New York and New Jersey hit by torrential rain and flash floods, forcing highway closures, suspending subway lines and flight delays.

Atlantic, Hill Country, Texas, central Florida, southern Arizona, and the Upper Midwest are at risk for more flooding rainfall on Tuesday.

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

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

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.

After seeing properties flood last fall from afternoon rainstorms, Mayor Diezel Depew knew he had no time to waste. For months, his staff has worked to widen retention ponds, clear culverts and armor canals to keep water flowing.

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.

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.