Why is the 2024 Atlantic hurricane season underperforming expectations?

[LarryWx]

What about the current very active sunspots and a possible lag to consider as possibly one of the main factors keeping things quiet recently? Aug of 2024 had a 216, the highest mean sunspots in Aug since 1991. That means that this Aug had the highest mean for Aug of the current active era so far.

https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

Per met. Joe D’Aleo:
“We have mentioned the strong solar spike which research has shown can suppress hurricane activity.”

“One negative may be the big spike in solar in cycle 25. Most cycles have had a dual max and recent ones had the second one higher. This warms the upper atmosphere and hampers development.”

Is there any papers that discuss any potential connection between solar activity and hurricane seasons? I've seen a few people mention this as a possibility but it seems like most mets believe there is no connection. I am personally skeptical but would be interesting to hear an argument that supports it.

D’Aleo seems to know of something. Regardless, I decided to look at the data, myself:

Here are the 13 ATL seasons since 1851 with 180+ ACE along with ASO averaged monthly sunspots:

1878: 5 (solar min)

1887: 20 (quiet)

1893: 160 (solar max)

1926: 110 (1.5 yrs before max)

1933: 5 (min)

1950: 95 (halfway from max to min)

1961: 75 (halfway from max to min)

1995: 20 (nearing min)

1998: 110 (2 years after min)

2004: 65 (3 years after max)

2005: 35 (quiet/3 years before min)

2017: 30 (quiet/2 years before min)

2020: 10 (just after min)

So, of the 13 180+ ACE seasons, 7 had low sunspots, 3 had near avg, and 3 had above avg. though only one of those 3 had well above avg (1893) like 2024. And 2024 has an excellent shot at exceeding the 160 of 1893 since Aug was 215. It could end up near 200 for all we know now. I’d say 175+ is pretty safe. Only 1 in 9 seasons have had 175+ ASO sunspots.

The avg monthly of these 13 seasons’ ASO sunspots was only ~55, which is well under the 1900-2022 avg of ~85 for all months. So, this at least suggests the possibility that very high ACE seasons really do prefer a not so overly active sun unlike what we have now.

Also consider this: Whereas none of the 15 non-El Nino seasons with 175+ ASO sunspots had 150+ ACE, five of the 13 non-El Nino (38%) 10- sunspot seasons had 150+ ACE.

That may mean it is going to be difficult for 2024 or a typical future year with ASO sunspots >175 to get to 175+ ACE (or maybe even just 150+ ACE) despite other very favorable factors like La Niña and near record warm Atlantic MDR SSTs.

Thus I think the research that D’Aleo mentioned about the tendency for a strong solar spike to hamper hurricane activity via a lowering of instability due to warming of the upper atmosphere should be investigated further as quite possibly being one of the main reasons for the recent quiet. I read elsewhere about the upper atmosphere being quite warm.

Solar data: https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

ACE: https://en.m.wikipedia.org/wiki/Accumul ... one_energy

@chaser1

[Teban54]

What about the current very active sunspots and a possible lag to consider as possibly one of the main factors keeping things quiet recently? Aug of 2024 had a 216, the highest mean sunspots in Aug since 1991. That means that this Aug had the highest mean for Aug of the current active era so far.

https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

Per met. Joe D’Aleo:
“We have mentioned the strong solar spike which research has shown can suppress hurricane activity.”

“One negative may be the big spike in solar in cycle 25. Most cycles have had a dual max and recent ones had the second one higher. This warms the upper atmosphere and hampers development.”

Is there any papers that discuss any potential connection between solar activity and hurricane seasons? I've seen a few people mention this as a possibility but it seems like most mets believe there is no connection. I am personally skeptical but would be interesting to hear an argument that supports it.

D’Aleo seems to know of something. Regardless, I decided to look at the data, myself:

Here are the 13 ATL seasons since 1851 with 180+ ACE along with ASO averaged monthly sunspots:

1878: 5 (solar min)

1887: 20 (quiet)

1893: 160 (solar max)

1926: 110 (1.5 yrs before max)

1933: 5 (min)

1950: 95 (halfway from max to min)

1961: 75 (halfway from max to min)

1995: 20 (nearing min)

1998: 110 (2 years after min)

2004: 65 (3 years after max)

2005: 35 (quiet/3 years before min)

2017: 30 (quiet/2 years before min)

2020: 10 (just after min)

So, of the 13 180+ ACE seasons, 7 had low sunspots, 3 had near avg, and 3 had above avg. though only one of those 3 had well above avg (1893) like 2024. And 2024 has an excellent shot at exceeding the 160 of 1893 since Aug was 215. It could end up near 200 for all we know now. I’d say 175+ is pretty safe. Only 1 in 9 seasons have had 175+ ASO sunspots.

