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 Saturday. 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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