is most at risk (east coast vs south coast) or if both will be in play,” the Boston NWS said Thursday.
A storm surge of 3 to 5 feet has been forecast from Cape Cod Bay to Narragansett Bay, a surge of 2 to 4 feet is expected for the coastline of Connecticut and New York, including Long Island, and 1 to 3 feet is forecast along the New Jersey Coast down to Cape May.
A storm surge watch has also been issued for much of the region. A Storm Surge Watch means there is a possibility of life-threatening inundation from rising water moving inland from the coastline.
Heavy rainfall will also be a threat during the day Sunday and into the beginning of next week. Henri is forecast to produce rain of 2 to 5 inches over southern New England, with isolated maximum totals near 8 inches.
“Generally by the time storms make it to New England, they are getting picked up by the jet stream and are moving very quickly,” says CNN meteorologist Brandon Miller. “It will be very rare for a storm to move this slowly over the Northeast.”
That means that storm surge, dangerous surf, coastal erosion, and heavy rain will continue to batter New England for days instead of hours.
Massachusetts National Guard activated in advance of Henri
In Massachusetts, Gov. Charlie Baker activated the state’s National Guard Friday, allowing up to 1,000 guardsman to help with highwater rescue, debris clearing and public safety related to Henri, he announced during a news conference.
Baker anticipates anywhere between 100,000 to 300,000 power outages could happen and said utility workers are being staged at Camp Edwards in advance of the storm.
Baker urged people planning to travel to Cape Code or islands this weekend to delay their trips, leave on Saturday, or plan to extend their stay until at least Monday or Tuesday because of Henri.
He asked Massachusetts residents to stay home Saturday night and remain there through Sunday, as Henri is expected to make potential landfall.
CNN’s Haley Brink, Monica Garrett and Amanda Watts contributed to this report.