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

[NotSparta]

https://twitter.com/yconsor/status/1415306297721901056

That is still a rising cell over the East Pacific even during hyperactive years. 2020 was the only year without -VP anomalies in the East Pacific.

No, the rising cell over the E Pacific is in the active (slightly above normal) year composite. The hyperactive years have a *sinking* cell over the eastern Pacific.

We haven't really had a sinking cell in the East Pacific for a while, ever since the 90s when it used to be a standing wave over the Americas. It's existed in some form pretty much every year except 2010 and 2020

[Shell Mound]

So we have a trend toward -ENSO (weak Niña) coupled with the Atlantic Niño + ASW, yet with the MDR remaining coolish come ASO. An interesting combination:

 https://twitter.com/BenNollWeather/status/1415055949903982594




Personally, I think this translates into numerous high-amplitude AEWs exiting at a low latitude and crashing into South America while failing to consolidate.

[AlphaToOmega]

So we have a trend toward -ENSO (weak Niña) coupled with the Atlantic Niño + ASW, yet with the MDR remaining coolish come ASO. An interesting combination:

https://twitter.com/BenNollWeather/status/1415055949903982594

The strong ASW should make the MDR significantly above-average come ASO. I think the models have a hard time dealing with the Atlantic Equatorial Mode.

[Shell Mound]

So we have a trend toward -ENSO (weak Niña) coupled with the Atlantic Niño + ASW, yet with the MDR remaining coolish come ASO. An interesting combination:

https://twitter.com/BenNollWeather/status/1415055949903982594

The strong ASW should make the MDR significantly above-average come ASO. I think the models have a hard time dealing with the Atlantic Equatorial Mode.

The ASW has been strong over the past several months, yet the MDR has barely budged in terms of its SST. As I mentioned previously, the suppressed ITCZ, coupled with the Atlantic Niño, emergent -ENSO, and active African monsoon, will likely lead to large waves exiting West Africa at a low latitude and, owing to their high amplitude and proximity to the equator, fail to develop much vorticity or organisation before crashing into South America or getting torn apart by the accelerating trades over the southeastern Caribbean Sea. Without the +AMM/+AMO stability and associated shear via the TUTT will act to suppress TCG, along with the waves’ being too large to organise before striking the northeastern tip of South America. Currently models strongly concur on the MDR being cool and thus the ITCZ being strongly suppressed come ASO.

[cycloneye]

Shell Mound So you no longer favor your S2K poll numbers of 17/11/6?

viewtopic.php?f=25&t=121766

[Shell Mound]

Shell Mound So you no longer favor your S2K poll numbers of 17/11/6?

You are correct, but please do not alter those numbers, as they are “finalised.” I have since altered my expectations since finalisation.

[cycloneye]

Shell Mound So you no longer favor your S2K poll numbers of 17/11/6?

You are correct, but please do not alter those numbers, as they are “finalised.” I have since altered my expectations since finalisation.

I never edit anything after the poll is closed in all the years of polling. That is for the S2K archives.

[ElectricStorm]

SSTs will probably warm before peak season like they do pretty much every single year. I personally don't really see much that suggests anything other than a very active season...

[NotSparta]

So we have a trend toward -ENSO (weak Niña) coupled with the Atlantic Niño + ASW, yet with the MDR remaining coolish come ASO. An interesting combination:

https://twitter.com/BenNollWeather/status/1415055949903982594

The strong ASW should make the MDR significantly above-average come ASO. I think the models have a hard time dealing with the Atlantic Equatorial Mode.

The ASW has been strong over the past several months, yet the MDR has barely budged in terms of its SST. As I mentioned previously, the suppressed ITCZ, coupled with the Atlantic Niño, emergent -ENSO, and active African monsoon, will likely lead to large waves exiting West Africa at a low latitude and, owing to their high amplitude and proximity to the equator, fail to develop much vorticity or organisation before crashing into South America or getting torn apart by the accelerating trades over the southeastern Caribbean Sea. Without the +AMM/+AMO stability and associated shear via the TUTT will act to suppress TCG, along with the waves’ being too large to organise before striking the northeastern tip of South America. Currently models strongly concur on the MDR being cool and thus the ITCZ being strongly suppressed come ASO.

