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

[AlphaToOmega]

2018 September: seven storms


2019 September: seven storms


2020 September: ten storms


What does this mean? It means that September has been super favorable for tropical cyclogenesis in the North Atlantic during both El Niño and La Niña years as of recent likely because of the African Standing Wave.

2021 September: who knows how many storms?



Based on these maps, we should see at least seven storms form in September 2021 at the bare minimum. One already formed: Larry. In my opinion, a realistic estimate would be ten storms à la 2020.

[Iceresistance]

The MJO is literally STUCK at Phases 2/3 & is expected to move into Phase 4 within the next several weeks . . .

[SFLcane]

Quite sept how about no.

 https://twitter.com/webberweather/status/1434519996302970882

[AlphaToOmega]

I think we may be tracking storms into December. A La Niña should help lower wind shear in the Atlantic basin, and we are overdue for a December storm. Emphasis on may

[CyclonicFury]

I think we may be tracking storms into December. A La Niña should help lower wind shear in the Atlantic basin, and we are overdue for a December storm. Emphasis on may

December activity is quite random and difficult to predict. Despite 2017 and 2020 being hyperactive seasons, neither had any storms form in December. The majority of December storms are over the eastern subtropical Atlantic, or less commonly, the Caribbean, and typically do not get very strong. Most of them avoid land.

[toad strangler]

I said it earlier and I'll say it again since the subject is at hand. Unless we get a very anomalous situation like we did one year ago, the season as far as threats to land in the WESTERN basin (and especially the CONUS) has another 55 days or so left. That's what climo says. Again, this is in a general climo historical sense. We'll see.. . we do have an inbound La Nina but that doesn't automatically mean late season storms.

[SFLcane]

I said it earlier and I'll say it again since the subject is at hand. Unless we get a very anomalous situation like we did one year ago, the season as far as threats to land in the WESTERN basin (and especially the CONUS) has another 55 days or so left. That's what climo says. Again, this is in a general climo historical sense. We'll see.. . we do have an inbound La Nina but that doesn't automatically mean late season storms.

+1

[toad strangler]

I said it earlier and I'll say it again since the subject is at hand. Unless we get a very anomalous situation like we did one year ago, the season as far as threats to land in the WESTERN basin (and especially the CONUS) has another 55 days or so left. That's what climo says. Again, this is in a general climo historical sense. We'll see.. . we do have an inbound La Nina but that doesn't automatically mean late season storms.

+1

The central and southern FL peninsula is the last vestige of CONUS that would be favorable for a hit all the way through this period. As you are well aware. If W Caribbean genesis is still a thing late, we could have an issue.

[CyclonicFury]

2018 September: seven storms
https://i.postimg.cc/8zJh5yzx/h6-YPRz-Vj-RK.png

2019 September: seven storms
https://i.postimg.cc/50M5Dw1T/s-DWa-Jk-T4e-T.png

2020 September: ten storms
https://i.postimg.cc/43Rh3sMh/Jg9890l2-Kp.png

What does this mean? It means that September has been super favorable for tropical cyclogenesis in the North Atlantic during both El Niño and La Niña years as of recent likely because of the African Standing Wave.

2021 September: who knows how many storms?
https://i.postimg.cc/prjmvSZB/cansips-chi200-global-1.png
https://i.postimg.cc/FFkd0f4J/cfs-mon-01-chi200-global-1.png

Based on these maps, we should see at least seven storms form in September 2021 at the bare minimum. One already formed: Larry. In my opinion, a realistic estimate would be ten storms à la 2020.

You have to look at more than just the last 3 years and more of a historical perspective. It's not that uncommon for September in active seasons to only have 3-4 storms, usually quality storms, in years where August was very active like 2021. September 2017, despite having more Atlantic ACE than any other month, only had 4 named storms form, including none after September 16. September 1995 only had 3 named storms form after an extremely active August, but all of the storms that formed were hurricanes. September 2004 was also significantly less active than August. I'd expect to see another 1-3 storms around the middle of the month when a weak CCKW passes through, but overall the MJO pattern doesn't look to be all that conducive for the rest of September. IMO September is more likely to finish with 3-5 storms than 7-10, but the quality of the storms that do form might be stronger than 2020. 2020 having 10 named storms in September set a record, I don't think we'll get that many this year.

[cycloneye]

Quite sept how about no.

https://twitter.com/webberweather/statu ... 6302970882?

There is always a twit. Dr Ventrice failed bigtime in 2017 and I would have be gone from twitter after that. Hello José, Irma and Maria.

[toad strangler]

Quite sept how about no.

https://twitter.com/webberweather/statu ... 6302970882?

There is always a twit. Dr Ventrice failed bigtime in 2017 and I would have be gone from twitter after that. Hello José, Irma and Maria.

https://i.imgur.com/QC8Zv3R.png

W O W

[SFLcane]

Quite sept how about no.

https://twitter.com/webberweather/statu ... 6302970882?

