10 October 2026

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.

09 October 2026

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.

07 October 2026

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.

06 October 2026

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/



30 September 2026

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).

28 September 2026

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.

26 September 2026

September will end and still no hurricane this season

There's not too much to report in this post, so it will be brief. Fay is a dissipating tropical depression, and since my last post on Thursday, Gonzalo formed and dissipated near Cabo Verde.

12-hour infrared satellite animation from September 26.

Gonzalo was the 7th named storm of the season, though it only lasted for two days. In fact, there have been named storms for a TOTAL of 13.25 "named storm days" this season, which is 27% of average for the date.

Amazingly, the hurricane drought continues with nothing in the foreseeable future.  No hurricane season has gotten this far along without a hurricane in the past century, and during the more reliable satellite era (mid-1970s), the previous record latest first hurricane formation was September 11.

With both Fay and Gonzalo active as tropical storms on September 25, it became the most active day of the entire season so far, in terms of both named storm activity and Accumulated Cyclone Energy. The ACE is up to 10.4% of average for the date. If nothing forms in the meantime, it will slip to 9% of average on October 8.


Looks like I picked an easy year as my final year for writing this blog!


24 September 2026

Still watching Fay, and Gonzalo could be on the near horizon

Two features of interest in this post: Tropical Storm Fay and Invest 90L -- which has a shot as becoming the next named storm, Gonzalo.

Since my previous post on Monday, Fay actually dissipated on Tuesday afternoon and then regenerated on Wednesday afternoon. It's currently a tropical storm located about 1000 miles west-southwest of the Azores and moving slowly toward the west. It could intensify slightly today, but is not expected to get close to hurricane intensity, before it starts weakening again.


Fay is expected to dissipate, again, on Saturday. We'll see if it sticks this time.


Elsewhere, Invest 90L is the wave I discussed in Monday's post. It is currently just barely off the African coast, southeast of the Cabo Verde Islands and is forecast to move toward the northwest in the coming days.


In a normal year, these large robust tropical waves would be cause for potential concern in 10-14 days on the other side of the Atlantic basin, but this is not one of those years, thanks to the developing very strong El Niño which has suppressed activity across the deep tropics so far this season.

This has pretty decent model support to develop into the next named storm, Gonzalo, rather soon. After that, dry air and vertical wind shear will start to impact it and it could dissipate later in the weekend. There is no model support for it reaching hurricane intensity, which means the record hurricane drought in the Atlantic continues.

Fay's resurgence has nudged the Accumulated Cyclone Energy (ACE) up to 8% of average for the date... still a record-low value for this point in the season by a big margin during the reliable satellite era (mid-1970s).  Prior to the satellite era when some activity was certainly missed, only three years were lower: 1914, 1907, and 1905.

  

21 September 2026

Fay continues the record hurricane-free Atlantic hurricane season

On Saturday afternoon, a small low pressure system in the north central Atlantic (tagged as Invest 99L) was upgraded to Tropical Depression Six, and then upgraded again on Sunday morning to Tropical Storm Fay... the sixth named storm of the season.


As of Monday morning, Fay is located about 400 miles southwest of the Azores and not moving much. It's expected to start moving toward the southwest and dissipate in the next couple of days.


Fay has very likely peaked in intensity, just shy of hurricane status. So, there still has not been a hurricane this season. The previous record-latest first hurricane formation was September 11 (during the more reliable satellite era), so that record continues to be broken every day.  Prior to the satellite era, some storms were likely missed, but 1907 and 1914 have zero hurricanes in the database. Will 2026 join that small list?

The next decent shot at activity appears to be a wave coming off of Africa at the end of the week. I can trace it back to the Ethiopian Highlands on September 15-16. Most models develop and intensify it fairly quickly once it leaves the coast, so we'll see if that ends up becoming the first hurricane??  The next name on the list is Gonzalo.

The season statistics through today are 6 named storms, 0 hurricanes, and 0 major hurricanes. The average by now is 9, 4, and 2. In terms of Accumulated Cyclone Energy (ACE), that is at 7% of average for the date. Looking at the ACE timeline, the average season is about 2/3 over by today. If this current season is also 2/3 over, it will end up around 7% of average by the end of the official season on November 30.


The last time a season has less ACE that this was well before the satellite era: 1929, 1925, 1914, 1907, and 1905.


As I've described in previous posts, the reason for this anemic season is almost entirely the building strong El Niño. It's a well-established teleconnection that strong El Niño act to suppress Atlantic hurricane activity, and La Niñas act to enhance it. Well, there has never been an El Niño as strong as what this one is shaping up to be, so it seems reasonable that we're also seeing a record-quiet hurricane season.

18 September 2026

Centennial of the Great Miami Hurricane of 1926

[this post is a reproduction of the webpage at https://bmcnoldy.earth.miami.edu/tropics/miami26/, which I first shared with the community on August 18]

This was the seventh known tropical cyclone to form during the 1926 Atlantic hurricane season, and it was the second out of three major hurricanes to impact Florida that year. An easterly wave likely left the African coast around September 6 but was not officially tracked until September 11 when it was identified as a tropical storm about 1,000 miles east of the Lesser Antilles.

The Great Miami Hurricane's track and intensity (colored by Saffir-Simpson category, which did not exist at the time); dates are labeled along the track at 0000 UTC each day.

