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Are we really having more hurricanes than usual this year?

A satellite image from left, Tropical Storm Katia, Hurricane Irma and Tropical Storm Jose, which would intensify into a hurricane. The 2017 Atlantic hurricane season has been unusually active. There have been 13 named storms this year.

NASA/NOAA GOES Project via The New York Times

A satellite image from left, Tropical Storm Katia, Hurricane Irma and Tropical Storm Jose, which would intensify into a hurricane. The 2017 Atlantic hurricane season has been unusually active. There have been 13 named storms this year.

You know their names.

Harvey. Irma. Jose.

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This year’s hurricane season has unleased a rapid succession of storms that have battered the Caribbean, Houston, South Florida, and surrounding locales, leaving residents to wonder how much more devastation they can take.

With Hurricane Maria now looming, the trend raises another question, too: What’s behind all these hurricanes?

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While there’s no easy answer, it appears that an odd combination of changing wind patterns and warming seas has made for a particularly stormy summer. And one thing is clear. The intensity of the storm surge didn’t catch forecasters by surprise.

“We are in the peak week of the peak month of hurricane season, in what was forecast to be an above average season,” said Dennis Feltgen, a spokesman for the National Hurricane Center, in an e-mail Tuesday morning.

Xun Jiang, a professor in the Department of Earth and Atmospheric Sciences at the University of Houston, drew a connection between the increased storm activity and climate change.

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“Sea surface temperature is very high in this season,” Jiang said via e-mail. “The warm ocean temperature coupled with the high humidity in the air will help to form strong hurricanes. In a funded NASA Energy and Water Cycle Study project, we also noticed that the weather tends to become more extreme as a response to climate change. Wet area tends to get wetter and dry area tends to get dryer.”

In an advisory, the National Oceanic and Atmospheric Administration warned of a potentially treacherous late summer under this heading: “Above-normal season likely with 14 to 19 named storms,” compared to 12 named storms for an average Atlantic hurricane season, which runs from June 1 to Nov. 30.

The advisory predicted an “extremely active” season, perhaps the busiest since 2010.

The NOAA advisory cited a number of contributing factors, including warmer waters across the tropical Atlantic than previously predicted; easterly wind patterns coming off the west coast of Africa; a weaker vertical wind shear, or change of winds with height; and weaker trade winds, which blow toward the equator from the northeast.

Gerry Bell, a hurricane forecaster at NOAA’s Climate Prediction Center, told reporters in August that researchers have seen “a lot of active hurricane seasons in the Atlantic” since 1995 that have been linked to warmer ocean temperatures. He said the Atlantic has historically produced 25 to 40-year stretches of warmth, when hurricane activity increases, followed by cooling, when it slows. Reduced activity between 2013 and 2015 led researchers to speculate that “maybe we’re getting out of” the warming phase, Bell said.

But now the experts aren’t so sure.

“It turns out it’s not clear if were getting out of this warm phase . . . or not yet,” Bell said.

Travis Andersen can be reached at travis.andersen@globe.com. Follow him on Twitter @TAGlobe.
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