La Niña has flirted and retreated, teased and taunted, encircled and rushed, but scientists still believe the global climate pattern will emerge in the waning weeks of 2024, bringing a warmer and drier winter to South Florida.
A seasonal forecast released Nov. 18 by the National Weather Service and the South Florida Water Management District said there is a 57% chance that La Niña will develop and persist until March 2025.
Traditionally for South Florida, La Niña means longer dry spells during the darkest days of the year, a greater threat of drought and wildfires, and temperatures 1 to 3 degrees above normal. Rainfall is typically 10% to 30% lower than normal during La Niña winters.
“Forecast models all point to warmer-than-normal temperatures through April,” said Robert Molleda, the meteorologist in charge at the NWS Miami office. “Each of the previous eight La Niña winters has resulted in moderate to severe drought conditions in at least parts of South Florida in the spring.”
But this La Niña has been hinting at a debut since February, when the Climate Prediction Center, an office of the National Oceanic and Atmospheric Administration, issued a La Niña watch. The forecast at the time gave the atmosphere-changing phenomenon a 55% chance of awakening during early summer, and a 74% chance of developing in October.
It was a no show.
“Not every event is equally easy to predict,” says Molleda. “We’ve gotten used to some pretty easy and well-defined events and we’ve had several of them over the last five to 10 years, but in the past the signals were often not that well defined.”
The La Niña climate pattern generally means warmer and drier winters for South Florida.
What are the weather patterns of El Niño and La Niña?
The El Niño and La Niña climate patterns are part of the powerful El Niño-Southern Oscillation, or ENSO.
La Niña occurs when waters in the equatorial Pacific Ocean cool and shift when and where tropical thunderstorms form, so wind shear in the Atlantic Ocean decreases during hurricane season, giving nascent tropical cyclones more room to grow.
In winter, La Niña storms pulse into the Pacific Northwest on a more northerly and inland route, keeping the jet stream longer at higher latitudes where it traps cold air to the north.
During El Niño, the equatorial water warms. In summer, El Niño causes wind shear that fragments Atlantic tropical cyclones. In winter, El Niño pushes the jet stream south, traditionally giving Florida cooler and wetter winters.
More: South Florida’s cloudy winter ends as the coolest in years thanks to El Niño
But there is no guarantee that either climate pattern will behave as predicted.
Water temperatures in the Pacific Ocean did cool this past summer, but not as much as scientists expected and not to the 0.9 degrees below the long-term average needed for a La Niña event to really cause problems in the tropics.
That doesn’t mean it wasn’t an active hurricane season, which ends on November 30.
Through November 19, there were 18 named storms, four more than in an average year. This included eleven hurricanes and five major hurricanes. Three hurricanes in particular – Category 1 Debby, Category 4 Helene and Category 3 Milton – made devastating landfalls on Florida’s Gulf Coast.
“In the end, it didn’t matter if La Niña was here during the tropical season,” DaSilva said. “It had no significant impact.”
And it may not have a significant impact this winter. Because La Niña is so late, it won’t have much time to strengthen, said Emily Becker, deputy director of the University of Miami’s Cooperative Institute for Marine and Atmospheric Studies.
Becker writes a blog for NOAA about the El Niño Southern Oscillation. She said there have only been two La Niña events in the 75-year historical record from October to December.
A weak La Niña means other weather patterns can take over its dominance, causing severe thunderstorms despite generally lower chances of severe weather.
The most recent La Niña event featured a strong EF-2 tornado that struck Palm Beach Gardens and North Palm Beach in April 2023. That was preceded by the historic Fort Lauderdale flood, which saw more than two feet of rain shut down the Fort Lauderdale-Hollywood area. International Airport and left neighborhoods flooded for days.
During the 2016-2017 La Niña, three tornadoes struck southeast Florida, including one that buzzed through Palm Beach Gardens and Juno Beach with peak winds of about 90 miles per hour.
“The only thing we can say with certainty is that nature will keep us in the dark,” says Becker in her blog about La Niña. “We’ve been saying it for months, and we’ll say it again: Forecasters still think La Niña will develop and last through the winter.”
Kimberly Miller is a journalist for The Palm Beach Post, part of the USA Today Network based in Florida. She covers real estate, weather and the environment. Subscribe to The Dirt for a weekly real estate roundup. If you have news tips, please send them to kmiller@pbpost.com. Support our local journalism and subscribe today.
This article originally appeared on Palm Beach Post: La Nina expected to appear by the end of the year, meaning a warmer, drier winter
