Saharan Dust Cools Down Hurricane Season

The month of August was the official midway point in the 2015 Atlantic hurricane season – a period of time that has yielded the formation of just one hurricane-force storm thus far. Hurricane experts are anticipating many fewer storms in the Atlantic this year, likely as a result of cooler-than-average water temperatures in tropical and subtropical regions.

sahara_dustThese cooler temperatures can be attributed to the increased concentrations of Saharan dust, a byproduct of the African easterly jet stream that forms over Western Africa and blows out across the Atlantic every year. The winds, which are generated by the differences between the hot, dry desert of northern Africa and the cool, wet rainforests of southern Africa, bring clouds of dust, which subsequently block the warming sunlight.

“Dust activity has been very intense this year and sea surface temperatures are unusually low,” said University of Miami meteorologist Joseph Prospero in a news release. “These may have been contributing factors to the unusually weak hurricane season this year.”

The downturn in hurricane activity has also been attributed to the strong El Niño season that has been occurring this year in the tropical Eastern Pacific. Wind patterns during this period create a vertical wind shear, which can limit humidity over the Caribbean and Atlantic, preventing tropical storms from developing into hurricanes. Areas where hurricane-level storms typically form have been stymied by an overall lack of humidity, preventing smaller storm cells from stacking and growing.

In contrast to this year’s quiet season, 2015 marks the 10-year anniversary of ‘sister storms’ Hurricane Katrina and Hurricane Rita. These storms were some of the costliest natural disasters in U.S. history, with Katrina being  one of the five deadliest hurricanes ever recorded. Nearly 2,000 lives were lost in the destruction that would ultimately total $108 billion in Louisiana and other neighboring Gulf states.

“The vastness of the destruction is just so big, I don’t think anyone expected this,” said Kevin Savoie, marine extension specialist for Louisiana Sea Grant in 2006 describing the challenges during initial efforts to provide aid and build back communities.

Katrina and Rita, which hit only a few weeks apart, causing similar destruction to Louisiana’s southwest coast, generated discussion on reforming how government prepares for  natural disasters. To date, many communities in Louisiana are adopting new internationally approved measures, such as better building materials and construction practices, that will enable buildings to withstand intense storms.

“Those who followed the new codes when rebuilding made it through Hurricane Ike (in 2008)” said Savoie. The fishing industry, which was reduced significantly following Hurricane Katrina, has also experienced a strong revival, as shown in this video from Louisiana Sea Grant.

Fifty-six hurricanes have hit Rhode Island since the 17th century, with several leaving trails of severe damage. But what is the worst-case scenario and are we prepared? The state has spent millions in working with the Army Corps of Engineers to supplement sand for refurbishment of the shoreline at locations like Misquamicut State Beach in Westerly, which suffered damages from Superstorm Sandy in 2012.

Although Sandy was not a worst-case scenario for Rhode Island, it did bring attention to communities as far north as Maine on how to improve coastal resilience, a task that has proven difficult in areas of coastal communities that have undergone intensive development and activity. Rhode Island’s response to Sandy, and its preparation for future storms, focuses on HurricanesImpactprotecting the vitality of the shoreline to alleviate damage to property and minimize any downturn in economic activity. Coastal tourism, an industry that contributes one out of every 10 jobs in the state and produced $1.63 billion in wages and salaries in 2014, is especially vulnerable to the potential impacts of a storm.

“The consequences of not preparing this sector of the economy for (storm) impacts would be devastating to the state,” said Extension Specialist Michelle Carnevale of Rhode Island Sea Grant and the URI Coastal Resources Center at a Shoreline Change Special Area Management Plan (Beach SAMP) presentation.

The Beach SAMP is currently in development to be a guide for the state in preparing coastal residents and businesses for future erosion and flooding associated with sea level rise and increased storm intensity. So while we’ve seen little hurricane activity this season, it doesn’t mean there isn’t a storm on the horizon.

What we may find in the future, according to Isaac Ginis, hurricane expert at the University of Rhode Island Graduate School of Oceanography at a Beach SAMP meeting last year,  is either the same number of storms or fewer in a season, but with greater intensity.

“We’ll see more Category 4 and 5 storms,” he said, explaining that this may be largely attributed to the impacts of climate change, as warmer water fuels these types of storms. “Hurricanes love warm water. The higher the temperature, the higher the potential for hurricanes to gain energy.”

While the new efforts in Rhode Island may not be put to task by a hurricane in the 2015 season, surely more efforts will be put forth and tested in the years to come.

 

Evan Ridley  | Rhode Island Sea Grant Science Communications