Several subway stations were flooded and major roads were cut in New York on Thursday ahead of the expected arrival of Storm Elsa, which has moved up the US East Coast after lashing Florida with wind and rain.
Between 2 and 4 inches of water fell in a series of thunderstorms over the city and surrounding areas on Thursday afternoon, the National Weather Service (NWS) said, "causing extensive flash flooding in certain places."
Subway passengers posted video footage on Twitter of flooded platforms at the 157th Street station north of Manhattan.
Commuters could be seen waist-deep in the water, crossing a dark pool to reach the station's platforms.
"Lines 1 and A have really taken a hit, with a lot of flooding in the stations," Sarah Feinberg, head of the MTA, New York's public transport authority, said on Thursday at a press briefing.
Some major roads, including in the Bronx, were temporarily closed, disrupting traffic. New York police tweeted footage of motorists being stranded by the water.
The NWS warned of possible new flooding by Friday morning, with the expected arrival of heavy rains brought by Storm Elsa, which is moving up from Florida.
Despite work to protect the city against flooding since Hurricane Sandy in 2012 -- which killed 44 people and paralyzed the American economic capital for days -- New York remains very vulnerable to flooding, with such incidents expected to increase because of climate change.
Several officials, including Eric Adams, president of Brooklyn and the favorite for the November mayoral election in New York after winning the Democratic primary this week, called for urgent investments to fortify the city's infrastructure.
"Extreme weather episodes like this are not going to go away," warned one of his primary opponents, Kathryn Garcia, who oversaw the water pumping after Hurricane Sandy.
"We must invest in strategies to protect the city," she said.