2024-2025 La Nina

[bluewave]

The PDO at 500 mb is also near the most negative on record for the first half of October matching the SST index. This is a continuation of the record Aleutian ridge which has been in place this year. The poleward extension over the next 10 days will help to amplify the Southeast Ridge to near record levels for late October as the AO sees a near record increase also.

 

 

[PhiEaglesfan712]

54 minutes ago, Stormchaserchuck1 said:

I'm not sure why you're posting September TAO/Triton subsurface.. the subsurface has since neutralized, with no regions greater than +1c. CPC is still showing cold subsurface waters though. I don't know which one is more accurate. 

I will say that we probably don't see an official La Nina with 5 consecutive months < -0.5. That would give us only our 2nd ENSO Neutral year in that last 11, if I'm right. Of course, other things like the MEI and RONI are showing La Nina, and they have higher pattern correlations. But I wonder how much those things are associated with the PDO? PDO at -3 right now is nothing to overlook, given how strong of an indicator it has been over the last 4-30 years. 

This October is fitting the -PDO H5 about as closely as you are ever going to see. I would love to separate this and ENSO, to see if my ENSO subsurface theory still holds up. 

The last real ENSO neutral season was 2013-14. However, 2014-15 and 2019-20 were pretty much ENSO neutral on both the MEI and RONI. Both years had at least 3+ trimonthlies of +0.5 on the ONI, so they technically meet the definition of a weak el nino.

That said, I think we eek out at least 3 trimonthlies of -0.5 on the ONI and get the weak la nina on that measure like 2016-17. Regardless of whether the ONI stays an ENSO neutral or meets weak la nina status, this year is going to be very hard to classify if we get the expected strong la nina on the MEI and moderate la nina on the RONI.

[Typhoon Tip]

52 minutes ago, bluewave said:

The PDO at 500 mb is also near the most negative on record for the first half of October matching the SST index. This is a continuation of the record Aleutian ridge which has been in place this year. The poleward extension over the next 10 days will help to amplify the Southeast Ridge to near record levels for late October as the AO sees a near record increase also.

 

 

more of an extended range forecast post above than an enso topic but yeah.  heh.

i would also add that wave lengths are in seasonal flux ... that aleu anomaly, once faster foot velocities are installed and the rossby wave numbers reduce, that's not likely to be there.   or if so ...it's likelier that the winter paradigm happened to end up doing the same thing thru a different wave number.   just sayn'   in a nut shell that's probably partial in why octobers bear so little statistical value wrt ensuing winters

frankly ... i think we're seeing a dominant +annular mode this winter, regardless ... and, doing so in this particular era of the 'hockey stick' cc explosive rise ... it's like trying to sniff out a winter fragrance in a room full o digshit.

[40/70 Benchmark]

4 minutes ago, PhiEaglesfan712 said:

The last real ENSO neutral season was 2013-14. However, 2014-15 and 2019-20 were pretty much ENSO neutral on both the MEI and RONI. Both years had at least 3+ trimonthlies of +0.5 on the ONI, so they technically meet the definition of a weak el nino.

That said, I think we eek out at least 3 trimonthlies of -0.5 on the ONI and get the weak la nina on that measure like 2016-17. Regardless of whether the ONI stays an ENSO neutral or meets weak la nina status, this year is going to be very hard to classify if we get the expected strong la nina on the MEI and moderate la nina on the RONI.

I don't think the MEI will be strong....-1.0 to -1.2. -1.2 to -1.4 RONI.

-.0.8 to -1  ONI

[PhiEaglesfan712]

1 hour ago, 40/70 Benchmark said:

I don't think the MEI will be strong....-1.0 to -1.2. -1.2 to -1.4 RONI.

-.0.8 to -1  ONI

I can't see the MEI peaking at -1.0 to -1.2 when it was at -0.7 in JJ/JA. In fact, it was probably already at -1.0 to -1.2 in AS. I think we're going even deeper, probably -1.4 to -1.6, in SO. Where things stand right now, I think a peak of -1.6 to -1.8 on the MEI makes more sense with a -1.2 to -1.4 RONI and -0.8 to -1 ONI.

[Terpeast]

FWIW, all models show a healthy MJO 4-6 pass from now through end of month as per RMM charts. Amplitude about 1.5 up to 2 or a bit more. 

