This year’s hurricane season has already had
some intensity with Hurricane Elsa creeping through Florida. But we haven’t gotten to the
peak of the season yet.
Meteorologists think it will be a busier-than-normal time for hurricanes this year, with one potential what if — a return to a La Niña climate phase following the end of a previous La Niña in May, which was hinted as a possibility in the fall, according to an outlook from the National Oceanic and Atmospheric Administration.
NOAA’s Climate Prediction Center issued a La Niña Watch, predicting changes in atmospheric conditions could emerge as early as the September to November season, which could affect hurricane season intensity. NOAA is expected to issue its next update Aug. 12.
A fall return for La Niña could favor more hurricane activity in a season already forecast to be above normal.
In July, Colorado State University updated its seasonal outlook with its expectation of two more named storms than initially forecast. Its researchers forecast 20 named storms, including nine hurricanes and four major hurricanes.
“Sea surface temperatures averaged across most of the tropical Atlantic are now near to slightly above normal, and most of the subtropical North Atlantic remains warmer than normal,” said Philip Klotzbach, hurricane researcher with Colorado State University’s Tropical Meteorology Project. “Elsa’s development and intensification into a hurricane in the tropical Atlantic also typically portends an active season.”
Colorado State and NOAA are expected to issue new updates to their hurricane season forecasts this month as the season’s traditional Sept. 10 peak approaches.
What La Niña Is
La Niña occurs when sea-surface temperatures in the Pacific Ocean are cooler than normal and low-level surface winds are stronger than normal, according to the Climate Prediction Center.
It’s one of three phases in a climate cycle known as the El Niño-Southern Oscillation, or ENSO. These phases are influential in determining a number of weather phenomena, including hurricane formation.
La Niña is the opposite of El Niño, which occurs when sea-surface temperatures in the Pacific Ocean are warmer than normal and low-level surface winds, which normally blow from east to west along the equator, weaken or blow in the opposite direction.
When neither El Niño or La Niña is in place, the climate is described as ENSO-neutral. The Earth is currently in an ENSO-neutral phase that began in May.
One of the most significant ways La Niña matters in a hurricane season is that the climate cycle is less favorable to vertical wind shear, or the change of winds with height, according to NOAA.
Strong wind shear, typical during El Niño phases, can rip hurricanes apart.
But when wind shear is weak over the Caribbean and tropical Atlantic, it allows hurricanes to develop and intensify, Mike Halpert, deputy director of NOAA’s Climate Prediction Center, said last year in a statement.
The 2020-21 La Niña, which the Climate Prediction Center stated lasted from August 2020 to this past May, was a factor in NOAA’s forecasts for above normal activity, Halpert said.
Likewise, the chance of such conditions returning this year factored into the 2021 outlooks, said Matthew Rosencrans, lead seasonal hurricane forecaster at the Climate Prediction Center.
Like NOAA’s hurricane forecasters, Paul Pastelok, senior meteorologist with Accuweather.com, based his own long-range forecasting on a number of factors, including the chance of La Niña conditions late in the season like in 2020.
“It’s been on our watch list since February,” he said. “Typically, we don’t see La Niña events until late fall. Again, we’re looking at an early start to a possible La Niña.”
Warming Caribbean Waters
Pastelok and NOAA’s forecasters are also monitoring predictions for above-normal sea surface temperatures in the Caribbean and eastern Atlantic, weaker tropical Atlantic trade winds, and a stronger west African monsoon.
The warmer-than-normal waters are of particular concern to Dave Towle, senior forecaster with WVLG 102.7 FM, 104.5 FM & 640 AM, who frequently describes warm ocean temperatures as “an engine” that fuels hurricanes.
“Most areas even right up to the shoreline are up at 85 degrees,” he said. “The water is very warm and very consistent, and I think it’s going to keep the season going.”
Warm oceans already produced an “early onslaught” of tropical weather, including Hurricane Elsa, which brought heavy rainfall to Central Florida in early July, he said.
“I’m more concerned we’ll see a more rapid increase of storm development,” said Towle, of the Village of LaBelle. “Almost like a light switch comes on and it explodes.”
While all the long-range forecasts agree that 2021 will be an active hurricane season, what they can’t tell us is where the storms will land. In Florida’s case, it was mostly spared from last season’s high activity with only Tropical Storm Eta making landfall.
“It’s difficult to forecast,” Pastelok said. “We could have 20 storms, but where are they going to be? That’s the tougher question to answer at this point.”
Klotzbach, the Colorado State researcher, gave a 43% chance of at least one major hurricane landfall in the U.S. East Coast and the Florida peninsula in 2021.
With an already busy hurricane season predicted to be more intense than initially forecast, experts urge preparedness, with or without La Niña.
That includes stocking up on emergency supplies, having an emergency plan in place, knowing whether you’re in a flood zone and if you have a weather alert radio, Sumter County Emergency Management Director David Casto said.
It also includes making sure Floridians have enough gas in their cars and generators.
Florida Agriculture Commissioner Nikki Fried recently issued a statement encouraging Floridians to incorporate a fuel plan to their emergency preparations to ensure they have enough gas prior to a storm.
Her agency is concerned about sudden surges in consumer demand during crises, not limited to but including hurricanes, that may strain fuel distribution and cause shortages at gas stations.
“We can all take simple, preparatory steps to help prevent a rush at the gas pump when hurricanes threaten, lessening the likelihood of potential supply shortages and pricing issues,” Fried said.
These steps include keeping vehicles at least half full during hurricane season and pre-purchasing gas for generators at the start of hurricane season, she said. Properly stored fuels for generators will last at least six months.
Senior writer Michael Salerno can be reached at 352-753-1119, ext. 5369, or firstname.lastname@example.org.