2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

[aspen]

What’s up with that persistent stream of -SST anomalies coming from the ABC islands? It’s been there for weeks, and in SST maps from 2020 that have been posted, it is either very weak or non-existent.

https://i.postimg.cc/Gp75NCYC/ssta-tropatl.png

It appears in the CDAS maps but especially in the CRW maps.

[Category5Kaiju]

Notice the below-average wind shear in the Caribbean Sea and the Gulf of Mexico
https://i.postimg.cc/85CVJ4d1/cansips-ashear-Mean-month-atl-1.png
It is nothing but wishful thinking to assume the Caribbean Sea and/or the Gulf of Mexico will be hostile for tropical development.

Ok, now at least that forecast for shear looks to make more sense than those models forecasting for above average shear in the Atlantic but below average in the EPAC

[Shell Mound]

:crazyeyes:

https://i.postimg.cc/QCTkDYyL/CED53-B93-EA5-B-4-EF6-93-E6-DA85-B0205-D5-A.jpg

As mentioned previously, VWS in the Caribbean was above average during July 2021, which typically correlates with lower overall seasonal ACE basin-wide.

[toad strangler]

All eyes on NOAA this morning. Their last update of the season as we approach lift off towards peak season will be the most significant indicator of the day.

[Category5Kaiju]

...we really need to watch out for anything that makes it into the Gulf. The entire region is at least... It’s a powder keg waiting to be lit.

For real, let's hope we don't get any storm that is able to take full advantage of those conditions and blow up into a monster

Regarding the Gulf: we say the same thing every year. It’s a broken record. The Gulf is always sufficiently warm to support Category-5 cyclones, even during -AMO cycles. “Record-high” SST and/or THC in the Gulf are irrelevant, whereas shear and dry air are relevant. Anyway, vertical wind shear was above average in the Caribbean during July 2021, which would actually correlate with lower seasonal ACE. Combined with the -VP over the EPAC, this could indicate more hostile conditions over the Gulf, Caribbean, and western MDR during the peak period of ASO.

Shell Mound, hopefully you don't mind if I ask, but where exactly are you getting this sense that there will be a -VP cell that would make conditions very unfavorable in the Atlantic, let alone persist in a strong manner throughout the season? From my understanding (and this is something NotSparta mentioned in a post a while ago), but 2010 and 2020 were the only two seasons since 1995 to not feature a EPAC rising cell at one point, and given that to be the case, we still managed to get storms like Opal (1995), Bret (1999), Ivan (2004), Katrina/Rita/Wilma (2005), Harvey (2017), and Michael (2018) that were powerful storms in the Gulf and made landfall as major hurricanes. Not to mention a -VP cell in the EPAC making the West Atlantic very unfavorable for storms and killing a season is something I personally have not really heard of before as being possible until you brought it up, so unless another poster here has any insight on this, I just find it somewhat hard to believe that that single parameter alone would be capable of exerting such a dominating influence of the Atlantic and ultimately ruin a season that is otherwise expected to occur during a La Nina. We'll see though, but that's just my take at least.

Also if you don't mind, but could you show where exactly you are getting the idea that more shear in the Caribbean in July correlates with lower seasonal ACE? I'm curious to see the data if you don't mind me asking.

[SFLcane]

:crazyeyes:

https://i.postimg.cc/QCTkDYyL/CED53-B93-EA5-B-4-EF6-93-E6-DA85-B0205-D5-A.jpg

As mentioned previously, VWS in the Caribbean was above average during July 2021, which typically correlates with lower overall seasonal ACE basin-wide.

Season is over.

[psyclone]

...we really need to watch out for anything that makes it into the Gulf. The entire region is at least... It’s a powder keg waiting to be lit.

For real, let's hope we don't get any storm that is able to take full advantage of those conditions and blow up into a monster

Regarding the Gulf: we say the same thing every year. It’s a broken record. The Gulf is always sufficiently warm to support Category-5 cyclones, even during -AMO cycles. “Record-high” SST and/or THC in the Gulf are irrelevant, whereas shear and dry air are relevant. Anyway, vertical wind shear was above average in the Caribbean during July 2021, which would actually correlate with lower seasonal ACE. Combined with the -VP over the EPAC, this could indicate more hostile conditions over the Gulf, Caribbean, and western MDR during the peak period of ASO.

