2024 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

[MarioProtVI]

CFS shows the opposite of this sentiment with at least 5-6 MDR storms through September 15..

Yes, indeed. A completely different picture...
https://i.ibb.co/18NHd2G/cfsa.jpg

It looks like mainly TD's / TS's, enseble members (out of 40) with one or two strengthening Cat1 near upper latitudes. It's hard to tell how many members show development.
I must admit that I am not familiar with CFSv2.
I found this from the latest run. It seems to forecast 3.7/3.8 storms over the next 30 days, unless I am misinterpreting:

Storm Count Forecast

RAW NUMBERS

PERIOD START END ATL ENP WNP NI SI AUS SP
-----------------------------------------------------------
Week 1 20240821 20240827 0.6 2.2 0.3 1.4 0.0 0.0 0.0
Week 2 20240828 20240903 1.2 3.1 0.4 1.1 0.1 0.0 0.0
Week 3 20240904 20240910 1.9 3.0 0.4 0.4 0.2 0.2 0.1
Week 4 20240911 20240917 2.5 3.0 1.1 0.9 0.3 0.1 0.1
Week 5 20240918 20240924 1.4 1.2 0.9 0.9 0.2 0.0 0.0
Week 6 20240925 20241001 0.0 0.0 0.0 0.0 0.0 0.0 0.0

30 Day 20240821 20240919 3.8 6.1 1.9 2.5 0.3 0.2 0.1


BIAS CORRECTED

PERIOD START END ATL ENP WNP NI SI AUS SP
-----------------------------------------------------------
Week 1 20240821 20240827 0.2 2.0 0.4 1.0 0.0 0.0 0.0
Week 2 20240828 20240903 1.1 2.3 0.5 0.5 0.0 0.0 0.0
Week 3 20240904 20240910 1.4 1.7 0.3 0.0 0.0 0.1 0.0
Week 4 20240911 20240917 2.0 2.3 0.9 0.0 0.0 0.0 0.0
Week 5 20240918 20240924 1.2 0.9 0.7 0.0 0.0 0.0 0.0
Week 6 20240925 20241001 0.0 0.0 0.0 0.0 0.0 0.0 0.0

30 Day 20240821 20240919 3.7 5.7 2.4 0.2 0.0 0.0 0.0

The CFS seems to undershoot intensity, probably because it’s a large-scale, low-res model. Basically if you’re seeing a solid TS on it, it could easily be a hurricane in reality. Like in the top plot where you can see Hurricane Gilma and none of the spaghetti tracks show even a C1.

Those MDR storms in weeks 2-4, if they verify, could easily be long-tracking hurricanes. Perhaps even at least one major. I’m not a fan of how close they get to the East Coast in week 3. While not gospel, the CFS sometimes can be shockingly accurate in its predictions, like with Isaias in 2020.

The one on the latest run (8/21 00z) that forms 8/31 (and is probably what ensembles - GEFS moreso and EPS at times - are occasionally sniffing out) and takes a Lee type track deepens to about 992 in the MDR and then near 985 as it moves northwards. On that res, that’s most likely a major, and you could probably subtract about 30-45 mb on average for a long tracking storm in the tropics.

[tolakram]

Looks like I need to remind people that if you include a post from twitter that violates S2K policy you own it and will be issued a warning or a ban depending on the offense. THINK before you post.

[toad strangler]

While the Tropics Rest, the Atlantic Heats Up ... Michael Lowry UPDATE

The Gulf of Mexico is nearing its seasonal temperature peak while warmth across the tropical Atlantic is trailing only 2023 and 2010
Michael Lowry
Aug 22

We all know how important warm waters are to hurricanes. The heat of the ocean is the power source of hurricanes and water temperature across the tropical Atlantic is the single biggest predictor of how active the hurricane season will be, especially by August when they explain a whopping 66% of the year-to-year difference in seasonal hurricane activity. Of course, in any given week or on any given day, other variables will help determine when or where we see big, strong hurricanes. As we discussed earlier this week, for last week or two of August, the other players will be benched, which means the hurricane season will be without key supporting characters.

