Ida similar to Katrina, but stronger, smaller – News-Herald
By SETH BORENSTEIN
Hurricane Ida looks suspiciously like a dangerous and perhaps scarier sequel to 2005 Hurricane Katrina, the costliest storm in American history. But there are a few twists to come that might make Ida meaner in some ways, but not as horrible in others.
“Katrina’s main story was the damage caused by the storm surges and over a large area. The main story with Ida will be a combination of damage from wind, storm surges and freshwater flooding, ”said meteorologist Jeff Masters, who flew hurricane missions for the government and founded Weather Underground.
Ida made landfall on the same calendar date, August 29, as Katrina 16 years ago, hitting the same general part of Louisiana with about the same wind speed, after rapidly strengthening as it passed through an area. similar to warm, deep water that supercharges hurricanes. .
What could be different, however, is crucial: direction, size and strength.
“Ida will most definitely be stronger than Katrina, and by a pretty big margin,” said Brian McNoldy, hurricane researcher at the University of Miami. “And, the worst of the storm will come through New Orleans and Baton Rouge, which had the weaker side of Katrina.”
Ida was a strong Category 4 storm with winds of 150 mph when it made landfall, “within a sneeze of becoming the fifth Category 5 to make landfall over the continental United States,” McNoldy said.
Katrina weakened a bit before landing, hitting Louisiana as a Category 3 storm with winds of 127 mph.
Katrina has hit Louisiana from the south, while Ida arrives in the same part of the state from the southeast. Ida’s hurricane-force winds on Sunday extended 37 miles from the center, compared to Katrina’s hurricane-force winds that spread 98 miles from the center when they made landfall, McNoldy said.
“It has the potential to be more of a natural disaster when the big problem in Katrina was more man-made” due to the dike failures, McNoldy said. The dike failures have pushed Katrina’s death toll to 1,833 and its overall damage to about $ 176 billion in current dollars, and experts don’t expect Ida to come close to those totals.
Ida came to the same general location from a slightly different direction. Several hurricane experts worry that the difference in angle could put New Orleans more in the dangerous storm quadrant – the right front part of a hurricane – than it was in Katrina, when the city was more. devastated by the failure of the dikes than by the storm surges. Katrina’s northeast quadrant pushed 28-foot storm surges into Mississippi, not New Orleans.
“Ida’s angle is potentially even worse,” McNoldy said. Because it’s smaller, “it won’t create a huge storm surge as easily… but the angle at which it presents itself is, I think, more conducive to pushing water into the lake (Pontchartrain). “
This northwestern route from Ida not only puts New Orleans more on target than Katrina, but it also targets Baton Rouge and crucial industrial areas more, Masters said. He said Ida would have to pass through “the absolute worst place for a hurricane.”
“It is planned to follow the industrial corridor between Baton Rouge and New Orleans, which is one of the major infrastructure regions in the United States, critical to the economy,” Masters said. “You’re probably going to shut down the Mississippi River to barge traffic for several weeks. “
Meteorologist Steve Bowen, head of global disaster analysis at the consultancy and risk management company Aon, said the impact would be felt beyond coastal areas.
“We are certainly looking at potential losses in the billions,” Bowen said.
The difference is that the size is not only huge physically, but it counts for damage. Storms that are larger have larger storm surges due to the larger water push.
Ida “isn’t going to generate the huge storm surge like Katrina did, she will have a more focused storm surge like Camille (1969),” Masters said.
But larger storms are often weaker, Bowen said. There is a trade-off between intense damage in a smaller area versus less damage, but still bad, in a larger area. Bowen and Gabriel Vecchi of Princeton University said they were unsure which scenario would be the worst in this case.
Ida late Saturday and early Sunday feasted on a whirlwind of what’s known as the Loop Current, going from winds of 105 mph to 150 mph in just eight hours. The Loop Current is that deep area of incredibly warm water. It draws warm water from the Yucatan Peninsula, loops in the Gulf of Mexico, and travels up the eastern edge of Florida in the Gulf Stream. Water above 79 degrees is the fuel for hurricanes.
Normally, when a storm intensifies or stops, it absorbs all the hot water in the area and then hits the cooler water which begins to weaken the storm or at least keep it from getting stronger. But these hot water points continue to fuel a storm. Katrina fed herself that way, as did Ida, gaining power over an area with hurricane fuel over 500 feet deep, “just a hot tub,” McNoldy said.
“Running on these Loop Currents (eddys) is a really big deal. It’s really dangerous,” said climate and hurricane specialist Kossin of the Climate Service.
Over the past 40 years, more and more hurricanes have intensified rapidly and climate change seems to be at least in part to blame, Kossin and Vecchi said. Hurricane Grace has already intensified rapidly this year and last year Hanna, Laura, Sally, Teddy, Gamma and Delta all intensified rapidly.
“There’s a human footprint on it,” said Kossin, who, along with Vecchi, participated in a 2019 study on recent rapid intensifications.
NEW EYE WALL
After a hurricane quickly intensifies, it becomes so strong and its eye so small that it often cannot continue that way, so it forms an outer eye wall and the inner eye wall collapses, Kossin said. This is called eye wall replacement.
When a new eye wall forms, a storm often gets bigger but a bit weaker, Kossin said. So the key for Ida is when and if this happens. This happened for Katrina, who steadily weakened in the 12 hours leading up to her landing.
Ida began the process of replacing the eye wall, but McNoldy said he didn’t think it mattered.
“There is no more time to do anything that can make a difference. “
Meteorologists have improved the forecast and they hope Louisiana is better prepared than in 2005 with a stronger dike system. However, Bowen said Ida would arrive a year after Hurricane Laura hit Louisiana in 2020 with winds of 150 mph.
“No US state since 1851 has ever recorded consecutive years of hurricanes above 150 km / h making landfall,” Bowen said. “After Laura’s landing in 2020, Louisiana is on the verge of making an unfortunate history.”
Follow Seth Borenstein on Twitter at @borenbears.
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