The avg monthly of these 13 seasons’ ASO sunspots was only ~55, which is well under the 1900-2022 avg of ~85 for all months. So, this at least suggests the possibility that very high ACE seasons really do prefer a not so overly active Sun unlike what we have now.

Also consider this: Whereas none of the 15 non-El Nino seasons with 175+ ASO sunspots had 150+ ACE, five of the 13 non-El Nino (38%) 10- sunspot seasons had 150+ ACE.

That may mean it is going to be difficult for 2024 or a typical future year with ASO sunspots >175 to get to 175+ ACE (or maybe even just 150+ ACE) despite other very favorable factors like La Niña and near record warm Atlantic MDR SSTs.

Thus I think the research that D’Aleo mentioned about the tendency for a strong solar spike to hamper hurricane activity via a lowering of instability due to warming of the upper atmosphere should be investigated further as quite possibly being one of the main reasons for the recent quiet. I read elsewhere about the upper atmosphere being quite warm.

Solar data: https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

ACE: https://en.m.wikipedia.org/wiki/Accumul ... one_energy

@chaser1

You might be onto something. Here's a visual of sun spots over the years:


The three peaks during the current +AMO era (which I arbitrarily defined as smoothed monthly sunspot numbers >=80) are:

• May 1998 - Jan 2004
  
  • Contains 2000-2002, a notable 3-year period that had near- or below-average ACE sandwiched between a hell lot of years with hyperactive ACE.
  • 2000 in particular underperformed expectations, although third-year La Nina could have also contributed to it.
• Jul 2011 - Mar 2015
  
  • Contains 2013 and 2014, lol. Also 2015 is close. These years literally made people think the +AMO era was over.
  • 2012 didn't really bust per se (above-average ACE for a "failed" El Nino year), but that year also had a bit of struggle producing major hurricanes despite a large number of Cat 1/2s.
• Jun 2022 - Now
  
  • Contains 2022, lol.

The major exceptions from this list are 1998, 1999, 2003, 2023, and arguably 2011. (If you think any effects of sunspots can be lagging in terms of being reflected in Atlantic activity, then 2004 also counts.) All but two of these years had hyperactive ACE (>=158), albeit just borderline. 2023 and 2011 were also still above-average.

Quickly looking through some earlier years, 1926, 1950 and 1969 also stood out as exceptions with hyperactive ACE despite large sunspot numbers (two of which you've mentioned). 1926 and 1969 was particularly notable for being peak or near-peak sunspot years, with magnitude similar to the 2012-14 period.

[Teban54]

I made this scatter plot of seasonal ACE and sunspot numbers during ASO, using the data from Larry above:

https://postimages.org/

(Years with labels were largely selected arbitrarily, as long as they're on or near the convex hull and can be displayed with reasonable aesthetics.)

When looking at all years, the correlation is very weak. But one interesting observation is that the "convex hull" (or, broadly speaking, the maximum ACE year with any given sunspot number) is clearly trending downwards.

If you take this at face value -- which I'm not necessarily suggesting should be done -- the conclusion would be that having elevated solar activity during ASO (in terms of sunspot numbers) would limit the ceiling of Atlantic ACE.

(Edit: Replaced the chart to add colored ACE boxes.)

[aspen]

Is there any papers that discuss any potential connection between solar activity and hurricane seasons? I've seen a few people mention this as a possibility but it seems like most mets believe there is no connection. I am personally skeptical but would be interesting to hear an argument that supports it.

D’Aleo seems to know of something. Regardless, I decided to look at the data, myself:

Here are the 13 ATL seasons since 1851 with 180+ ACE along with ASO averaged monthly sunspots:

1878: 5 (solar min)

1887: 20 (quiet)

1893: 160 (solar max)

1926: 110 (1.5 yrs before max)

1933: 5 (min)

1950: 95 (halfway from max to min)

1961: 75 (halfway from max to min)

1995: 20 (nearing min)

1998: 110 (2 years after min)

2004: 65 (3 years after max)

2005: 35 (quiet/3 years before min)

2017: 30 (quiet/2 years before min)

2020: 10 (just after min)

So, of the 13 180+ ACE seasons, 7 had low sunspots, 3 had near avg, and 3 had above avg. though only one of those 3 had well above avg (1893) like 2024. And 2024 has an excellent shot at exceeding the 160 of 1893 since Aug was 215. It could end up near 200 for all we know now. I’d say 175+ is pretty safe. Only 1 in 9 seasons have had 175+ ASO sunspots.

