Scientists at the United States National Oceanic and Atmospheric Administration Climate Prediction Center recently noted a rapid cooling of ocean temperatures in the east-central equatorial Pacific Ocean, possibly indicating the formation of a La Niña event.
A press release issued by NOAA Tuesday stated that La Niña conditions impact tropical rainfall patterns and atmospheric winds over the Pacific Ocean, which in turn influences the patterns of rainfall and temperatures in other areas of the world.
Retired Navy Vice Admiral Conrad Lautenbacher, who is under secretary of commerce for oceans and atmosphere and NOAA administrator, explained the possible effects of a La Niña in the press release:
‘Although other scientific factors affect the frequency of hurricanes, there tends to be a greater-than-normal number of Atlantic hurricanes and fewer-than normal number of eastern Pacific hurricanes during La Niña events,’ he said.
La Niña events sometimes form soon after the end of El Niño events. El Niño events like the one that occurred last year bring a warming of ocean temperatures in the Pacific Ocean.
Fred Sambula, senior manager of the Cayman Islands Meteorological Service, said the El Niño events tend to reduce the number of hurricanes in the Atlantic basin.
‘When there is an El Niño, there is a shift in high pressure systems that leads to a lot more shearing in the Atlantic,’ he said, adding that the amount of wind shear is critical to the development of tropical storm systems.
High wind shears during last year’s hurricane season have been cited as a reason far fewer tropical systems developed than predicted.
‘The El Niño last year was unexpected, but it was a help for us,’ Mr. Sambula said.
Although a La Niña event this year would likely lower the wind shear in the Atlantic Ocean, Mr. Sambula said it was just one of the conditions that affected tropical storm development.
Water temperatures in the tropical Atlantic are another condition that affect storm development, and Mr. Sambula said those temperatures are ‘fairly warm’ right now. Warmer sea surface temperatures help strengthen tropical storms systems.
Mr. Sambula said it was too early to tell if a La Niña was likely to have a significant affect on the upcoming Atlantic basin hurricane season. He noted that the La Niña was just beginning and that there is usually a lag between its formation and changes in atmospheric conditions.
‘It depends how quickly the La Niña forms,’ he said.
Mr. Sambula said his advice was for residents of the Cayman Islands to remain vigilant.
‘Even in a so-called inactive season, that doesn’t mean there is not a storm out there with your name on it,’ he said. ‘All it takes is one hurricane to hit you and make it an active season. We have to be on our guard.’
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