Why is the 2024 Atlantic hurricane season underperforming expectations?

[psyclone]

The roughly 50 days from 8/20 to 10/10 deliver two thirds of our canes...we're just entering the 2nd quarter of that time frame with no score in q1.

[Hammy]

If there isn’t TCG by Sep 7th, I believe it would be the first season since 1968 without a TC during 8/21-9/7.

Are we talking formation or active systems? 1992 had nothing actually form between August 18 and September 17

[LarryWx]

If there isn’t TCG by Sep 7th, I believe it would be the first season since 1968 without a TC during 8/21-9/7.

Are we talking formation or active systems? 1992 had nothing actually form between August 18 and September 17

Active systems. But I still could have missed something else since 1968.

[LarryWx]

“Rare deluge to hit parts of the Sahara” and its interconnection with ITCZ moving further N in Africa:

https://m.youtube.com/watch?v=RTGlN6yq3 ... nwx.com%2F

[Audrey2Katrina]

This season is slipping fast in its ranks. At one point, the NATL was at #3 in ACE on record through around the time of Ernesto's dissipation. Since, the NATL has fallen to 13th, but could be at risk of even falling below average if the basin does not wake up soon.

I know I'll be the thrill killer here, but I wouldn't mind it even a LITTLE bit if the basin keeps right on snoozing. I'm not wealthy and I'm OLD, and yet I have to get by the best way I can. Ida nearly wiped me out. So pardon my saying it, but I'd be quite happy if the seasonal ACE stays below 100, although realistically, I know this isn't very likely. We haven't even reached peak of the season yet, and sometimes September and October outproduce July and August, they certainly did last year.

[cycloneye]

 https://x.com/webberweather/status/1830952226300555550

@webberweather
This Atlantic Hurricane Season is teaching &/or reminding folks (including myself to a degree) that we are hyper fixated on/overweighting local, tropical SSTa for seasonal forecasting.

This season also could be offering us a glimpse into what future hurricane seasons may potentially look like.

(e.g., weaker seasonal persistence of Atlantic (subtropical & tropical) spring SSTa into the peak of the season, greater dependence on dry/stable air, wetter Sahel & Sahara Desert/poleward shifted ITCZ, similar or lower numbers of total TCs, but more strong storms per capita, etc.)

[skyline385]

If there isn’t TCG by Sep 7th, I believe it would be the first season since 1968 without a TC during 8/21-9/7.

Are we talking formation or active systems? 1992 had nothing actually form between August 18 and September 17

Active based on this tweet

 https://x.com/philklotzbach/status/1830918338458923381

[tolakram]

 https://x.com/webberweather/status/1830952226300555550

@webberweather
This Atlantic Hurricane Season is teaching &/or reminding folks (including myself to a degree) that we are hyper fixated on/overweighting local, tropical SSTa for seasonal forecasting.

This season also could be offering us a glimpse into what future hurricane seasons may potentially look like.

(e.g., weaker seasonal persistence of Atlantic (subtropical & tropical) spring SSTa into the peak of the season, greater dependence on dry/stable air, wetter Sahel & Sahara Desert/poleward shifted ITCZ, similar or lower numbers of total TCs, but more strong storms per capita, etc.)

As far as that tweet goes I will say it again here:

You cannot predict an outlier of anything, the odds are stacked against you.

As I said earlier in the season ... it will be slower than expected and people will say the world has changed. Here we have the first example, I'm sure this will be echoed by more as we move forward.

[Hypercane_Kyle]

It's September 3rd and no sign of a named storm anytime soon.

If we don't get even another system by September 10th, we're going to struggle to reach 10 named. Heading for one of the least active hurricane seasons of all time.

[Ubuntwo]

Mid-level dry, stable air is what prevented the developing vortex on the west basin tropical wave from surviving a diurnal cycle. One diurnal minimum period with persistent concentrated convection, and we would be talking about a caribbean cruiser and likely high end Gulf coast landfall (hence the highly bifurcated ensemble solutions between limited/no development and long tracking major hurricane). The precursor waves to both Ernesto and Debby also dealt with this same airmass delaying development. Transport of mid level dryness and overall levels of stability are two big things to look into, IMO.

