The National Hurricane Center is making changes to one of its most iconic forecast maps. Starting this hurricane season, they plan on shrinking their “cone of uncertainty,” since they say their forecast record is improving, they announced Monday.
In addition, forecasters will extend watches and warnings to 72 hours in advance of a potential storm, providing a full 24 extra hours to prepare. A few experimental maps from last year will also now become permanent features. They include arrival times for dangerous winds.
"The changes are to improve information contained in the hurricane center products and to provide it in maybe easier to understand formats," said Dan Brown, a senior hurricane specialist in charge of warning coordination.
Storms usually stay inside the cone 70 percent of the time. But 30 percent of the time they end up outside of the cone. Even with this discrepancy, the forecasts have improved since just a few years ago. The cone is designed to show you where the center of the storms is likely to track.
Atlantic basin tropical cyclone track forecast error cones issued by @NWSNHC in 2018 will be smaller at all time periods. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone roughly 60-70% of the time. #FLwxpic.twitter.com/8iFSCSKn9e
— NWS Key West (@NWSKeyWest) April 17, 2018
The forecast cone is a longtime part of the hurricane forecasts but has been much debated because the public tends to focus on the center track, ignoring dangerous winds that can extend for many more miles.
Two years ago, the Hurricane Center extended the cone to five days from three. Storm surge maps were also recently introduced, which the weather service believes helped the public make better decisions.
"Despite the fact three Cat 4 hurricane landfalls occurred in the U.S., there were no known storm surge-related deaths. There may have been other factors, but (storm surge warnings) certainly played into it," Brown said. "The mapping is helping with better awareness."