ORLANDO, Fla. – Hearken back to early September when you maybe first read our article about the “delayed kickstart” to our hurricane season. It may have seemed like a one-off explanation for why things were so abnormally quiet during the traditional calendar peak. But looking at our latest Tropical Weather Outlook from the Hurricane Center confirms our suspicions were justified.
The usual peak for the tropical Atlantic season tends to occur on September 10. However, if we were to rewind the clock to late August and the first few weeks of September, the basin was eerily quiet. We were moving at a pace of one storm at a time, since we kicked off the season with Alberto in the middle of June. This is just a tad unusual, especially when we entered what should have been the most active segment of the hurricane season.
Take a look at the two tropical outlooks below, set for the same date and time but exactly one year apart. In 2023, major hurricane Idalia had just struck the Big Bend of Florida. We had made short work of the first half of the named storms list for the year. Lee was making its appearance in the Main Development Region as the large orange shade you can see highlighted in the central tropical Atlantic.
Now, in 2024, we had a few areas of interest. But keep in mind, the next named storm at this point would be Francine. Let’s not forget the long break after Ernesto chewed through the Greater Antilles before rocketing northward toward Bermuda then safely out to sea.
So, what happened? This year was coined as “hyperactive” through all the pre-season forecasts that were released in April, May, and into June.
Let’s break down a few things.
First and foremost, La Nina!
La Nina was the pride and joy of numerous pre-season discussions regarding why major tropical weather agencies were banking on the season going gangbusters right off the rip. This forecast did not verify. In fact, La Nina didn’t quite show itself until very late September into the beginning of October. This was initially to take effect by May, if not June.
On top of this, we had what’s called “disorganized sea surface heating” ongoing across the Atlantic. If you take a look at a few sea surface temperature charts for the months of March, April and May, we had a very distinct horseshoe of very cool anomalies off the Mid-Atlantic and Northeast coastlines of the United States. The generally cooler pool of waters extended well into the subtropical Atlantic, which resides north of 25 degrees latitude.
As a result, tropical forecasters made mention of this focusing of heat, particularly on the tropical regions. This would help keep persistent rising motions and mixing in the environment, which makes the chances of tropical formation higher. Once we entered June and especially July of this year, the trademark horseshoe shape disappeared, and the subtropics started to warm alongside the rest of the central Atlantic basin. This definitely put a hamper on things in terms of favoring organization in the main development region off the African coast.
Finally, because of the excess oceanic heat, and the general configuration of our cooler and warmer waters in the Pacific, we dealt with a lot of “wave breaking” over the north and east Atlantic. Wave breaking induces tremendous amounts of windshear into areas where we’d usually favor seeing tropical waves brew into something more. As these atmospheric waves “break”, like an ocean wave you see cresting and breaking along the shores of our beaches, they also bring down very dense, stable dry air.
This doesn’t sound too good for our hyperactive season does it? Great news for us where we can get it. Imagine if these limitations weren’t imposed, and the basin was cut loose to generate storm after storm with the same magnitude of impactfulness.
Now to present day: We’ve seen the waters cooling to the north, our La Nina has successfully established itself across the east and central Pacific. The wave breaking over the Atlantic has subsided with the introduction of cooler temps up north. With things becoming far more traditional, this has also allowed the Madden Julian Oscillation (a staple in the hurricane season for large scale aid in developing tropical cyclones) to move from west to east through our area of responsibility.
If you look at the graphic below, there is a dramatic uptick in named storm activity through September and especially October. September did not start to produce until the last 7-10 days of the month, which is roughly when La Nina made its fateful entrance.
All eyes are on the Caribbean for the potential that we see Patty enter the fray as we wander into the early parts of next week.
You can find out more during our recurring tropical weather updates on the News 6 YouTube channel and our News 6 Plus app.