What you should know about the incredible scale of Ida’s flooding in the Northeast

Ida satellite view Sept 1 2021
Source: CIRA / Colorado State University
The remnants of Hurricane Ida move over New York and New Jersey on Sept. 1 2021

NEW YORK CITY– On Wednesday night the storm that will forever be remembered as Hurricane Ida was not a hurricane and hadn’t been for some time. The storm that was in fact no longer a tropical system merged with another storm to become the remnants of Ida in official forecasts from the National Hurricane Center.

That mattered little when three inches of rain fell in an hour in Central Park and floodwaters invaded the baggage claim in a New Jersey airport.  The deadly flash flooding in the Northeast serves as a reminder that tropical systems’ paths of destruction often go on well after they’ve supposedly weakened.

Ida satellite view Sept 1 2021

Source: CIRA / Colorado State University

The remnants of Hurricane Ida move over New York and New Jersey on Sept. 1 2021

Ida rainfall estimate Ida totals

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estimated rainfall-gallons in Manhattan from Ida

In total, 7.15 inches of rain fell in Central Park, the heart of Manhattan. If we use that number as an estimate for the surrounding area, it means that around 2.5 billion gallons of water fell on just Manhattan. At current river flows, it would take five days to watch 2.5 billion gallons flow over Spokane Falls.

 

https://twitter.com/NWSNewYorkNY/status/1433510418056548379?s=20

The timeframe is critical in understanding the disaster. The rain came in just a few hours, overpowering the stormwater systems of every city and town from Philadelphia to New York with trillions of gallons of water. The result is that at least 40 people died because of the flooding.

Explainer: How Ida Can Be So Deadly 1000 Miles From Landfall

Matt Rourke

Vehicles are under floodwater from Schuylkill River in the Manayunk section of Philadelphia, Thursday, Sept. 2, 2021 in the aftermath of downpours and high winds from the remnants of Hurricane Ida that hit the area.

This is not the first time hurricanes merging with other weather systems caused major disasters in this part of the country.

In 1991 “The Perfect Storm” caused serious coastal flooding from New Jersey to New England. The loss of the fishing boat Andrea Gail in the storm would inspire a book and a movie starring George Clooney.  Two decades later, Hurricane Sandy was merging with a front when it made landfall in New Jersey, earning it the infamous nickname “Superstorm Sandy.” In the case of Ida however, some of the floods are surpassing all storms that came before it.

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