For Rick Knabb, halfway through his first season as director of the National Hurricane Center, the last few weeks have underscored one of the biggest challenges of the job.

It’s not figuring out where storms will go. The center’s scientists, analyzing sophisticated computer models, have become increasingly precise at predicting tracks. Persuading the public that there is no such thing as a minor hurricane, however, remains a continuing struggle.

Hurricane Isaac offered only the latest lesson that hurricanes, or tropical storms for that matter, can’t be judged by wind speed alone.

“Historically, we’ve done a better job of conveying wind hazard than we have the water-related hazards, and we realize that and have for some time,’’ said Knabb, 44, a veteran hurricane center forecaster who returned to the center in June after two years as an on-air expert at The Weather Channel. “You have to learn from every event and we’re going to learn from Isaac.”

As a tropical storm skirting South Florida, Isaac only ruffled the hair of bar patrons on Key West’s Duval Street but it dumped a once-a-century deluge over Central Palm Beach County that left neighborhood streets looking like lakes for a week. As a massive but minimal Category 1 hurricane, it pushed the Gulf of Mexico over the roof eaves of homes in Louisiana’s low-lying Plaquemines Parish. Despite evacuation orders from emergency managers and repeated warnings from forecasters of a storm surge up to 12 feet — easily capable of topping the community’s 8 1/2-foot-high protective levee — dozens of bedraggled residents had to be rescued by boat.

In the wake of Isaac, there have been numerous calls in the media, from weather bloggers to the New York Times, for an overhaul of the familiar Saffir-Simpson scale, which ranks storms on the strength of winds alone, from Cat 1 to Cat 5.

One pointed criticism of the NHC, which occupies a bunker-like building bristling with satellite dishes and antennas at the western edge of Florida International University’s main campus in West Miami-Dade County, came from a former colleague at the Weather Channel, hurricane expert Bryan Norcross.

“The NHC’s system for disseminating the forecast is archaic and relies on the media to sort it out and get it right,” Norcross wrote in a blog post last week. The center and local National Weather Service offices produce excellent and accurate forecasts, Norcross wrote, but the torrents of information can be difficult for even trained meteorologists to digest.

Norcross said the NHC’s official advisory — posted online in an all-capital-letters format resembling an old teletype dispatch — buried the critical storm surge forecast for Isaac at the bottom of the text. He argued it should have been the headline and written in plainer language. Many media outlets were complicit in downplaying Isaac as “only a tropical storm,’’ wrote Norcross, who gained national fame as a Miami television weather forecaster during Hurricane Andrew in 1992.

“The message for Plaquemines Parish should have been, “Listen, if the forecast is right, the Gulf is coming over that levee and the water will up to your roof. Now get the hell out!’’

Knabb, in an interview before flying to the Gulf Coast for post-Isaac briefings with regional emergency managers and forecasters, agreed the center needs to do a better job of explaining all the threats posed by an approaching hurricane — not just wind but tornadoes, flooding rains and especially storm surge, which has historically killed the most people.