[LarryWx]

There are three AOIs on the TWO that are between 12N and 15N, which are not north at all. Furthermore, they’ve been at 15N or further S since leaving Africa:

https://www.nhc.noaa.gov/archive/xgtwo/ ... 2409031153

[SFLcane]

 https://x.com/ericblake12/status/1831002481062514710

[Woofde]

 https://x.com/webberweather/status/1830952226300555550

@webberweather
This Atlantic Hurricane Season is teaching &/or reminding folks (including myself to a degree) that we are hyper fixated on/overweighting local, tropical SSTa for seasonal forecasting.

This season also could be offering us a glimpse into what future hurricane seasons may potentially look like.

(e.g., weaker seasonal persistence of Atlantic (subtropical & tropical) spring SSTa into the peak of the season, greater dependence on dry/stable air, wetter Sahel & Sahara Desert/poleward shifted ITCZ, similar or lower numbers of total TCs, but more strong storms per capita, etc.)

As far as that tweet goes I will say it again here:

You cannot predict an outlier of anything, the odds are stacked against you.

As I said earlier in the season ... it will be slower than expected and people will say the world has changed. Here we have the first example, I'm sure this will be echoed by more as we move forward.

Eric is basically just reading off the main points of the recent study regarding climate change and hurricanes. The study's idea was that in the future there will be fewer total storms due to increased shear and lower instability, with a higher percentage of major hurricanes and record breaking storms due to an established vortex being able to plow through that and use the warmer waters.

This season does make a lot of sense under that lense, but I agree with you. It's far more likely just a fluke of probability. I don't buy climate change being the main reason this season failed. We've had 2020 with the most named storms at 30, 2021 with 21 storms, and 2023 with 20. That's all within the last 5 years and those are all top 5 named storm quantity seasons. The data just doesn't suggest we are there yet. People have a tendency to underestimate how fickle weather is, and overestimate our understanding and grasp on the whole system. When a seemingly favorable season underperforms or vice versa, we all want to know why. Many times though instead of there being some new phenomena we completely overlooked, it's just random chance.

[caneman]

 https://x.com/webberweather/status/1830952226300555550

@webberweather
This Atlantic Hurricane Season is teaching &/or reminding folks (including myself to a degree) that we are hyper fixated on/overweighting local, tropical SSTa for seasonal forecasting.

This season also could be offering us a glimpse into what future hurricane seasons may potentially look like.

(e.g., weaker seasonal persistence of Atlantic (subtropical & tropical) spring SSTa into the peak of the season, greater dependence on dry/stable air, wetter Sahel & Sahara Desert/poleward shifted ITCZ, similar or lower numbers of total TCs, but more strong storms per capita, etc.)

As far as that tweet goes I will say it again here:

You cannot predict an outlier of anything, the odds are stacked against you.

As I said earlier in the season ... it will be slower than expected and people will say the world has changed. Here we have the first example, I'm sure this will be echoed by more as we move forward.

Eric is basically just reading off the main points of the recent study regarding climate change and hurricanes. The study's idea was that in the future there will be fewer total storms due to increased shear and lower instability, with a higher percentage of major hurricanes and record breaking storms due to an established vortex being able to plow through that and use the warmer waters.

This season does make a lot of sense under that lense, but I agree with you. It's far more likely just a fluke of probability. I don't buy climate change being the main reason this season failed. We've had 2020 with the most named storms at 30, 2021 with 21 storms, and 2023 with 20. That's all within the last 5 years and those are all top 5 named storm quantity seasons. The data just doesn't suggest we are there yet. People have a tendency to underestimate how fickle weather is, and overestimate our understanding and grasp on the whole system. When a seemingly favorable season underperforms or vice versa, we all want to know why. Many times though instead of there being some new phenomena we completely overlooked, it's just random chance.

I agree with you on the explanation. It wasn't that long ago that we were told climate change would cause more hurricanes. The reasoning will have to be found and not just bend something as a solution or reason to fit a narrative

[Hypercane_Kyle]

 https://x.com/webberweather/status/1830952226300555550

@webberweather
This Atlantic Hurricane Season is teaching &/or reminding folks (including myself to a degree) that we are hyper fixated on/overweighting local, tropical SSTa for seasonal forecasting.

This season also could be offering us a glimpse into what future hurricane seasons may potentially look like.

(e.g., weaker seasonal persistence of Atlantic (subtropical & tropical) spring SSTa into the peak of the season, greater dependence on dry/stable air, wetter Sahel & Sahara Desert/poleward shifted ITCZ, similar or lower numbers of total TCs, but more strong storms per capita, etc.)

