Intensifying Hurricane Isaias to make landfall Friday night

Since my previous post on Wednesday, Isaias did indeed become the first hurricane of the season on October 8. Related to that, I shared this on Bluesky: "During the satellite era (I'm using 1966), that is BY FAR the latest... by 27 days! It's an incredible 63 days after the median date."

Now, on Friday morning, Isaias is nearly a Category 3 hurricane and will likely reach that intensity at the 11am EDT advisory. The first sunrise satellite image of it today (at the top of the post) shows a clearing eye as the powerful hurricane heads north... the infrared satellite animation below shows the evolution over the previous 8 hours.

The NHC's forecast map shows the track forecast cone with the hurricane and tropical storm watches and warnings. Note how far inland these wind impacts extend. It takes some time for the hurricane's strong winds to decay after landfall. The storm is expected to weaken slightly prior to reaching the coast, so the peak intensity will likely be midday Friday, but that will be a small difference.

Landfall will be somewhere right around midnight close to Pensacola FL. Impacts extend very far from the landfall point of course. Here is this morning's suite of HTI (Hurricane Threats and Impacts) graphics from the NWS:

I also have a long regional updating radar loop available at https://bmcnoldy.earth.miami.edu/tropics/radar/... the version as of this writing is shown below, where the inner core of the hurricane is barely in radar range yet, but stay tuned throughout the day and into tonight as the loop builds.

I am still quite amazed at the lead time we've had in watching this storm take shape, and the accuracy of very long-range model output, particularly from Google Deepmind. My post from September 30 --10 days ago-- serves as a good documentation of this: Eyes shift to southern Gulf of Mexico for next potential storm. Certainly can't say it took anyone by surprise!

Aside from Isaias, no new activity is on the horizon, so I'll update the seasonal ACE and put together some updated preliminary forecast verification stats shortly.

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Tropical Storm Isaias likely to become first hurricane of the season

The area of concern I mentioned in last Wednesday's post was upgraded to Tropical Depression 9 on Tuesday afternoon and then to Tropical Storm Isaias on Wednesday morning. There is high confidence that it will intensify in the central Gulf of Mexico and become the first hurricane of the 2026 Atlantic season, nearly one month later than the previous record-latest first hurricane formation, which was September 11.

The official forecast from early Wednesday morning brings Isaias up to a borderline Category 2-3 hurricane in the central Gulf, then shows some weakening prior to landfall overnight on Friday, likely between New Orleans LA and Panama City FL.  Tropical storm force winds should arrive along the north-central Gulf coast on Friday evening.

Rainfall and storm surge impacts will be noticeably more severe for places to the right of the track... for example, roughly Mobile to Tampa. Storm surge guidance isn't available yet, but stay closely tuned to the NHC webpage for the latest... storm surge will likely be fairly significant.

The storm will also be moving rather quickly by the time it makes landfall, so the wind impacts will also be carried further inland than "normal", again, primarily to the right of the track.

I brought this up in my annual "cone" refresher post, but remember that the intensity forecast also contains uncertainty, just like the track does. You can see the track forecast cone above, but here's my take on the intensity forecast cone, as of Wednesday morning's Advisory #3. The cone is based on NHC's intensity forecast errors over the previous five seasons.

With an active tropical storm (and likely hurricane soon), the Accumulated Cyclone Energy will get its biggest boost of the entire season by far.  As of today, it's at about 11% of average, but the next 3 days could nudge that up to approximately 16-20% of average.

Some name history: Isaias (pronounced ees-ah-EE-ahs) was first introduced to List 6 (the one we're using this year) in 2014... it replaced Ike after the 2008 season. In 2014 however, the name never got used because the very quiet season ended with Hanna. It was used in 2020 and now in 2026. It most likely will not get retired this year, so we'll see it again in 2032.

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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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