Why is the 2024 Atlantic hurricane season underperforming expectations?

[weeniepatrol]

Interestingly, NAO is used as a proxy for AMO/THC. It’s probably not a coincidence that the lowest Greenland pressure seasons (low pressure over Greenland projects onto the positive phase of the nao) was 1994 and 2013, very inactive and -AMO like seasons.

[Kingarabian]

There's a lot of rich discussions going on regarding this topic. It's really fascinating, to be honest.

But I do have a point I'd like to share, and that is: is there a possibility that the inhibitory factors in the Atlantic we're seeing now is somewhat associated with the El Nino from last year? I've noticed that some -ENSO seasons that occur right after a traditional El Nino tend to struggle in some shape or form. Since the +AMO era in 1995, here are the patterns I've seen:

1995: Right after the moderate El Nino of 1994. This is perhaps a classic example of a hyperactive year post-El Nino. No comment otherwise.

1998: Right after the very strong El Nino of 1997. While hyperactive, activity was heavily backloaded, and the two significant storms of the season (Georges and Mitch) happened after mid-September.

2007: Right after the weak El Nino of 2006. Aside from Category 5 twins Dean and Felix, activity was fairly weak and basically a slightly more juiced-up version of 2013 as there were no hurricanes that reached Cat 2-4 strength.

2010: Right after the moderate El Nino of 2009. While hyperactive, Wikipedia notes that "In spite of the high number of tropical cyclones, mid-level dry air dominated the tropical Atlantic throughout the peak of the season, perhaps hindering the season from being even more active."

2016: Right after the very strong El Nino of 2015. The season featured a fairly inactive July-August and even a September where only tropical storms formed. Then by the tail end of the month, Category 5 Matthew happened, followed by Category 4 Nicole and Category 3 Otto in the latter months of hurricane season.


** I will also add that in quite a few of these cases, the following year, assuming it also ended up as -ENSO, actually ended up being more active, especially if the first year failed to reach hyperactivity. 1999 featured more major hurricanes than 1998, 2008 was simply a much more impactful and active year than 2007, and 2017 ended up being the legendary hurricane season we remember it as. Pre-1995 examples of this include 1932/1933 and 1954/1955. Almost gets you wondering if 2025, assuming it is also a -ENSO year, may end up being what we initially thought 2024 would be.

Next year being more active would be a strong possibility if this level of inactivity keeps up for the rest of the season.

2nd after an El Nino is usually pretty active.

[WeatherBoy2000]

Interestingly, NAO is used as a proxy for AMO/THC. It’s probably not a coincidence that the lowest Greenland pressure seasons (low pressure over Greenland projects onto the positive phase of the nao) was 1994 and 2013, very inactive and -AMO like seasons.

Yeah it's interesting how this year has taken on some aspects of a -amo despite how warm the western mdr/Caribbean is. As pointed out by Eric Webb, the waters south of Greenland/off North Africa are relatively cool which is much more in line with a -amo than a positive one:



It's an odd hybrid set up.

[Hammy]

Interestingly, NAO is used as a proxy for AMO/THC. It’s probably not a coincidence that the lowest Greenland pressure seasons (low pressure over Greenland projects onto the positive phase of the nao) was 1994 and 2013, very inactive and -AMO like seasons.

So by extension, did what happened in 2013 essentially create a -AMO setup on steroids?

[AnnularCane]

There's a lot of rich discussions going on regarding this topic. It's really fascinating, to be honest.

But I do have a point I'd like to share, and that is: is there a possibility that the inhibitory factors in the Atlantic we're seeing now is somewhat associated with the El Nino from last year? I've noticed that some -ENSO seasons that occur right after a traditional El Nino tend to struggle in some shape or form. Since the +AMO era in 1995, here are the patterns I've seen:

1995: Right after the moderate El Nino of 1994. This is perhaps a classic example of a hyperactive year post-El Nino. No comment otherwise.

