Highly Unusual ‘Brown Ocean Effect’ Keeps Hurricane Ida’s Eyewall Intact Hours after Landfall
Anyone who's spent even a few minutes watching hurricane coverage knows there's a pretty familiar pattern with most tropical systems. The storm makes landfall and quickly weakens. Its eyewall begins to lose structure and eventually the storm dissipates.
Hurricane Ida, which struck Louisiana Sunday (August 29) as an intense Category 4 storm with winds of 150 miles per hour did something rather unusual. It did not immediately weaken and its eyewall did not crumble once the storm came ashore near Port Fourchon.
Conventional weather knowledge says it's the heat of the tropical seas that rev up a storm. Once the system hits land, the energy that fed the storm is gone. That's not what happens when the Brown Ocean effect comes into play. This rare phenomenon involves warm, wet soil that continues to feed a storm over land.
The Brown Ocean Effect in Action
Watch this radar image show how the storm keeps right on trucking even after encountering Louisiana:
This scientist with NOAA states how rare a phenomenon Hurricane Ida's displayed post-landfall.
While the Brown Ocean Effect is rare, it has been seen before. The University of Georgia studied it following the 2017 hurricane season.
The scientists are building on an idea first advanced in two UGA-based studies suggesting that wet soils could sustain or intensify hurricanes, typhoons and other tropical cyclones, a phenomenon they call the “brown ocean” effect.
“The more common behavior is that hurricanes weaken when they move over land so this research has implications for assessing storm hazards and flood potential as storms move over land,” said [Georgia Athletic Association Distinguished Professor of Geography and Atmospheric Sciences Marshall] Shepherd, the study’s principal investigator. “Our previous work found that smaller or weakening storms can be the biggest rain producers, not the powerhouse Category 5 storms.”
This intense storm, of course, will bring destruction. Hot 107.9 in Lafayette showcases collected videos and photos here.
As a storm that is already in the 10 ten all-time intense/windiest hurricanes at landfall in the United States, Ida's destruction will be long remembered. As will these storms that have gone down in the record books: