Scientists concerned about ferocious, life-threatening intensification in hurricanes have developed a tool to help predict when the storms will make such quick changes.
Hurricanes gain strength suddenly in part because they pass over rings, swirls and eddies of unusually deep, warm water that have previously gone unrecognized.
Those "bumps" of expanded warm water are areas of hurricane fuel sometimes reaching 2 inches higher than the rest of the ocean.
Scientist Gustavo Goni and others have developed a tool, called the tropical cyclone heat potential, which measures how warm the water is in these areas and how deep the higher temperatures reach.
Cases such as Hurricane Mitch, which killed 9,000 people in Central America in 1998 when it suddenly grew in strength from Category 3 to Category 5, make such discoveries important, meteorologists say.
Michelle Mainelli, a meteorologist at the National Hurricane Center in Miami, said the measurement is currently being used in computer forecast models.
"We already know that it will improve the models, though we still need to polish things up," said Goni, who works at NOAA's Atlantic Oceanographic and Meteorological Laboratory on Virginia Key. "We have examples we can show of hurricanes that intensified after passing over these very warm areas."
Scientists have known for years that the ocean's surface must be at least 78.8 degrees Fahrenheit for hurricanes to form and thrive.
But researchers have found that those temperatures can range from typical temperatures of 78.8 degrees and depths of 45 feet, to as high as 87.8 degrees and reach depths of 600 feet in some swirls of the ocean. That's enough to make a big difference to a hurricane that's threatening lives and coastal property, Goni said.
The measurements are being taken and reported for all seven basins around the globe where hurricanes can form.
"Many people are contributing to this," Mainelli said. "And now we want to fine-tune this information and make it more precise."