They're (gulf temps) are far from irrelevant. Hurricane Michael just taught us this lesson in 2018 as it traversed the gulf just after an exceptional marine heatwave which gave it the fuel to intensify right up to landfall at a very late point in the season. Shelf waters lurch around a good bit but upper 80's right up against the coast is vastly more dangerous than more modest temp regimes. To be fair we had exceptionally warm shelf waters around here for significant portions of last season as well and that "grass fire fuel" went untapped. Thankfully it frequently does.

[Shell Mound]

For real, let's hope we don't get any storm that is able to take full advantage of those conditions and blow up into a monster

Regarding the Gulf: we say the same thing every year. It’s a broken record. The Gulf is always sufficiently warm to support Category-5 cyclones, even during -AMO cycles. “Record-high” SST and/or THC in the Gulf are irrelevant, whereas shear and dry air are relevant. Anyway, vertical wind shear was above average in the Caribbean during July 2021, which would actually correlate with lower seasonal ACE. Combined with the -VP over the EPAC, this could indicate more hostile conditions over the Gulf, Caribbean, and western MDR during the peak period of ASO.

Also if you don't mind, but could you show where exactly you are getting the idea that more shear in the Caribbean in July correlates with lower seasonal ACE? I'm curious to see the data if you don't mind me asking.

There is a strong negative correlation between July vertical wind shear in the Caribbean and seasonal Atlantic ACE, that is, stronger vertical wind shear typically correlates with a quieter overall Atlantic hurricane season.

Source, p. 25

 https://twitter.com/philklotzbach/status/1290710456475115520



 https://twitter.com/philklotzbach/status/1153368493737144320

[Stormybajan]

What’s up with that persistent stream of -SST anomalies coming from the ABC islands? It’s been there for weeks, and in SST maps from 2020 that have been posted, it is either very weak or non-existent.

https://i.postimg.cc/Gp75NCYC/ssta-tropatl.png

Even though the far eastern MDR has been cooling a bit, everything past 30W is toasty! Warming should continue for atleast the next 4 days and with that it will be soon time to watch for to see if any systems can take advantage during peak season

[Huckster]

Such a night and day difference between certain schools of thought on this season. Some of the extrapolations seem a bit off, especially trying to extend them out to specific storm sizes and styles for storms in late August through Oct while we are still in early August. I would like a crystal ball as much as anyone else, but it doesn't exist, yet I feel like sometimes it would be helpful if people would just go ahead and say EXACTLY what they believe will or will not happen, given the desire to be so specific so far out. This would be preferable, possibly, to posting lots of images or links to tweets that aren't necessarily chronologically or materially related or connected in any other way than that they have something to do with hurricanes this season. There are lots of dots, but the way they're connected yields vastly different pictures.

I do not, however, understand the "need" to apparently diminish (not necessarily eliminate) ALL potential impacts from hurricanes to the continental US this year. In other words, no matter what scenario, it could be potentially worse but because of X, Y, and Z, it won't be for the US. This seems to me more like psychology than meteorology because I don't think there is any real skill being demonstrated here.

[toad strangler]

NOAA update is out. Buckle up.

[CyclonicFury]

This keeps showing up…

https://i.postimg.cc/W4jLpZSd/0-BD164-F4-7455-4983-8425-9-F7-C9-A411891.jpg

...except nothing is likely to be out there before the last few days of August. August 18 is still too early. By early September that ridge is likely to be gone. According to the CFSv2’s weeklies, ridging over southeastern Canada is likely to be strongest during 18–25 August, so if a TC were present near the islands during that timeframe, it would be in a prime position to affect the CONUS. Afterward, however, the CFSv2 shows ridging gradually shifting northward and leaving a trough underneath in time for the peak of the season. So maybe the CONUS will escape serious impacts this season, given that most Category-4+ landfalls tend to be associated with storms that develop in the MDR.

https://i.ibb.co/xf29FNH/Weekly-1.png

https://twitter.com/AndyHazelton/status/1422658917344108554

Why do you think the Atlantic will be dead until the last few days of August? And to say statements like the latter is VERY premature.

