Meteorologists have issued a flash flood emergency for parts of the Lower Hudson Valley in southeastern New York, warning that powerful thunderstorms have dumped several inches of rain and are causing "life threatening" and catastrophic flash flooding.

Flash flood warnings were in effect Sunday evening for several areas in the region, including southeastern and central Orange County, western Putnam County, northern Westchester County and Rockland County, which has seen the heaviest rainfall, according to the National Weather Service. Parts of northeastern New Jersey were also under a flash flood warning, the service said.

"Move to higher ground now! This is an extremely dangerous and life-threatening situation. Do not attempt to travel unless you are fleeing an area subject to flooding or under an evacuation order," the service warned Sunday evening.

A flood watch is also in effect across New York City until 6 a.m. Monday morning, the city said on its website, adding that areas that were low-lying, had poor drainage or are close to creeks, streams or rivers are particularly at risk for flash flooding. An "excessive rainfall event" is expected to begin around 7 p.m. Sunday, the city said.

The heavy rain coming in Sunday night and Monday "may cause rapid, life-threatening flooding to basements," the city's emergency notification officials said on Twitter. "Prepare now to move to higher ground if needed. If you must travel, exercise caution and avoid flooded roadways."

In nearby Rockland County, New York State Police said "numerous roadways consisting of State Route 9W and Palisades Interstate Parkway are experiencing heavy flooding and washouts. The Palisades NB is closed from exit 14 to Long Mountain Traffic circle. Avoid The Area!!!"