1998: Right after the very strong El Nino of 1997. While hyperactive, activity was heavily backloaded, and the two significant storms of the season (Georges and Mitch) happened after mid-September.

2007: Right after the weak El Nino of 2006. Aside from Category 5 twins Dean and Felix, activity was fairly weak and basically a slightly more juiced-up version of 2013 as there were no hurricanes that reached Cat 2-4 strength.

2010: Right after the moderate El Nino of 2009. While hyperactive, Wikipedia notes that "In spite of the high number of tropical cyclones, mid-level dry air dominated the tropical Atlantic throughout the peak of the season, perhaps hindering the season from being even more active."

2016: Right after the very strong El Nino of 2015. The season featured a fairly inactive July-August and even a September where only tropical storms formed. Then by the tail end of the month, Category 5 Matthew happened, followed by Category 4 Nicole and Category 3 Otto in the latter months of hurricane season.


** I will also add that in quite a few of these cases, the following year, assuming it also ended up as -ENSO, actually ended up being more active, especially if the first year failed to reach hyperactivity. 1999 featured more major hurricanes than 1998, 2008 was simply a much more impactful and active year than 2007, and 2017 ended up being the legendary hurricane season we remember it as. Pre-1995 examples of this include 1932/1933 and 1954/1955. Almost gets you wondering if 2025, assuming it is also a -ENSO year, may end up being what we initially thought 2024 would be.

Next year being more active would be a strong possibility if this level of inactivity keeps up for the rest of the season.

Or if it's backloaded, like 1998 or 2016.

[869MB]

 https://x.com/webberweather/status/1835172468308242652




Another reason I suspect this year's "busted" Atlantic Hurricane Season forecasts were forced largely by "internal" variability from the extratropics rather than say a poleward shift in the Africa ITCZ (tho that played a role too!):

When I go back and look at climate model forecasts for this Hurricane Season, what really strikes me is they correctly predicted the potential for very (& possibly record) low SLP over NE Africa & Mediterranean, which ultimately helped drag the ITCZ anomalously northward over the Sahel & Sahara.

What about the record low SLP over Greenland/Iceland associated w/ the +NAO? It was grossly underestimated to put it lightly w/ only a slightly higher chance for lower tercile SLP.

Oops.

[WeatherBoy2000]

Interestingly enough, if you ignore the much warmer western mdr/Caribbean, the sst configuration now is very reminiscent of 2013 at this time:





The global mean demonstrates this even better:



The cooler waters around Greenland/Iceland, the very warm band off Newfoundland, and the cooler waters off North Africa are all there in both years. Imo the much warmer western deep tropics has allowed for much more intense activity than in 2013, but the hostility of this set up is winning out overall.

[al78]

A pattern somewhat like 2013 but much warmer overall across the basin.

[aspen]

 https://x.com/webberweather/status/1835172468308242652




Another reason I suspect this year's "busted" Atlantic Hurricane Season forecasts were forced largely by "internal" variability from the extratropics rather than say a poleward shift in the Africa ITCZ (tho that played a role too!):

When I go back and look at climate model forecasts for this Hurricane Season, what really strikes me is they correctly predicted the potential for very (& possibly record) low SLP over NE Africa & Mediterranean, which ultimately helped drag the ITCZ anomalously northward over the Sahel & Sahara.

What about the record low SLP over Greenland/Iceland associated w/ the +NAO? It was grossly underestimated to put it lightly w/ only a slightly higher chance for lower tercile SLP.

Oops.

So based on everything I’ve been reading from this forum and the mets on Twitter (including this very good thread), it seems like there’s decent consensus that the factors that led to this season’s unexpected under-performance are:

1.) The northerly displaced and hyperactive AEJ/ITCZ/African monsoon, which tangled up AEWs and tossed them over less favorable waters. Enhanced by the significant -MSLP anomalies over the Mediterranean.

2.) A strong +NAO that cooled the Canary Current and helped to stabilize the basin, kill any waves that made it out of the tangled ITCZ, etc.

