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

[AlphaToOmega]

GFS and ECMWF show Phase III and null phase for the rest of September, which would favor Atlantic tropical cyclogenesis. The most favorable phases are I, II, III, IV.


This might be the smoking gun.

[AlphaToOmega]

Let me ask: does this look like an inactive September?


The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

[Hammy]

Let me ask: does this look like an inactive September?
https://i.postimg.cc/xjmC2Xgc/two-atl-5d0.png

The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

There's a decent chance (probably higher than the maps indicate) that none of these develop. I don't like using the outlook maps as a determinant of activity because they can always give a false impression--remember when we had five circled areas just a few days ago.

[hurricanes1234]

Let me ask: does this look like an inactive September?
https://i.postimg.cc/xjmC2Xgc/two-atl-5d0.png

The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

But are any of those areas actually doing anything?

Everything out in the open Atlantic post-Larry has been hitting a wall or just falling apart entirely. Even Larry itself struggled in a marginal atmosphere and a marginal thermodynamic environment. Since the month only has 2 weeks left, a bunch of hurricanes forming and going bonkers across the basin (so as to meet the definition of a hyperactive September) when the intraseasonal state is pretty bad would be rather surprising at this point.

2021 does seem to be a year with a strong intraseasonal influence and it's reasonable to speculate that October could be more active based on the enhanced MJO predicted to arrive during the month. But IMO a hyperactive September is off the table. Probably a couple more systems and even a hurricane or two which would make the month average/slightly above-average at most but not hyperactive.

[AlphaToOmega]

Let me ask: does this look like an inactive September?
https://i.postimg.cc/xjmC2Xgc/two-atl-5d0.png

The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

But are any of those areas actually doing anything?

Everything out in the open Atlantic post-Larry has been hitting a wall or just falling apart entirely. Even Larry itself struggled in a marginal atmosphere and a marginal thermodynamic environment. Since the month only has 2 weeks left, a bunch of hurricanes forming and going bonkers across the basin (so as to meet the definition of a hyperactive September) when the intraseasonal state is pretty bad would be rather surprising at this point.

2021 does seem to be a year with a strong intraseasonal influence and it's reasonable to speculate that October could be more active based on the enhanced MJO predicted to arrive during the month. But IMO a hyperactive September is off the table. Probably a couple more systems and even a hurricane or two which would make the month average/slightly above-average at most but not hyperactive.

We are in Phase III. That is a favorable phase for tropical cyclone development.

[Category5Kaiju]

Let me ask: does this look like an inactive September?
https://i.postimg.cc/xjmC2Xgc/two-atl-5d0.png

The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

But are any of those areas actually doing anything?

Everything out in the open Atlantic post-Larry has been hitting a wall or just falling apart entirely. Even Larry itself struggled in a marginal atmosphere and a marginal thermodynamic environment. Since the month only has 2 weeks left, a bunch of hurricanes forming and going bonkers across the basin (so as to meet the definition of a hyperactive September) when the intraseasonal state is pretty bad would be rather surprising at this point.

2021 does seem to be a year with a strong intraseasonal influence and it's reasonable to speculate that October could be more active based on the enhanced MJO predicted to arrive during the month. But IMO a hyperactive September is off the table. Probably a couple more systems and even a hurricane or two which would make the month average/slightly above-average at most but not hyperactive.

Yeah I agree; I just am not sure if September is going to be as active as we once thought (while August performed better than expected in contrast). Given our state, I do think that October will feature activity pick up once again, and honestly that actually is a bit concerning given how climo favors west based activity then and in recent years the strongest storm of the season for some reason happened after late September. In fact, I am going to be bold and predict that I expect to see at least two major hurricanes occur during October. With this season doing well in August and meager in September (with the Pacific basins underperforming substantially), something tells me that this is simply the calm before the storm and that we are in for a fiercely backloaded year (with activity possibly lasting into November). That’s just my take though.

[AlphaToOmega]

Let me ask: does this look like an inactive September?
https://i.postimg.cc/xjmC2Xgc/two-atl-5d0.png

The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

But are any of those areas actually doing anything?

Everything out in the open Atlantic post-Larry has been hitting a wall or just falling apart entirely. Even Larry itself struggled in a marginal atmosphere and a marginal thermodynamic environment. Since the month only has 2 weeks left, a bunch of hurricanes forming and going bonkers across the basin (so as to meet the definition of a hyperactive September) when the intraseasonal state is pretty bad would be rather surprising at this point.

2021 does seem to be a year with a strong intraseasonal influence and it's reasonable to speculate that October could be more active based on the enhanced MJO predicted to arrive during the month. But IMO a hyperactive September is off the table. Probably a couple more systems and even a hurricane or two which would make the month average/slightly above-average at most but not hyperactive.

Yeah I agree; I just am not sure if September is going to be as active as we once thought (while August performed better than expected in contrast). Given our state, I do think that October will feature activity pick up once again, and honestly that actually is a bit concerning given how climo favors west based activity then and in recent years the strongest storm of the season for some reason happened after late September. In fact, I am going to be bold and predict that I expect to see at least two major hurricanes occur during October. With this season doing well in August and meager in September (with the Pacific basins underperforming substantially), something tells me that this is simply the calm before the storm and that we are in for a fiercely backloaded year (with activity possibly lasting into November). That’s just my take though.

