In late May, WeatherTiger’s hurricane season outlook called 2023 a “once-in-a-generation slugfest between twin titans of the Tropics,” pitting the awfully hot coffee pot of the Tropical Atlantic against a vigorous El Niño event.
With these two reliable predictors in diametric opposition, I cautioned that the forecast was more uncertain than usual, with no good way of knowing whether the Atlantic’s hurricane-fueling oceanic warmth or El Niño’s storm-smothering shear would win the fight.
We have an answer.
When it comes to influence on the first three quarters of the Atlantic hurricane season, El Niño has had sand kicked in its face like a 98-pound weakling. The 2023 season has been more active to date than 80% of years since 1950, notching a punishing major hurricane strike on Florida in the process.
Hurricane Nigel a no-show, but North Florida may deal with mild disturbance or Subtropical Storm Ophelia
But will this trend continue? Has the Florida skunk ape seen its shadow at Ochopee’s Bigfoot Research Headquarters, auguring six more weeks of hurricane season?
In the short term, there is no reprieve from the record streak of ten named storms roiling the Atlantic since August 20. Ongoing Hurricane Nigel is fortunately among the seven of those to remain well east of the continental U.S. Mild-mannered Nigel, noted for its unusually large eye, is peeling northeast into the open waters of the Central Atlantic today and is only a concern for ship traffic.
However, Florida and the East Coast will not be without an irritant-level tropical threat this week.
The cold front that brought the Deep South a tantalizing glimpse of fall has stalled over the Bahamas, and its upcoming interaction with an upper-level low will cause surface low pressure to develop on Thursday. As this low meanders east of Florida on Friday and Saturday, the smoldering Gulf Stream waters may help it shed its frontal origins and become a subtropical cyclone.
You can think of a subtropical storm as a kind of middle ground between hurricanes and frontal lows. While a subtropical storm does have organized, deep convection, its higher winds are more spread out than in a tropical cyclone. They are named and tracked by the Hurricane Center just like tropical storms and hurricanes, so this system could nab the moniker of Ophelia.
It also might not.
Even if it remains a frontal low, the impacts on Florida, the Carolinas, and the mid-Atlantic won’t be all that different. Coastal sections of east-central and northeast Florida will be windy and possibly showery between Thursday and Saturday, with breezy but dry conditions inland. As the low pivots north across eastern North Carolina by late Saturday and the mid-Atlantic on Sunday, heavier rainfall and gusty coastal winds are possible there.
The good news is that subtropical lows have limited upside intensity potential, so this feature will annoy, not destroy.
Meanwhile, the eastern Atlantic continues to yield one potential storm after another, with a tropical wave just leaving West Africa potentially developing in the next week as it rolls west. Models are split on how fast this wave may develop. Counterintuitively, faster development is better, as that probably means an eventual track north into the open Atlantic.
A system that is slower to get going could make it farther west and would need to be watched down the road.
The rate at which storms form east of the Lesser Antilles drops off in late September, as wind shear increases in the eastern portion of the Atlantic’s Main Development Region. While October is less active than September, the favored region for major hurricane development shifts west towards the continental U.S., favoring the western Caribbean, southwestern Atlantic, and southern Gulf.
This proximity means the eastern Gulf Coast sees its highest frequency of historical hurricane landfalls in the season’s final quarter, which begins in late September.
Unfortunately, 2022 was a stark reminder of this.
Don’t look to wind shear to save us from a strike
In a more typical El Niño hurricane season, the outlook for the final quarter of the season would be prosaic. With Niño-driven wind shear usually strongest over the western Caribbean late-season development zone, these hurricane seasons usually have a quiet end.
In 2023, however, shear in the Caribbean actually has been weaker than normal for the last two months. In short, wind shear has done even less to stop hurricanes in 2023 than Publix banning hurricanes from cakes. (Memo to Publix: humor is a way humans manage stress and anxiety. Trust me on this.)
There is no strong indication from long-range guidance that this will change, with some models hinting at a less conducive Caribbean in October and others showing continued favorable conditions. While wind shear in the Gulf is likely to be higher than average in October, this shear also has a habit of getting out of the way when a hurricane is approaching from the south, right when it would be needed most.
Though Franklin, Lee, and Margot have churned up cooler waters east of the U.S., the oceanic heat content of the Gulf, Caribbean, and southern Gulf Stream also remains extreme entering the final quarter, at or above record values.
Additionally, long-range modeling and previous El Niño Octobers have a tendency for a dip in the jet stream over the eastern U.S. and western Atlantic that might offer anything that develops in the Caribbean a potential path north. The models and analogs aren’t a perfect match to the steering pattern in historical Octobers with Florida hurricane hits, but there’s enough similarities to be somewhat worrisome.
Model points to a 50% chance of another hurricane hit in the U.S.
WeatherTiger’s real-time seasonal model, which over the summer correctly sniffed out a busy August and September, has been digesting trends in the key predictors of late-season Atlantic activity. Our verdict is that hurricane action is likely to slow relative to the furious pace of the last six weeks, but that this October won’t be a tranquil late season, either.
Another 25 to 50 units of Accumulated Cyclone Energy beyond the current tally of 110 or so is most likely, which translates to about a 50% chance of at least one more U.S. hurricane landfall in 2023. You can follow updated odds each day on weathertiger.com as we run out the clock on the season.
Overall, like the purported cryptozoological wonders of the southern wild, wind shear has been seldom observed in 2023, though it is unknown whether El Niño’s reach will be totally absent or just extremely tardy. If shear shows, the late season could be more typical for an El Niño year, with fewer storms near the U.S. coastline.
If it doesn’t, hurricane season may keep rolling through October, with additional Gulf Coast threats a possibility. Let’s hope that the skunk ape, North America’s southernmost native sasquatch, is the only beast roaming Florida swamps this fall.
Keep watching the skies.
Source: Tallahassee Democrat