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

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

This benignant of distant and deadly flooding from hurricanes has happened before, and meteorologists had warned that Ida could origin it. But the caput of the National Weather Service said the storm's onslaught of rainfall was truthful beardown and came truthful rapidly that it overwhelmed the region's quality to header with the downpour.

Although Ida had mislaid astir of its 150 mph (240 kph) upwind force, the tempest kept its beardown rainy core. Then it merged with a bedewed and strengthening non-tropical tempest front, according to meteorologists and atmospheric scientists.

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

“This is not rare," Emanuel added. “For example, it happened with Hurricane Camille of 1969, which took a akin path.” Camille killed more than 100 radical successful Virginia from flooding aft making landfall arsenic a Category 5 hurricane successful Mississippi.

Over the weekend, National Weather Service Director Louis Uccellini and different meteorologists started seeing an eerie similarity to Camille and it raised alarms for them.

“We collectively were alert of this possibility. These discussions were stared adjacent earlier the tempest made landfall successful Louisiana,” Uccellini told The Associated Press successful an interrogation Thursday.

Hurricane Ivan successful 2004 took a akin way and triggered grounds rainfall successful Pittsburgh, said meteorologist Bob Henson of Yale Climate Connections. In Ida’s case, helium said, conditions were ripe “for rainmaking and it each came to fruition on the I-95 corridor.”

The tempest dumped much than 3 inches of rain connected New York's Central Park successful conscionable an hr Wednesday night, obliterating a grounds acceptable little than 2 weeks earlier by Tropical Storm Henri. Parts of New Jersey, Massachusetts, Rhode Island and Pennsylvania got much than 9 inches of rain.

The decease toll and harm amounts are mounting.

“Some of this is conscionable atrocious luck too. If Ida had tracked conscionable 100 miles farther east, that heaviest swath of rainfall would person been implicit the water and nary 1 would care,” said University of Miami hurricane researcher Brian McNoldy.

“The terrible upwind menace and the flash flooding menace successful these areas were precise well-forecast days successful advance, but that doesn’t trim the demolition they cause,” McNoldy said successful an email, attaching National Weather Service warnings from Monday and Tuesday.

Ken Kunkel, a National Oceanic and Atmospheric Administration meteorologist who specializes successful utmost rainfall and heat, said his survey a fewer years agone recovered that one-third of the utmost rainfall events successful the Northeast came from remnants of hurricanes and tropical storms.

Government officials successful New York had been readying for dense rain, but Uccellini said the rainfall that fell — much than 3 to 8 inches of rainfall forecast Tuesday — conscionable overwhelmed infrastructure successful the Northeast.

“People are acceptable but is the infrastructure acceptable for the magnitude of these storms?” Uccellini said. “It doesn’t look to beryllium that way.”

“I deliberation with the upwind getting worse. .. This is thing we person to look astatine present and into the future," helium said.

Human-caused planetary warming from burning of fossil fuels besides apt made Ida's far-reaching impacts a spot worse, experts said.

Warmer aerial holds much moisture that it tin dump, said erstwhile hurricane huntsman meteorologist Jeff Masters, besides of Yale Climate Connections. Air supra the oceans has astir 10% much moisture than successful 1970 and that comes down successful storms, helium said.

That other moisture condenses wrong storms and releases other vigor energy, which leads to updrafts and makes storms much aggravated and longer lasting,“ This tin pb to a 30% summation successful rainfall, arsenic has been documented successful respective cases of large flooding,” helium said.

Heavier rainfall falls onto municipality areas wherever pavement specified arsenic roads and parking tons worsens h2o runoff starring to flooding, said University of Georgia meteorology prof Marshall Shepherd. “That quality interaction is simply a portion of flooding disasters often overlooked.”

Despite readying and efforts since 2012's Superstorm Sandy to beryllium much resilient to utmost weather, much remains to beryllium done, Columbia University clime idiosyncratic Adam Sobel said. “Obviously our infrastructure is not up to events similar this.”

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Follow Seth Borenstein connected Twitter astatine @borenbears .

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This Associated Press bid was produced successful concern with the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely liable for each content.

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