El Niño is back.
That means Louisiana is looking at a colder, wetter spring, but also, maybe, the promise of fewer hurricanes this summer.
An El Niño occurs when sea surface temperatures in the central and east-central Pacific Ocean heat up for an extended period of time. El Niño, along with its opposite, La Niña, influences temperature, rainfall and severe weather around the world.
While an El Niño was predicted for last year — and the conditions were very close — it never fully formed.
“We’ve been El Niño-like for almost three-quarters of a year,” said Barry Keim, the state climatologist.
The National Oceanic and Atmospheric Administration scientists announced March 5 that all the conditions were in place to declare an El Niño. But it’s a weak version of the weather event, which one NOAA official predicted would be unlikely to bring strong rains to drought-plagued California, as happened in previous years. There’s also a possibility the conditions could dissipate by summer, when El Niño is potentially most helpful along the Gulf Coast by driving away hurricanes.
Still, NOAA noted that the Gulf Coast should expect a rainy spring. Historically, during an El Niño year, March through May brings a good chance of more than average rainfall in Louisiana.
“Big picture with an El Niño is a lot of times it will split the jet stream,” said Ken Graham, meteorologist in charge at the National Weather Service in Slidell. A part of the jet stream will head north, but another part will come from the Pacific Ocean and bring moisture with it as it crosses California, Texas and into Louisiana.
Typically, that means Louisiana’s springs are a little cloudier as more rain comes into the state. “History says more rain and cooler temperatures,” Graham said.
Of course, as with anything weather-related, nothing is guaranteed.
With the additional rainfall, there is also the possibility of more severe weather as well, Keim said.
The real benefit to Louisiana comes with the typical impacts of an El Niño on the hurricane season, which starts June 1.
An El Niño typically brings stronger wind shear to the Gulf of Mexico and the Atlantic Ocean, hampering the formation of tropical storms and keeping those storms from strengthening.
“For hurricane seasons going back 100 years, El Niño means fewer hurricanes in the Atlantic and more in the Pacific,” Graham said.
Keim added that the 2014 hurricane season was so mild in the Atlantic Ocean because of El Niño-like conditions. In comparison, the Pacific Ocean hurricane season was extremely busy last year.
Although El Niño usually means fewer storms in the Atlantic Ocean, that doesn’t mean people can let down their guard, Graham and Keim said.
Louisiana is no stranger to getting a devastating storm during an El Niño year, even if the season’s total storm count was below average.
In 1957, there were only eight named storms, but southwest Louisiana got hit by Category 4 Hurricane Audrey, leading to the deaths of at least 500 people. In 1965, there were only six named storms, but one was the devastating Hurricane Betsy, which struck New Orleans. Then there were Hurricane Andrew in 1992 and Hurricane Danny in 1997, which dropped large amounts of rain on the state.
It all points to the fact that while having fewer storms is a good thing, Graham said, it doesn’t change the need for people, government agencies and emergency responders to prepare for the season.
“It doesn’t matter if there’s one storm in the Atlantic; if that one storm hits us, it’s a bad year,” Graham said.
It’s hard to say if the currently weak El Niño will continue into the summer. NOAA lists a 50 percent to 60 percent chance that the conditions will last through the spring.
“It’s so weak it’s not going to take much of a nudge to make it disappear,” Keim said.
Declaring an El Niño means that sea surface temperatures are elevated in the tropical Pacific, that those temperatures are expected to stay elevated for several seasons and that the atmosphere is responding to those elevated temperatures with additional rain in the central Pacific and other changes.
While Louisiana residents could use a raincoat more than usual this spring, El Niño also brings changes to weather patterns around the world. In the winter and spring, it can bring drier than normal conditions over northern Australia, Indonesia, parts of South America and southeast African countries.
In the summer, El Niño brings warm weather to Peru and Brazil and dry weather to large parts of Australia and India.
Follow Amy Wold on Twitter, @awold10.