El Niño may skip hurricane season, which could mean greater storm activity for Florida
Hurricane season will start in June, regardless of a virus
Early climate signals are raising red flags that El Niño will be a no-show this hurricane season, a bad sign for storm-weary states that have suffered four consecutive years of above-normal activity.
Hurricanes are a low priority with coronavirus turning the world upside down, but June 1 will come regardless of what the virus is doing.
Meteorologists acknowledge March is a tricky time for predictions with Earth in the throes of seasonal metamorphosis, but the clues almost all point to a neutral or La Niña pattern come summer.
The two patterns, both recurring phases of the El Niño -Southern Oscillation cycle, are more accommodating to Atlantic tropical cyclones than the cutting western gales that shred hurricanes during an El Niño event.
February forecast models were leaning against an El Niño for the 2020 hurricane season. That was reinforced this week with updates in the Euro (ECMWF) and the American Global Forecast System (GFS) showing a cooling over the next several months in the equatorial Pacific more consistent with a neutral or La Niña pattern.
“I think we have a pretty high confidence that we are not going to have an El Niño,” said Todd Crawford, chief meteorologist for IBM’s The Weather Company. “We’ve had slight El Niño conditions a couple of years now so it’s time to slosh back here toward La Niña given the natural oscillation. It’s kind of due.”
El Niño occurs in tandem with the relaxation of the trade winds - those Earth-skimming easterlies that have guided sailing ships across the world’s oceans for centuries.
With the trade winds reduced, warm water that has piled up in the western Pacific Ocean and around Indonesia rushes back toward the east. That movement of warm water shifts rainfall patterns and the formation of deep tropical thunderstorms. The exploding storms whose cloud tops can touch the jet stream disrupt upper air patterns so winds come more out of the west
The west winds create shear in the Atlantic, which can be deadly to budding hurricanes.
La Niña is marked by strong winds from the east that push warm Atlantic waters toward the U.S., while weaker winds from the west are less able to disrupt storms. The eastern Pacific Ocean is cooler than normal as east winds push surface water toward Asia.
During neutral years - between La Niña and El Niño - ocean temperatures, tropical rainfall patterns and wind patterns are closer to long term averages.
“I find it striking that only two out of 20 models are predicting El Niño for the August through October peak of hurricane season, and barely so,” said Jeff Masters, co-founder of Weather Underground and a writer for Scientific American. “Thus, the odds favor an above-average Atlantic hurricane season based on the likely absence of a significant El Niño.”
Last year, a weak El Niño abruptly called it quits in August – an unexpected twist to an explosive hurricane season that ended with 18 named storms, including six hurricanes, three of which were major hurricanes of Category 3 or higher.
That’s compared to an average season of 12 named storms. The 2019 season was also marked by Category 5 Dorian’s brutal assault on the northern Bahamas and was the first time since 2012′s Hurricane Sandy that a season spawned an “S” storm.
The last strong El Niño was 2015 into early 2016. Since then, an overactive Atlantic has spawned six Category 5 cyclones – Matthew in 2016, Irma and Maria in 2017, Michael in 2018, and 2019′s Dorian and Lorenzo.
“In recent years, water temperatures have been so warm, that even neutral years have been busy,” said Bob Henson, a meteorologist and writer for Weather Underground. “It’s too early to make a confident forecast of how the upcoming hurricane season will evolve, but the tea leaves now on the table suggest that 2020 could be the Atlantic’s fifth season in a row with above-average activity.”
Seas are warmer than average over nearly all of the tropical and subtropical Atlantic with the Caribbean and Bahamas waters running a degree warmer than normal for this time of year.
Crawford said he believes Atlantic water temperature is more strongly tied to hurricane activity than the El Nino phase, with warmer waters spawning more storms. Still, having an El Niño or La Niña can skew the season to be under or overachieving.
“What’s unsettling is that 2018 and 2019 overperformed even though La Nina was absent,” Henson said. “One factor making these last two season so active was consistently and unusually warm sea-surface temperatures in the Atlantic basin.”
Henson called the abnormal ocean heat a “flashing red indicator of human-produced climate change.”
Most of the earliest hurricane forecasts are made in April, including Colorado State University’s prediction, which is scheduled for release on April 2. The National Oceanic and Atmospheric Administration don’t typically release its forecast until May.
News 6 partner Florida Today contributed to this story
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