Hurricanes Are Slowing Down

According to a new study recently published in the scientific journal Nature, some hurricanes are moving slower and spending more time over land, which is leading to catastrophic rainfall and flooding. The speed at which hurricanes track along their paths – known as translational speed – can play a major role in a storm’s damage and devastation.  17

Their movement (or lack thereof) influences how much rain falls in a given region. This is particularly true as climate change leads to warmer global temperatures.  According to James Kossin, a researcher at NOAA’s Center for Weather and Climate and the study’s author, “just a 10% slowdown in hurricane translational speed can double the increase in rainfall totals caused by a 1 degree Celsius” increase in global temperature.

The study examined 68 years of hurricane track and intensity data, from 1949 to 2016, and compared the changes in translational speeds.  During this time frame, the study revealed that hurricane translational speed has averaged a 10% slowdown.

But there is regional variation in the slowdown rates.  According to researchers, hurricanes moving across the Western North Pacific Region, which includes Southeast Asia, have slowed 20%, but those moving across the North Atlantic Region, which includes the United States, have slowed just 6%.

A recent storm that highlights the potential consequences of this slowing trend is Hurricane Harvey.  In 2017, instead of dissipating over land, Harvey stalled over eastern Texas, drenching Houston and the surrounding regions with as much as 50 inches of rain over several days.

The results of this study indicate that devastating storms like Harvey will be increasingly common in years to come.

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Hurricanes are slowing down, and that’s bad news

Photo, posted August 27, 2017, courtesy of the Texas Military Department via Flickr.

‘Hurricanes Are Slowing Down’ from Earth Wise is a production of WAMC Northeast Public Radio.