EXPLAINER: How Ida can be so deadly 1000 miles from landfall

Natural and some man-made ingredients came together, causing the weakened but still soggy remnants of Hurricane Ida to devastate the Northeast more than 1,000 miles (1,600 kilometers) away from its landfall.

This sort of distant and deadly flooding from hurricanes has happened before, and meteorologists had warned that Ida could cause it.

Although Ida had lost most of its 150 mph (240 kph) wind force, the storm kept its strong rainy core. Then it merged with a wet and strengthening non-tropical storm front, according to meteorologists and atmospheric scientists.

When this happens, “very exceptional rainfall can occur,” said MIT meteorology professor Kerry Emanuel.

“This is not rare," Emanuel added. “For example, it happened with Hurricane Camille of 1969, which took a similar path.” Camille killed more than 100 people in Virginia from flooding after making landfall as a Category 5 hurricane in Mississippi.

Hurricane Ivan in 2004 took a similar track and triggered record rainfall in Pittsburgh, said meteorologist Bob Henson of Yale Climate Connections. In Ida’s case, he said, conditions were ripe “for rainmaking and it all came to fruition along the I-95 corridor.”

The storm dumped more than 3 inches of rain on New York's Central Park in just an hour Wednesday night, obliterating a record set less than two weeks earlier by Tropical Storm Henri. Parts of New Jersey, Massachusetts, Rhode Island and Pennsylvania got more than 9 inches of rain.

The death toll and damage amounts are mounting.

“Some of this is just bad luck too. If Ida had tracked just 100 miles farther east, that heaviest swath of rainfall would have been over the ocean and no one would care,” said University of Miami hurricane researcher Brian McNoldy.

“The severe weather threat and the flash flooding...