The avg monthly of these 13 seasons’ ASO sunspots was only ~55, which is well under the 1900-2022 avg of ~85 for all months. So, this at least suggests the possibility that very high ACE seasons really do prefer a not so overly active Sun unlike what we have now.

Also consider this: Whereas none of the 15 non-El Nino seasons with 175+ ASO sunspots had 150+ ACE, five of the 13 non-El Nino (38%) 10- sunspot seasons had 150+ ACE.

That may mean it is going to be difficult for 2024 or a typical future year with ASO sunspots >175 to get to 175+ ACE (or maybe even just 150+ ACE) despite other very favorable factors like La Niña and near record warm Atlantic MDR SSTs.

Thus I think the research that D’Aleo mentioned about the tendency for a strong solar spike to hamper hurricane activity via a lowering of instability due to warming of the upper atmosphere should be investigated further as quite possibly being one of the main reasons for the recent quiet. I read elsewhere about the upper atmosphere being quite warm.

Solar data: https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

ACE: https://en.m.wikipedia.org/wiki/Accumul ... one_energy

@chaser1

You might be onto something. Here's a visual of sun spots over the years:
https://i.postimg.cc/Y2sgFjt6/image.png

The three peaks during the current +AMO era (which I arbitrarily defined as smoothed monthly sunspot numbers >=80) are:

• May 1998 - Jan 2004
  
  • Contains 2000-2002, a notable 3-year period that had near- or below-average ACE sandwiched between a hell lot of years with hyperactive ACE.
  • 2000 in particular underperformed expectations, although third-year La Nina could have also contributed to it.
• Jul 2011 - Mar 2015
  
  • Contains 2013 and 2014, lol. Also 2015 is close. These years literally made people think the +AMO era was over.
  • 2012 didn't really bust per se (above-average ACE for a "failed" El Nino year), but that year also had a bit of struggle producing major hurricanes despite a large number of Cat 1/2s.
• Jun 2022 - Now
  
  • Contains 2022, lol.

The major exceptions from this list are 1998, 1999, 2003, 2023, and arguably 2011. (If you think any effects of sunspots can be lagging in terms of being reflected in Atlantic activity, then 2004 also counts.) All but two of these years had hyperactive ACE (>=158), albeit just borderline. 2023 and 2011 were also still above-average.

Quickly looking through some earlier years, 1926, 1950 and 1969 also stood out as exceptions with hyperactive ACE despite large sunspot numbers (two of which you've mentioned). 1926 and 1969 was particularly notable for being peak or near-peak sunspot years, with magnitude similar to the 2012-14 period.

Very interesting possible correlation. If high levels of solar activity do serve to hamper TCG, then no wonder why we’re seeing such an uncharacteristic shutdown this season. 2024’s solar activity has been insane. It’s not every year you get a solar storm strong enough to produce auroras in Mexico, on top of the numerous other pretty solid aurora-producing geomagnetic storms and the highest number of sunspots in ~20 years.

However, solar activity can’t be the sole cause of this shutdown, because if so, we should’ve seen similar underperformances during the early 2000s. Probably solar activity combined with the early July NAO flip, cooling Greenland waters/Canary Current, and hyperactive/northerly-displaced AEJ is behind 2024’s collapse. A freak alignment of factors that either nobody saw coming, or were known ahead of time but not recognized as activity-hampering.

[Hammy]

I made this scatter plot of seasonal ACE and sunspot numbers during ASO, using the data from Larry above:

[url]https://i.postimg.cc/qB1H0h8d/Sunspots-vs-ACE.png [/url]https://postimages.org/

(Years with labels were largely selected arbitrarily, as long as they're on or near the convex hull and can be displayed with reasonable aesthetics.)

When looking at all years, the correlation is very weak. But one interesting observation is that the "convex hull" (or, broadly speaking, the maximum ACE year with any given sunspot number) is clearly trending downwards.

