Isaias makes landfall after quick shot up to major hurricane

From Thursday morning through Friday morning, Isaias rapidly intensified and became the first major hurricane of the season, which is conventionally defined to be Category 3+ on the Saffir-Simpson Scale.  In terms of exact values, the wind speed increased from 75 knots to 105 knots in a 24-hour period, just barely meeting the criteria to count as RI.

Then just as it was approaching the coastline for landfall, it weakened slightly to a 90-knot Category 2 hurricane.  Radar and satellite data showed the eyewall quickly deteriorating as wind shear finally took its toll.

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

This is thankfully in stark contrast to what we witnessed eight years ago today when Michael rapidly intensified to a Category 5 hurricane right up to landfall just 70 miles east of where Isaias just made landfall.  That radar animation is shown below for reference:

Radar animation of Category 5 Hurricane Michael on October 10, 2018. https://bmcnoldy.earth.miami.edu/tropics/radar/ 

Isaias is no longer a tropical cyclone, but rain associated with it continues into the southeast U.S. over the next couple of days.

I plotted up some preliminary track and intensity forecast verification for Isaias. For track, the Google Deepmind ensemble mean (GDMI) was by far the leading model guidance... it left the other conventional guidance in the dust. The National Hurricane Center's forecasts (OFCL) closely followed that AI guidance and ended up doing quite well.

For intensity, it's not as clear-cut. Overall, the NHC (OFCL) has the lowest errors, then the Navy's COAMPS-TC hurricane model (CTCI) did quite well.  NOAA's flagship hurricane model, HWRF (HWFI), did really well at the important 2-3-day lead times. The Google Deepmind ensemble (GDMI) does not stand out too much in this category for this storm.

The Accumulated Cyclone Energy (ACE) has jumped up to about 17% of average for the date, as I eluded to in Wednesday's post.

There is still nothing else on the foreseeable horizon, but if and when the tenth storm comes comes around, the next name on this year's list Josephine.

• Visit the Tropical Atlantic Headquarters.
• Subscribe to get these updates emailed to you.
• Follow me on Bluesky

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.

• Visit the Tropical Atlantic Headquarters.
• Subscribe to get these updates emailed to you.
• Follow me on Bluesky

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.

• Visit the Tropical Atlantic Headquarters.
• Subscribe to get these updates emailed to you.
• Follow me on Bluesky