After this season, I won’t be surprised if we see agencies/pro mets tweak how they assess and forecast upcoming hurricane seasons. Some of the factors that shut down this season were caught on the models beforehand but not realized to be negative factors (-MSLP anomalies over the Mediterranean, potentially northerly ITCZ, etc), while others that weren’t caught until later (like the +NAO) probably wouldn’t have been thought of as severely negative factors if correctly modeled in advance. Therefore, I think we may see indicators like these be given more weight in future seasonal forecasts. They were enough to almost completely shut down the basin despite textbook examples of the indicators we usually focus on: first year -ENSO, +AMO (at least until the +NAO began to kick in), record warm SSTs, favorable precip anomalies, favorable shear forecasts, active analog years, etc.

[Ntxw]

 https://x.com/webberweather/status/1835172468308242652




Another reason I suspect this year's "busted" Atlantic Hurricane Season forecasts were forced largely by "internal" variability from the extratropics rather than say a poleward shift in the Africa ITCZ (tho that played a role too!):

When I go back and look at climate model forecasts for this Hurricane Season, what really strikes me is they correctly predicted the potential for very (& possibly record) low SLP over NE Africa & Mediterranean, which ultimately helped drag the ITCZ anomalously northward over the Sahel & Sahara.

What about the record low SLP over Greenland/Iceland associated w/ the +NAO? It was grossly underestimated to put it lightly w/ only a slightly higher chance for lower tercile SLP.

Oops.

So based on everything I’ve been reading from this forum and the mets on Twitter (including this very good thread), it seems like there’s decent consensus that the factors that led to this season’s unexpected under-performance are:

1.) The northerly displaced and hyperactive AEJ/ITCZ/African monsoon, which tangled up AEWs and tossed them over less favorable waters. Enhanced by the significant -MSLP anomalies over the Mediterranean.

2.) A strong +NAO that cooled the Canary Current and helped to stabilize the basin, kill any waves that made it out of the tangled ITCZ, etc.

After this season, I won’t be surprised if we see agencies/pro mets tweak how they assess and forecast upcoming hurricane seasons. Some of the factors that shut down this season were caught on the models beforehand but not realized to be negative factors (-MSLP anomalies over the Mediterranean, potentially northerly ITCZ, etc), while others that weren’t caught until later (like the +NAO) probably wouldn’t have been thought of as severely negative factors if correctly modeled in advance. Therefore, I think we may see indicators like these be given more weight in future seasonal forecasts. They were enough to almost completely shut down the basin despite textbook examples of the indicators we usually focus on: first year -ENSO, +AMO (at least until the +NAO began to kick in), record warm SSTs, favorable precip anomalies, favorable shear forecasts, active analog years, etc.

Still some time to go, but my take away this season is, over-emphasis on SSTA and ENSO does not always work. Background warming, has changed how interpreting these indicators influence the overall global patterns. But in the end, you're talking months and months advance forecasting which one simply can't rely on other than an educated guess.

[REDHurricane]

 https://x.com/webberweather/status/1835172468308242652




Another reason I suspect this year's "busted" Atlantic Hurricane Season forecasts were forced largely by "internal" variability from the extratropics rather than say a poleward shift in the Africa ITCZ (tho that played a role too!):

When I go back and look at climate model forecasts for this Hurricane Season, what really strikes me is they correctly predicted the potential for very (& possibly record) low SLP over NE Africa & Mediterranean, which ultimately helped drag the ITCZ anomalously northward over the Sahel & Sahara.

What about the record low SLP over Greenland/Iceland associated w/ the +NAO? It was grossly underestimated to put it lightly w/ only a slightly higher chance for lower tercile SLP.

Oops.

So based on everything I’ve been reading from this forum and the mets on Twitter (including this very good thread), it seems like there’s decent consensus that the factors that led to this season’s unexpected under-performance are:

1.) The northerly displaced and hyperactive AEJ/ITCZ/African monsoon, which tangled up AEWs and tossed them over less favorable waters. Enhanced by the significant -MSLP anomalies over the Mediterranean.

