Climate Matters: 20 years after Katrina, hurricanes are rapidly intensifying at record pace

August 29th, 2005 is a day the nation will never forget, as a devastating major hurricane inundated over 80% of New Orleans with flood waters.

Katrina remains one of the most intense and deadliest tropical cyclones to make landfall in the United States, and it is tied with 2017 Hurricane Harvey as the costliest hurricane ever.

Now, two decades later, hurricane forecasting is better than ever, but the tropics have changed.

"We're seeing storms that are doing things that are outside kind of the historical realms," says Dr. Ryan Truchelet, President and Chief Meteorologist at WeatherTiger LLC in Tallahassee, Florida. "They do seem to be doing things that we don't have a record of them doing before."

Climate change has warmed the waters in the Gulf beyond what is typical for hurricane season. Dr. Truchelet says it is not unusual for sea surface temperatures to reach the mid-80s in August and September for the peak of hurricane season. However, in the last half decade, those temperatures are now climbing to 86, 87, 88 degrees or higher.

Warmer waters contain more energy for developing tropical cyclones, which means predicting these storms is more important than ever.

Newer weather models, like the Hurricane Analysis and Forecast System (HAFS) developed by NOAA, are able to analyze hurricanes better than models of years past. Hurricane prediction can be done using global weather models, like the American Global Forecast System (GFS) or the Euro model from the ECMWF, but these models rely on coarse data grids that can't capture the complex physics within a hurricane.

Hurricane-specific models like the HAFS are much better suited to analyze and forecast tropical cyclones that are intensifying faster and more frequently.

Dr. Truchelet says the progress made in hurricane forecasting in recent decades is one of the biggest lessons learned from Katrina. "It really goes to show that the investments that we've made in improving hurricane forecasting in the public sector have really paid off in terms of doing a better job of managing, you know, what's always going to be a very bad situation."