New Jersey Flooding, July 15 -- Flash flood warnings have been issued for New York City and several key areas across the US Northeast, placing more than 50 million Americans under flood watches this Monday. The National Weather Service (NWS) has warned of a heightened risk of flash flooding, with some regions facing potentially life-threatening conditions.

New York City, Washington DC, Baltimore, Newark, and Arlington - including Reagan National Airport - remain on high alert for severe flooding through Monday evening.

In New Jersey, western Union County has been flagged for possible dangerous flash floods, while Bergen County and New York's Westchester County are also under active flash flood warnings.

Heavy rain pummeled large swaths...