2024-2025 La Nina

[so_whats_happening]

3 hours ago, snowman19 said:

IMO it doesn’t get warm in the east until after mid-January. Come late month, I think it’s canonical La Niña time…..-PNA/RNA and the SE ridge pops

This is a big thing in question right now the only thing that could truly disrupt that potential is a Major SSW event which interestingly enough is starting to show some signs at hour 240 (about first week of January onward) of something trying to develop. Now I would like to see a few more runs as we get into the new year and continue showing this.

As for the pattern this has been the strongest 850mb wind response so far this event from mid November to mid December. The last was back at the end of summer (end of August/early September) with the enhanced trades. This was when we saw our first Nina like response show up where we went from warm neutral into cool neutral. This should start to level off and create another small rise in 3.4 SST coming up over the next 2-3 weeks before things potentially restart with stronger trades around mid January?

A trimonthly of below -.5 may be hard to come by again depending on how things evolve the next month. This monthly should come in around -.7 ish maybe -.8. If we get January to cooperate in the same manner we can hit that -.5 threshold for a trimonthly just barely pushing the Nina status (not officially since we won't have 5 months most likely) but the effects of this should be enough to allow the atmosphere to respond.

If we continue to cool into January and February we definitely start to run the risk of it being officially being labeled La Nina via CPC standards I'm not sure of this yet. We could potentially be setting ourselves up for another string of Ninas as several years have had Nina-like conditions before a Nino spike and going back to Nina the following years. It is fairly odd to get this type of push this late in the typical ENSO timeframe but seemingly not too unheard of as several seasons did have a late peak of NDJ and even DJF.

This season has definitely thrown some curveballs so far and I'm not sure we are done with those surprises.

[snowman19]

19 minutes ago, so_whats_happening said:

This is a big thing in question right now the only thing that could truly disrupt that potential is a Major SSW event which interestingly enough is starting to show some signs at hour 240 (about first week of January onward) of something trying to develop. Now I would like to see a few more runs as we get into the new year and continue showing this.

As for the pattern this has been the strongest 850mb wind response so far this event from mid November to mid December. The last was back at the end of summer (end of August/early September) with the enhanced trades. This was when we saw our first Nina like response show up where we went from warm neutral into cool neutral. This should start to level off and create another small rise in 3.4 SST coming up over the next 2-3 weeks before things potentially restart with stronger trades around mid January?

A trimonthly of below -.5 may be hard to come by again depending on how things evolve the next month. This monthly should come in around -.7 ish maybe -.8. If we get January to cooperate in the same manner we can hit that -.5 threshold for a trimonthly just barely pushing the Nina status (not officially since we won't have 5 months most likely) but the effects of this should be enough to allow the atmosphere to respond.

If we continue to cool into January and February we definitely start to run the risk of it being officially being labeled La Nina via CPC standards I'm not sure of this yet. We could potentially be setting ourselves up for another string of Ninas as several years have had Nina-like conditions before a Nino spike and going back to Nina the following years. It is fairly odd to get this type of push this late in the typical ENSO timeframe but seemingly not too unheard of as several seasons did have a late peak of NDJ and even DJF.

This season has definitely thrown some curveballs so far and I'm not sure we are done with those surprises.

Even if we were to see a SSW, I’m not sure that would stop a canonical La Niña response (-PNA/trough in the west) in the NPAC. It may modulate the AO/NAO states, but I can’t see it stopping a -PNA from forming or altering the Niña progression or tropical PAC convection/MJO 

[Daniel Boone]

3 minutes ago, snowman19 said:

Even if we were to see a SSW, I’m not sure that would stop a canonical La Niña response (-PNA/trough in the west) in the NPAC. It may modulate the AO/NAO states, but I can’t see it stopping a -PNA from forming or altering the Niña progression or tropical PAC convection/MJO 

Dec and January 10-11 come to mind. Moderate to strong Nina then. There's other instances as well. Enough blocking, backed flow can alter the typical response as most know. Particularly a weak Nina . 

[BuffaloWeather]

1 hour ago, so_whats_happening said:

This is a big thing in question right now the only thing that could truly disrupt that potential is a Major SSW event which interestingly enough is starting to show some signs at hour 240 (about first week of January onward) of something trying to develop. Now I would like to see a few more runs as we get into the new year and continue showing this.

As for the pattern this has been the strongest 850mb wind response so far this event from mid November to mid December. The last was back at the end of summer (end of August/early September) with the enhanced trades. This was when we saw our first Nina like response show up where we went from warm neutral into cool neutral. This should start to level off and create another small rise in 3.4 SST coming up over the next 2-3 weeks before things potentially restart with stronger trades around mid January?