[Stormchaserchuck1]

4 hours ago, 40/70 Benchmark said:

Why? Hasn't +NAO been the rule?

Yeah.. I mean something globally than before. -PNA's (-PDO) have been historically associated with -NAO. I wonder if the start of +NAO's this year.. which we really haven't seen like this in a very long time could be somewhat of a change to more of a +ENSO global state, that takes place next year or something.  Despite what the CPC says the NAO is, we haven't seen troughs like this over Greenland for a long time. 

Here was the 1st one

It got up to 80* in DC one of those days

It hasn't changed the PNA/PDO yet, but maybe over the next few years it will.. coming up being the 9th time it has happened this year.  All I really saw was global High pressure 2020-2023. 

[bluewave]

2 hours ago, Typhoon Tip said:

more of an extended range forecast post above than an enso topic but yeah.  heh.

i would also add that wave lengths are in seasonal flux ... that aleu anomaly, once faster foot velocities are installed and the rossby wave numbers reduce, that's not likely to be there.   or if so ...it's likelier that the winter paradigm happened to end up doing the same thing thru a different wave number.   just sayn'   in a nut shell that's probably partial in why octobers bear so little statistical value wrt ensuing winters

frankly ... i think we're seeing a dominant +annular mode this winter, regardless ... and, doing so in this particular era of the 'hockey stick' cc explosive rise ... it's like trying to sniff out a winter fragrance in a room full o digshit.

Pretty much the October version of our recent highly amplified Aleutian Ridge and Southeast Ridge decadal winter pattern 

 

 

[40/70 Benchmark]

5 hours ago, PhiEaglesfan712 said:

I can't see the MEI peaking at -1.0 to -1.2 when it was at -0.7 in JJ/JA. In fact, it was probably already at -1.0 to -1.2 in AS. I think we're going even deeper, probably -1.4 to -1.6, in SO. Where things stand right now, I think a peak of -1.6 to -1.8 on the MEI makes more sense with a -1.2 to -1.4 RONI and -0.8 to -1 ONI.

No way.

My rationale is in here.

https://easternmassweather.blogspot.com/2024/09/consensus-aligning-with-expectations.html?m=1

[40/70 Benchmark]

13 hours ago, bluewave said:

Pretty much the October version of our recent highly amplified Aleutian Ridge and Southeast Ridge decadal winter pattern 

 

 

MJO seems to end up reasonably amplified this month....

[40/70 Benchmark]

5 hours ago, Terpeast said:

FWIW, all models show a healthy MJO 4-6 pass from now through end of month as per RMM charts. Amplitude about 1.5 up to 2 or a bit more. 

 

1 minute ago, 40/70 Benchmark said:

MJO seems to end up reasonably amplified this month....

 

[PhiEaglesfan712]

7 hours ago, 40/70 Benchmark said:

No way.

My rationale is in here.

https://easternmassweather.blogspot.com/2024/09/consensus-aligning-with-expectations.html?m=1

I guess we won't know for sure until we get the AS and SO updates, but if @bluewave's post about  "getting a very strong October La Niña atmospheric response with a record 500mb +EPO Alaskan vortex for October" is correct, then the SO number is coming in around -1.5, as the MEI was already at -0.7 at last update (JA).

It will be interesting to see after the SO number comes in (whether it's -1.2, -1.5, or even -1.8), if the MEI levels out (like it did in 1998-99), and the ONI/RONI catch up to it. If that were to happen, then 98-99 would be a great MEI/RONI match, and 2020-21 would be the best ONI/RONI/MEI match.

[bluewave]

8 hours ago, 40/70 Benchmark said:

MJO has seems to end up reasonably amplified this month....

The MJO forecasts look like we are following the warmer and less snowy groupings of La Ninas since 2010 in October 2011, 2016, 2021, and 2022 staying under +2. The better La Nina’s were higher than +2.8 like we got in 2010, 2017, and 2020. I will update the exact RMM number we reach in a few weeks.