Do not assume that September will be lackluster just because of not-so-stellar storm performances. By that logic, Hurricane Matthew, a September hurricane, should not have become a major hurricane.

[aspen]

Let me ask: does this look like an inactive September?
https://i.postimg.cc/xjmC2Xgc/two-atl-5d0.png

The chance of none of these developing is (100% - 80%) * (100% - 70%) * (100% - 20%) = 4.8%

There's a decent chance (probably higher than the maps indicate) that none of these develop. I don't like using the outlook maps as a determinant of activity because they can always give a false impression--remember when we had five circled areas just a few days ago.

I don’t know why the NHC highlighted that fifth AOI near Portugal. It had zero model support, a marginal at best environment, and limited time to develop. The other four AOIs had more time and model support.

Edit: 96L actually had pretty lackluster ensemble support, and the OP models never showed it becoming a strong system off the SEUS coast since that one GFS run where it was a MH Florida landfall.

[CyclonicFury]

But are any of those areas actually doing anything?

Everything out in the open Atlantic post-Larry has been hitting a wall or just falling apart entirely. Even Larry itself struggled in a marginal atmosphere and a marginal thermodynamic environment. Since the month only has 2 weeks left, a bunch of hurricanes forming and going bonkers across the basin (so as to meet the definition of a hyperactive September) when the intraseasonal state is pretty bad would be rather surprising at this point.

2021 does seem to be a year with a strong intraseasonal influence and it's reasonable to speculate that October could be more active based on the enhanced MJO predicted to arrive during the month. But IMO a hyperactive September is off the table. Probably a couple more systems and even a hurricane or two which would make the month average/slightly above-average at most but not hyperactive.

Yeah I agree; I just am not sure if September is going to be as active as we once thought (while August performed better than expected in contrast). Given our state, I do think that October will feature activity pick up once again, and honestly that actually is a bit concerning given how climo favors west based activity then and in recent years the strongest storm of the season for some reason happened after late September. In fact, I am going to be bold and predict that I expect to see at least two major hurricanes occur during October. With this season doing well in August and meager in September (with the Pacific basins underperforming substantially), something tells me that this is simply the calm before the storm and that we are in for a fiercely backloaded year (with activity possibly lasting into November). That’s just my take though.

Do not assume that September will be lackluster just because of not-so-stellar storm performances. By that logic, Hurricane Matthew, a September hurricane, should not have become a major hurricane.

September is already over half over. So far it has probably been about average, if not slightly above if you include Larry. Overall so far this September has been a lot less active than 2017-2020, as we have not even had a time with simultaneously active hurricanes so far this year. The MDR has not seen any TC develop since Larry. 95L and 96L still may develop but neither appear likely to be strong at this moment. The models aren't showing much of a signal for anything behind the 0/20 wave for the next 10 days. We could see activity perk up again at the very end of September, but it's not unreasonable to say activity will be below average for the next 7-10 days. The EPS seems to have a bias to show -VP200 over Africa and the IO all the time, it seems as if the suppressed phase will be a negative factor for development for the next week or two.

Thus far, your prediction of a hyperactive September has not verified.

[AlphaToOmega]

Maybe the bears have some magical crystal ball that is better than the GFS, GEFS, ECMWF, and ECENS. I would be very impressed.

[CyclonicFury]

Maybe the bears have some magical crystal ball that is better than the GFS, GEFS, ECMWF, and ECENS. I would be very impressed.

https://i.postimg.cc/CRKpDBDB/ECMF-phase-51m-full.gif
https://i.postimg.cc/qthfbP1p/ensplume-full.gif
https://i.postimg.cc/zHLDKqBW/ecens-2021-09-16-12-Z-072-50-258-0-350-MSLP-Surface-tracks-lows.png
https://i.postimg.cc/phcXmm2R/gefs-2021-09-16-12-Z-072-50-258-0-350-MSLP-Surface-tracks-lows.png

Most of those members are very weak, and the EPS signal is a lot less impressive than it was a few days ago.

[AlphaToOmega]

Maybe the bears have some magical crystal ball that is better than the GFS, GEFS, ECMWF, and ECENS. I would be very impressed.

https://i.postimg.cc/CRKpDBDB/ECMF-phase-51m-full.gif
https://i.postimg.cc/qthfbP1p/ensplume-full.gif
https://i.postimg.cc/zHLDKqBW/ecens-2021-09-16-12-Z-072-50-258-0-350-MSLP-Surface-tracks-lows.png
https://i.postimg.cc/phcXmm2R/gefs-2021-09-16-12-Z-072-50-258-0-350-MSLP-Surface-tracks-lows.png

Most of those members are very weak, and the EPS signal is a lot less impressive than it was a few days ago.