I would think the Atlantic Niño would help those waves spin up similarly to Elsa. It's one reason these features actually enhance TC activity. Given the current ITCZ activity, unless we see waves quickly gain latitude for some reason stability probably won't be an issue, and I've seen very little signal for a strong TUTT (actually more for a weak one, which also makes sense given it was able to entirely lift out of the Caribbean a few weeks ago) aside from the CFS which has had issues propagating the MJO and typically turns Africa into a mass sink. Low latitude could still be an issue for these waves but I can't see stability or shear being any more of a problem than usual

[SFLcane]

Just to put in perspective why I am so worried about potential impacts to Florida. Taking another look at z500 forecast for this season. Like the Cánsips the JMA (Tokyo) and ECMWF are similar and Korea showing High latitude ridging. Thanks to Yaakov for the site.

Buckle up! No fish food this season

[NotSparta]

SSTs will probably warm before peak season like they do pretty much every single year. I personally don't really see much that suggests anything other than a very active season...

This is a good point, in the past decade or so and especially since 2015, there have been many -AMMs that have developed in spring or the beginning of summer just for it to recover and get less negative or flip positive by fall, when the values typically maximize as of late. Sort of like the opposite of the 1960s where consistent strong wintertime -NAOs would create strong +AMM events in springtime, for them to usually fade or even flip negative by fall

[Shell Mound]

The strong ASW should make the MDR significantly above-average come ASO. I think the models have a hard time dealing with the Atlantic Equatorial Mode.

The ASW has been strong over the past several months, yet the MDR has barely budged in terms of its SST. As I mentioned previously, the suppressed ITCZ, coupled with the Atlantic Niño, emergent -ENSO, and active African monsoon, will likely lead to large waves exiting West Africa at a low latitude and, owing to their high amplitude and proximity to the equator, fail to develop much vorticity or organisation before crashing into South America or getting torn apart by the accelerating trades over the southeastern Caribbean Sea. Without the +AMM/+AMO stability and associated shear via the TUTT will act to suppress TCG, along with the waves’ being too large to organise before striking the northeastern tip of South America. Currently models strongly concur on the MDR being cool and thus the ITCZ being strongly suppressed come ASO.

I've seen very little signal for a strong TUTT

The EPS suggests a strongly +NAO during ASO, hence a northward displacement of the STR, implying more of a weakness or TUTT underneath (SFLcane’s images).

[SFLcane]

Stop it Ben…

 https://twitter.com/bennollweather/status/1415312124096794624

[SFLcane]

The ASW has been strong over the past several months, yet the MDR has barely budged in terms of its SST. As I mentioned previously, the suppressed ITCZ, coupled with the Atlantic Niño, emergent -ENSO, and active African monsoon, will likely lead to large waves exiting West Africa at a low latitude and, owing to their high amplitude and proximity to the equator, fail to develop much vorticity or organisation before crashing into South America or getting torn apart by the accelerating trades over the southeastern Caribbean Sea. Without the +AMM/+AMO stability and associated shear via the TUTT will act to suppress TCG, along with the waves’ being too large to organise before striking the northeastern tip of South America. Currently models strongly concur on the MDR being cool and thus the ITCZ being strongly suppressed come ASO.

I've seen very little signal for a strong TUTT

The EPS suggests a strongly +NAO during ASO, hence a northward displacement of the STR, implying more of a weakness or TUTT underneath (SFLcane’s images).

Please give this up.

[cycloneye]

Stop it Ben…

https://twitter.com/bennollweather/status/1415312124096794624

Those words long-lived. Yikes.