My guess is that these weaker MJO 4-6 Octobers were able to rebound stronger from December into January allowing the MJO 4-6 to have a strong influence on the pattern. The stronger MJO 4-6s in October were more muted in December allowing the other phases and factors to dominate. But even though 17-18 started out great through early January getting into phase 8, we did end up with record 4-6 activity from mid-January into February. So it was one case where the strong October MJO 4-6 reemerged mid to late winter. While 16-17 was a warmer La Niña winter, the MJO 4-6 activity wasn’t too outrageous. But the warmth was driven by the very amplified Aleutian Ridge which acted like a strong MJO 4-6 even though the RMM wasn’t as strong as say 2011-2012, 2021-2022, and 2023. In general the MJO 4-7 phases have been very amplified regardless of ENSO state since December 2015. We could even point to March 2012 as a bit of a precursor as to what would happen to the MJO several years later.

 

 
 

It’s based on the MJO RMM amplitude and VP anomalies in phase 5-6 during La Niña Octobers since 2010. The stronger October MJO responses had better winters in NYC relative to the other La Ninas in the multiyear event group. Those stronger MJO 5-6 Octobers also had the more robust peak La Niña ONIs from fall into winter of the multiyear groups.  All the La Niña winters around NYC since 11-12 have averaged warmer than normal. But even the warmer than average 17-18 and 20-21 winters had better snowfall than the other years in the multiyear group.

In addition, we haven’t had any cold neutral ENSOs in the -0.1 to -0.5 peak range with a strong -PDO since 2010. So not sure how the relationship would work for any year with the official CPC ONI not getting colder than -0.5. The other thing to consider is that we don’t know how long this relationship will continue to work it.

So I will update this post with some early ideas for the coming winter after we see how the MJO verifies for the month of October. 

http://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt

https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

 

Multiyear La Niña groupings below with peak MJO 5-6 strength and the peak ONI from the fall into winter…….Strongest October MJO 5-6 and La Niña ONI leading to best NYC winters of the multiyear group bolded…

 

October 2022…Phase 6 peak +2.177…..ONI….-1.0

October 2021….Phase 5 peak +2.087….ONI….-1.0

October 2020…Phase 5 peak +2.818….ONI…..-1.3

 

October 2017….Phase 6 peak +3.353….ONI….-1.0

October 2016….Phase 5 peak +1.800….ONI….-0.7

 

October 2011….Phase 6 peak +1.674….ONI….-1.1

October 2010….Phase 5 peak +2.880…ONI…..-1.6 

[40/70 Benchmark]

28 minutes ago, bluewave said:

The MJO forecasts look like we are following the warmer and less snowy groupings of La Ninas since 2010 in October 2011, 2016, 2021, and 2022 staying under +2. The better La Nina’s were higher than +2.8 like we got in 2010, 2017, and 2020. I will update the exact RMM number we reach in a few weeks.

My guess is that these weaker MJO 4-6 Octobers were able to rebound stronger from December into January allowing the MJO 4-6 to have a strong influence on the pattern. The stronger MJO 4-6s in October were more muted in December allowing the other phases and factors to dominate. But even though 17-18 started out great through early January getting into phase 8, we did end up with record 4-6 activity from mid-January into February. So it was one case where the strong October MJO 4-6 reemerged mid to late winter. While 16-17 was a warmer La Niña winter, the MJO 4-6 activity wasn’t too outrageous. But the warmth was driven by the very amplified Aleutian Ridge which acted like a strong MJO 4-6 even though the RMM wasn’t as strong as say 2011-2012, 2021-2022, and 2023. In general the MJO 4-7 phases have been very amplified regardless of ENSO state since December 2015. We could even point to March 2012 as a bit of a precursor as to what would happen to the MJO several years later.

 

 
 

It’s based on the MJO RMM amplitude and VP anomalies in phase 5-6 during La Niña Octobers since 2010. The stronger October MJO responses had better winters in NYC relative to the other La Ninas in the multiyear event group. Those stronger MJO 5-6 Octobers also had the more robust peak La Niña ONIs from fall into winter of the multiyear groups.  All the La Niña winters around NYC since 11-12 have averaged warmer than normal. But even the warmer than average 17-18 and 20-21 winters had better snowfall than the other years in the multiyear group.

In addition, we haven’t had any cold neutral ENSOs in the -0.1 to -0.5 peak range with a strong -PDO since 2010. So not sure how the relationship would work for any year with the official CPC ONI not getting colder than -0.5. The other thing to consider is that we don’t know how long this relationship will continue to work it.

