(CNN)Parts of the Northeast began to feel Hurricane Henri’s first impacts Saturday evening as the storm barreled toward the coast ahead of an anticipated Sunday landfall, threatening to bring damaging winds, dangerous storm surge and flooding to an already saturated area.
The storm’s first showers drifted from southern New Jersey and into the northern part of the state Saturday evening and began soaking parts of southwestern New York, heading toward New York City, CNN meteorologist Gene Norman said.
“This rain band could produce rainfall rates of 1-3″ per hour this evening into the overnight hours, with considerable flash flooding possible,” the National Weather Service of the Eastern Region said on Twitter.
In addition to the rain, coastal flooding is expected in parts of New Jersey and Delaware’s coasts with Saturday evening’s high tide, the weather service in Mount Holly said on Twitter.
Henri, which strengthened from a tropical storm late Saturday morning over the Atlantic, could make landfall at or near hurricane strength on New York’s Long Island or southern New England on Sunday, the National Hurricane Center said.
Strong wind and rain will likely smack a broad area from New York City into New England — and since the area is saturated from recent rain, Henri could easily down trees and set up days of power outages.
New York City Mayor Bill de Blasio declared a state of emergency Saturday afternoon ahead of the storm, saying in a news conference that heavy wind, rain and storm surges are expected Sunday morning and urged everyone to stay indoors if they can.
The mayor also issued a travel advisory, recommending that residents limit travel on Sunday, especially driving.
And New York Gov. Andrew Cuomo warned people in flood-prone areas: Move to safety now.
More than 35 million people are under a flood watch across the Northeast, with the hurricane center warning the heavy rain could cause “considerable flash, urban and small stream flooding” and create the potential for “widespread minor and isolated moderate river flooding.”
The Weather Prediction Center has a moderate — a level 3 of 4 — risk for excessive rainfall for parts of western Connecticut and Massachusetts, southern New York, northeastern Pennsylvania and northern New Jersey.
Significant damage is possible in this already-soaked region even if Henri is not a hurricane at landfall, Federal Emergency Management Agency administrator Deanne Criswell said.
“We’re going to see power outages, we’re going to see downed trees, and even after the storm has passed, the threat of falling trees and limbs is still out there,” Criswell told CNN Saturday morning.
In Connecticut, mandatory evacuations were ordered for the coastal towns of Guilford and Branford, according to a tweet from state Rep. Sean Scanlon.
“If you live in a coastal, low-lying or area prone to historic flooding due in Guilford, evacuate now. If you live in Zone 1 or 2 in Branford (see map), evacuate by 9pm,” Scanlon wrote. “PLEASE TAKE THIS SERIOUSLY.”
Groton Mayor Keith Hedrick also told CNN the city decided to order mandatory evacuations in some neighborhoods, and authorities will go door-to-door in those parts of town to advise residents to leave ahead of the hurricane.
Earlier Saturday, the city recommended a voluntary evacuation for some residents by 10 p.m., including those who live on Shore Ave., Beach Pond Road, Pine Island Road and Jupiter Point.
Connecticut Gov. Ned Lamont told residents Saturday afternoon to prepare to shelter in place on Sunday and urged them to pile up on food and get extra gasoline. Energy company Eversource said Saturday between 50% and 69% of customers in Connecticut could lose power and restoration efforts could take up to three weeks.
Henri’s center had sustained winds of 75 mph late Saturday afternoon.
Rain showers will likely become more widespread starting Saturday night and into Sunday, when Henri is expected to make landfall.
The storm will likely slow its forward speed after landfall, meaning the risk for showers and isolated thunderstorms will remain through Tuesday morning in the Northeast.
Hurricane warnings have been issued for nearly 6 million people in areas including parts of Long Island, and from New Haven, Connecticut, to west of Westport, Massachusetts.
More than 36 million other people are under tropical storm warnings, including parts of New Jersey and New York — including New York City — and large parts of southern New England.
A hurricane landfall in this region would be somewhat rare. Long Island has not had a direct hurricane hit since Gloria in 1985; New England last saw a hurricane landfall with Hurricane Bob in 1991.
Superstorm Sandy made landfall in New Jersey in 2012 with hurricane force winds and devastated swaths of the Northeast, though it technically was a post-tropical cyclone when it came ashore. Henri’s wind field at landfall is expected to be a quarter of the size, CNN meteorologists said.