2.) A strong +NAO that cooled the Canary Current and helped to stabilize the basin, kill any waves that made it out of the tangled ITCZ, etc.

After this season, I won’t be surprised if we see agencies/pro mets tweak how they assess and forecast upcoming hurricane seasons. Some of the factors that shut down this season were caught on the models beforehand but not realized to be negative factors (-MSLP anomalies over the Mediterranean, potentially northerly ITCZ, etc), while others that weren’t caught until later (like the +NAO) probably wouldn’t have been thought of as severely negative factors if correctly modeled in advance. Therefore, I think we may see indicators like these be given more weight in future seasonal forecasts. They were enough to almost completely shut down the basin despite textbook examples of the indicators we usually focus on: first year -ENSO, +AMO (at least until the +NAO began to kick in), record warm SSTs, favorable precip anomalies, favorable shear forecasts, active analog years, etc.

I agree with your analysis except for the part where you talk about this season in past tense like it's already mid-November or something -- yeah, it's looking less and less likely that this season will reach hyperactive status as September goes by without any major hurricanes in the picture, but it'd be naive to think there's zero chance that October/early November blow up with several MHs and get up to 175 ACE or whatever the usual threshold is for hyperactivity. There's still a long way to go.

[Hammy]

 https://x.com/webberweather/status/1835172468308242652




Another reason I suspect this year's "busted" Atlantic Hurricane Season forecasts were forced largely by "internal" variability from the extratropics rather than say a poleward shift in the Africa ITCZ (tho that played a role too!):

When I go back and look at climate model forecasts for this Hurricane Season, what really strikes me is they correctly predicted the potential for very (& possibly record) low SLP over NE Africa & Mediterranean, which ultimately helped drag the ITCZ anomalously northward over the Sahel & Sahara.

What about the record low SLP over Greenland/Iceland associated w/ the +NAO? It was grossly underestimated to put it lightly w/ only a slightly higher chance for lower tercile SLP.

Oops.

So based on everything I’ve been reading from this forum and the mets on Twitter (including this very good thread), it seems like there’s decent consensus that the factors that led to this season’s unexpected under-performance are:

1.) The northerly displaced and hyperactive AEJ/ITCZ/African monsoon, which tangled up AEWs and tossed them over less favorable waters. Enhanced by the significant -MSLP anomalies over the Mediterranean.

2.) A strong +NAO that cooled the Canary Current and helped to stabilize the basin, kill any waves that made it out of the tangled ITCZ, etc.

After this season, I won’t be surprised if we see agencies/pro mets tweak how they assess and forecast upcoming hurricane seasons. Some of the factors that shut down this season were caught on the models beforehand but not realized to be negative factors (-MSLP anomalies over the Mediterranean, potentially northerly ITCZ, etc), while others that weren’t caught until later (like the +NAO) probably wouldn’t have been thought of as severely negative factors if correctly modeled in advance. Therefore, I think we may see indicators like these be given more weight in future seasonal forecasts. They were enough to almost completely shut down the basin despite textbook examples of the indicators we usually focus on: first year -ENSO, +AMO (at least until the +NAO began to kick in), record warm SSTs, favorable precip anomalies, favorable shear forecasts, active analog years, etc.

I agree with your analysis except for the part where you talk about this season in past tense like it's already mid-November or something -- yeah, it's looking less and less likely that this season will reach hyperactive status as September goes by without any major hurricanes in the picture, but it'd be naive to think there's zero chance that October/early November blow up with several MHs and get up to 175 ACE or whatever the usual threshold is for hyperactivity. There's still a long way to go.

We're almost 100 ACE below the hyperactive threshold, most of these Caribbean/Gulf majors that we get are about 15-20 ACE so it would take four of those AND a long-tracker to reach that point. The chances are pretty close to zero of reaching that, and even a Wilma-type storm would only put us at 100.

