2023 Indicators (SST, SAL, MSLP, Wind shear, Steering, Instability) and Day 16+ Models

[weeniepatrol]

What happened to the West African standing wave, though?

It was neutral-ish until about mid month then became very favorable. Assuming things continue progress, sinking air will return.

So why is rising air over West Africa not present this year, unlike 2018, 2019, 2020, 2021, and 2022? 2018 and 2019 were +ENSO years, yet they both had a West African standing wave.

This year is a moderate to strong classical/east-Pacific based el Nino; 2018 was much weaker (less amplitude) and modoki/central-Pacific based (-VP anomalies were displaced relative to the canonical el Nino response unlike this year). Additionally 2019 was only warm neutral.

[canebeard]

Looks like some long, swayback dachshund dog about to jump in the ocean to me. How far west can he swim with those tiny legs? Anyone else see this?

[WalterWhite]

Despite the ongoing strong El Niño, the CFSv2 is showing a favorable background state for Atlantic tropical cyclogenesis in October and November. Rising air over West Africa is favorable for Atlantic development.





The JMA is also indicating the same velocity potential pattern.





These models also, for some reason, seem to be indicating a more favorable background state for November than for October. If that is true, this could possibly be a late-ending hurricane season.

[WalterWhite]

So nature is telling me that third-year La Niñas are less favorable for Atlantic activity than strong El Niños?

I see it in pretty simple terms. Pattern changes are more favorable than stagnant patterns. I don't see this year as being unusual because I see everything in terms of odds. Flip to el nino, pattern change +%. Very good conditions in the Atlantic except for el nino, and right now el nino shear has not been as bad as typically expected (neutral to slightly negative).

I think we've become a little too addicted to SOMETHING OUTRAGEOUS IS HAPPENING.

Is there a specific reason as to why you think pattern change years are more favorable?

[WalterWhite]

The models seem to be suggesting:
- Invest 95L developing into Lee, which could become a major hurricane around September 6
- A tropical wave behind that developing into Margot, which will probably be another 50-knot tropical storm around September 8
After this is the realm of fantasyland.

[cycloneye]

#5 for 2023 season.

 https://twitter.com/philklotzbach/status/1698450266582925327

[Teban54]

#5 for 2023 season.

https://twitter.com/philklotzbach/status/1698450266582925327

Notice how 2020 isn't in that list. This means that even though it might feel like this season has too many short-lived slop storms, in reality the storms are reasonably long-lived as seen from the named storm days.

[Category5Kaiju]

The models seem to be suggesting:
- Invest 95L developing into Lee, which could become a major hurricane around September 6
- A tropical wave behind that developing into Margot, which will probably be another 50-knot tropical storm around September 8
After this is the realm of fantasyland.

It's basically not out of the realm of possibilities that this season achieves 14 nameable storms by mid-month or perhaps sooner, which would officially meet the "average" climatological NS count.

[Hurricane2022]

 https://twitter.com/DerekOrtt/status/1698495758557680052

[jconsor]

Need to be careful. The 1968-1996 shear climo is likely significantly higher for the Caribbean than 1991-2020. If we were to compare Aug 2023 Caribbean shear to 1991-2020, would probably come out just slightly below normal.

Caribbean shear was actually BELOW average in August, despite the El Nino.
https://i.imgur.com/JdNHgEq.png

When you average out June-August as a whole, it comes out near to slightly below average.
https://i.imgur.com/rwS5kCb.gif

So far, the model forecasts showing unusually low shear for an El Nino are verifying, which definitely is a factor for why this season has been so active despite El Nino conditions. Both the CFS and CanSIPS are predicting below average shear in the Caribbean/MDR for October and November, so it really makes me question if we'll see a standard Nino early shutdown this year. We've already seen 3 TCs form in or enter the Caribbean Sea this year, when some El Ninos have practically no Caribbean activity at all.

[WalterWhite]

Need to be careful. The 1968-1996 shear climo is likely significantly higher for the Caribbean than 1991-2020. If we were to compare Aug 2023 Caribbean shear to 1991-2020, would probably come out just slightly below normal.