Most GEFS and ECENS ensemble members show both Invests 95L and 96L getting to tropical storm status. For the MJO forecasts, both the GFS and ECMWF show a retrogression of the MJO, which would keep us in Phase III for longer. Phase III is favorable for tropical cyclogenesis in the Atlantic. Cape Verde development is becoming less likely by the day, but that just means Invest 95L is likely to develop farther west. Unless you want to say both the GFS and ECMWF keeping the MJO in favorable Phase III is a common bias both of them have, I am still convinced September is going to be active.

[Category5Kaiju]

But are any of those areas actually doing anything?

Everything out in the open Atlantic post-Larry has been hitting a wall or just falling apart entirely. Even Larry itself struggled in a marginal atmosphere and a marginal thermodynamic environment. Since the month only has 2 weeks left, a bunch of hurricanes forming and going bonkers across the basin (so as to meet the definition of a hyperactive September) when the intraseasonal state is pretty bad would be rather surprising at this point.

2021 does seem to be a year with a strong intraseasonal influence and it's reasonable to speculate that October could be more active based on the enhanced MJO predicted to arrive during the month. But IMO a hyperactive September is off the table. Probably a couple more systems and even a hurricane or two which would make the month average/slightly above-average at most but not hyperactive.

Yeah I agree; I just am not sure if September is going to be as active as we once thought (while August performed better than expected in contrast). Given our state, I do think that October will feature activity pick up once again, and honestly that actually is a bit concerning given how climo favors west based activity then and in recent years the strongest storm of the season for some reason happened after late September. In fact, I am going to be bold and predict that I expect to see at least two major hurricanes occur during October. With this season doing well in August and meager in September (with the Pacific basins underperforming substantially), something tells me that this is simply the calm before the storm and that we are in for a fiercely backloaded year (with activity possibly lasting into November). That’s just my take though.

Do not assume that September will be lackluster just because of not-so-stellar storm performances. By that logic, Hurricane Matthew, a September hurricane, should not have become a major hurricane.

When I said "not as active as once thought," all I was trying to point out there is that we likely will not see Cape Verde Cat 4s and 5s hit land back to back like 2004 or 2017 as some individuals were predicting earlier this season. However, in no way am I saying that we will see no more named storms this month. In fact, as of now my prediction is that we will see 2-3 NSs before October 1 comes. While I tend to be a bullish tracker, at this point I just do not think seeing a hyperactive September will come to fruition. However, I do think that with sacrificing a September the Atlantic will instead kick into high gear in October, and that's when I expect things to become spicy. If anything, I actually would not be shocked to see a bunch of ACE points racked up in early October onward when I expect activity to resume in high levels again. A good example as you pointed out was in 2016. Another good example is 1932. You can still get high ACE storms after September, it's just that such storms will likely not be CV hurricanes.

[Ubuntwo]

Most GEFS and ECENS ensemble members show both Invests 95L and 96L getting to tropical storm status. For the MJO forecasts, both the GFS and ECMWF show a retrogression of the MJO, which would keep us in Phase III for longer. Phase III is favorable for tropical cyclogenesis in the Atlantic. Cape Verde development is becoming less likely by the day, but that just means Invest 95L is likely to develop farther west. Unless you want to say both the GFS and ECMWF keeping the MJO in favorable Phase III is a common bias both of them have, I am still convinced September is going to be active.

Phase 3 is usually favorable, though significantly less so than phases 1-2 i.e. August. Not currently in a position to really amplify Atlantic TC activity.

The subsidence over the basin right now can be attributed to a suppressive CCKW. Yeah, it is September. Storms are gonna form. Just not a pattern for a hyperactive month (above-average is in the cards). It's all relative.

October is another can of worms.

[Category5Kaiju]

If it happens I'll laugh, but what if...just what if...October ends up as a more active month than September, with more ACE, majors, hurricanes, and named storms?

[ElectricStorm]

If it happens I'll laugh, but what if...just what if...October ends up as a more active month than September, with more ACE, majors, hurricanes, and named storms?

Probably a decent chance that happens honestly

[IcyTundra]

95L and 96L will likely develop, but I'm not expecting much out of them. Maybe 95L can develop into a cat 1 or 2, but I just don't think a major hurricane is a realistic possibility for 95L. I still think we are in for atleast 1 or 2 more majors probably developing in October somewhere in the Carribean.

[SFLcane]

I urge SFL residents to read this blog by Dr.Ryan Truchelut. Eyes open for a Florida hurricane strike this October.

These predictive analytics suggest a solid chance of a hurricane strike somewhere in Florida before the end of the season.

https://weathertiger.substack.com/p/wea ... -hurricane

[Ubuntwo]

EPS does not propagate the MJO. Has several kelvin waves passing across the basin. Verbatim, this would be an active mid-late October following a pause earlier that month.
 https://twitter.com/AndyHazelton/status/1438612786385498113

[aspen]

EPS does not propagate the MJO. Has several kelvin waves passing across the basin. Verbatim, this would be an active mid-late October following a pause earlier that month.
https://twitter.com/AndyHazelton/status/1438612786385498113

October looks nasty. The western to central Atlantic will be enhanced by -VP anomalies from roughly October 10th through 26th, plenty of time to produce several storms and probably at least one major.