As far as that tweet goes I will say it again here:

You cannot predict an outlier of anything, the odds are stacked against you.

As I said earlier in the season ... it will be slower than expected and people will say the world has changed. Here we have the first example, I'm sure this will be echoed by more as we move forward.

Eric is basically just reading off the main points of the recent study regarding climate change and hurricanes. The study's idea was that in the future there will be fewer total storms due to increased shear and lower instability, with a higher percentage of major hurricanes and record breaking storms due to an established vortex being able to plow through that and use the warmer waters.

This season does make a lot of sense under that lense, but I agree with you. It's far more likely just a fluke of probability. I don't buy climate change being the main reason this season failed. We've had 2020 with the most named storms at 30, 2021 with 21 storms, and 2023 with 20. That's all within the last 5 years and those are all top 5 named storm quantity seasons. The data just doesn't suggest we are there yet. People have a tendency to underestimate how fickle weather is, and overestimate our understanding and grasp on the whole system. When a seemingly favorable season underperforms or vice versa, we all want to know why. Many times though instead of there being some new phenomena we completely overlooked, it's just random chance.

You're focusing on named storm count, which doesn't make much sense in the context of the study you're referring to. If you look at most of the seasons that are high in named storm counts (above 15) since 2005, you'll find that many of those had an average number of hurricanes/major hurricanes and ACE.

In fact, in the last 20 years since 2005, only one season has topped out in the Top 10 for ACE ~ 2017. 2020 isn't even on the list. However, we are seeing more quick spin-up major hurricanes with devastating impacts, while the big ACE-producing Cape Verde hurricanes have clearly lessened. That does seem to align with that study.

[LarryWx]

From Joe Bastardi:
“Preparing the hurricane update now including discussion of 3 pronged reason its been quiet since Ernesto ( Solar, MJO, Distorted warming) VV pattern has been hostile for 2 weeks but should reverse by mid Sept You can still have development and in fact Gulf is place to watch”

https://twitter.com/BigJoeBastardi/stat ... 8899525799?

[Woofde]

As far as that tweet goes I will say it again here:

You cannot predict an outlier of anything, the odds are stacked against you.

As I said earlier in the season ... it will be slower than expected and people will say the world has changed. Here we have the first example, I'm sure this will be echoed by more as we move forward.

Eric is basically just reading off the main points of the recent study regarding climate change and hurricanes. The study's idea was that in the future there will be fewer total storms due to increased shear and lower instability, with a higher percentage of major hurricanes and record breaking storms due to an established vortex being able to plow through that and use the warmer waters.

This season does make a lot of sense under that lense, but I agree with you. It's far more likely just a fluke of probability. I don't buy climate change being the main reason this season failed. We've had 2020 with the most named storms at 30, 2021 with 21 storms, and 2023 with 20. That's all within the last 5 years and those are all top 5 named storm quantity seasons. The data just doesn't suggest we are there yet. People have a tendency to underestimate how fickle weather is, and overestimate our understanding and grasp on the whole system. When a seemingly favorable season underperforms or vice versa, we all want to know why. Many times though instead of there being some new phenomena we completely overlooked, it's just random chance.

You're focusing on named storm count, which doesn't make much sense in the context of the study you're referring to. If you look at most of the seasons that are high in named storm counts (above 15) since 2005, you'll find that many of those had an average number of hurricanes/major hurricanes and ACE.

In fact, in the last 20 years since 2005, only one season has topped out in the Top 10 for ACE ~ 2017. 2020 isn't even on the list. However, we are seeing more quick spin-up major hurricanes with devastating impacts, while the big ACE-producing Cape Verde hurricanes have clearly lessened. That does seem to align with that study.

This is what I was referencing. It's the modern current line of thinking and understanding of the future effects of climate change on the Hurricane season. Its very inline with Eric Webb's tweet. Named storms and proportions are there. I never brought up ACE because I have zero idea of what is expected there.

https://www.gfdl.noaa.gov/global-warmin ... -statement

[LarryWx]

Eric is basically just reading off the main points of the recent study regarding climate change and hurricanes. The study's idea was that in the future there will be fewer total storms due to increased shear and lower instability, with a higher percentage of major hurricanes and record breaking storms due to an established vortex being able to plow through that and use the warmer waters.

