A rare early-season warning from Accuweather meteorologists forecasts an ominous 2024 hurricane season due to, among other reasons, February sea temperatures in the Atlantic Ocean resembling summertime.
Accuweather forecasters are also seeing the El Nino weather pattern in place right now giving way to the hurricane-favorable La Nina pattern, which might be in place by the start of tropical weather season June 1.
"Accuweather’s long-range expert team here is really sounding the alarm bells about what this upcoming hurricane season could become in terms of making it a supercharged season with the risks for many storms with some of these factors coming together," Porter said in a special online segment the forecasters felt important to produce even this much in advance of the 2024 Hurricane season.
Here in Florida, where since 2000 there has been some 13 hurricanes and 79 tropical or extra-tropical storms, the outlook, just yet, hasn't risen to alarm level.
"So first thing to note is that we are over three months away from the official start of the 2024 Atlantic Hurricane Season. Do systems sometimes form before June 1? Yes," said Megan Borowski, chief meteorologist, Florida Public Radio Emergency Network. "But even with that in mind, we still have a lot of time before things may start developing.
I mention that because this far out, we can only look at long term signals — climate signals and seasonal patterns to help guide our thinking of what the upcoming season will bring."
She added: "And meteorologists will typically look at things that may influence the ingredients for tropical weather: sea surface temperatures and upper level wind patterns."
The top aspects of 2024's storm season causing some concern: The return of La Niña and historically warm water across the Atlantic Ocean.
The crux of the Accuweather cautionary alert was the transition of the current El Niño pattern that is forecast to transition into a La Niña pattern during the second half of the hurricane season, Alex DaSilva, AccuWeather's lead hurricane forecaster, said.
"We’re going to see a transition from that El Nino pattern to more of a la Nino pattern, which means cooler than average temperatures in the eastern and central Pacific equatorial regions," he explained. "And so what that would mean is less wind shear across the Atlantic basin, which could promote more tropical development."
DaSilva said the second biggest indicating factor was water temperature:
"Oh, absolutely, this is going to be the probably the second biggest X Factor for the season thus far are temperatures across the Atlantic basin, if you take the average temperature across the Atlantic basin as a whole, we are currently where we should be in middle May," he said. "If we're seeing those water temperatures, this warm this far early. That leads us to be very concerned, as we move into the tropical season later on in the year."
Borowski, who is also interim director for FPREN, said that regarding sea surface temperatures — they are very warm in the lower latitudes of the Atlantic — on the order of 1-2 degrees above average now, and if the forecast holds, they will remain warmer than normal into the hurricane season. This is a concern, she said, because the warm ocean serves as a source of energy for tropical systems.
She, too, pointed to the El Nino to La Nina change.
"Another thing that we are watching the is phase of the El Nino Southern Oscillation—we are in an El Nino, which has contributed to a cool and rainy winter for most Floridians, but the El Nino is forecasted to transition to neutral conditions, then followed by La Nina during the summer," she said. "Although El Nino and La Nina are detected over the Pacific, but they have implications around the world, including in the upper level wind pattern over the tropical Atlantic. La Nina can reduce vertical wind shear over the Atlantic, and this reduction in shear can in turn help keep thunderstorms vertically oriented."
In layman’s terms, reduced shear means that a system can remain organized, and provided other factors are in place, a tropical system can grow.
Borowski conceded that there is above average warmth in the Atlantic already, and the signs that we are going to enter a La Nina just in time for hurricane season, that are giving us clues that 2024 might be an active Atlantic hurricane season.
"Those are things that are giving us clues that 2024 might be an active Atlantic hurricane season. Other than that, we need to wait until closer to season to make more detailed forecasts," she said.
The Accuweather forecast is one of the earliest made so far this year. The 2024 hurricane season forecast from Colorado State University, considered the pre-eminent forecasting center, isn't due out until April 4.
Philip Klotzbach, a CSU meteorologist specializing in Atlantic basin seasonal hurricane forecasts, cautioned in a Tweet earlier this month: "It should be noted that it's only February, and a lot can change between now and when the Atlantic hurricane season really ramps up (typically in early to mid August)."
Klotzbach said he would certainly agree with AccuWeather that the odds favor an above-normal Atlantic hurricane season at this point.
"It's very unlikely that we will have El Nino for the peak of the Atlantic hurricane season in 2024. NOAA currently gives the odds at 2% for August-October,." he said. "Normally El Nino reduces Atlantic hurricane activity via increases in vertical wind shear."
Currently, the Atlantic is in a highly favorable sea surface temperature configuration for an active hurricane season:
This pattern is very similar to the sea surface temperature pattern that has historically correlated with busy Atlantic hurricane seasons:
However, the CSU weather expert said that it is important to realize that a lot can change between now and when the hurricane season typically ramps up in August.
For example, he said, at this time last year, the Atlantic was pretty unremarkable from a sea surface temperature anomaly perspective:
But by the end of June 2023, the CSU meteorologist said forecasters were dealing with record warm anomalies across vast swaths of the Atlantic, leading to big increases in their seasonal forecast last year, despite the strong El Nino:
Klotzbach said that an extremely weak subtropical high during March-June 2023 caused much weaker than normal winds blowing across the tropical and subtropical Atlantic, leading to less evaporation than normal, and hence anomalous warming (e.g., warming much faster than normal) last year.
"While I'm not saying that the opposite is going to happen this year, there's just too much uncertainty at this long lead time to be too confident in a hyperactive season," he said. "If these current anomalies persist through the end of March, however, I do expect we'll be coming out with quite an aggressive forecast with our 4 April outlook. However, I've seen a lot of crazy things happen in the weather department in March.
The 2005 and 2020 hurricane seasons are tied for the most active in recorded history with each season generating 31 tropical systems. La Niña was building fast during the 2005 season, and was firmly established amid the 2020 season.
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