Flash flooding hits major Northeast metro areas as extreme rain threatens millions

By Luke Snyder, Amanda Musa, CNN

(CNN) — Dozens of flash flood warnings are in effect for millions across several states and major cities in the Northeast, as slow-moving summer storms impact the East Coast Monday evening.

Flooding has been reported near Newark, New Jersey, New York City, northern Virginia and southern Maryland, according to the National Weather Service. More warnings are likely to come overnight into Tuesday.

A state of emergency has been declared in New Jersey due to ongoing flooding, Gov. Phil Murphy announced Monday night.

“I urge New Jerseyans to exercise caution, follow all safety protocols, and remain off the roads unless absolutely necessary,” Murphy said in a statement.

Flash flood warnings were extended well in to the evening hours in Essex and Union counties due the rain, according to the National Weather Service.

The steady rainfall has slowly moved East towards New York City, which experienced its second wettest hour on record Monday night after a little over 2 inches fell between 7 p.m. and 8 p.m. local time. This record is only beat by the approximately three-and-a-half inches of rain recorded during the remnants of Hurricane Ida in 2021. These record numbers of hourly rain in New York City are usually a once in a decade event.

At least one subway station was flooded by the deluge after water seeped into the MTA station on 23rd street, according to a spokesperson with the Metropolitan Transit Authority. Several trains were suspended, delayed or rerouted due to the flooding, according to MTA’s website.

Metro-North Railroad and New Jersey Transit said on their X accounts that they are also experiencing delays due to flooding.

As of 9 p.m., several airports in the New York City area issued ground stops and delays, according to the Federal Aviation Administration. Impacts to air travel are also being reported at Ronald Reagan Washington National Airport and Boston Logan International Airport.

In Lancaster County, Pennsylvania, 16 water rescues were reported in Mount Joy Township Monday afternoon, according to the Mount Joy Fire Department.

“Starting around 2:00 p.m., intense rainfall dropped over 7 inches of rain in less than five hours, overwhelming stormwater infrastructure and inundating portions of the borough,” the fire department said in a Facebook post. “The west end of town was hardest hit, with reports of over 5 feet of water in some homes.”

Video captured several cars struggling to navigate through the municipality’s flooded streets. A photo taken by the Franklin Fire Company showed firefighters conducting a water rescue after occupants became trapped in their vehicle in flood waters.

In Virginia, the National Weather Service issued a flash flood emergency late Monday for the cities of Petersburg and Colonial Heights, where upwards of 2-3 inches of rain has fallen in less than 2 hours.

Numerous water rescues are in progress in Petersburg, it said in a post on X, as stream gauges surge to flood levels and intense rainfall rates continue.

Storms will continue overnight Monday, but most will move off the coast by Tuesday morning.

As of Monday evening, more than 70 million people remain in a Level 2 of 4 risk of flooding rain, but a more significant Level 3 out of 4 threat for 20 million people including the Washington, DC, Baltimore and Philadelphia metro areas represents the core of the threat into the overnight hours.

Showers began developing Monday morning and dominated the Northeast by the latter half of the day as temperatures rose. The heaviest storms arrived by early evening, threatening rush hour commuters.

Much of the area inside the flood watch has seen up to 300% of their normal rainfall over the past two weeks. Given that, and the staggering rainfall in parts of central New York and Pennsylvania over the weekend, it won’t take much to cause serious flooding in the region.

Places along the Berkshires in Massachusetts and Binghamton, New York, recorded as much as 4.5 inches of rain over the past 72 hours.

In a typical year, the National Weather Service office in the DC-Baltimore area issues one or two moderate risk rainfall outlooks. This July alone, there have already been three: July 1, 9 and 14. In the past month, there have only been seven days when the DC-Baltimore area wasn’t under any excessive rainfall threat.

Record-breaking flood events have happened nearly back-to-back in recent weeks, most notably in Texas’ Hill Country, where more than 130 people died after catastrophic flooding on July 4. New Mexico, North Carolina and other East Coast states have also seen life-threatening floods and historic rainfall this month.

Overwhelming rainfall is becoming more prevalent in a warming world, as rising global temperatures drive weather toward extremes. Hourly rainfall rates have grown heavier in nearly 90% of large US cities since 1970, according to a recent study from the nonprofit research group Climate Central.

Storms thrive on warm, moist air, and with the nation approaching peak summer heat, this month has seen the perfect conditions for flooding rain. Heat-driven storms can drop torrential rain and tend to move more slowly and stagnate, as upper-level winds in the atmosphere weaken this time of year.

In urban areas, flood risk increases in part due to infrastructure. Many roads, sewers and drainage systems in the US were not designed to handle the kind of extreme rainfall events that are now becoming more common.

Concrete and pavement disrupt the natural absorption of water runoff, which keeps rain from soaking into the ground and instead sends it to storm drains that can easily overflow or become clogged with debris.

This is a developing story and will be updated.

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CNN’s Jillian Sykes, Taylor Romine, Sarah Dewberry and Briana Waxman contributed to this report.