If you take this at face value -- which I'm not necessarily suggesting should be done -- the conclusion would be that having elevated solar activity during ASO (in terms of sunspot numbers) would limit the ceiling of Atlantic ACE.

(Edit: Replaced the chart to add colored ACE boxes.)

What really stands out is that most of those years with high sunspots had significant lull periods:

2000 had practically nothing, save for a short-lived tropical storm, between August 24 and September 11 (and nothing before August)
2001 had nothing in July followed by an underperforming August, and limited activity before September 8
1989 had only two storms develop in September--while one of those was Hugo, that's still not a lot--and fairly little for the middle half of August
1979 had nothing from late July until August 25
1981 likewise had nothing in July, Dennis at the start of August, and then nothing else formed from Aug 7-30
1991 had only had six storm days in August (where Bob formed) and then nothing at all for the latter two thirds of September

[Ptarmigan]

There are so many factors why Atlantic has quiet despite warm tropical waters. They range from cooler waters in Equatorial Atlantic, ITCZ location, monsoon, and Sunspots. The ITCZ is further than usual. I believe they all play a role.

[LarryWx]

D’Aleo seems to know of something. Regardless, I decided to look at the data, myself:

Here are the 13 ATL seasons since 1851 with 180+ ACE along with ASO averaged monthly sunspots:

1878: 5 (solar min)

1887: 20 (quiet)

1893: 160 (solar max)

1926: 110 (1.5 yrs before max)

1933: 5 (min)

1950: 95 (halfway from max to min)

1961: 75 (halfway from max to min)

1995: 20 (nearing min)

1998: 110 (2 years after min)

2004: 65 (3 years after max)

2005: 35 (quiet/3 years before min)

2017: 30 (quiet/2 years before min)

2020: 10 (just after min)

So, of the 13 180+ ACE seasons, 7 had low sunspots, 3 had near avg, and 3 had above avg. though only one of those 3 had well above avg (1893) like 2024. And 2024 has an excellent shot at exceeding the 160 of 1893 since Aug was 215. It could end up near 200 for all we know now. I’d say 175+ is pretty safe. Only 1 in 9 seasons have had 175+ ASO sunspots.

The avg monthly of these 13 seasons’ ASO sunspots was only ~55, which is well under the 1900-2022 avg of ~85 for all months. So, this at least suggests the possibility that very high ACE seasons really do prefer a not so overly active Sun unlike what we have now.

Also consider this: Whereas none of the 15 non-El Nino seasons with 175+ ASO sunspots had 150+ ACE, five of the 13 non-El Nino (38%) 10- sunspot seasons had 150+ ACE.

That may mean it is going to be difficult for 2024 or a typical future year with ASO sunspots >175 to get to 175+ ACE (or maybe even just 150+ ACE) despite other very favorable factors like La Niña and near record warm Atlantic MDR SSTs.

Thus I think the research that D’Aleo mentioned about the tendency for a strong solar spike to hamper hurricane activity via a lowering of instability due to warming of the upper atmosphere should be investigated further as quite possibly being one of the main reasons for the recent quiet. I read elsewhere about the upper atmosphere being quite warm.

Solar data: https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

ACE: https://en.m.wikipedia.org/wiki/Accumul ... one_energy

@chaser1

You might be onto something. Here's a visual of sun spots over the years:
https://i.postimg.cc/Y2sgFjt6/image.png

The three peaks during the current +AMO era (which I arbitrarily defined as smoothed monthly sunspot numbers >=80) are:

• May 1998 - Jan 2004
  
  • Contains 2000-2002, a notable 3-year period that had near- or below-average ACE sandwiched between a hell lot of years with hyperactive ACE.
  • 2000 in particular underperformed expectations, although third-year La Nina could have also contributed to it.
• Jul 2011 - Mar 2015
  
  • Contains 2013 and 2014, lol. Also 2015 is close. These years literally made people think the +AMO era was over.
  • 2012 didn't really bust per se (above-average ACE for a "failed" El Nino year), but that year also had a bit of struggle producing major hurricanes despite a large number of Cat 1/2s.
• Jun 2022 - Now
  
  • Contains 2022, lol.

The major exceptions from this list are 1998, 1999, 2003, 2023, and arguably 2011. (If you think any effects of sunspots can be lagging in terms of being reflected in Atlantic activity, then 2004 also counts.) All but two of these years had hyperactive ACE (>=158), albeit just borderline. 2023 and 2011 were also still above-average.