There is always a twit. Dr Ventrice failed bigtime in 2017 and I would have be gone from twitter after that. Hello José, Irma and Maria.

https://i.imgur.com/QC8Zv3R.png

Oops!

[AlphaToOmega]

2018 September: seven storms
https://i.postimg.cc/8zJh5yzx/h6-YPRz-Vj-RK.png

2019 September: seven storms
https://i.postimg.cc/50M5Dw1T/s-DWa-Jk-T4e-T.png

2020 September: ten storms
https://i.postimg.cc/43Rh3sMh/Jg9890l2-Kp.png

What does this mean? It means that September has been super favorable for tropical cyclogenesis in the North Atlantic during both El Niño and La Niña years as of recent likely because of the African Standing Wave.

2021 September: who knows how many storms?
https://i.postimg.cc/prjmvSZB/cansips-chi200-global-1.png
https://i.postimg.cc/FFkd0f4J/cfs-mon-01-chi200-global-1.png

Based on these maps, we should see at least seven storms form in September 2021 at the bare minimum. One already formed: Larry. In my opinion, a realistic estimate would be ten storms à la 2020.

You have to look at more than just the last 3 years and more of a historical perspective. It's not that uncommon for September in active seasons to only have 3-4 storms, usually quality storms, in years where August was very active like 2021. September 2017, despite having more Atlantic ACE than any other month, only had 4 named storms form, including none after September 16. September 1995 only had 3 named storms form after an extremely active August, but all of the storms that formed were hurricanes. September 2004 was also significantly less active than August. I'd expect to see another 1-3 storms around the middle of the month when a weak CCKW passes through, but overall the MJO pattern doesn't look to be all that conducive for the rest of September. IMO September is more likely to finish with 3-5 storms than 7-10, but the quality of the storms that do form might be stronger than 2020. 2020 having 10 named storms in September set a record, I don't think we'll get that many this year.

The VP anomaly pattern forecasted by both the CanSIPS and CFSv2 for September 2021 quite closely matches September 2020. The ECMWF also suggests an African Standing Wave during September 2021. MJO is not a big factor during the peak season. The African Standing Wave, which was seen in 2018, 2019, and 2020, is likely to make September 2021 very active.

[SFLcane]

Might have another screen shot in a few weeks.

[gatorcane]

I said it earlier and I'll say it again since the subject is at hand. Unless we get a very anomalous situation like we did one year ago, the season as far as threats to land in the WESTERN basin (and especially the CONUS) has another 55 days or so left. That's what climo says. Again, this is in a general climo historical sense. We'll see.. . we do have an inbound La Nina but that doesn't automatically mean late season storms.

+1

The central and southern FL peninsula is the last vestige of CONUS that would be favorable for a hit all the way through this period. As you are well aware. If W Caribbean genesis is still a thing late, we could have an issue.

South Florida’s month for most cyclone hits from a climatological perspective is is October so it will be again a month to watch this year given La Niña. Somehow since 2005, South Florida has managed to escape a hit from a Caribbean hurricane. Those cyclones that have formed seem to impact the panhandle, or northern Gulf as well as Central America with stout ridging that has setup over the Bahamas preventing a N NE ejection out of the Caribbean.

[IcyTundra]

I highly doubt September will be as inactive as some models are suggesting. It is the peak of hurricane season climatologically and there is a favorable base state with a transition to a La Nina from ENSO cool-neutral expected sometime soon.

[AlphaToOmega]

Nail in the coffin for bearish predictions for September

[jconsor]

 https://twitter.com/yconsor/status/1434578292389126144

[AlphaToOmega]

https://twitter.com/yconsor/status/1434578292389126144

That looks like a standing wave over Africa to me! September is going to feature many storms simply due to the African Standing Wave. I need to see a scenario in which a below-average September can be achieved with an African Standing Wave.

[AlphaToOmega]

I split every September from 1997 to 2020 into three categories: above-average, average, and below-average. An above-average September features seven or more storms. An average September features four to six storms. A below-average September features three or fewer storms.

Above-average September:


Average September:


Below-average September:


There is one key difference between the above-average Septembers, the average Septembers, and the below-average Septembers: the VP anomalies in the Indian Ocean. For above-average Septembers, VP anomalies in the Indian Ocean are consistently negative. For average Septembers, VP anomalies in the Indian Ocean are negative in some parts and positive in other parts. For below-average Septembers, VP anomalies in the Indian Ocean are consistently positive. What will September 2021 likely feature?





This matches with an above-average September (seven or more storms) signature. The CanSIPS, CFSv2, and JMA would all have to bust in a major way for September 2021 to have fewer than seven storms.