Hurricane Ida remained a hurricane for 16 hours after it made landfall on Sunday, Aug. 29. It remained a major hurricane (Category 3 or above) for six hours of that time. So, how did Idea have such staying power?
The short answer is, according to meteorologists, Hurricane Idea didn’t know it was over land.
Hurricanes draw forth their energy and fuel from the warm ocean waters. When they hit landfall, that power begins to dissipate. In the case of Ida, it made landfall over wet, marshy terrain which enabled it to power itself with evaporating moisture.
“We always knew that places like the Everglades or the swampy wetlands of Louisiana could provide a fuel supply for storms that might linger over them, and I think that’s what we saw with Ida,” said Marshall Shepherd, a meteorologist and the director of the Atmospheric Sciences Program at the University of Georgia.
This is called the “brown ocean effect,” the phenomenon of hurricanes and tropical storms that stay strong even as they travel inland.
After all, hurricanes draw their power from warm ocean waters. When that warm water evaporates and rises, it condenses. This releases heat and drives the rotation of the storm. As the hurricane’s winds gather around its eye, they blow across the ocean surface, driving faster evaporation, thus feeding even more energy into the storm.
Whenever a hurricane hits land, it typically loses this fuel source and begins to weaken, eventually falling part. However, whenever the “land” is a swamp, there’s still plenty of moisture to draw from.
Another factor that helped Ida remain strong was the unique topography of southern Louisiana just west of New Orleans. The area the hurricane came through is extremely flat and low-lying. There was little topography to stop it, and little land friction to help stop the storm.