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

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

#4141 Postby tolakram » Sun Oct 24, 2021 5:52 pm

jconsor wrote:Long thread offering some thoughts on why the ITCZ and Caribbean activity have been suppressed up until now in Oct...
https://twitter.com/yconsor/status/1452331676537925635

...Why some forecasters are convinced the season is over in the Atlantic:
https://twitter.com/yconsor/status/1452368332678647809

...And how a significant change in the pattern is coming next two weeks that favors better chance of Caribbean activity:
https://twitter.com/yconsor/status/1452370864473792523


What bias is it when someone claims everyone else is calling the season over, when most of us are expecting some November activity? :) The pause in activity is notable, and rare for a nina year.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4142 Postby Teban54 » Sun Oct 24, 2021 7:30 pm

tolakram wrote:
jconsor wrote:Long thread offering some thoughts on why the ITCZ and Caribbean activity have been suppressed up until now in Oct...
https://twitter.com/yconsor/status/1452331676537925635

...Why some forecasters are convinced the season is over in the Atlantic:
https://twitter.com/yconsor/status/1452368332678647809

...And how a significant change in the pattern is coming next two weeks that favors better chance of Caribbean activity:
https://twitter.com/yconsor/status/1452370864473792523


What bias is it when someone claims everyone else is calling the season over, when most of us are expecting some November activity? :) The pause in activity is notable, and rare for a nina year.

People have different opinions regarding whether having only random subtropics TS (like Rina 2017 or Theta 2020) counts as "season over" or not. But some (and a growing number of) people seem to think that intense storms are over more likely than not, even though I personally think we can still see a WCar hurricane in November. At this point the season over debate is more about semantics, IMO.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4143 Postby Spacecoast » Sun Oct 24, 2021 8:00 pm

tolakram wrote:
jconsor wrote:Long thread offering some thoughts on why the ITCZ and Caribbean activity have been suppressed up until now in Oct...
https://twitter.com/yconsor/status/1452331676537925635

...Why some forecasters are convinced the season is over in the Atlantic:
https://twitter.com/yconsor/status/1452368332678647809

...And how a significant change in the pattern is coming next two weeks that favors better chance of Caribbean activity:
https://twitter.com/yconsor/status/1452370864473792523


What bias is it when someone claims everyone else is calling the season over, when most of us are expecting some November activity? :) The pause in activity is notable, and rare for a nina year.


straw man - An informal fallacy of having the impression of refuting an argument, whereas the real subject of the argument was not addressed or refuted, but instead replaced with a false one. The typical straw man creates the illusion of having completely refuted a proposition through the covert replacement of it with a different proposition (i.e., "stand up a straw man") and the subsequent refutation of that false argument ("knock down a straw man").
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4144 Postby Ubuntwo » Mon Oct 25, 2021 4:47 pm

Very low latitude ITCZ indeed. We will see how the pattern evolves through November.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4145 Postby Category5Kaiju » Mon Oct 25, 2021 4:58 pm

It would be interesting if after this season ends we review this season again and find out that the lingering Atlantic Nino favoring waves traveling at too low of latitudes actually was to blame for the lack of activity this October in the Atlantic (while Pamela and Rick formed instead from such waves). Imho, that does make a bit of sense. Sure, the Nino could allow low latitude, strong hurricanes in the MDR during the peak months, but during October and November when climo favors the W. Atlantic, that could be unfavorable for development as South America is in the way.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4146 Postby aspen » Mon Oct 25, 2021 5:22 pm

The WPac, EPac, Atlantic, and Mediterranean all have at least one active storm and/or AOI. If the Atlantic is the only one to not see a single named storm develop in October, then I have no idea what to say anymore.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4147 Postby toad strangler » Mon Oct 25, 2021 5:58 pm

Category5Kaiju wrote:It would be interesting if after this season ends we review this season again and find out that the lingering Atlantic Nino favoring waves traveling at too low of latitudes actually was to blame for the lack of activity this October in the Atlantic (while Pamela and Rick formed instead from such waves). Imho, that does make a bit of sense. Sure, the Nino could allow low latitude, strong hurricanes in the MDR during the peak months, but during October and November when climo favors the W. Atlantic, that could be unfavorable for development as South America is in the way.