[Category5Kaiju]

So based on everything I’ve been reading from this forum and the mets on Twitter (including this very good thread), it seems like there’s decent consensus that the factors that led to this season’s unexpected under-performance are:

1.) The northerly displaced and hyperactive AEJ/ITCZ/African monsoon, which tangled up AEWs and tossed them over less favorable waters. Enhanced by the significant -MSLP anomalies over the Mediterranean.

2.) A strong +NAO that cooled the Canary Current and helped to stabilize the basin, kill any waves that made it out of the tangled ITCZ, etc.

After this season, I won’t be surprised if we see agencies/pro mets tweak how they assess and forecast upcoming hurricane seasons. Some of the factors that shut down this season were caught on the models beforehand but not realized to be negative factors (-MSLP anomalies over the Mediterranean, potentially northerly ITCZ, etc), while others that weren’t caught until later (like the +NAO) probably wouldn’t have been thought of as severely negative factors if correctly modeled in advance. Therefore, I think we may see indicators like these be given more weight in future seasonal forecasts. They were enough to almost completely shut down the basin despite textbook examples of the indicators we usually focus on: first year -ENSO, +AMO (at least until the +NAO began to kick in), record warm SSTs, favorable precip anomalies, favorable shear forecasts, active analog years, etc.

I agree with your analysis except for the part where you talk about this season in past tense like it's already mid-November or something -- yeah, it's looking less and less likely that this season will reach hyperactive status as September goes by without any major hurricanes in the picture, but it'd be naive to think there's zero chance that October/early November blow up with several MHs and get up to 175 ACE or whatever the usual threshold is for hyperactivity. There's still a long way to go.

We're almost 100 ACE below the hyperactive threshold, most of these Caribbean/Gulf majors that we get are about 15-20 ACE so it would take four of those AND a long-tracker to reach that point. The chances are pretty close to zero of reaching that, and even a Wilma-type storm would only put us at 100.

While I do agree that reaching hyperactivity at this point would require a phenomenal burst of activity between now and November's end (which, in the grand scheme of things, may not be very likely), I also wouldn't necessarily discount the possibility of a late-season, powerful, slow-moving system that also generates a lot of ACE as a result. Some notable examples of such include 1932's Cuba Hurricane (which produced 60 ACE, leaving 1932 with 110 total ACE had that storm not happened), 1998's Mitch (which produced 33 ACE, leaving 1998 with 147 total ACE had that storm not happened), and 2016's Matthew (which produced 50 ACE, leaving 2016 with 90 total ACE had that storm not happened). Interestingly enough, these storms notably also happened during first-year La Nina seasons.

It remains to be seen what 2024 has in store, but sometimes, a single storm can indeed make the difference between an above average season and an average/below average season and a hyperactive season and an above average season, at least ACE-wise.

[Teban54]

I agree with your analysis except for the part where you talk about this season in past tense like it's already mid-November or something -- yeah, it's looking less and less likely that this season will reach hyperactive status as September goes by without any major hurricanes in the picture, but it'd be naive to think there's zero chance that October/early November blow up with several MHs and get up to 175 ACE or whatever the usual threshold is for hyperactivity. There's still a long way to go.

We're almost 100 ACE below the hyperactive threshold, most of these Caribbean/Gulf majors that we get are about 15-20 ACE so it would take four of those AND a long-tracker to reach that point. The chances are pretty close to zero of reaching that, and even a Wilma-type storm would only put us at 100.

While I do agree that reaching hyperactivity at this point would require a phenomenal burst of activity between now and November's end (which, in the grand scheme of things, may not be very likely), I also wouldn't necessarily discount the possibility of a late-season, powerful, slow-moving system that also generates a lot of ACE as a result. Some notable examples of such include 1932's Cuba Hurricane (which produced 60 ACE, leaving 1932 with 110 total ACE had that storm not happened), 1998's Mitch (which produced 33 ACE, leaving 1998 with 147 total ACE had that storm not happened), and 2016's Matthew (which produced 50 ACE, leaving 2016 with 90 total ACE had that storm not happened). Interestingly enough, these storms notably also happened during first-year La Nina seasons.

