It had lost its status as an active tropical storm long before reaching the I-95 corridor. The reasons for such a disaster could've been both meteorological and a matter of public perception.
Updated Sep. 8, 2021 4:20 PM EDT
Ida made landfall as a Category 4 hurricane in Louisiana, but its devastating and deadly impact on the southern Louisiana coast was just the beginning of its rampage. More than 1,000 miles away, and despite the storm having lost wind intensity, Ida inflicted devastating destruction to the Northeast due to flooding rainfall and outbreaks of severe weather that it spawned across the region.
How could a storm that had lost its status as a hurricane while moving over Mississippi unleash such widespread devastation -- killing more than 50 just in the Northeast -- near the end of its journey across United States territory?
For one thing, Ida was weakening as it surged northward through the Tennessee Valley, but as it made its way into western Pennsylvania, the precipitation from Ida was enhanced as it interacted with atmospheric energy associated with a weather system across Canada. AccuWeather Chief Broadcast Meteorologist Bernie Rayno warned of this very atmospheric collision in a forecast a day ahead Ida's arrival across the mid-Atlantic and Northeast.
And then, "feeding on the contrast between warm, humid air south and east of the storm center and much cooler air to its northwest," AccuWeather Senior Meteorologist Bob Larson said, "there were tremendous amounts of rain over a relatively short period of time, which led to serious flash flooding."
There is also the matter of where the flash floods occurred.
Much of the flash flooding was centered in high-density population areas, like New York City and Philadelphia, where major highways were left under feet of water and residents' homes and apartments were deluged by floodwaters. Along with the extreme flooding came an eruption of tornadoes and other severe weather, which left some homes, particularly in New Jersey, outside Philadelphia, in tatters.
AccuWeather Chief Broadcast Meteorologist Bernie Rayno on Aug. 31 showed viewers the energy associated with a weather system over Canada that he said would drop down and combine with Ida's moisture, resulting in enhanced precipitation as the tropical rainstorm pushed through the mid-Atlantic and Northeast.
AccuWeather meteorologists had been shouting from the rooftops for days about the possibility for life-threatening flash flooding, and as AccuWeather Chief Meteorologist Jonathan Porter had put it, rain across northern New Jersey and the New York City area would come down "fast and furious," with the heaviest rainfall and rapidly rising floodwaters occurring at night -- an added complication.
On top of that, Porter pointed out, the flooding caused by Ida was amplified by the fact that the areas hit the hardest by Ida in the Northeast had been drenched a week earlier with heavy rain from Tropical Storm Henri, which dumped as much as 14 inches of rain on one part of New Jersey. And, prior to that, Tropical Rainstorm Fred had rolled through, which contributed to some places having picked up two to three times the normal rainfall since July before Ida had arrived.
Other factors, in addition to the high population density in the Northeast compared to Louisiana, are hydrological impacts such as how land use affects rain runoff, with there being a much higher percentage of paved-over land in the New York City area than in other places.
Yet another factor in the catastrophe may have been public perception as the storm approached. People living in the Northeast had likely seen news of Ida's destructive landfall in Louisiana. However, upon hearing that Ida lost wind intensity and was no longer considered an active tropical storm as it moved north across Mississippi, many may not have been captivated by the threat it wielded as it charged north.
“We did not know that between 8:50 and 9:50 p.m. last night, that the heavens would literally open up and bring Niagara Falls level of water to the streets of New York," Kathy Hochul, the state's governor, said the following day. She was referring to a record 3.15 inches of rain that was recorded in Central Park during the course of just one hour at the height of the storm.
Cars are stranded by high water Thursday, Sept 2, 2021, on the Major Deegan Expressway in the Bronx borough of New York as high water left behind by Hurricane Ida still stands on the highway hours later. (AP Photo/Craig Ruttle)
Underscoring the sense of surprise many Northeasterners felt immediately after Ida had moved out was a headline from The Associated Press delivering news of the rising death toll: "More than 45 dead after Ida’s remnants blindside Northeast," it read, despite the flooding having been forecast well ahead of time by both AccuWeather and the National Weather Service, (NWS).
The NWS issued watches and warnings ahead of time to cover other dangers, such as storm surge, flash flooding, tornadoes, and more.
And that AP headline raises another aspect of this disaster: the word "remnants."
The Saffir-Simpson Hurricane Wind Scale to rate hurricanes "was developed years ago, and as the [National] Hurricane Center explains, is strictly a wind scale, not taking into account other potentially dangerous hazards such as storm surge, rainfall, flooding and tornadoes," Larson explained.
The Saffir-Simpson Hurricane Wind Scale being a measure used strictly to account for wind speeds is part of the reason AccuWeather developed the RealImpact™ Scale for Hurricanes, which is designed to more accurately warn how much damage a storm has the potential to cause.
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AccuWeather meteorologists rated Ida a 4 on the RealImpact™ Scale for Hurricanes to highlight the threat for dangerous flooding and destruction all along the storm's path. Porter said this decision was made to "showcase the continued dangerous threat from flooding rain." He added that the scale, introduced by AccuWeather in 2019, "takes into account a holistic view of hurricane impacts including flooding rainfall and other parameters, which, on average, result in more deaths and damage than wind alone."
After a tropical depression's structure has deteriorated, the National Hurricane Center uses the term "remnants" to describe what is left of the storm. AccuWeather instead uses the term "tropical rainstorm" to describe what is left of the storm in hopes to better express the severity of the storm. According to Larson, some people could hear the word remnants and be confused by its meaning and assume there is not much left of the storm and, for that matter, the threat to lives and property.
“Tropical rainstorm [is meant to] help let people know this is still very much a storm, even if it is no longer producing hurricane or tropical-storm-force winds," Larson explained.
A Manville Police Officer stands guard near the remains of a house that exploded due to severe flooding from Tropical Storm Ida in Manville, NJ., Friday, Sept. 3, 2021. Dozens of people in five states died as storm water cascaded into people’s homes and engulfed automobiles, overwhelming urban drainage systems never meant to handle so much rain in such a short time. (AP Photo/Eduardo Munoz Alvarez)
Tropical rainstorms can vary greatly by strength, speed, moisture and the path they travel. According to Larson, "many of these factors came together in such a way to produce the horrific weather that unfolded across the Northeast."
Despite the fact that it was no longer considered a tropical storm or hurricane, Ida remained a strong storm system full of tropical moisture when it made its way through the Northeast, resulting in more than 50 deaths across the region.
"The human toll was tremendous," Hochul said.
"It’s tough to speculate on why the deaths may have occurred, but it might be a combination of not knowing the severity of the storm and also not having experienced anything such as this in the past," Larson said.
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