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The National Hurricane Center says preparations for Hurricane Isaias should be rushed to completion because the weather's about to go downhill quickly. Isaias is the first official hurricane in the Atlantic this year, and it's very late in the season for that. Hasn't happened this late in 60 years of modern record-keeping. NPR's Lauren Sommer asked why.
LAUREN SOMMER, BYLINE: It's been a very unusual hurricane season in the Atlantic this year.
SUZANA CAMARGO: Extremely quiet, very long period without any hurricanes.
SOMMER: Suzana Camargo studies extreme weather at Columbia University. She says it's been unusual but not unexpected.
CAMARGO: This is not a surprise, since we have had forecast of an El Nino.
SOMMER: Not just an El Nino - a super El Nino. El Nino is a naturally occurring climate pattern that kicks in every few years. It happens when the Pacific Ocean gets extremely warm around the equator, which sends ripple effects into the atmosphere and changes weather patterns globally. In the Atlantic, it changes the winds.
CAMARGO: That's a problem because, you can imagine, you know, you have some clouds. They are trying to organize and become a hurricane.
SOMMER: Storms that become hurricanes have to start spinning in that classic hurricane shape to really gain power.
CAMARGO: If the winds are pushing the bottom part of those clouds to one direction and the top in another direction, it will be hard for those clouds to become more organized and become a hurricane.
SOMMER: The storms tend to get ripped apart, which means fewer Atlantic hurricanes during El Nino years. In the Pacific, it's been the opposite story. El Ninos tend to mean more hurricanes there. Hawaii has had some close calls with several hurricanes this year, and the heavy rains and winds damaged communities on several islands. Some of the Pacific hurricanes are also examples of what scientists expect to see in a hotter climate with warmer oceans.
CAMARGO: What we're seeing is very intense hurricanes - the Cat 4s, Cat 5s - and also how often they go to this - what we call rapid intensification, when they blow up in intensity very fast.
SOMMER: The warmer the ocean, the faster and stronger a hurricane can grow. Camargo says Hurricane Isaias could do some major damage due to rain and storm surge. And even if this year ends quietly in the Atlantic, no one should get too comfortable. After El Ninos come La Ninas, which usually mean a more active Atlantic hurricane season.
Lauren Sommer, NPR News.
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