[Shell Mound]

Stop it Ben…

https://twitter.com/bennollweather/status/1415312124096794624

 https://twitter.com/BenNollWeather/status/1415289223268257796



 https://twitter.com/AndyHazelton/status/1415026722806931456



 https://twitter.com/juvenalb17/status/1415027760838422536



 https://twitter.com/AndyHazelton/status/1415077858007977989

[NotSparta]

The ASW has been strong over the past several months, yet the MDR has barely budged in terms of its SST. As I mentioned previously, the suppressed ITCZ, coupled with the Atlantic Niño, emergent -ENSO, and active African monsoon, will likely lead to large waves exiting West Africa at a low latitude and, owing to their high amplitude and proximity to the equator, fail to develop much vorticity or organisation before crashing into South America or getting torn apart by the accelerating trades over the southeastern Caribbean Sea. Without the +AMM/+AMO stability and associated shear via the TUTT will act to suppress TCG, along with the waves’ being too large to organise before striking the northeastern tip of South America. Currently models strongly concur on the MDR being cool and thus the ITCZ being strongly suppressed come ASO.

I've seen very little signal for a strong TUTT

The EPS suggests a strongly +NAO during ASO, hence a northward displacement of the STR, implying more of a weakness or TUTT underneath (SFLcane’s images).

Oh yeah I could certainly see that. Just haven't seen a lot of shear forecasts lately that look like a classic TUTT. The most recent IMME run actually had a lot of westerly shear in the MDR but the TUTT was nowhere to be seen, it seemed to be caused by an overactive ITCZ

[Shell Mound]

I've seen very little signal for a strong TUTT

The EPS suggests a strongly +NAO during ASO, hence a northward displacement of the STR, implying more of a weakness or TUTT underneath (SFLcane’s images).

Oh yeah I could certainly see that. Just haven't seen a lot of shear forecasts lately that look like a classic TUTT. The most recent IMME run actually had a lot of westerly shear in the MDR but the TUTT was nowhere to be seen, it seemed to be caused by an overactive ITCZ

If the NAO is strongly positive during the same timeframe, then the coolish MDR + any EPAC convection + TUTT + ITCZ-related VWS could really kill the CV season.

Additionally, such a strongly +NAO, by imparting a TUTT-related weakness beneath the displaced STR, could allow storms that develop to head OTS earlier.

[NotSparta]

The EPS suggests a strongly +NAO during ASO, hence a northward displacement of the STR, implying more of a weakness or TUTT underneath (SFLcane’s images).

Oh yeah I could certainly see that. Just haven't seen a lot of shear forecasts lately that look like a classic TUTT. The most recent IMME run actually had a lot of westerly shear in the MDR but the TUTT was nowhere to be seen, it seemed to be caused by an overactive ITCZ

If the NAO is strongly positive during the same timeframe, then the coolish MDR + any EPAC convection + TUTT + ITCZ-related VWS could really kill the CV season.

EPAC convection looks suppressed, and you can't have the TUTT and an active ITCZ shearing the tropics at the same time. If the ITCZ is that strong, all the upper level heat release and -VP generation will severely stunt the TUTT

[Shell Mound]

Oh yeah I could certainly see that. Just haven't seen a lot of shear forecasts lately that look like a classic TUTT. The most recent IMME run actually had a lot of westerly shear in the MDR but the TUTT was nowhere to be seen, it seemed to be caused by an overactive ITCZ

If the NAO is strongly positive during the same timeframe, then the coolish MDR + any EPAC convection + TUTT + ITCZ-related VWS could really kill the CV season.

EPAC convection looks suppressed, and you can't have the TUTT and an active ITCZ shearing the tropics at the same time. If the ITCZ is that strong, all the upper level heat release and -VP generation will severely stunt the TUTT

Do you think the active ITCZ could partly offset the coolish MDR (implied stability) and thus still produce some large storms, à la Frances, Ivan, or Irma?

 https://twitter.com/DerekOrtt/status/1415076770743832581