"The main story about Katrina was the storm surge damage. This happened over a large area. "The main story for Ida will be wind, storm surge and fresh water flooding damage," stated Jeff Masters, a meteorologist who flew missions to assess hurricanes and created Weather Underground.
Ida made landfall on the same calendar date, Aug. 29, as Katrina did 16 years ago, striking the same general part of Louisiana with about the same wind speed, after rapidly strengthening by going over a similar patch of deep warm water that supercharges hurricanes.
But, there are three things that could make a difference: strength, direction and size.
Brian McNoldy, University of Miami hurricane researcher, said that "Ida" will be more powerful than Katrina and by a large margin. "And the worst of the storm is expected to pass over New Orleans, Baton Rouge, and Baton Rouge which were the most affected by Katrina."
McNoldy stated that Ida was a powerful Category 4 storm with 150 mph winds (231 kph).
Katrina was quite weak before it made landfall in Louisiana. It struck Louisiana as a Category-3 storm with winds of 127 mph (204 km/h).
Katrina struck Louisiana from the south, while Ida is heading to the same area from the southeast. McNoldy stated that Ida's hurricane force winds were 37 miles (about 60 km) away from the center. This is in contrast to Katrina’s hurricane-force winds which spread 98 miles (1158 kilometers) from its center.
McNoldy stated that this could be a more natural disaster than Katrina's. However, the main issue with Katrina was a man-made catastrophe due to levee failures. Katrina's death total rose to 1,833 with its damage at $176 billion. Experts don't believe Ida will reach those levels.
Ida arrived in the same area from a slightly different direction. Many hurricane experts worry that the angle could place New Orleans in the dangerous storm quarter -- the right front of a hurricane -- more than Katrina when it was more damaged by storm surge than levee failure. Katrina's northeast quarter pushed storm surges of 28 feet (8.5 meters) in Mississippi, not New Orleans.
McNoldy stated that Ida's angle is "potentially even worse." It is smaller so it won't create as much of a storm surge, but the angle at which this is coming in, I believe is more conducive for pushing water into the lake. (Pontchartrain).
Masters stated that Ida's northwestern path puts New Orleans in the bullseye more than Katrina did. It also targets Baton Rouge as well as crucial industrial areas. Masters said that Ida will move through "the absolute worst place for hurricanes."
Masters stated that the track is expected to follow the industrial corridor connecting Baton Rouge and New Orleans. This is critical infrastructure for the U.S. economy. Masters stated, "You are likely to close the Mississippi River for barge traffic multiple times a week."
Steve Bowen, a meteorologist and head of Aon's global catastrophe insight at risk and consulting firm Aon said that the impacts will not be limited to coastal areas.
Bowen stated that potential losses could reach the billions.
It is important for damage to be able to tell the difference in size. Because of the greater push of water, storms with a larger width experience a stronger storm surge.
Masters stated that Ida "isn't going to generate the massive storm surge like Katrina, but it'll have a more focused storm surge than (1969's') Camille."
Bowen stated that storms of greater size are more likely to be weaker than those of smaller sizes. It's possible to have more severe damage in a small area than less damage in a larger area. However, the consequences can be devastating. Gabriel Vecchi, Princeton University's Bowen, said that they aren't sure which scenario would be worse.
Ida spent Saturday night and Sunday eating an eddy called the Loop Current. It went from 105 mph winds up to 150 mph winds (169 km/h winds to 241 KPH winds) in eight hours. It's very dangerous," stated Kossin, a climate and hurricane scientist from The Climate Service.
According to Vecchi and Kossin, more hurricanes have intensified in the last 40 years. Climate change may be partly to blame. Hurricane Grace already rapidly intensified this year and last year Hanna, Laura, Sally, Teddy, Gamma and Delta all rapidly intensified.
"It has a human fingerprint on it," said Kossin, who with Vecchi was part of a 2019 study on recent rapid intensifications.
Kossin stated that a hurricane that intensifies rapidly becomes so powerful and its eye is so small that it can't keep going the same way for long periods of time, so it creates an outer eyewall, and then the inner eyewall falls. This is called eyewall replacement.
Kossin stated that storms often grow in size when a new eyewall is formed. However, they can also become weaker. It is important for Ida to know when and if this happens. Katrina experienced it, and its strength slowed in the 12 hours that followed.
McNoldy stated that although Ida started the process of replacing her eyewalls, he doesn’t believe it matters.
"It is running out of time to make any difference."
Meteorologists are now able to make better forecasts. They hope that Louisiana will be more prepared than 2005, when it had a stronger levee system. Bowen however said that Ida will be arriving one year after Hurricane Laura battered Louisiana in 2020 with 150 mph winds.
Bowen stated that "No U.S. State since 1851 has ever seen back-to-back 150+ mph hurricanes make landfall in the United States." "Louisiana is set to make a terrible history after Laura's 2020 landfall."