Eyes still on southern Gulf of Mexico for next potential storm

I chose the title of this post to mimic the one from last Wednesday, because that post hardly needs any updating today! The area I highlighted six days ago is coming together... it's currently tagged as Invest 92L but is close to becoming the season's 9th named storm, Isaias. As of Tuesday morning, it's located in the far western Gulf of Mexico and has had a significant flare-up of strong thunderstorm activity over the center.

And, as mentioned last Wednesday, if it forms, it has good odds of becoming the season's first hurricane. Recall that within the past century and within the more reliable satellite era (mid-1970s), the record-latest first hurricane formed on September 11. Will 2026 finally get its first hurricane this week? If not, the chances start dropping off quickly in the final six weeks of the season.

The tracks shown below are from the operational (left) and experimental (right) Google Deepmind ensemble. They provide some confidence in a track forecast because there is so little spread among the members. But the majority of them are also quite bullish on the intensity. Even in the 1000-member version of the ensemble (not shown), this has a roughly 70% chance of becoming a hurricane.

https://www.weathernerds.org/models/fnv3.html

Among the ensemble and deterministic models, the timing of landfall is fairly tight around Friday afternoon into Saturday morning. However, the intensity at landfall is another story... very little agreement among models with an enormous range from tropical depression to Category 3 hurricane.

It does not appear that time, moisture, or water temperature will hinder the storm's potential for substantial development, but wind shear probably will. The current wind shear in the western Gulf is moderate and the forecast wind shear in the northern Gulf is substantial, so even if the system does develop in the next couple of days, its final day or two should be greeted by a wall of strong vertical wind shear which would weaken it. With that in mind, the intensity forecasts shown above that indicate a peak intensity in the 48-72-hour window followed by weakening seem more likely to me.

A feature that could play a role in the storm's evolution at the end of the week is an anticyclonic warm eddy in the central Gulf. There is deep warm water there that could provide a temporary boost to a system which should be beginning its battle against increasing wind shear.

https://bmcnoldy.earth.miami.edu/tropics/sectors/

The sea surface temperature under Invest 92L is currently about 31°C and will only decrease to about 29°C as it approaches the Gulf coast -- all plenty warm to sustain a hurricane of any intensity.

https://bmcnoldy.earth.miami.edu/tropics/sectors/

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Eyes shift to southern Gulf of Mexico for next potential storm

Fay and Hanna have dissipated, and the Atlantic will be quiet for a week or so, then the long-range models begin hinting at something brewing in the Bay of Campeche in the southern Gulf of Mexico. If this ends up developing into the ninth named storm, the next name on the list is Isaias. But it's a looong way off.

As of the Wednesday morning cycle, the 1000-member Google Deepmind ensemble gives this a 27% chance of becoming a tropical storm late next week, and of those members, they show a 60% chance of it becoming the season's first hurricane and even a 22% chance of reaching major hurricane intensity (Cat3+). Other AI and conventional ensembles agree with a decent chance of something forming here in 7-10 days. There's a LOT of uncertainty of course, but the signal in the models is there.

Image from https://tcatlas.org/realtime_ir.html

This area is not as favored for development in early October.as one might think, at least for storms that eventually reach hurricane intensity. The last one that did so was Milton in 2024, then Roxanne in 1995, then Fern in 1967. It's a very short list.

Just for curiosity's sake, I ran some preliminary homogeneous track and intensity verification statistics on the meager activity so far this season. This covers Arthur through Hanna, and you can see on the charts that there are actually ZERO 5-day (120-hour) verification times, but it's what we've got. All six of the 4-day (96-hour) verifying forecasts come from Fay.

For track, the Google Deepmind ensemble mean (GDMI) leads the pack overall, then it gets a bit more noisy. The National Hurricane Center's forecasts (OFCL) were very closely aligned with GDMI except for the six forecasts for Fay when the model was superior.

For intensity, it's definitely a mixed bag, but the thing I see is the two consensus aides, HCCA and IVCN, did the best overall. The Google Deepmind ensemble mean was quite good too, but lost a little bit of ground on the 4-day forecasts of Fay. Also worth noting is that the HWRF hurricane model (HWFI) beat the NHC's average forecast error at every lead time -- none of the other hurricane models did that (HMNI, HFAI, HFBI, CTCI).

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Fay lingers, Gonzalo dissipates, Hanna forms

The title of the post makes it sounds like there is a lot of activity.  There isn't.

Fay is a stubborn tropical depression that isn't strengthening or weakening, Gonzalo dissipated about 1.5 days after it formed, and Hanna formed on Monday morning in the north-central Atlantic. It too is forecast to dissipate within a couple of days.

Image from https://www.polarwx.com/tropical/

There is no hint of real activity in the long-range models, so we will likely make it well into October without a single hurricane, and then the odds start dwindling quickly if the Caribbean is shut down due to the El Niño-induced strong vertical wind shear there.

It would be unprecedented in the satellite era and even in the past century to have a hurricane season with no hurricanes. In the past century (1926-2025) the fewest number of hurricanes in a season is two, and that happened in 1930, 1982, and 2013. Among those three years, only 1982 and 2013 were during the more reliable satellite era. So even if this season manages to crank out a single hurricane, it would still be a record.

Just to provide some additional context, the record number of hurricanes in a season is 15, and the average is 7. Today is actually the climatological date of the 5th hurricane formation.

The track map through today is shown below, keeping in mind that Fay and Hanna are still active tropical cyclones... barely.

Whenever the next storm forms, the next name on the list is Isaias. In 2020, the last time this list of names was used, Isaias formed on July 30.

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