It remains to be seen what 2024 has in store, but sometimes, a single storm can indeed make the difference between an above average season and an average/below average season and a hyperactive season and an above average season, at least ACE-wise.

I do think the likelihood of such a late-season monster is still substantial (or at least higher than average). That said, it takes a lot of randomness for a late-season 40+ ACE storm to happen. In addition to the obvious precondition that the Caribbean needs to be favorable for activity, the system needs to be slow-moving and remain strong while doing so, but it also needs to move north at some point instead of crashing into Central America like Eta and Iota. This requires a combination of the right steering conditions.

2020 is a good counterexample to this. Despite insane late-season activity with 7/6/5 in October and November, most of the intense storms bombed out too close to land and were too brief to contribute a lot of ACE. IIRC, each of 2020's late-season majors only contributed 15-20 ACE at most, and the season basically brute-forced its way to hyperactive ACE by the sheer number of them. (Yes, they were collectively more impactful than a single high-ACE storm, but that just shows a flaw of ACE.)

Whether another Matthew happens is probably just a coin flip at this point. However, note that 2022 did have 5 named storms and 4 Cat 1 hurricanes in October and November, 2 of which were classic west-moving Caribbean hurricanes that developed from waves, and the season probably would have had more if not for a random Pacific MJO during most of October. I think waves will still be able to get into the Caribbean, at the very least.

[MetroMike]

Many posters here were saying after Beryl and the following storm drought that this year would favor quality over quantity. Now it seems we will have neither.

[Spacecoast]

We are just past halftime, and the score is:
Season24: 61.0
Climatology: 69.6
Most other indicators are also below normal, except # of Hurricanes.

To be clear, these indicators are backward-looking, and are not predictive of activity remainder of season. They weren't predictive last July, or August, and they are not predictive now. However, a 'season from hell' ACE of 240 seems unlikely to happen at this point.

[Teban54]

https://i.ibb.co/JpqX7RQ/natl.jpg
https://i.ibb.co/x6vS57h/natla.jpg

We are just past halftime, and the score is:
Season24: 61.0
Climatology: 69.6
Most other indicators are also below normal, except # of Hurricanes.

To be clear, these indicators are backward-looking, and are not predictive of activity remainder of season. They weren't predictive last July, or August, and they are not predictive now. However, a 'season from hell' ACE of 240 seems unlikely to happen at this point.

When we said in mid-August that the Atlantic can afford to have no ACE until mid-September and still be above average, I'm sure very few of us expected that to actually happen.

[REDHurricane]

We're almost 100 ACE below the hyperactive threshold, most of these Caribbean/Gulf majors that we get are about 15-20 ACE so it would take four of those AND a long-tracker to reach that point. The chances are pretty close to zero of reaching that, and even a Wilma-type storm would only put us at 100.

While I do agree that reaching hyperactivity at this point would require a phenomenal burst of activity between now and November's end (which, in the grand scheme of things, may not be very likely), I also wouldn't necessarily discount the possibility of a late-season, powerful, slow-moving system that also generates a lot of ACE as a result. Some notable examples of such include 1932's Cuba Hurricane (which produced 60 ACE, leaving 1932 with 110 total ACE had that storm not happened), 1998's Mitch (which produced 33 ACE, leaving 1998 with 147 total ACE had that storm not happened), and 2016's Matthew (which produced 50 ACE, leaving 2016 with 90 total ACE had that storm not happened). Interestingly enough, these storms notably also happened during first-year La Nina seasons.

It remains to be seen what 2024 has in store, but sometimes, a single storm can indeed make the difference between an above average season and an average/below average season and a hyperactive season and an above average season, at least ACE-wise.

I do think the likelihood of such a late-season monster is still substantial (or at least higher than average). That said, it takes a lot of randomness for a late-season 40+ ACE storm to happen. In addition to the obvious precondition that the Caribbean needs to be favorable for activity, the system needs to be slow-moving and remain strong while doing so, but it also needs to move north at some point instead of crashing into Central America like Eta and Iota. This requires a combination of the right steering conditions.