Once the other players return to the field, however, they’ll find their star performer ready for primetime. The Gulf of Mexico is nearing its annual sea surface temperature zenith, and the warmth it’s experiencing is far above the normal range and running second only to the unprecedented warmth of 2023.

Not only is the Gulf blistering warm at the surface, the heat extends down hundreds of feet. Waters as warm as 85 degrees Fahrenheit have been recorded at depths of 160 feet or more according to instruments peppering the Gulf of Mexico designed to profile the subsurface.




Credit: Brian McNoldy/University of Miami


Ocean temperature profiles from floats across the Gulf of Mexico via the Argo research program. Notice how some floats show water temperatures above 29 degrees Celsius (84.2 degrees Fahrenheit) extending to a depth of nearly 70 meters (230 feet). Credit: Dr. Kim Wood/University of Arizona
With temperatures as warm and deep as they are, the ocean heat content over the Gulf of Mexico – a measurement describing the amount of heat energy stored in the ocean – hasn’t been as high as it is today since we began tracking it in 2013.
In fact, the eastern MDR doesn’t hit its seasonal temperature peak until later in September but continues to ride above the warmth of waters during hyperactive years like 2005. So far, its only trailing 2023’s unprecedented warmth and for now 2010, though that may be eclipsed soon.

So once the other players return to the field in the next few weeks, their clean-up hitter will be juiced. Stay vigilant because once the Atlantic picks up again, it will be ready for primetime action.


© 2024 Michael Lowry

[kevin]

For archival purposes, doesn't get much crazier than this in the GOM. Also, 3 days ago the average temperature of the North Atlantic reached 25C for only the second time since 1981. The only other time was last year, which peaked at a record value of 25.4C on August 31.

[Hammy]

Convergence/wind shift line (top line) and the lower edge of the ITCZ (bottom line) have both moved several degrees south over the last three days which is notable

[WiscoWx02]

For archival purposes, doesn't get much crazier than this in the GOM. Also, 3 days ago the average temperature of the North Atlantic reached 25C for only the second time since 1981. The only other time was last year, which peaked at a record value of 25.4C on August 31.

https://i.imgur.com/lR5nL23.png

It's fascinating that we can calculate maximum strength of what a tropical cyclone can do just based on water temperature...I'm sure it's a long and lengthy calculation involving more rates of change and integrals than I even want to think about but cool nontheless!

[Category5Kaiju]

For archival purposes, doesn't get much crazier than this in the GOM. Also, 3 days ago the average temperature of the North Atlantic reached 25C for only the second time since 1981. The only other time was last year, which peaked at a record value of 25.4C on August 31.

https://i.imgur.com/lR5nL23.png

Yikes…..kind of unnerving to think that assuming the upper level conditions cooperate, we could theoretically get a Patricia-like storm there. Thankfully that isn’t very likely, but at the same time….you never know.

[LarryWx]

Euro weeklies mean ACE forecast update vs norm last 7 days (newest far right, which is 0Z of Wed):

8/26-9/1: 50%/50%/50%/30%/20%/20%/10%; Norm 14
9/2-8: 120%/100%/110%/70%/70%/60%/60%; norm 15
9/9-15: 90%/80%/100%/80%/90%/80%/80%; norm 16
9/16-22: 90%/80%/90%: norm 13

So, in today’s Euro Weeklies update regarding these 4 weeks, the progged ACE mean is 35, which is the same as yesterday’s run had. This is significantly below the 1991-2020 avg of 58. Over 80% of this deficit is due to weeks 1-2.

[NDG]

 https://x.com/NDGMETCHEF/status/1826721691323806019

[NDG]

For archival purposes, doesn't get much crazier than this in the GOM. Also, 3 days ago the average temperature of the North Atlantic reached 25C for only the second time since 1981. The only other time was last year, which peaked at a record value of 25.4C on August 31.

https://i.imgur.com/lR5nL23.png

We put too much stock on the OHC, is a crappy measure if the atmosphere is not cooperating.
Gilma is on its way to Cat 4 over zero OHC EPAC waters.