[captainbarbossa19]

Notice the below-average wind shear in the Caribbean Sea and the Gulf of Mexico
https://i.postimg.cc/85CVJ4d1/cansips-ashear-Mean-month-atl-1.png
It is nothing but wishful thinking to assume the Caribbean Sea and/or the Gulf of Mexico will be hostile for tropical development.

Meanwhile, the eastern MDR is more hostile which means that storms may not develop much until reaching the Caribbean. Not good!

[Shell Mound]

This keeps showing up…

https://i.postimg.cc/W4jLpZSd/0-BD164-F4-7455-4983-8425-9-F7-C9-A411891.jpg

...except nothing is likely to be out there before the last few days of August. August 18 is still too early. By early September that ridge is likely to be gone. According to the CFSv2’s weeklies, ridging over southeastern Canada is likely to be strongest during 18–25 August, so if a TC were present near the islands during that timeframe, it would be in a prime position to affect the CONUS. Afterward, however, the CFSv2 shows ridging gradually shifting northward and leaving a trough underneath in time for the peak of the season. So maybe the CONUS will escape serious impacts this season, given that most Category-4+ landfalls tend to be associated with storms that develop in the MDR.

https://i.ibb.co/xf29FNH/Weekly-1.png

https://twitter.com/AndyHazelton/status/1422658917344108554

Why do you think the Atlantic will be dead until the last few days of August? And to say statements like the latter is VERY premature.

Operative words: “likely” and “maybe.” Recently I have never made a definitive statement without adding qualifiers such as these two.

What about deep-layer shear in the Caribbean during July 2021? I believe it was above average. Do you have access to charts from that period?

[CyclonicFury]

...except nothing is likely to be out there before the last few days of August. August 18 is still too early. By early September that ridge is likely to be gone. According to the CFSv2’s weeklies, ridging over southeastern Canada is likely to be strongest during 18–25 August, so if a TC were present near the islands during that timeframe, it would be in a prime position to affect the CONUS. Afterward, however, the CFSv2 shows ridging gradually shifting northward and leaving a trough underneath in time for the peak of the season. So maybe the CONUS will escape serious impacts this season, given that most Category-4+ landfalls tend to be associated with storms that develop in the MDR.

https://i.ibb.co/xf29FNH/Weekly-1.png

https://twitter.com/AndyHazelton/status/1422658917344108554

Why do you think the Atlantic will be dead until the last few days of August? And to say statements like the latter is VERY premature.

Operative words: “likely” and “maybe.” Recently I have never made a definitive statement without adding qualifiers such as these two.

What about deep-layer shear in the Caribbean during July 2021? I believe it was above average. Do you have access to charts from that period?

Looks pretty close to average according to this chart:

[Iceresistance]

Global SST anomalies in the North Atlantic.

The GoM is Boiling at between 29-31°C

[Woofde]

31-32 degrees is definitely above the normal for the Gulf. If a tropical seed finds favorable conditions in the Gulf, these SST's are going to make for some explosive convection.

Sent from my SM-G988U1 using Tapatalk

[Shell Mound]

Global SST anomalies in the North Atlantic.

The GoM is Boiling at between 29-31°C

https://s6.gifyu.com/images/crw_ssta_natl.png

The subtropics and equatorial regions are still relatively warmer than the MDR and Caribbean, however, so the -AMO “horseshoe” is still in place, despite warming.

[AlphaToOmega]

[Shell Mound]

Why do you think the Atlantic will be dead until the last few days of August? And to say statements like the latter is VERY premature.

Operative words: “likely” and “maybe.” Recently I have never made a definitive statement without adding qualifiers such as these two.

What about deep-layer shear in the Caribbean during July 2021? I believe it was above average. Do you have access to charts from that period?

Looks pretty close to average according to this chart:
https://i.imgur.com/mYaABdl_d.webp?maxwidth=640&shape=thumb&fidelity=medium

Do you mind posting the link to the original source? In the near future I would very much like to refer to it as a resource. Thank you.