Quickly looking through some earlier years, 1926, 1950 and 1969 also stood out as exceptions with hyperactive ACE despite large sunspot numbers (two of which you've mentioned). 1926 and 1969 was particularly notable for being peak or near-peak sunspot years, with magnitude similar to the 2012-14 period.

Very interesting possible correlation. If high levels of solar activity do serve to hamper TCG, then no wonder why we’re seeing such an uncharacteristic shutdown this season. 2024’s solar activity has been insane. It’s not every year you get a solar storm strong enough to produce auroras in Mexico, on top of the numerous other pretty solid aurora-producing geomagnetic storms and the highest number of sunspots in ~20 years.

However, solar activity can’t be the sole cause of this shutdown, because if so, we should’ve seen similar underperformances during the early 2000s. Probably solar activity combined with the early July NAO flip, cooling Greenland waters/Canary Current, and hyperactive/northerly-displaced AEJ is behind 2024’s collapse. A freak alignment of factors that either nobody saw coming, or were known ahead of time but not recognized as activity-hampering.

Teban, awesome graph!! Yeah, I can see that the safest conclusion from this data/graph is that the implied ceiling appears to drop as sunspots rise.

What I’d like to know is how much warmer has the upper atmosphere been actually observed to be when solar is high vs when it is low. I’m assuming this has been verified/measured. I’m aware that the ground is only very minimally affected. For there to be increased stability, the upper atmosphere has to warm more than the very minimal rise at the surface. Anyone know?

One more general item: is there a lag?

Also, shouldn’t this increase in stability with higher solar also affect other basins at least to some extent? If so, does it appear that the implied ACE ceiling inversely correlates to sunspots in other basins, too?

aspen, Regarding 2000-2002:
-2000’s ASO solar was quite active but at 160 is somewhat below where I think 2024 is headed (175-200) fwiw. Also, though 2000’s ACE was fairly active at 119, that was ~60 lower than the two prior seasons as Teban alluded to.

-2001’s ACE was ~70 lower than 1998-9.

-2002 only had 68 ACE. However, to be fair, I’d throw this out because it was already a moderate Nino by ASO. The quiet ACE that year could have been caused primarily by that.

[chaser1]

"Also, shouldn’t this increase in stability with higher solar also affect other basins at least to some extent? If so, does it appear that the implied ACE ceiling inversely correlates to sunspots in other basins, too?"

I was thinking about the same a bit earlier this evening. Solar radiance and any suggested influence such as radiative forcing should theoretically impact all of Earth's upper atmosphere therefore creating a somewhat equal detriment to all oceanic basins. Going further down the rabbit hole, there appears to be something referred to as "Arctic Amplification" which causes faster near surface temperatures in the Northern Hemisphere. I was approaching the concept of solar induced upper atmosphere warming as an upper "capping" akin to increased subsidence (sinking air). However now, I'm reading implications of top down heating impact reaching or nearly reaching the surface. Oh lord..... I can't believe that I am saying this but - can't we PLEASE just have a 12 hr. subtropical low spin up? My head is starting to hurt.

[tolakram]

Calle me a solar skeptic. The sun isn't real ... wait, that's not what I meant.

Just a month or so ago the solar activity was going to be part of the cause of increased activity. Sure, it should be looked into, but for reference look at 2005:

During the first half of September 2005, a period of increased solar activity occurred that rivaled the number and magnitude of flares produced during the “Halloween” storm in October-November of 2003.Sep 17, 2005

That was a huge storm, and I don't think it had any effect on the season.

[LarryWx]

Calle me a solar skeptic. The sun isn't real ... wait, that's not what I meant.

Just a month or so ago the solar activity was going to be part of the cause of increased activity. Sure, it should be looked into, but for reference look at 2005:

During the first half of September 2005, a period of increased solar activity occurred that rivaled the number and magnitude of flares produced during the “Halloween” storm in October-November of 2003.Sep 17, 2005

That was a huge storm, and I don't think it had any effect on the season.

Thanks tolakram for your reply. Despite this period of activity in the 1st half of 9/05, the month still had mean sunspots of only 37 vs the longterm avg (1900-2022) of ~85. So, that month was actually well below avg and thus is considered a relatively quiet month in that regard. That’s the way that I graded each season, the ASO monthly mean sunspot number (see link below).