[aspen]

 https://x.com/NDGMETCHEF/status/1826721691323806019

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

[xpost] https://x.com/AndyHazelton/status/1826704821891879165[/xpost]

[Hammy]

 https://x.com/NDGMETCHEF/status/1826721691323806019

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

[xpost] https://x.com/AndyHazelton/status/1826704821891879165[/xpost]

One thing this has in common with 2022 is the high latitude and strength of the monsoon trough, so I can't help wonder if that's helping suck it down into the tropics

[MarioProtVI]

 https://x.com/NDGMETCHEF/status/1826721691323806019

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

[xpost] https://x.com/AndyHazelton/status/1826704821891879165[/xpost]

Something about Saskatchewan blocking? But also think the monsoon trough position / AEJ is also causing it.

[Ubuntwo]

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

One thing this has in common with 2022 is the high latitude and strength of the monsoon trough, so I can't help wonder if that's helping suck it down into the tropics

Agreed. In a bit of a feedback loop, it seems like some high-latitude heat lows are dragging dry air along in their inflow.

[Hammy]

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

One thing this has in common with 2022 is the high latitude and strength of the monsoon trough, so I can't help wonder if that's helping suck it down into the tropics

Agreed. In a bit of a feedback loop, it seems like some high-latitude heat lows are dragging dry air along in their inflow.

Double checked the models and the mid-level dry air actually seems like it's both moistening as it moved west, but also (seen on the second image) being blocked by the waves, so most of what's impacting the waves themselves does appear to be coming from the Sahara

[tolakram]

I don't think we know anything yet. I'm not trying to be disrespectful here but every time there's an unexpected development the reasoning starts to pop up. If it was that easy forecasting would also be easy.

I've never thought we would hit the numbers, but I don't think the season is dead. Maybe, just maybe, we should stop looking for excuses and just admit predicting an outlier season is a really bad idea? Someone quote this, just in case we end up with a record breaker.

[Ubuntwo]

I don't think we know anything yet. I'm not trying to be disrespectful here but every time there's an unexpected development the reasoning starts to pop up. If it was that easy forecasting would also be easy.

I've never thought we would hit the numbers, but I don't think the season is dead. Maybe, just maybe, we should stop looking for excuses and just admit predicting an outlier season is a really bad idea? Someone quote this, just in case we end up with a record breaker.

It's natural to try and explain short-term synoptic changes, especially the unexpected ones. I disagree with the sentiment that 'If it was that easy forecasting would also be easy'. Explaining the present is inherently easier than predicting the future.

This discussion is also relevant to the question 'why are conditions unfavorable right now'. It doesn't have to be tied into whatever the seasonal forecast #'s were. Nobody is saying these conditions will persist two weeks from now, or a month from now, or till the end of the season. It's a matter of scratching the itch of curiosity.

[Teban54]

 https://x.com/NDGMETCHEF/status/1826721691323806019

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

[xpost] https://x.com/AndyHazelton/status/1826704821891879165[/xpost]

I think we need to first ask whether 2024 is a 2022 redux before thinking about why. In particular:

• Are the dust patterns of the two years actually similar? Specifically, is 2024 as anomalously dry as 2022 in the first place, and is the distribution and spread of dry air similar to 2022? Or is "it seems dry" the only thing in common?
• The most common hypothesis about 2022 is excessive wave breaking. Is that actually happening in 2024? I recall someone saying 2024's patterns earlier this year (possibly just 1-2 weeks ago) was the opposite of a wavebreaking-heavy one.
• There's already a plausible hypothesis for 2024: the ITCZ was too far north, and the AEJ was too strong. Were these also happening in 2022? Is there evidence to suggest there's some other factor limiting activity, even if both start improving as per climo?

Some of the answers may be yes, but some could also jolly well be no. From what I can recall on top of my head:

• 2022's ITCZ position in Africa was near average, at least for August 1-10;
• 2022 had below average (or at most near average) shear in the eastern MDR associated with the AEJ;
• 2024's relative humidity at some mid-levels was actually near or below average.

(I'm on mobile now so I can't check my prior analysis, even though I've looked at each of them recently. Therefore, I can't guarantee all of thm are correct.)

