HurricanesPowerful hurricanes strengthen faster now than thirty years ago

Hurricanes that intensify rapidly — a characteristic of almost all powerful hurricanes — do so more strongly and quickly now than they did thirty years ago, according to a study published recently in Geophysical Research Letters, a journal of the American Geophysical Union.

While many factors are at play, the chief driver is a natural phenomenon that affects the temperature of the waters in the Atlantic where hurricanes are powering up, according to scientists at the U.S. Department of Energy’s Pacific Northwest National Laboratory and the National Oceanic and Atmospheric Administration.

They found that a climate cycle known as the Atlantic Multidecadal Oscillation or AMO is central to the increasing intensification of hurricanes, broadly affecting conditions like sea temperature that are known to influence hurricanes.

Stronger hurricanes in a day’s time
PNNL says that last year’s lineup of powerful storms — Harvey, Irma, Jose and Maria — spurred the scientists to take a close look at the rapid intensification process. This occurs when the maximum wind speed in a hurricane goes up by at least 25 knots (28.8 miles per hour) within a 24-hour period. It’s a rite of passage for nearly all major hurricanes, including the big four of 2017.

The team, comprised of Karthik Balaguru and Ruby Leung of PNNL and Greg Foltz of NOAA, analyzed 30 years’ worth of satellite hurricane data encompassing 1986 through 2015. Information came from NOAA’s National Hurricane Center and the U.S. Navy’s Joint Typhoon Warning Center.

Consistent with other studies, the scientists did not find that rapid intensification is happening more often nowadays.

But the scientists also looked closely at just how much the storms are strengthening. They found a sizeable jump in the strength of fast-growing storms — the storms are getting more powerful more quickly within a 24-hour period than they were thirty years ago.