Regarding ASO of 2005 mean sunspots overall: ~35 (37 to be more exact). This ASO of 37 is not even half the longterm avg of ~85 and thus makes 2005 pretty quiet relatively speaking:

2005 08 2005.623 60.5 5.3 706
2005 09 2005.707 37.2 4.5 691
2005 10 2005.790 13.2 3.4 534

In stark contrast, Aug of 2024 had a whopping ~215, ~6 times as high!

2024 08 2024.624 215.5

And 2003 ASO averaged ~95 (slightly above longterm avg of 85).

https://www.sidc.be/SILSO/DATA/SN_m_tot_V2.0.txt

[WeatherBoy2000]

Calle me a solar skeptic. The sun isn't real ... wait, that's not what I meant.

Just a month or so ago the solar activity was going to be part of the cause of increased activity. Sure, it should be looked into, but for reference look at 2005:

During the first half of September 2005, a period of increased solar activity occurred that rivaled the number and magnitude of flares produced during the “Halloween” storm in October-November of 2003.Sep 17, 2005

That was a huge storm, and I don't think it had any effect on the season.

I agree, I've never seen a met talk about solar activity and TC formation tbh. As stated above the correlation is weak and hyperactive seasons are rare enough in the historical record that it could all be down to coincidence still. There are plenty of meteorological/climatological factors that have been brought up to explain this lack of activity that sound much more plausible imo.

[Hypercane_Kyle]

I don't think solar maximum has much to do with it, and I think any perceived correlation is coincidental. Years like 1999 were close to solar maximum, and the 70s-80s were incredibly quiet compared to modern times.

I think the actual cause is AGW creating less of a need for warm air to reach northern latitudes; but in the same breath creating hotter, deeper temperatures close to land for storms like Otis, Dorian, Michael, and Ian to unexpectedly become monsters. Less ACE, more "garbage bin" quality storms, but the ones that do crank up become much more intense, much more quickly. AGW impacts on hurricane seasons aren't fully understood, so that would also explain such a major miss in seasonal forecasts.

[Teban54]

I think the actual cause is AGW creating less of a need for warm air to reach northern latitudes; but in the same breath creating hotter, deeper temperatures close to land for storms like Otis, Dorian, Michael, and Ian to unexpectedly become monsters. Less ACE, more "garbage bin" quality storms, but the ones that do crank up become much more intense, much more quickly.

On the other hand, some people used the same idea as the bolded part to predict a quiet ATL 2023 just before peak season.

[Hypercane_Kyle]

I think the actual cause is AGW creating less of a need for warm air to reach northern latitudes; but in the same breath creating hotter, deeper temperatures close to land for storms like Otis, Dorian, Michael, and Ian to unexpectedly become monsters. Less ACE, more "garbage bin" quality storms, but the ones that do crank up become much more intense, much more quickly.

On the other hand, some people used the same idea as the bolded part to predict a quiet ATL 2023 just before peak season.

2023 was literally a classic example of what I'm talking about. 20 named storms, only 3 major hurricanes. Idalia was an example of an compact, rapidly intensifying storm close to land (fortunately it weakened and hit a relatively unpopulated area of FL). Lee was the only true Cape Verde hurricane that season, albeit a noteworthy one.

[LarryWx]

Calle me a solar skeptic. The sun isn't real ... wait, that's not what I meant.

Just a month or so ago the solar activity was going to be part of the cause of increased activity. Sure, it should be looked into, but for reference look at 2005:

During the first half of September 2005, a period of increased solar activity occurred that rivaled the number and magnitude of flares produced during the “Halloween” storm in October-November of 2003.Sep 17, 2005

That was a huge storm, and I don't think it had any effect on the season.

I agree, I've never seen a met talk about solar activity and TC formation tbh. As stated above the correlation is weak and hyperactive seasons are rare enough in the historical record that it could all be down to coincidence still. There are plenty of meteorological/climatological factors that have been brought up to explain this lack of activity that sound much more plausible imo.

The met. Joe D’Aleo (aka “Dr. Dewpoint” from years ago) recently talked about it and is the sole reason I brought up the idea of a potential solar connection in the 1st place:

“We have mentioned the strong solar spike which research has shown can suppress hurricane activity.”

“One negative may be the big spike in solar in cycle 25. Most cycles have had a dual max and recent ones had the second one higher. This warms the upper atmosphere and hampers development.”

Otherwise, I still would have never heard of it. Is it all coincidence or not? That’s the big question. Wxman57 just posted a chart showing the tropical ATL instability at only April levels! If anything, Teban’s chart shows that very high solar MAY tend to limit the ceiling and thus make it more difficult to have a hyper season.