2020 is a good counterexample to this. Despite insane late-season activity with 7/6/5 in October and November, most of the intense storms bombed out too close to land and were too brief to contribute a lot of ACE. IIRC, each of 2020's late-season majors only contributed 15-20 ACE at most, and the season basically brute-forced its way to hyperactive ACE by the sheer number of them. (Yes, they were collectively more impactful than a single high-ACE storm, but that just shows a flaw of ACE.)

Whether another Matthew happens is probably just a coin flip at this point. However, note that 2022 did have 5 named storms and 4 Cat 1 hurricanes in October and November, 2 of which were classic west-moving Caribbean hurricanes that developed from waves, and the season probably would have had more if not for a random Pacific MJO during most of October. I think waves will still be able to get into the Caribbean, at the very least.

Good point about ACE not necessarily correlating with overall impacts -- even if ACE doesn't technically reach the hyperactive threshold, I don't think anyone would be calling the season a "bust" in the case that we see a 2020-like October/November, so that's another thing to consider as well. But just from an ACE perspective, if the following occurs:

Atlantic to date: 61 ACE, plus...
- Late September Ian-like Caribbean/Gulf MH like some recent model runs have indicated (~15 ACE)
- Early October Sam-like MDR long tracker (~45 ACE)
- Early/mid-October Matthew-like (but less powerful) Caribbean MH (~25 ACE)
- Mid/late October Delta-like Caribbean/Gulf MH (~15 ACE)
- Any other TS/weaker hurricanes that form throughout October/November (~15 ACE combined)
- TOTAL: ~175 ACE

Does this seem likely based on what we currently know? Of course not. But is this scenario completely out of the question given the still anomalously high SSTs throughout the western MDR/Caribbean/Gulf, developing La Niña conditions, and general weirdness of this season? Also no. It's important to remember that very improbable ≠ impossible -- let's say there's only a 10-20% chance something like this happens; it's still likely enough that calling the season a "huge bust" already (on September 15) is premature at best and irresponsible at worst. There's still 7-8 weeks left of potential tropical activity in the Atlantic basin, and that's more than enough time (as we saw only 4 years ago) for an unexpected/unprecedented burst of hurricanes to take place; that's all I'm saying.

[MarioProtVI]

One thing I have noticed recently: every single season since 2005 that’s had an expected ACE forecast by experts of roughly 180-230 ACE has underperformed in some way. 2005 was the sole expectation since it was basically a season in its own ranking, as forecasts in early August called for over 200 ACE (and rightfully so at the time after the freaks of Dennis and Emily the previous month), and the season went well above that (even TSR had predicted 249 and 2005 finished a whole point higher!).

