A warmer atmosphere can hold more moisture, making storms capable of unleashing huge amounts of rain over land. Studies have shown that for every degree Fahrenheit that the planet heats up, the atmosphere can hold around 3% to 4% more moisture. As a result, flooding risks across the country are expected to increase in the coming years.

The first round of tropical downpours have begun in parts of the Carolinas. NOAA's Weather Prediction Center has issued a Level 2 out of 4 flash flood risk for parts of the Carolinas, with heavy rain also expected in Georgia.

Torrential rain pummeled parts of the Northeast on Thursday, including New York City and New Jersey, stranding rush-hours passengers on a train.