[TomballEd]

Is the lowered stability, the upper atmosphere warming with the oceans or even more than the oceans, a new part of the warming climate? I'd guess not, I wouldn't think the change would be this drastic.

IRI ENSO plots would seem to suggest a neutral to weakly warm ENSO next year, not unfavorable to development. If heat wasn't removed from the oceans by TCs as much as normal this year, and the stability issue isn't directly (and permanently) ties to climate, will 2025 be the 20+ storm year that 2024 was predicted to be?

[tolakram]

Calle me a solar skeptic. The sun isn't real ... wait, that's not what I meant.

Just a month or so ago the solar activity was going to be part of the cause of increased activity. Sure, it should be looked into, but for reference look at 2005:

During the first half of September 2005, a period of increased solar activity occurred that rivaled the number and magnitude of flares produced during the “Halloween” storm in October-November of 2003.Sep 17, 2005

That was a huge storm, and I don't think it had any effect on the season.

I agree, I've never seen a met talk about solar activity and TC formation tbh. As stated above the correlation is weak and hyperactive seasons are rare enough in the historical record that it could all be down to coincidence still. There are plenty of meteorological/climatological factors that have been brought up to explain this lack of activity that sound much more plausible imo.

The met. Joe D’Aleo (aka “Dr. Dewpoint” from years ago) recently talked about it and is the sole reason I brought up the idea of a potential solar connection in the 1st place:

“We have mentioned the strong solar spike which research has shown can suppress hurricane activity.”

“One negative may be the big spike in solar in cycle 25. Most cycles have had a dual max and recent ones had the second one higher. This warms the upper atmosphere and hampers development.”

Otherwise, I still would have never heard of it. Is it all coincidence or not? That’s the big question. Wxman57 just posted a chart showing the tropical ATL instability at only April levels! If anything, Teban’s chart shows that very high solar MAY tend to limit the ceiling and thus make it more difficult to have a hyper season.

But solar activity does not effect us unless it's aimed right towards us. We had the huge flare and Aurora display earlier in the year, and 2005 had a big storms as well, aimed at us. I feel like some of this solar talk is not really understanding the significance of the types of activity and storms experienced here on earth. But it's certainly worthy of research and proving some of those assumptions. Our magnetic field protects us from most of the energy, otherwise we'd be very dead.

https://www.climate.gov/news-features/c ... to%20space.

This is on the topic of heat waves, but there are hints that upper atmosphere warning needs more investigation. My question, though, is why would upper atmosphere warming influence tropical waves which are in the lower atmosphere?

[LarryWx]

I agree, I've never seen a met talk about solar activity and TC formation tbh. As stated above the correlation is weak and hyperactive seasons are rare enough in the historical record that it could all be down to coincidence still. There are plenty of meteorological/climatological factors that have been brought up to explain this lack of activity that sound much more plausible imo.

The met. Joe D’Aleo (aka “Dr. Dewpoint” from years ago) recently talked about it and is the sole reason I brought up the idea of a potential solar connection in the 1st place:

“We have mentioned the strong solar spike which research has shown can suppress hurricane activity.”

“One negative may be the big spike in solar in cycle 25. Most cycles have had a dual max and recent ones had the second one higher. This warms the upper atmosphere and hampers development.”

Otherwise, I still would have never heard of it. Is it all coincidence or not? That’s the big question. Wxman57 just posted a chart showing the tropical ATL instability at only April levels! If anything, Teban’s chart shows that very high solar MAY tend to limit the ceiling and thus make it more difficult to have a hyper season.

But solar activity does not effect us unless it's aimed right towards us. We had the huge flare and Aurora display earlier in the year, and 2005 had a big storms as well, aimed at us. I feel like some of this solar talk is not really understanding the significance of the types of activity and storms experienced here on earth. But it's certainly worthy of research and proving some of those assumptions. Our magnetic field protects us from most of the energy, otherwise we'd be very dead.

https://www.climate.gov/news-features/c ... to%20space.

This is on the topic of heat waves, but there are hints that upper atmosphere warning needs more investigation. My question, though, is why would upper atmosphere warming influence tropical waves which are in the lower atmosphere?