So I will update this post with some early ideas for the coming winter after we see how the MJO verifies for the month of October. 

http://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt

https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

 

Multiyear La Niña groupings below with peak MJO 5-6 strength and the peak ONI from the fall into winter…….Strongest October MJO 5-6 and La Niña ONI leading to best NYC winters of the multiyear group bolded…

 

October 2022…Phase 6 peak +2.177…..ONI….-1.0

October 2021….Phase 5 peak +2.087….ONI….-1.0

October 2020…Phase 5 peak +2.818….ONI…..-1.3

 

October 2017….Phase 6 peak +3.353….ONI….-1.0

October 2016….Phase 5 peak +1.800….ONI….-0.7

 

October 2011….Phase 6 peak +1.674….ONI….-1.1

October 2010….Phase 5 peak +2.880…ONI…..-1.6 

The ONI is def. going to be towards the less snowy group...with the exception of 2017 and 2021.

I continue to think a season like 2021-2022 is doable, whereas we got the one very good stretch.

[40/70 Benchmark]

1 hour ago, PhiEaglesfan712 said:

I guess we won't know for sure until we get the AS and SO updates, but if @bluewave's post about  "getting a very strong October La Niña atmospheric response with a record 500mb +EPO Alaskan vortex for October" is correct, then the SO number is coming in around -1.5, as the MEI was already at -0.7 at last update (JA).

It will be interesting to see after the SO number comes in (whether it's -1.2, -1.5, or even -1.8), if the MEI levels out (like it did in 1998-99), and the ONI/RONI catch up to it. If that were to happen, then 98-99 would be a great MEI/RONI match, and 2020-21 would be the best ONI/RONI/MEI match.

Yea, its def. tougher to say with the gap in data.

[snowman19]

more of an extended range forecast post above than an enso topic but yeah.  heh.
i would also add that wave lengths are in seasonal flux ... that aleu anomaly, once faster foot velocities are installed and the rossby wave numbers reduce, that's not likely to be there.   or if so ...it's likelier that the winter paradigm happened to end up doing the same thing thru a different wave number.   just sayn'   in a nut shell that's probably partial in why octobers bear so little statistical value wrt ensuing winters
frankly ... i think we're seeing a dominant +annular mode this winter, regardless ... and, doing so in this particular era of the 'hockey stick' cc explosive rise ... it's like trying to sniff out a winter fragrance in a room full o digshit.

I remember reading an article a few years ago musing that the record low arctic sea ice was one of the contributing factors leading to the propensity of +AO/NAM. I can absolutely buy that. There was another theory running around the first year sea ice went very low that it was going to lead to well above normal/record snowfall in the arctic (increased evaporation/moisture) and cause a -AO winter. That was obviously a miserable failure and lead to a bunch of busted winter forecasts

[bluewave]

29 minutes ago, 40/70 Benchmark said:

The ONI is def. going to be towards the less snowy group...with the exception of 2017 and 2021.

I continue to think a season like 2021-2022 is doable, whereas we got the one very good stretch.

It’s little details like that which can be challenging detect much before we get to within the range of the 6-10 and 11-15 day forecast. The winter began with the near record Aleutian Ridge -PNA and very amplified MJO 6-7 forcing in December leading to the +13 warmest December at DFW. But we got the great MJO 8 in January salvaging the entire winter. Even though areas south of New England flipped back to the warmer and less snowy pattern in February. Unfortunately, we have had more examples of big MJO 4-7 transits weakening before 8 only to reload in 4-7 again. So we will probably need some help from the MJO 8 or even something else in order to avoid the winter pattern which has been locked in since February 2022.

[40/70 Benchmark]

14 minutes ago, snowman19 said:

I remember reading an article a few years ago musing that the record low arctic sea ice was one of the contributing factors leading to the propensity of +AO/NAM. I can absolutely buy that. There was another theory running around the first year sea ice went very low that it was going to lead to well above normal/record snowfall in the arctic (increased evaporation/moisture) and cause a -AO winter. That was obviously a miserable failure and lead to a bunch of busted winter forecasts

We have had a good deal of -AO these past several years...I think I could buy that argument more with respect to the NAO.

