The National Weather Service urged people to avoid travel if a flash flood warning was in place for their area.

Heavy rain caused flash flooding and road closures around the Lehigh Valley on Monday evening as storms made their way through. More rain is expected this week.

New Jersey is expected to miss the heaviest rainfall in the latest round of thunderstorms on Tuesday, but more flash flooding is possible.

The extreme rainfall that occurred in the Northeast on Monday could happen more often in the future as a result of climate change, research shows.

The MTA announced last year that it would spend $6 billion over the next decade to flood-proof the system, including adding new pump rooms and drainage capacity. Stormwater is a major threat to public transportation. On a dry day, the MTA pumps about 14 million gallons of water out of the subways.

As the water rises, so does the Kerr County community, especially one man who reunited a brother and sister, swept away in the flood.

A state of emergency was declared in New Jersey after slow-moving thunderstorms unloaded a significant amount of rain, resulting in dangerous flash flooding across the Northeast into Monday night. At least 2 were killed.