I follow you, tolakram. Joe’s theory is based on average sunspot levels, not individual solar storms/flares. Where he read about this I have no idea. He didn’t cite a paper. He may have even been part of the research team on this for all I know. I was just passing it along because he just said these things and due to the continued mysteries about the recent quiet and the various theories that continue to be suggested.

My guess is that with upper atmospheric warming reducing instability of the overall atmosphere, convection being generated by AEWs is not going to be as generous or persistent.

[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.

[Teban54]

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.

In addition, the number of storm formations this season has been legitimately unimpressive: thus far, the NATL has only seen 5 named storms, which is actually below the 1991-2020 average of 6.6. The NATL has also fallen slightly below average in named storm days, and is likely to fall even further below average in the coming days. The NATL has fallen behind below-average seasons like 2013 and 2015 in named storms, and is likely to fall behind 2006 in just 2 days. It's still so baffling: you would think with an early July Category 5 in the deep tropics, well below average shear, and well above average tropical Atlantic SSTs, 2024 would be a slam dunk for a hyperactive season but it just hasn't been so far. The Atlantic hasn't even gone through the entire rotation of invest numbers yet!

I think it goes to show that dry air is more of a killer than shear. Shear could be literally nothing but if it's dry as bone then nothing will form.

Data from August 20-29 shows the basin wasn't nearly as anomalously dry as every comment here is suggesting, though. Can someone please explain the discrepancy or point out what I was doing wrong here, before we take "dry air killing the basin" as a given? I'm genuinely lost, because it feels increasingly like the charts below go against everything else I've seen.

https://i.postimg.cc/d0FJqTxJ/ezgif-com-animated-gif-maker-2.gif

The tweet below from Eric Webb attempts to give an answer to the question. He thinks that boundary layer moisture (at 850 mb) is low, "making it difficult for convection to fire at all", and he thinks "-SSTa over the Canary Current" is a contributing factor if not the cause.

 https://x.com/webberweather/status/1830243258556879026




Yet, I still find a caveat to this explanation that makes things even muddier. His graphic was July 1 to August 29. If we zoom into August 1-31, you can still see a line of dry air from Portugal and Canary Islands down to tropical Atlantic, which he described as "dry air import from off NW Africa".

BUT... If you select August 20-31 (you know, the period when no genesis is actually highly anomalous and Ernesto had already moved out of the picture, unlike early August), suddenly 850 mb doesn't look that dry, either!





Now, to be fair, that may have to do with wave patterns during the specific time periods. It turns out that the Aug 20-25 period is wet in the entire eastern Atlantic, whereas Aug 26-31 has a dry tongue right in the MDR. Yet, that should have implied the area closer to Lesser Antilles was still very wet, but that doesn't match anecdotal evidence -- I'm sure many people were frustrated (from an activity perspective only) that the Caribbean wave didn't get organized enough while just north of South America. (Though 925 mb just offshore South America was dry during both the entire August and Aug 26-31, which may have been the real culprit.)

Comparing this to other years also gives conclusions that are at least somewhat inconsistent with this explanation:

• 2022: Despite people saying 2022 also had significant dry air problems (even using SSTA patterns to justify them), August 2022, especially late August, was generally pretty moist in the MDR at 850 mb. A notable dry line can be seen in the subtropics between Spain and Lesser Antilles, but that's much further west and much more extensive than 2024's.
  
  • The real dryness in 2022 came from 925 mb, where most of the basin was dry in August and continued into September. However, that's not the case for 2024, at least in the eastern half of MDR.
• 2013: The entire basin was dry at 850 mb during late August, which was almost comical. (Various parts of the basin moistened up at various other times of that year and at other levels, but the MDR largely remained dry.) That's about the polar opposite of 2024's 850 mb charts above.
• 2017: Can you believe the entire basin was dry at 850 mb in both August and September of that year? Not just that, but during September -- the month with the highest ACE on record -- 925 mb was also dry across the entire basin, and so was 700 mb in eastern MDR.

(I also can't really buy his argument about -SSTA offshore Africa as well, especially when he was literally bringing up 2013 on that very point. While the 2013's JAS SSTAs may seem a little bit more comparable as visualized in the previous link, August 2013's SSTAs are polar opposites of August 2024's in every sense, other than warmth in western MDR.)

Once again, this explanation left me more questions than answers. The one single way I can think of to reconcile the difference is that dry air started in the boundary layer (or even higher) around NW Africa, and gradually sank while moving SW towards South America. Even then, every level of the atmosphere seems wetter than average holistically speaking.