The National Hurricane Center has modified the forecast cone, but to what end?



The hurricane forecast cone was introduced in 2002 as a means of communicating the path of an impending storm to the public.

He has been maligned, misunderstood and regretted ever since. During Hurricane Ian, the cone swung significantly from Pensacola to Miami, with the Category 4 storm eventually making landfall near its eastern edge where people may have thought they were safe.

“People don’t understand the cone, absolutely not,” said Bryan Koon, vice president of homeland security and emergency management for IEM, a company that works with government and private organizations to improve preparedness, response and emergency management. disaster response and recovery.

Koon also served as director of Florida’s Division of Emergency Management from 2011 to September 2017. “It’s good that people pay attention to the cone, but they look at it and think that’s where the hurricane will get. an impact and nowhere else.”

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Projected track of Hurricane Ian at 11 p.m. Tuesday, September 27, 2022.

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The cone is brilliant in its graphic simplicity – a driving light on a region destined for grief.

But it is also its downfall, as people fall into the trap of thinking that the destructive winds, storm surges and torrential rains of a hurricane will fit perfectly within the boundaries of the fuzzy white funnel, and that the tropical cyclone will follow the middle.

Storm impacts may extend beyond cone area

Instead, the center of a storm can move anywhere inside the cone with very distant impacts. Thirty-three percent of the time the storm moves outside the cone.

It’s a challenge for the National Hurricane Center, which got so frustrated with people focusing on the “skinny black line” in the center of the cone as the storm’s absolute path, that it removed the line from the main graph. . (You can always manually add the central forecast track line if you know which button to click.)

Related:The hurricane’s “cone of uncertainty” grabs everyone’s attention; so will that change again this year?

In 2017, the hurricane center gave the cone a makeover that included shaded areas surrounding the center of a storm to show the range of tropical storm and hurricane force winds. It was hoped that the change would be a better indication of the distance at which dangerous winds could exist.

In 2017, the National Hurricane Center revamped its forecast track cone, making it sleeker and adding an area that shows the extent of damaging winds.  In the new graphic, the solid white and dashed white areas reflect forecast uncertainty as to where the center of the storm might move.  The solid white area corresponds to days 1 through 3 of the forecast, while the dotted areas represent the uncertainty for days 4 and 5. Courtesy of the National Hurricane Center

A year later, the Improved hurricane forecasts The project announced that it plans to study the effectiveness of several hurricane center communication tools, including the cone.

“We know there are limitations with the cone graph, and the concern is that people think if you’re not there, you’re safe,” Ed Rappaport said in 2018 when he was acting director of the National Hurricane Center. “The cone chart is almost impossible to replace because it’s so ingrained, but maybe we could add something to it or introduce something that could become even more popular.”

Rappaport retired in 2021 after 33 years at the hurricane center.

New graphics amplify the storm’s projected impact, but the cone is what people see

New charts showing flood extent and storm surge flood levels have also been introduced in recent years. But then people have to look at several different charts to get an idea of ​​the storm track, wind field, and storm surge.

Hal Needham, an extreme weather and disaster specialist with Project GeoTrek, which studies storm surges, said that instead of emphasizing the hurricane forecast cone in the broadcasts, the impacts of the storm should take center stage.

National Hurricane Center 2 p.m. Wednesday, September 28, 2022 Advisory tracking cone for Hurricane Ian.
National Hurricane Center 2 p.m. Wednesday, September 28, 2022 Notice of storm surge sightings/warnings for Hurricane Ian.
National Hurricane Center 2 p.m. Wednesday, September 28, 2022 Advisory regarding the most likely time of arrival of tropical storm-force winds for Hurricane Ian.
National Hurricane Center 2 p.m. Wednesday, Sept. 28, 2022 advisory for initial wind rays for Hurricane Ian.

“With the cone, you’re sinking into a hole that’s hard to get out of,” he said. “People are busy and most of them are not passionate about the weather. They will look at one or two images and that is what will influence them.

The size of the hurricane forecast cone is adjusted each year before June 1 based on the error rates of the previous five seasons. It has steadily become smaller as predictions have become more accurate, but this also means that more impacts can occur outside of the cone.

Brian McNoldy, a principal investigator at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, created this graph to show improvements since 2003 in track prediction accuracy.

In defending evacuation decisions during Hurricane Ian, Governor Ron DeSantis and Lee County Sheriff Carmine Marceno said there were times when Lee was not in Ian’s forecast cone. .

But at all times, at least part of Lee County, even if it was just Cayo Costa where Ian made landfall, was in the cone.

Advisory from the National Hurricane Center As of 11 a.m. Sunday, Sept. 25, the nearest Lee County was outside of Hurricane Ian's likelihood cone.  The area to the left of the blue line is within the cone, which includes the tiny islands of Lee County, Boca Grande, and Cayo Costa.  Lee County, according to NHC updates, was never completely out of the cone.

“Mother Nature taught us a lesson. It’s unpredictable,” Marciano said Oct. 3, five days after Ian landed. “I am confident in the decisions that have been made. I support them and I wouldn’t change a thing.

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