EXPLAINER: Ida, Katrina similar but tiny differences are key

Hurricane Ida is looking eerily like a dangerous sequel to 2005’s Hurricane Katrina, the costliest storm in American history. But there's a few still-to-come twists that could make Ida nastier in some ways, but not quite as horrific in others.

Ida is forecast to make landfall on the same calendar date, August 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.

What could be different is crucial though: Direction and size.

Katrina hit Louisiana from due south, while Ida is coming to the same part of the state from southeast. A day-and-a-half before landfall Ida’s hurricane-force winds extended 13 miles (21 kilometers) from the center compared to 106 miles (170 kilometers) for the much more massive Katrina at the same time before landfall.

“This has the potential to be more of a natural disaster whereas the big issue in Katrina was more of a man-made one” because of levee failures, said University of Miami hurricane researcher Brian McNoldy. Levee failures 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 near those totals.

DIFFERENT DIRECTION

Ida is coming to the same general place from a slightly different direction. Several hurricane experts fear that difference in angle may 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 levee failure than storm surge. Katrina’s northeast quadrant pushed 28-foot (8.5-meter) storm surges in Mississippi not New Orleans.

Ida’s “angle is potentially even worse,” McNoldy said. Because...