This season does make a lot of sense under that lense, but I agree with you. It's far more likely just a fluke of probability. I don't buy climate change being the main reason this season failed. We've had 2020 with the most named storms at 30, 2021 with 21 storms, and 2023 with 20. That's all within the last 5 years and those are all top 5 named storm quantity seasons. The data just doesn't suggest we are there yet. People have a tendency to underestimate how fickle weather is, and overestimate our understanding and grasp on the whole system. When a seemingly favorable season underperforms or vice versa, we all want to know why. Many times though instead of there being some new phenomena we completely overlooked, it's just random chance.

You're focusing on named storm count, which doesn't make much sense in the context of the study you're referring to. If you look at most of the seasons that are high in named storm counts (above 15) since 2005, you'll find that many of those had an average number of hurricanes/major hurricanes and ACE.

In fact, in the last 20 years since 2005, only one season has topped out in the Top 10 for ACE ~ 2017. 2020 isn't even on the list. However, we are seeing more quick spin-up major hurricanes with devastating impacts, while the big ACE-producing Cape Verde hurricanes have clearly lessened. That does seem to align with that study.

This is what I was referencing. It's the modern current line of thinking and understanding of the future effects of climate change on the Hurricane season. Its very inline with Eric Webb's tweet. Named storms and proportions are there. I never brought up ACE because I have zero idea of what is expected there.

https://www.gfdl.noaa.gov/global-warmin ... -statementhttps://uploads.tapatalk-cdn.com/20240903/5e60a102f9fa77b1b72f1c5fa866a4da.jpg https://uploads.tapatalk-cdn.com/20240903/70f7e3d568b1306aa78f5e39fbfc76da.jpg

Also, rainfall has been increasing supposedly due to CC for two reasons:
-higher SSTs/higher dewpoints/higher PWATs leading to heavier rates of rain
-slightly slower average speed of motion supposedly caused by more warming in the Arctic vs tropics reducing contrast thus leading to slower steering winds thus causing an increased length of time of heavier rainfall

[Teban54]

Mid-level dry, stable air is what prevented the developing vortex on the west basin tropical wave from surviving a diurnal cycle. One diurnal minimum period with persistent concentrated convection, and we would be talking about a caribbean cruiser and likely high end Gulf coast landfall (hence the highly bifurcated ensemble solutions between limited/no development and long tracking major hurricane). The precursor waves to both Ernesto and Debby also dealt with this same airmass delaying development. Transport of mid level dryness and overall levels of stability are two big things to look into, IMO.

Assuming we're talking about the diurnal min on the night of Aug 31 - Sep 1, when the wave had the best possible chances of organizing, it looks like the layer that's significantly dryer than average was actually in the lower levels. The loop below plays from 500 to 925 mb, and the wave was at roughly 10N 50W at that time. While 600 mb is a little bit dry, other levels seem roughly okay -- except when you get to 925 mb, where that exact spot has one of the lowest RH anomalies in the Atlantic.

This is also a persistent theme during the entire August 2024: 925 mb dry air off the coast of South America.



Mid levels do look dry when you look at absolute values, not anomalies. But that's where I found another interesting discovery -- You know what's even drier? 2023!

Here's mid-level water vapor imagery at the same time in 2024 vs. 2023. Low-level images look similar.

12z Aug 31, 2024



12z Aug 31, 2023
(NW Atlantic looks wet primarily due to Franklin.)



I've also checked 2023's averages during the Aug 20 - Sep 1 period: It was exceptionally dry at 925 mb, and at all other levels, the tropical Atlantic seems at least a bit drier than the same period in 2024.



Yet, 7 storms formed during the 12-day period in 2023, vs. 0 in 2024, despite a drier tropics overall. But why?

This is where things may relate to Woofde's comment about randomness. Our 0/40 wave found one of the worst possible spots to be in on that night in the entire tropical Atlantic; if only it was a bit further north near the Leeward Islands, it would have moisture to develop into a strong (likely recurving) hurricane. Or, if the western MDR was just a little bit wetter to sustain convection, we could be looking at a storm similar to Laura and Ida right now. This is not saying bad luck was the only reason for the lull, but 2024 was probably just extremely unlucky in getting all kinds of random negative factors -- many of which are unpredictable -- at the same time.

[Teban54]

 https://x.com/DrKimWood/status/1830996681833488758