Study: Gulf waters warmest on record around Hurricane Harvey landfall

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By: Charles Roop | WCTV Pinpoint Weather
May 11, 2018

TALLAHASSEE, Fla. (WCTV) — The warm Gulf of Mexico waters might have given Hurricane Harvey a boost in strength and climate change may have been a factor, a study released on Thursday noted.

Hurricane Harvey, which made landfall in Texas as a category 4 storm in August 2017, caused flooding in the region; notably in the Houston-metro area. Rainfall totals were as high as 60 inches, according to the study.

The authors used a global dataset of ocean heat content up to nearly 1,900 feet below the ocean’s surface for different regions in the Gulf of Mexico and constructed two time periods, before (Aug. 1-20) and after Harvey (Sept. 1-20). They also looked at sea surface temperatures in the Gulf, and precipitation in the region via satellite.

The researchers found that ocean heat content was the highest ever recorded in the Gulf of Mexico during the early summer of 2017. The gulf waters, for the most part, were undisturbed, allowing for plenty of juice to develop and sustain the hurricane as it moved out of the Caribbean Sea and into the western gulf. Sea surface temperatures were also more than enough, greater than 86 degrees, to make Harvey a dangerous storm.

But despite the storm's passage, which usually would cool the water through mixing, the surface water temperature only dropped by two degrees Celsius. The temperature drop was still enough to sustain the hurricane - especially since it stayed close enough to the gulf to pull in moisture.

The storm’s strength and location, along with the overall weather pattern to keep Harvey at its location for so long, did not help the flooding situation. Still, the overall heat content did drop after the storm moved over the water.

As the Earth warms, the authors note concern of tropical systems becoming more potent in the future. The sea surface temperatures have increased over a half-degree Celsius since 1960, which means about 5 percent more moisture overall in the atmosphere, they wrote. But moisture convergence with these tropical systems can produce more rainfall. Two studies they cited found that, with Harvey, the moisture increase was between 20 and 38 percent.

“The implication is that the warmer oceans increased the risk of greater hurricane intensity and duration,” Kevin Trenberth, one of the authors, said in a press release. “While we often think of hurricanes as atmospheric phenomena, it’s clear that the oceans play a critical role and will shape future storms as the climate changes.”

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