Tropical seasons are like snowflakes. No two ever the same. Regardless of similar past conditions / indicators.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4148 Postby Hammy » Mon Oct 25, 2021 6:54 pm

Category5Kaiju wrote:It would be interesting if after this season ends we review this season again and find out that the lingering Atlantic Nino favoring waves traveling at too low of latitudes actually was to blame for the lack of activity this October in the Atlantic (while Pamela and Rick formed instead from such waves). Imho, that does make a bit of sense. Sure, the Nino could allow low latitude, strong hurricanes in the MDR during the peak months, but during October and November when climo favors the W. Atlantic, that could be unfavorable for development as South America is in the way.


So in effect, it's entirely possible that this year could've suffered from the exact opposite of what happened in 2019, where waves were often coming off too far north.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4149 Postby AlphaToOmega » Mon Oct 25, 2021 8:18 pm

The GEFS is noting toughing over the Caribbean Sea, which might make things interesting.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4150 Postby hurricanes1234 » Mon Oct 25, 2021 8:54 pm

Every week, this so-called "burst of activity" keeps getting pushed back by another week and at this point with November almost here and climatology soon dropping the curtain, so to speak, I'm not sure how much of anything this "burst" is going to be. It honestly feels like an El Niño with the season basically shutting down completely at the end of September.

I remember posting a couple weeks ago that I'd be genuinely surprised if we made it to the auxiliary list. At this point, multiply that feeling by 10. I wouldn't even be surprised if we saw no more named storms. In fact, that's lowkey what I'm thinking might happen but things have a way of surprising us, plus I'm no expert, so I wouldn't completely discount another surge in activity. Just that I think it's getting less and less likely with each passing week. Or less and less likely to be significant enough to make much of a difference.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4151 Postby AlphaToOmega » Mon Oct 25, 2021 9:01 pm

hurricanes1234 wrote:Every week, this so-called "burst of activity" keeps getting pushed back by another week and at this point with November almost here and climatology soon dropping the curtain, so to speak, I'm not sure how much of anything this "burst" is going to be. It honestly feels like an El Niño with the season basically shutting down completely at the end of September.

I remember posting a couple weeks ago that I'd be genuinely surprised if we made it to the auxiliary list. At this point, multiply that feeling by 10. I wouldn't even be surprised if we saw no more named storms. In fact, that's lowkey what I'm thinking might happen but things have a way of surprising us, plus I'm no expert, so I wouldn't completely discount another surge in activity. Just that I think it's getting less and less likely with each passing week. Or less and less likely to be significant enough to make much of a difference.


We are fairly confident that the burst of activity will occur in late October and early November based on models.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4152 Postby Category5Kaiju » Mon Oct 25, 2021 10:04 pm

hurricanes1234 wrote:Every week, this so-called "burst of activity" keeps getting pushed back by another week and at this point with November almost here and climatology soon dropping the curtain, so to speak, I'm not sure how much of anything this "burst" is going to be. It honestly feels like an El Niño with the season basically shutting down completely at the end of September.

I remember posting a couple weeks ago that I'd be genuinely surprised if we made it to the auxiliary list. At this point, multiply that feeling by 10. I wouldn't even be surprised if we saw no more named storms. In fact, that's lowkey what I'm thinking might happen but things have a way of surprising us, plus I'm no expert, so I wouldn't completely discount another surge in activity. Just that I think it's getting less and less likely with each passing week. Or less and less likely to be significant enough to make much of a difference.