Caribbean shear was actually BELOW average in August, despite the El Nino.
https://i.imgur.com/JdNHgEq.png

When you average out June-August as a whole, it comes out near to slightly below average.
https://i.imgur.com/rwS5kCb.gif

So far, the model forecasts showing unusually low shear for an El Nino are verifying, which definitely is a factor for why this season has been so active despite El Nino conditions. Both the CFS and CanSIPS are predicting below average shear in the Caribbean/MDR for October and November, so it really makes me question if we'll see a standard Nino early shutdown this year. We've already seen 3 TCs form in or enter the Caribbean Sea this year, when some El Ninos have practically no Caribbean activity at all.

That is still unusual for a Strong El Niño year, though. (Yes, I am saying this winter is going to have a Strong El Niño.)

[zzzh]

https://twitter.com/DerekOrtt/status/1698495758557680052?t=yJj2mae0c_M37-hQnBl8HQ&s=19

Not very uncommon. It happened in 1997 and 2009.

[Ianswfl]

https://twitter.com/DerekOrtt/status/1698495758557680052?t=yJj2mae0c_M37-hQnBl8HQ&s=19

Makes you wonder if the gulf is still near 80 if we have a late nov or early dec ts into Florida if shear is low. Remember kate 1985.

[cycloneye]

 https://twitter.com/philklotzbach/status/1698757692230340632

[weeniepatrol]

#lolnino

[LarryWx]

Whereas the amount of activity to this point has been well above the average for a moderate+ Nino, the steering/tracks seem to have been pretty El Niñoish. Other opinions?

[weeniepatrol]

Whereas the amount of activity to this point has been well above the average for a moderate+ Nino, the steering/tracks seem to have been pretty El Niñoish. Other opinions?

Definitely agree there! Subtropics just north of the MDR seems especially favored this year (and this is where guidance shows 95L doing most of its deepening and then peaking), as well as recurvature - both seem consistent with the El Nino

[LarryWx]

Whereas the amount of activity to this point has been well above the average for a moderate+ Nino, the steering/tracks seem to have been pretty El Niñoish. Other opinions?

Definitely agree there! Subtropics just north of the MDR seems especially favored this year (and this is where guidance shows 95L doing most of its deepening and then peaking), as well as recurvature - both seem consistent with the El Nino

As I understand it, steering is based on the wind flow at 500 mb and below whereas shear is produced largely way up at 200 mb or so. So, is it possible that El Niño is behaving closer to normal lower in the atmosphere but not higher up? If so, does that make sense and why would that be?

[SconnieCane]

Whereas the amount of activity to this point has been well above the average for a moderate+ Nino, the steering/tracks seem to have been pretty El Niñoish. Other opinions?

Definitely agree there! Subtropics just north of the MDR seems especially favored this year (and this is where guidance shows 95L doing most of its deepening and then peaking), as well as recurvature - both seem consistent with the El Nino

It's often been said here and on other forums that it was La Nina that strongly favored Eastern troughing and recurves, usually citing 2010 as a classic example.

[weeniepatrol]

Whereas the amount of activity to this point has been well above the average for a moderate+ Nino, the steering/tracks seem to have been pretty El Niñoish. Other opinions?

Definitely agree there! Subtropics just north of the MDR seems especially favored this year (and this is where guidance shows 95L doing most of its deepening and then peaking), as well as recurvature - both seem consistent with the El Nino

As I understand it, steering is based on the wind flow at 500 mb and below whereas shear is produced largely way up at 200 mb or so. So, is it possible that El Niño is behaving closer to normal lower in the atmosphere but not higher up? If so, does that make sense and why would that be?

Not sure about your question, but steering is dependent on a storms' vertical depth (largely correlated to intensity) - a shallow, weak tropical cyclone will not feel 500mb steering nearly as much as it does surface and low level flow. Shear is largely produced by 200mb winds but can occur at any layer - we have seen prolific easterly shear from strong 20+kt surface trades in light / otherwise conducive upper level flow and prohibitive shear at the mid-levels around 500mb, for example.