Hurricanes are some of the deadliest storms on the planet, and scientists predict they'll pack even stronger punches as climate change advances. After forming over tropical oceans, these tempests wreak havoc once they make landfall, bringing with them winds of up to 140 miles (225 kilometers) per hour, storm surges and even tornados. As hurricanes approach the shore, satellites and weather radar can help project when and where a storm will hit. But forecasters have been stumped when it comes to predicting when they'll hit peak strength. New research promises to solve this problem by keeping tabs on – of all things – lightning, which until recently, was believed to be rare in such storms.
The research, published online today in Nature Geoscience, analyzed the strongest 58 hurricanes from 2005 to 2007 and found that an increase of lightning reliably preceded the maximum winds by about a day (in all but two of the storms). "Changes in lightning activity can signal changes in storm dynamics, organization, development and so on," according to the study led by Colin Price, a professor of atmospheric sciences at the Tel Aviv University in Israel.
Hurricane Dennis, for instance, which swept over Cuba, Haiti and Jamaica before slamming into Florida and Georgia in early July 2005, caused more than 85 deaths and $4 billion in damages. Dennis had a jump in lightning flashes – more than 1,500 flashes – on July 7 (up from about 800 on the 6th), and by July 8, winds reached peak speeds of nearly 150 miles (220 kilometers) an hour (up from about 70 miles – 110 kilometers – an hour the day before) as the storm was just off the coast of Cuba. The researchers saw the same pattern repeatedly, thanks to data collected by the World Wide Lightning Location Network (WWLLN), which provides real-time maps of lightning around the globe.
The WWLLN, however, "detects only a small fraction of total lightning," the study notes, "without any information about the type of lightning," so improved lightning detection should be able to strengthen the wind force predictions.
In the U.S. hurricanes are monitored by the National Hurricane Center (based in Miami, and run by the National Oceanic and Atmospheric Administration, or NOAA), which uses satellites, weather radar, planes and ocean buoys to track and forecast hurricane behavior. Computer modeling has also allowed the agency to make long-term projections that estimate the number of storms for a given hurricane season (including the prediction of four hurricanes hitting the U.S. this year). Director of operations at the National Weather Service's Honolulu Forecast Office, Richard Knabb is not so sure lightning will prove the final stroke in hurricane forecasting. "Unfortunately, there is no silver bullet to improve intensity forecasting," he tells ScientificAmerican.com in an e-mail. "There are just too many other factors that affect intensity change."
Image of worldwide hurricane paths between 1985 and 2005 courtesy of Nilfanion via Wikimedia Commons