Ultimately, just because two years both seem dry on August 22 doesn't mean the underlying causes are the same. By that argument, you could have compared every such year to 2013. And I don't think "Andy said so" is sufficient, either -- even more so because the last time he said this about 10 days ago, someone on Storm2K posted a detailed analysis that showed 2024's patterns were the complete opposite of 2022.

If the environment is still the same as today on September 14, the date when Fiona formed, then it's time to revisit the question. But I think right now is too early to think there's some inexplicable inhibiting factor that could only be compared to 2013 or 2022, when much simpler explanations exist.

[aspen]

 https://x.com/NDGMETCHEF/status/1826721691323806019

Andy’s saying the dry air pattern is similar to 2022. The big question is: why? What did we miss about 2024 that led to this 2022-like dry air pattern?

[xpost] https://x.com/AndyHazelton/status/1826704821891879165[/xpost]

Ultimately, just because two years both seem dry on August 22 doesn't mean the underlying causes are the same. By that argument, you could have compared every such year to 2013. And I don't think "Andy said so" is sufficient, either -- even more so because the last time he said this about 10 days ago, someone on Storm2K posted a detailed analysis that showed 2024's patterns were the complete opposite of 2022.

I remember someone posted his pre-Dorian tweet where he thought we’d go the rest of August 2019 without a single NA formation. So yeah he doesn’t always nail his assessments, but I found his comparison of the dry air in the eastern MDR in 2022 and 2024 interesting.

And yeah we’re not seeing the same wave-breaking as 2022. As far as we can tell at this point, most issues with 2024’s muted TCG and delayed switch-flip are due to the overactive AEJ/monsoon. But this is another instance of a negative factor that wasn’t picked up during the pre-season indicators timeframe, even though there may have been hints towards the strength of the AEJ in the spring model runs. And the delayed switch in combination with the factors destroying most waves does give off an implication that we may be missing something else. There’s always at least a few curveballs in forecasting a hurricane season; this seems to be a particularly challenging and confusing year.

Also it’s still kind of funny how 2022 has basically become 2013 2.0.

[Ubuntwo]

I think we need to first ask whether 2024 is a 2022 redux before thinking about why. In particular:

• Are the dust patterns of the two years actually similar? Specifically, is 2024 as anomalously dry as 2022 in the first place, and is the distribution and spread of dry air similar to 2022? Or is "it seems dry" the only thing in common?
• The most common hypothesis about 2022 is excessive wave breaking. Is that actually happening in 2024? I recall someone saying 2024's patterns earlier this year (possibly just 1-2 weeks ago) was the opposite of a wavebreaking-heavy one.
• There's already a plausible hypothesis for 2024: the ITCZ was too far north, and the AEJ was too strong. Were these also happening in 2022? Is there evidence to suggest there's some other factor limiting activity, even if both start improving as per climo?

Some of the answers may be yes, but some could also jolly well be no. From what I can recall on top of my head:

• 2022's ITCZ position in Africa was near average, at least for August 1-10;
• 2022 had below average (or at most near average) shear in the eastern MDR associated with the AEJ;
• 2024's relative humidity at some mid-levels was actually near or below average.

(I'm on mobile now so I can't check my prior analysis, even though I've looked at each of them recently. Therefore, I can't guarantee all of thm are correct.)

Ultimately, just because two years both seem dry on August 22 doesn't mean the underlying causes are the same. By that argument, you could have compared every such year to 2013. And I don't think "Andy said so" is sufficient, either -- even more so because the last time he said this about 10 days ago, someone on Storm2K posted a detailed analysis that showed 2024's patterns were the complete opposite of 2022.

If the environment is still the same as today on September 14, the date when Fiona formed, then it's time to revisit the question. But I think right now is too early to think there's some inexplicable inhibiting factor that could only be compared to 2013 or 2022, when much simpler explanations exist.

You raise a good point. I had the same question and your post pushed me to check. 2022's August zonal wind anomalies were the opposite of 2024's in the eastern MDR - 2022 had moderate positive zonal wind anomalies whereas 2024 has intense negative anomalies (associated with the AEJ). One similarity was a strong monsoon trough, and like Hammy has mentioned, waves also struggled to break away and become discrete entities. This was earlier in the month for 2022 though.