Models have definitely been hinting at the 20/50 system forming and a WCAR system early next month, so I’m personally confident we will reach at least Adria. If we don’t then I would genuinely be surprised.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4153 Postby LarryWx » Tue Oct 26, 2021 9:58 am

Some climo to keep in mind for November quoted from elsewhere:


“Since 1950 (71 years), 45
named storms have been ob-
served in the month of November
including 23 hurricanes, five be-
coming major hurricanes.”

So, average for November since 1950:

45/71 = 0.63 named storms

23/71 = 0.32 hurricanes

5/71 = 0.07 major hurricanes
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4154 Postby CyclonicFury » Tue Oct 26, 2021 11:04 am

AlphaToOmega wrote:
hurricanes1234 wrote:Every week, this so-called "burst of activity" keeps getting pushed back by another week and at this point with November almost here and climatology soon dropping the curtain, so to speak, I'm not sure how much of anything this "burst" is going to be. It honestly feels like an El Niño with the season basically shutting down completely at the end of September.

I remember posting a couple weeks ago that I'd be genuinely surprised if we made it to the auxiliary list. At this point, multiply that feeling by 10. I wouldn't even be surprised if we saw no more named storms. In fact, that's lowkey what I'm thinking might happen but things have a way of surprising us, plus I'm no expert, so I wouldn't completely discount another surge in activity. Just that I think it's getting less and less likely with each passing week. Or less and less likely to be significant enough to make much of a difference.


We are fairly confident that the burst of activity will occur in late October and early November based on models.

We're getting awfully late for a real "burst" in activity. 94L has a shot to become a subtropical/tropical storm, but the Caribbean signal has backed off, and I don't buy the models showing an MDR storm this late. CFS has seemingly showed a favorable VP anomaly setup in the 8-14 day range for a couple weeks now, and nothing has formed yet.
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2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4155 Postby skyline385 » Tue Oct 26, 2021 12:07 pm

Category5Kaiju wrote:
hurricanes1234 wrote:Every week, this so-called "burst of activity" keeps getting pushed back by another week and at this point with November almost here and climatology soon dropping the curtain, so to speak, I'm not sure how much of anything this "burst" is going to be. It honestly feels like an El Niño with the season basically shutting down completely at the end of September.

I remember posting a couple weeks ago that I'd be genuinely surprised if we made it to the auxiliary list. At this point, multiply that feeling by 10. I wouldn't even be surprised if we saw no more named storms. In fact, that's lowkey what I'm thinking might happen but things have a way of surprising us, plus I'm no expert, so I wouldn't completely discount another surge in activity. Just that I think it's getting less and less likely with each passing week. Or less and less likely to be significant enough to make much of a difference.


Models have definitely been hinting at the 20/50 system forming and a WCAR system early next month, so I’m personally confident we will reach at least Adria. If we don’t then I would genuinely be surprised.

There hasn't been any concrete indication of a WCar system, it's always just a few very long range rogue ensemble members which keep shifting every run.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4156 Postby aspen » Tue Oct 26, 2021 12:52 pm

CyclonicFury wrote:
AlphaToOmega wrote:
hurricanes1234 wrote:Every week, this so-called "burst of activity" keeps getting pushed back by another week and at this point with November almost here and climatology soon dropping the curtain, so to speak, I'm not sure how much of anything this "burst" is going to be. It honestly feels like an El Niño with the season basically shutting down completely at the end of September.

I remember posting a couple weeks ago that I'd be genuinely surprised if we made it to the auxiliary list. At this point, multiply that feeling by 10. I wouldn't even be surprised if we saw no more named storms. In fact, that's lowkey what I'm thinking might happen but things have a way of surprising us, plus I'm no expert, so I wouldn't completely discount another surge in activity. Just that I think it's getting less and less likely with each passing week. Or less and less likely to be significant enough to make much of a difference.


We are fairly confident that the burst of activity will occur in late October and early November based on models.

