South Florida Sun-Sentinel

FORT LAUDERDALE, Fla. – Despite highly accurate track forecasts last summer, the National Hurricane Center plans to discourage residents from putting too much faith in that skinny black line by offering a new supplement: a strike probability map.

The color-coded map will be posted on the center’s Web site, www.nhc.noaa.gov, by the June 1 start of the season. It will display the odds that a given area could face hurricane- or tropical-force winds. It also will attempt to project a storm’s size and intensity.

In that way, officials hope residents won’t be caught off guard as they were with Hurricane Charley, which initially was predicted to hit Tampa but struck Punta Gorda and Port Charlotte on Aug 13.

“If people had been looking at this probability product rather than focusing on the line, nobody would have come to the conclusion they were safer in Port Charlotte than Tampa,” hurricane specialist James Franklin said Thursday.

He noted that the probability of Charley’s core hitting Tampa or Port Charlotte was the same: 30 percent 24 hours before landfall.

The hurricane center already provides a strike probability chart, showing the chances that a storm will come within 75 miles of larger coastal cities.

But the map, to be used on an experimental basis, would provide the most comprehensive information as storms approach, Franklin said.

“It considers a whole wide range of things that can happen in the forecast,” he said.

The hurricane center is considering getting rid of the skinny black line, or projected path, and replacing it with circles or dots to emphasize a much broader cone of uncertainty.

Bill O’Brien, director of Palm Beach County emergency management, said the map should be a good tool to prompt preparations.

“Any legitimate information we can get, the more logic people have to make good decisions,” he said.

On the other hand, Tony Carper, director of Broward County emergency management, said he is concerned the map might show low probabilities when storms are four or five days out – and convince residents to let down their guard.

“If you’re on the fringes, four or five days out, your probability might be less than 10 percent, and you ultimately could be the one to get the landfall,” he said. “That’s problematic.”

In 2004, the National Hurricane Center in Miami-Dade County achieved record-breaking accuracy in its track forecasts of nine hurricanes, five tropical storms and one subtropical storm.

The center’s average track error was 67 miles when the systems were 24 hours away, a marked improvement over the 10-year average error of 90 miles. Those errors are half of what they were 15 years ago.

The steady improvement is the result of more sophisticated computer forecast models, as well as more and better information about the atmosphere that surrounds hurricanes, Franklin said.

The best forecast last year: Hurricane Frances was projected to strike 40 miles from its actual landfall point when the storm was 24 hours out in early September. When the system was five days out, the track error was 144 miles, which is less than half the 10-year average error of 367 miles.

“We have to remind people that we’re not perfect every time,” Franklin said. “That was a big problem with Charley; people assumed the forecast would be perfect.”

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