Heavy thunderstorms triggered flash floods across New York, New Jersey, and Connecticut late Monday, disrupting transit networks, grounding flights, and prompting emergency declarations as rainfall overwhelmed infrastructure across the region.

As reported by Bloomberg, multiple subway stations in New York City were flooded, leading to suspension or severe delays across several lines, the Metropolitan Transportation Authority (MTA) said. Metro-North also halted service on parts of the Harlem line and reported delays on the New Haven line due to waterlogged tracks.

Flash floods submerged roads, highways, and vehicles across the Tri-State Area, stranding motorists and closing key arteries, according to the National Weather Service (NWS).

In New Jersey, Governor Phil Murphy declared a state of emergency late Monday, citing the “flash flooding and high levels of rainfall in parts of the state.”

“I am declaring a State of Emergency given flash flooding and high levels of rainfall in parts of the state. Please stay indoors and avoid unnecessary travel. Stay safe, New Jersey,” Murphy said on X.

Air travel was also heavily impacted. Over 1,200 flights were cancelled across major East Coast airports, including LaGuardia, Newark Liberty, John F. Kennedy International, and Reagan National, according to data from FlightAware.

At the height of the storm, Central Park recorded more than two inches of rain per hour, the NWS said, while rainfall totals across New Jersey reached several inches before easing later in the night.

“Two to three inches-plus per hour — that is incredible,” Brian Hurley, a senior branch forecaster at the US Weather Prediction Center, told Bloomberg. “The atmosphere is so juicy. There are so many flash flood warnings.”

The NWS issued flash flood warnings for parts of New Jersey through early Tuesday and flood watches for areas of Maryland and Virginia. River levels in the region were rising rapidly. The Passaic River at Pine Brook, New Jersey, was forecast to rise over three feet by midnight, while the Ramapo River at Mahwah had already crossed that mark.

The system responsible is a large, moisture-laden air mass stretching from Florida to Maine. A weak low-level jet stream is contributing to stationary storm systems, which have stalled over the region, increasing the risk of prolonged heavy rain.

Meanwhile, parts of central Texas are also forecast to receive another round of rainfall through Monday night, though the worst of the storms are expected to bypass areas still recovering from deadly floods earlier this month.