We're getting awfully late for a real "burst" in activity. 94L has a shot to become a subtropical/tropical storm, but the Caribbean signal has backed off, and I don't buy the models showing an MDR storm this late. CFS has seemingly showed a favorable VP anomaly setup in the 8-14 day range for a couple weeks now, and nothing has formed yet.

The question is why. Having 20 NS by early October only to shut off as soon as a La Niña develops has never been seen before in the recorded database. All other basins have been able to produce something since — even the Mediterranean.

My suspicion is that part of the reason for the shutoff is that we’re seeing a changing base state that’s a signal for a warm ENSO next year. Yellow Evan pointed out in Rick’s thread how late-season Mexico landfalls generally preceded warm ENSO events.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4157 Postby hurricanes1234 » Tue Oct 26, 2021 1:36 pm

aspen wrote:
CyclonicFury wrote:
AlphaToOmega wrote:
We are fairly confident that the burst of activity will occur in late October and early November based on models.

We're getting awfully late for a real "burst" in activity. 94L has a shot to become a subtropical/tropical storm, but the Caribbean signal has backed off, and I don't buy the models showing an MDR storm this late. CFS has seemingly showed a favorable VP anomaly setup in the 8-14 day range for a couple weeks now, and nothing has formed yet.

The question is why. Having 20 NS by early October only to shut off as soon as a La Niña develops has never been seen before in the recorded database. All other basins have been able to produce something since — even the Mediterranean.

My suspicion is that part of the reason for the shutoff is that we’re seeing a changing base state that’s a signal for a warm ENSO next year. Yellow Evan pointed out in Rick’s thread how late-season Mexico landfalls generally preceded warm ENSO events.


So true, this year has just been super weird in every possible respect regarding the tropics.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4158 Postby Ubuntwo » Tue Oct 26, 2021 2:36 pm

aspen wrote:My suspicion is that part of the reason for the shutoff is that we’re seeing a changing base state that’s a signal for a warm ENSO next year. Yellow Evan pointed out in Rick’s thread how late-season Mexico landfalls generally preceded warm ENSO events.

Steering is not even giving waves a chance in the Caribbean and is instead bringing them to the eastern Pacific. The pattern has to change to allow deep tropical development. No hints of that even 2-4 weeks out in the models.

The La Nina base state is weakening the MJO so the intraseasonal 'boost' will not be as big as originally forecast. I don't think the potential for a +ENSO event months into the future can influence the Atlantic now. There is more at play here.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4159 Postby tolakram » Tue Oct 26, 2021 3:17 pm

I don't think it's really that big of a deal. ENSO, shear, MJO, water temps, kelvin waves, these are all modifiers for chance of development and strength of storms, but there are still plenty of variables that, when missing, reduce development chances by an unknown amount.

Every season is different for a reason, and sometimes those reasons are not known in advance. If we end up with a super active November we might look back at this and put more stock into the idea of a delayed season rather than one that mysteriously shut down. If not, then perhaps the Atlantic nino, which I had never heard of until this year, might be to blame.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

#4160 Postby Ubuntwo » Tue Oct 26, 2021 3:39 pm

tolakram wrote:I don't think it's really that big of a deal. ENSO, shear, MJO, water temps, kelvin waves, these are all modifiers for chance of development and strength of storms, but there are still plenty of variables that, when missing, reduce development chances by an unknown amount.

Every season is different for a reason, and sometimes those reasons are not known in advance. If we end up with a super active November we might look back at this and put more stock into the idea of a delayed season rather than one that mysteriously shut down. If not, then perhaps the Atlantic nino, which I had never heard of until this year, might be to blame.

Could easily see a pattern change in November allowing more activity. Regardless, the October lull is interesting and rare for a year like 2021. May be worth looking back in post with better data. The late developing La Nina, long lasting Atlantic Nino, low latitude ridging, and persistent upper trough all may have played some role.

2007 keeps cropping up as an analog:
 https://twitter.com/philklotzbach/status/1453093102822912004


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