- 2007: while I cannot find explicit ACE forecasts, early predictions called for roughly 17 / 9 / 5, which likely would’ve ended up being around ~175-185 ACE. Season ended up basically pulling a 2013 before 2013 or as we now know a 2024 with a probable THC collapse and monsoonal mess in the Caribbean late season and had only C1s and TSs outside of Dean and Felix. ACE total was 74, which was 100 or so off probably.
- 2010: Early predictions had forecasts of around 180 ACE which is very close to 200, and I’m pretty sure in internal discussions that number may have been thrown around given how extremely favorable the base state looked around late spring. While still ending up hyperactive, it only did so just barely ACE wise at only 165 ACE with 19-12-5, around 20-25 ACE off. It’s been said that some dry air around peak season (probably the later half of July to mid August? but probably referring to September) capped 2010 from being even more active like 2005. Prime example of this was Gaston which despite initial model projections and NHC forecasts to become a long track CV hurricane, it died almost immediately after forming because of very dry air. Had Gaston and some other storms later on like Matthew or the Caribbean Cat 2s been slightly stronger, and especially Tomas if its original forecasts of a major verified before it fell apart in the SE Caribbean, 2010 would’ve likely made it over 200 ACE.
- 2013: don’t even need to explain this one with its 36 ACE lol.
- 2020: Forecasts by June/July/early August began calling for over 200 ACE. While we did reach hyperactive status at 180 ACE, that was only after half of it came from a record breaking late season that came after September pretty much flopped ACE wise (for the record, September ended with us at something like 21-7-2 but only ~80-90 ACE) - mainly because of the TUTT from the recurving typhoons. If it weren’t for that, 2020 would’ve likely beaten out 2005 in all metrics sans ACE but probably come very close, since Paulette, Teddy and Rene likely would’ve been stronger and longer lived CV hurricanes (majors in Paulette and maybe even Rene’s case) and kicked up a lot of ACE - if the waves for some of them came off just a bit further south then they actually did.
- 2022: Early season forecasts had around 180 ACE, but then the entire months of July (Bonnie and Colin were at the very start but nothing came after) and August shut down across the basin because of SSTA and wavebreaking issues and only came back very slow through mid-September before making a marked recovery after that but it was too late, and only finished with 95 ACE which was half of what was expected.

It remains to be seen how much 2024’s forecasts are off by, but one thing is for certain is we are likely not seeing any hyperactive forecasts (even in favorable years) for the foreseeable future based on possible losses of funding similar to 2013’s backlash. Perhaps for their sake we hope it’s not that bad of a bust, but we’re in the dark here at this point.

[Teban54]

It remains to be seen how much 2024’s forecasts are off by, but one thing is for certain is we are likely not seeing any hyperactive forecasts (even in favorable years) for the foreseeable future based on possible losses of funding similar to 2013’s backlash. Perhaps for their sake we hope it’s not that bad of a bust, but we’re in the dark here at this point.

Honestly, if we're heading towards a future where every agency constantly predicts near-average or slightly above-average numbers -- either due to fear of losing funding or being called a "bust", or because seasons like 2022 and 2024 made them too scared about underestimating effects of indicators that we don't understand well, while overestimating effects of indicators that we do understand "well" (e.g. SSTAs, ENSO) -- that sounds not only dull, but more importantly, wildly unscientific and not beneficial for enhancing human knowledge of hurricane seasons in the long term.

When a surprise like 2024 happens, the most important task should be to study it, understand it, and apply it to the future so that we can predict more seasons (including hyperactive ones) with greater confidence. It shouldn't be to run away from it for fear or repercussions.

Edit to add: Think of it this way -- if we take it as granted that seasons with forecasted hyperactivity often end up busting, on the flip side, seasons that actually ended with top-tier ACE and/or impacts were rarely forecasted accurately in advance, either. Of the top 10 ACE seasons, 5 occurred in the era with professional forecasts:

• 1995: CSU August forecast 16/9/3, actual 19/11/5 227.1 ACE
• 1998: CSU August forecast 10/6/2, actual 14/10/3 181.8 ACE
• 2004: CSU August forecast 13/7/3, actual 15/9/6 226.9 ACE
• 2005: CSU August forecast 20/10/6, actual 28/15/7 245.3 ACE
• 2017: CSU August forecast 16/8/3 135 ACE, actual 17/10/6 224.9 ACE

Every single year outperformed CSU forecasts in all of NS, H and MH -- every single year, every single metric. For every single one of these seasons, CSU "missed" at least 2 NS, 2 H and 1 MH. The average misses were 3.6 NS, 3 H and 2 MH. And in the only such year after CSU started forecasting ACE, the ACE forecast ended too low by a whopping 90 (quite plausibly the same amount that 2024's ACE forecast would miss the mark by, but in the opposite direction).

It should be obvious that there's great value in being able to predict such 180+ ACE or 200+ ACE seasons in advance when they actually occur. Just because we haven't been successful at doing that (with false positives and false negatives in both directions) doesn't mean we should stop trying, or that seasonal forecasters should be discouraged from trying.