In 1926, routine weather satellite coverage was still five decades away, so observations came from "ships of opportunity" or nearby islands which could provide helpful observations of wind and pressure from which the storm center, pressure, and intensity could be estimated.

The storm first reached land on the afternoon of September 16 as it crossed the Turks and Caicos Islands as a Category 4 hurricane with 150 mph sustained winds... this was the peak intensity of the storm's lifetime. On September 17-18 it crossed the Bahamas, still at Category 4 intensity with 145 mph peak sustained winds as it tracked over Andros Island.

Surface wind swath over the lifetime of the storm produced using a parametric model that utilizes observed storm parameters such as intensity, radius of maximum wind, radii of tropical storm force wind, and track. Any missing parameters were carefully estimated. The color families correspond to the Saffir-Simpson Scale: tropical storm in blues, Category 1 hurricane in greens, Category 2 in yellows, Category 3 in reds, Category 4 in purples, and Category 5 in grays. 

Surface wind swath zoomed in over Florida, produced using a parametric model that utilizes observed storm parameters such as intensity, radius of maximum wind, radii of tropical storm force wind, and track. Any missing parameters were carefully estimated. The color families correspond to the Saffir-Simpson Scale: tropical storm in blues, Category 1 hurricane in greens, Category 2 in yellows, Category 3 in reds, Category 4 in purples, and Category 5 in grays. 

After the eye exited Andros Island, it was a short 7-hour, 140-mile trek across the Straits of Florida. The Category 4 hurricane made landfall 13.5 miles south of downtown Miami at 6:30 am on September 18. Peak sustained winds were 145 mph, and the radius of maximum wind in the eyewall was 23 miles at the time. That put Miami directly in the calm eye for approximately 35 minutes, and in the northern eyewall with the maximum onshore winds immediately before and after that.

Estimated surface wind field during a 12-hour period centered on the time of landfall in Miami-Dade County (called Dade County then). The decay of wind speed over land is modeled using approximate land use data from the time.


The first storm warning for the Miami area was issued just 18 hours prior to landfall, and a hurricane warning was issued only 7 hours prior to landfall. Several ingredients converged to make this an especially destructive and deadly storm: 1) the extreme intensity and storm surge, 2) the urban area it impacted, 3) the large number of people living there who had never experienced a hurricane, 4) the rush of people into the open during the calm eye, not knowing the worst would come abruptly just minutes later, and 5), the very brief warning previously mentioned.

There is nothing like the 1926 hurricane in the historical record for Miami – it was very intense, very large, and passed directly over downtown. It came at a time when forecasts were primitive, warnings were insufficient, and people were inexperienced. This hurricane struck around sunrise on September 18, 1926 and instantly halted the seemingly boundless land boom, shattered the image of a tropical paradise, and plunged the area into an economic depression three years before the Great Depression began for the rest of the country.

This storm also has special significance to the University of Miami. The university was established in 1925, and construction on the campus began shortly after. The new buildings suffered extensive damage, but amazingly, the university still opened for classes in October 1926. This is the origin of the "Miami Hurricanes".

I will not attempt to retell the impacts in words and photos, that has been done in many places, most succinctly by the NWS Miami Office. Experts have shown that if this exact hurricane were to occur in 2026, it would be the costliest hurricane in U.S. history.

The only Category 3+ hurricane since 1926 to pass directly over Miami was Hurricane King in 1950. It was slightly weaker than the 1926 hurricane at landfall (peak sustained winds of 130 mph compared to 145 mph), but still a Category 4 hurricane. Furthermore, it was significantly smaller (eyewall was about 12 miles in diameter compared to 46 miles) and the warning time leading up to it was twice as long (36 hours compared to 18 hours). Those factors all helped to make King much less deadly, destructive, and infamous than the 1926 hurricane.

Then in 1992, Category 5 Hurricane Andrew did not pass directly over Miami, but the eye made landfall about 20 miles south of downtown and was very impactful. Hurricanes can be small, large, and anything in between. The Great Miami Hurricane of 1926 was very large. King was extraordinarily compact and Andrew was very small. One measure of a hurricane’s destructive power is called the “integrated kinetic energy”. The 1926 hurricane had approximately 6 times more energy than King and 4 times more than Andrew at their landfalls in southeast Florida (170 TJ vs 30 TJ vs 43 TJ).

Estimated surface wind field at landfall for the Great Miami Hurricane of 1926 (left), Hurricane King in 1950 (center), and Hurricane Andrew in 1992 (right). Select storm statistics are listed in the upper right of each panel: intensity ("VMAX" in knots), radius of maximum wind ("RMW" in nautical miles), and integrated kinetic energy ("IKE" in Terajoules). The storm track is shown by the thin maroon line.

I want to thank John Knaff, Chris Landsea, and Dave Nolan for various contributions to bringing the wind field of this historic hurricane to life. I worked with John to iterate on several values of the radius of tropical storm winds ("R34"), Chris provided feedback and approval from a seasoned veteran of hurricane reanalysis, and Dave provided a WRF-derived "roughness length" dataset to properly handle the decay of wind speed over land. To adapt the modern high-resolution roughness length data to 1926, I reduced any urban areas to woodland to somewhat reproduce the smaller and fewer buildings of the time. I then applied a smoothing filter to remove the impression of spatial precision. Both the data and the model have assumptions, approximations, and estimates, so this is only intended to provide an educated rough guess of what this hurricane's wind field may have looked like.

Additional information and resources: