2026 Atlantic Hurricane Season

[GaWx]

 Is 99L going to be the first TC formation of the month? Edouard became a TC in August. When was the last Sept that didn’t have a TC formation by now? 2025 took til Sep 17th.

 1976 didn’t have one that later became a TS til the TD that formed on 9/26 and that became TS Gloria on 9/27. And there was a ST storm on Sept 13th. So, that doesn’t count as a TC. However, 1976 also had 2 TCs that maxed out as only TDs early in Sep. in the satellite era.

 So, even if a TD is declared today, 2026 has already beaten 2025 for the latest 1st TC declared in Sept. during the satellite era. Now, if it becomes a TS, that would mean that 1976 would remain the season with the latest first named TS in Sept. in the satellite era, which is Sept 27th.

[GaWx]

99L is now a cherry:

1. Eastern Subtropical Atlantic (AL99):
Showers and thunderstorms have changed little in organization since 
this morning in association with an area of low pressure located 
several hundred miles southwest of the Azores. However, just a small 
increase in organization is likely to result in the formation of a 
tropical depression as soon as later today. The system is expected 
to move slowly over the next couple of days remaining southwest of 
the Azores, followed by a turn to the southwest by early next week, 
when environmental conditions are forecast to become less favorable 
for additional development. 
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...70 percent.

[GaWx]

 Yesterday’s Euro Weeklies suggested a pretty active period in and near FL during the week of Sept 28-Oct 3rd. This suggests a recurving TC in that area is quite possible:

 This matches long-term climo well, which is at least close to the most active period for FL throughout the season:

 

 

 These 5 strong+ El Niño analogs with hits in FL during or near this active period shown on the Weeklies suggest to be wary especially in FL then although it’s interesting that these 5 were all 1902 and earlier as the subsequent 11 strong+ Ninos didn’t have a FL hit around then:

1902:

1899:

 

1896:

 

1888:

 

1877:

[GaWx]

4 hours ago, WEATHER53 said:

Remember vividly the declarations of ever increasing disaster during the Katrina year.  Has not happened and various drivers of our patterns have changed a lot in last 25 years 

I don’t know about “ever increasing disaster”, but you must know that there have been some bad seasons since including 2008, 2012, and most of 2016-24. 2016-24 was one of the worst 9 year periods for the SE US overall. Fortunately 2025 as well as 2026 so far have given us a much needed break, especially after the horrible 2024. But that’s less than 2 seasons.

[WEATHER53]

1 hour ago, GaWx said:

I don’t know about “ever increasing disaster”, but you must know that there have been some bad seasons since including 2008, 2012, and most of 2016-24. 2016-24 was one of the worst 9 year periods for the SE US overall. Fortunately 2025 as well as 2026 so far have given us a much needed break, especially after the horrible 2024. But that’s less than 2 seasons.

The signal that Katrina  was the sure sign of global warming causing ever increasing destruction to the USA was Gore style hype. 

[yoda]

3 hours ago, GaWx said:

99L is now a cherry:

1. Eastern Subtropical Atlantic (AL99):
Showers and thunderstorms have changed little in organization since 
this morning in association with an area of low pressure located 
several hundred miles southwest of the Azores. However, just a small 
increase in organization is likely to result in the formation of a 
tropical depression as soon as later today. The system is expected 
to move slowly over the next couple of days remaining southwest of 
the Azores, followed by a turn to the southwest by early next week, 
when environmental conditions are forecast to become less favorable 
for additional development. 
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...70 percent.

Nothing at 5pm

[GaWx]

56 minutes ago, WEATHER53 said:

The signal that Katrina  was the sure sign of global warming causing ever increasing destruction to the USA was Gore style hype. 

 There may very well be a reduction in the # of storms due to GW because it has warmed the poles much more than the tropics. Because tropical systems bring heat out of the tropics to higher latitudes, it’s possible that the lower contrast means fewer storms albeit with perhaps stronger storms on average due to the warming oceans.
 

 Indeed, we’ve had stronger storms in the Atlantic basin with more cat 5 since 2016 per year than for the prior period. But OTOH, I do wonder if just having warmer oceans is enough to generate stronger storms. Isn’t it the contrast of the avg tropical ocean temp vs the avg global temp that matters most? The oceans in the tropical/subtropical regions are obviously warmer, but the rest of the globe is warmer, too. It used to be that ~79F was a crucial SST to support TCG. Is that crucial SST going to warm up due to GW?

Your thoughts?

[vortex95]

6 hours ago, NorthHillsWx said:

Special update increased odds of 99L developing to 60% and that seems low given satellite. To me I’m not sure how this isn’t a depression at least but I think it is classified as such at 5 regardless 

Convection has not been persistent enough.  For developing systems, you do not want irregular blobs pulsing.  There has been no curved banding evident yet for the system.  1016 mb c.p. shows a high environmental pressure field w/ synoptic gradient weak from the high centers to its NE and W

99L is in a very narrow margin area.  Look at the WV loop attached,  Strong shear evident t toe S, more starting to press in from the NW, and deformation zones N-W-S.  18z SHIPS output environment is not good.  Shear is high and 700-500 RH quite low..
https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al992026/stext/26091818AL9926_ships.txt
 

Intensity models usually for nascent systems are bullish in taking them to min TS quickly, but about half of them currently do not even do that.  A testament to this Atlantic season I suppose when nothing can go "right!"

TD status appears mdt-high, but TS is more of challenge.

[GaWx]

18 minutes ago, vortex95 said:

Convection has not been persistent enough.  For developing systems, you do not want irregular blobs pulsing.  There has been no curved banding evident yet for the system.  1016 mb c.p. shows a high environmental pressure field w/ synoptic gradient weak from the high centers to its NE and W

99L is in a very narrow margin area.  Look at the WV loop attached,  Strong shear evident t toe S, more starting to press in from the NW, and deformation zones N-W-S.  18z SHIPS output environment is not good.  Shear is high and 700-500 RH quite low..
https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al992026/stext/26091818AL9926_ships.txt
 

Intensity models usually for nascent systems are bullish in taking them to min TS quickly, but about half of them currently do not even do that.  A testament to this Atlantic season I suppose when nothing can go "right!"

TD status appears mdt-high, but TS is more of challenge.

Did you see this?

[NorthHillsWx]

1 hour ago, vortex95 said:

Convection has not been persistent enough.  For developing systems, you do not want irregular blobs pulsing.  There has been no curved banding evident yet for the system.  1016 mb c.p. shows a high environmental pressure field w/ synoptic gradient weak from the high centers to its NE and W

99L is in a very narrow margin area.  Look at the WV loop attached,  Strong shear evident t toe S, more starting to press in from the NW, and deformation zones N-W-S.  18z SHIPS output environment is not good.  Shear is high and 700-500 RH quite low..
https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al992026/stext/26091818AL9926_ships.txt
 

Intensity models usually for nascent systems are bullish in taking them to min TS quickly, but about half of them currently do not even do that.  A testament to this Atlantic season I suppose when nothing can go "right!"

TD status appears mdt-high, but TS is more of challenge.

If this was worth flying a plane into they’d called is a TD

[vortex95]

2 hours ago, GaWx said:

 There may very well be a reduction in the # of storms due to GW because it has warmed the poles much more than the tropics. Because tropical systems bring heat out of the tropics to higher latitudes, it’s possible that the lower contrast means fewer storms albeit with perhaps stronger storms on average due to the warming oceans.
 

 Indeed, we’ve had stronger storms in the Atlantic basin with more cat 5 since 2016 per year than for the prior period. But OTOH, I do wonder if just having warmer oceans is enough to generate stronger storms. Isn’t it the contrast of the avg tropical ocean temp vs the avg global temp that matters most? The oceans in the tropical/subtropical regions are obviously warmer, but the rest of the globe is warmer, too. It used to be that ~79F was a crucial SST to support TCG. Is that crucial SST going to warm up due to GW?

Your thoughts?

Great questions and critical thinking above.  That's the right thing to in practicing good science -- asks lots of questions! 

See this paper 2011 paper (pdf attached):

On the Classification of Extreme Atlantic Hurricanes Utilizing Mid-Twentieth-Century Monitoring Capabilities*
A methodology is created to determine how many of these 10 recent Category 5 hurricanes likely would have been recorded as Category 5 if they had occurred during this period using only the observations that likely would have been available with existing technology and observational networks. Late-1940s and early- 1950s best-track intensities are determined for the entire lifetime of these 10 recent Category 5 hurricanes. It is found that likely only 2 of these 10—both Category 5 landfalling hurricanes—would have been recorded as Category 5 hurricanes if they had occurred during the late-1940s period. The results suggest that intensity estimates for extreme tropical cyclones prior to the satellite era are unreliable for trend and variability analysis.

So it virtually certain due to limitations of tech, esp. prior to the satellite era, many cat 4s even some cat 3s documented were actually cat 5s.  The hurricane reanalysis project has found solid evidence of cat 5sifor some system, and that has been corrected in HURDAT, but due to the mesoscale nature or the inner cores of these beasts, you just can't tell many times.  Also, hurricanes do not remain at cat 5 strength very long, so that makes them even harder to detect historically.

Even today, some are missed in the absence of recon since Dvorak estimates work best for systems 60 to 105 kt.  This means two things.  One, many TDs are actually weak TSs and two, many intense HUs are underestimated.  There is very little difference on satellite what a strong cat 4 and a minimal Cat 5 looks like, and Dvorak cannot account for storm size, RMW, environmental pres gradient, storm forward motions, and other factors that go into actual wind speed of a TC.

As an example, take HU Patrica from 2015.  If not for recon, it likely would have been capped at 160 kt.  I have yet to see NHC assign a HU in their AOR above 160 kt in the absence of recon or other in situ data.  Even JTWC rarely goes above 160 kt.  Patricia was rather small, and Dvorak does not do well for small TCs (underestimates).  Now we did have recon, and initial obs were 175 kt. when it was 880 mb.  However, the next recon, over 6 hr later, and it found 879 mb, but the satellite signature had weakened a bit, so recon missed Patricia’s absolute peak intensity.  They gave Patricia and estimated 872 mb pressure, but it could have been lower.  And on post-season analysis, the found Patricia peak winds were actually 185 kt!   So you see how tricky and elusive these beasts can be, even when recon is available!

I know Patricia was a cat 5 all along, but see the margin of error there w/ in actual in situ obs? 

The first official cat 5 in the Atlantic is not until 1924.  Does that mean there were none prior?  Of course not, just it was very hard to get actual obs to verify something that intense the further you go back,  An unfortunate ship would have to survive getting into the core of these things or a land station would have to be at the just the right location and the instruments survive to verify a cat 5.

Also, GFS dropsondes were not put into used until 1998, and the SFMR not until 2004.  These were game changers as to recons to get a much better idea of the winds sfc and aloft in a TC.  They way they got sfc winds prior?  They would take about 90% of the FL (700 mb) winds, and go w/ that that.  That works often, but not all the time.  It can vary quite a bit as GPS dropsondes and the SFMR have shown!

So really, using data prior to the 1990s for overall trends in intense hurricanes is not an apples to apples comparison.  Our detection and documentation, technology, and knowledge/understanding has improved immensely in the last 30 years alone, giving us a much better idea of reality for TCs, esp. for the intense ones!  And 30 years is too short of period to determine TC trends, esp. the in Atlantic since the AMO cycles are approx 25-45 years in length.

And the idea that hurricanes are getting stronger overall?  That notion is partially artificial b/c of the above.  Non-wx/climate factors play a big role here.  We are better than ever in observing and measuring the wx, getting better all the time, so we have been seeing things in recent decades due to better tech that were always there, just not able to be detected prior (go back to how the first cat 5 in the Atlantic is not until 1924). And the odds of seeing more absolute extremed and setting new records go up b/c of this tech factor as well.

jcliD1100420 4461..4475 - hagen-landsea-jclimate-2012.pdf

[vortex95]

1 hour ago, GaWx said:

Did you see this?

No I hadn't . What model is this?

I was looking at the various primarily model outputs  for intensity fcst (see attachment).

The operational GFS and ECMWF do very little w/ the system.  ECMWF brings it down to 1012 mb and makes it a TD.  Since the overall environment is marginal and fcst to gradually degrade, I am not optimistic at this time more than a TD.

That being said, the convection that has developed on the N side in the last few hours is more organized, but we need to see if it persists.  The dry air present makes it prone to pulsing up and down.  This makes it hard to pull the trigger and declare.  At 03z, it could look quite good and get declared, and then all the convection could collapse, and we are back at square one.  So NHC tends to hold off until clear trend or consistency exists.  These kind of high-latitude systems are often a challenge!

[vortex95]

22 minutes ago, NorthHillsWx said:

If this was worth flying a plane into they’d called is a TD

If was close to land, odds are they would declare it a TD as well.  I do not agree w/ such a policy. Treat all systems the same regardless of location or risk in terms of calling it for what it actually is.

One could call this a TD taking a snapshot as it is right now, but I go back to the persistence factor of convection and the marginal environment. 

[GaWx]

7 minutes ago, vortex95 said:

No I hadn't . What model is this?

I was looking at the various primarily model outputs  for intensity fcst (see attachment).

The operational GFS and ECMWF do very little w/ the system.  ECMWF brings it down to 1012 mb and makes it a TD.  Since the overall environment is marginal and fcst to gradually degrade, I am not optimistic at this time more than a TD.

That being said, the convection that has developed on the N side in the last few hours is more organized, but we need to see if it persists.  The dry air present makes it prone to pulsing up and down.  This makes it hard to pull the trigger and declare.  At 03z, it could look quite good and get declared, and then all the convection could collapse, and we are back at square one.  So NHC tends to hold off until clear trend or consistency exists.  These kind of high-latitude systems are often a challenge!

Google Deep Mind

[vortex95]

6 hours ago, GaWx said:

 Is 99L going to be the first TC formation of the month? Edouard became a TC in August. When was the last Sept that didn’t have a TC formation by now? 2025 took til Sep 17th.

 1976 didn’t have one that later became a TS til the TD that formed on 9/26 and that became TS Gloria on 9/27. And there was a ST storm on Sept 13th. So, that doesn’t count as a TC. However, 1976 also had 2 TCs that maxed out as only TDs early in Sep. in the satellite era.

 So, even if a TD is declared today, 2026 has already beaten 2025 for the latest 1st TC declared in Sept. during the satellite era. Now, if it becomes a TS, that would mean that 1976 would remain the season with the latest first named TS in Sept. in the satellite era, which is Sept 27th.

Edouard was named a TS at 00z 9/1.  So it depends on what type of time you  use if it formed in Sep or not!  And if you go by when it was declared a TC, that is in August solidly.

[vortex95]

42 minutes ago, GaWx said:

Google Deep Mind

I am not sure AI models would do well for systems in this part of the Atlantic since TCs are not nearly as common as in other parts of the Atlantic.