[40/70 Benchmark]

10 minutes ago, bluewave said:

It’s little details like that which can be challenging detect much before we get to within the range of the 6-10 and 11-15 day forecast. The winter began with the near record Aleutian Ridge -PNA and very amplified MJO 6-7 forcing in December leading to the +13 warmest December at DFW. But we got the great MJO 8 in January salvaging the entire winter. Even though areas south of New England flipped back to the warmer and less snowy pattern in February. Unfortunately, we have had more examples of big MJO 4-7 transits weakening before 8 only to reload in 4-7 again. So we will probably need some help from the MJO 8 or even something else in order to avoid the winter pattern which has been locked in since February 2022.

This isn't very scientific, but we are "due" for some of those little nuances to go our way. Obviously seasonal forecasing is a next to impossible endeavor due to most of our skill being relegeated to the medium range, as you point out, so at the end of the day it often comes down to anecdotal, educated hunches.

[snowman19]

4 minutes ago, 40/70 Benchmark said:

We have had a good deal of -AO these past several years...I think I could buy that argument more with respect to the NAO.

Yes, I think it definitely affects the NAO too. No argument there. I think it’s more of a potentiating factor on the AO when other +AO factors are present. This year, I have to agree with @Typhoon Tip that we very likely see a dominant +AO given the -ENSO/solar/+QBO/low arctic sea ice states

[40/70 Benchmark]

[40/70 Benchmark]

6 minutes ago, snowman19 said:

Yes, I think it definitely affects the NAO too. No argument there. I think it’s more of a potentiating factor on the AO when other +AO factors are present. This year, I have to agree with @Typhoon Tip that we very likely see a dominant +AO given the -ENSO/solar/+QBO/low arctic sea ice states

On paper, I would agree....but careful of an instance like Dec 22, whereas you get one huge -AO month that skews the mean. That season is a very good analog and is also an illustration of why blocking is not impossible in a high solar/+QBO-La Nina.

[40/70 Benchmark]

I know folks like to shit on the climate guidance, but I think they are going to have a better idea than they did last season, since ENSO is congruent with the predominate hemispheric background state of the past several years.

[bluewave]

1 hour ago, 40/70 Benchmark said:

This isn't very scientific, but we are "due" for some of those little nuances to go our way. Obviously seasonal forecasing is a next to impossible endeavor due to most of our skill being relegeated to the medium range, as you point out, so at the end of the day it often comes down to anecdotal, educated hunches.

Yeah, we can try to outline some of the broad general themes for the winter in October. But the finer details usually have to wait until we get to the medium range. While the recent MJO is a little more amplified, it’s still closer to +2 than the better La Niña years near +3. It’s interesting how this pattern also matches the general La Niña strength. And the stronger ONI La Niña winters back to 2010 were the best of the multiyear groupings. Goes against the pattern of the weaker La Ninas being better from 1995 to 2009 than the really strong ones.

 

[snowman19]

[40/70 Benchmark]

6 minutes ago, snowman19 said:

 

Yay, a winter of solar orgies!

[40/70 Benchmark]

I remember there was some thought that last year was the solar max and it just kept rising, so we'll have to see. Given that the ascending phase if most favorable for high latitude blocking, we are probably a little less prone than 2022 was to amplified abouts of -AO/NAO.

[rclab]

28 minutes ago, 40/70 Benchmark said:

Yay, a winter of solar orgies!

Good morning 40/70 …. In retrospect, maybe you should go for those union suit snow angels. Stay well and calm, as always ……

[snowman19]

@40/70 Benchmark @Typhoon Tip

Here is a 2021 study on arctic sea ice loss and QBO effects. Per the study: “The stratospheric polar vortex in the northern hemisphere weakens in response to Arctic sea-ice loss during QBO easterly but strengthens in response to Arctic sea-ice loss during QBO westerly. The polar vortex state is not found to be as strongly modulated by ENSO as the QBO. During El Niño with QBO westerly however, there is an observed change in seasonality of the tropospheric response to sea-ice loss compared to the neutral ENSO state”

https://ui.adsabs.harvard.edu/abs/2021AGUFM.A15I1771W/abstract

[qg_omega]