A trimonthly of below -.5 may be hard to come by again depending on how things evolve the next month. This monthly should come in around -.7 ish maybe -.8. If we get January to cooperate in the same manner we can hit that -.5 threshold for a trimonthly just barely pushing the Nina status (not officially since we won't have 5 months most likely) but the effects of this should be enough to allow the atmosphere to respond.

If we continue to cool into January and February we definitely start to run the risk of it being officially being labeled La Nina via CPC standards I'm not sure of this yet. We could potentially be setting ourselves up for another string of Ninas as several years have had Nina-like conditions before a Nino spike and going back to Nina the following years. It is fairly odd to get this type of push this late in the typical ENSO timeframe but seemingly not too unheard of as several seasons did have a late peak of NDJ and even DJF.

This season has definitely thrown some curveballs so far and I'm not sure we are done with those surprises.

Buffalo NWS says we had a SSW 10-14 days ago? Their morning discussion.

Looking further ahead into the start of 2025...

A BIG change in our weather can be expected immediately after the
New Year. The relatively low amplitude Pacific based flow that will
have dominated the Lower 48 the past week or so with above normal
temperatures will be replaced by a high amplitude, coupled +PNA/
-NAO pattern that will feature our first cross polar flow in at
LEAST two years. Boiling this down, it simply means that there is
HIGH confidence that our temperatures will plunge back to well BELOW
normal, with the potential for this change to persist at least a
week.

The first signal of this dramatic change back to mid winter weather
was a fairly significant stratospheric warming event that took place
some 10 to 14 days ago. Sudden warming above 10mb usually results in
a change in the arctic jet that translates into significant changes
to the Arctic oscillation along with the corresponding North
Atlantic oscillation. Within two to three weeks, this change in the
high latitude flow will lead to an impressive surge of cold air that
will make its way across eastern Canada and the northeastern portion
of the Lower 48. Supporting this compelling change to mid winter
conditions is agreement among many of the ensembles that anomalously
strong ridging will be found along the West Coast (+PNA) while broad
ridging will also build across Greenland and the North Atlantic (-
NAO). This coupled pattern has a very high correlation to below
normal temperatures throughout the Great Lakes region.

The proverbial `icing on the cake` for this event is that many
ensembles also suggest that a cross polar flow will develop. This
will allow arctic air to settle southwards across eastern Canada
where H85 temps in the -20s C will be common. Fortunately, the
source region for the air in this event does is not especially cold
at this time, or the event could be more noteworthy.

[mitchnick]

1 hour ago, so_whats_happening said:

This is a big thing in question right now the only thing that could truly disrupt that potential is a Major SSW event which interestingly enough is starting to show some signs at hour 240 (about first week of January onward) of something trying to develop. Now I would like to see a few more runs as we get into the new year and continue showing this.

As for the pattern this has been the strongest 850mb wind response so far this event from mid November to mid December. The last was back at the end of summer (end of August/early September) with the enhanced trades. This was when we saw our first Nina like response show up where we went from warm neutral into cool neutral. This should start to level off and create another small rise in 3.4 SST coming up over the next 2-3 weeks before things potentially restart with stronger trades around mid January?

A trimonthly of below -.5 may be hard to come by again depending on how things evolve the next month. This monthly should come in around -.7 ish maybe -.8. If we get January to cooperate in the same manner we can hit that -.5 threshold for a trimonthly just barely pushing the Nina status (not officially since we won't have 5 months most likely) but the effects of this should be enough to allow the atmosphere to respond.

If we continue to cool into January and February we definitely start to run the risk of it being officially being labeled La Nina via CPC standards I'm not sure of this yet. We could potentially be setting ourselves up for another string of Ninas as several years have had Nina-like conditions before a Nino spike and going back to Nina the following years. It is fairly odd to get this type of push this late in the typical ENSO timeframe but seemingly not too unheard of as several seasons did have a late peak of NDJ and even DJF.

This season has definitely thrown some curveballs so far and I'm not sure we are done with those surprises.

One caveat on the possible SSW. We have had an extremely anomalous PV; hat tip to Snowman banging that drum. Notwithstanding, the shape/trajectory has not precluded the cold, and possibly enhanced it, idk. But if we get that warming as progged, that may alter the trajectory but not be enough to help the threat of cold/snow in the east. I have no control over it, obviously, but I  think I'd prefer leaving 10mb alone at this point. Lol

[michsnowfreak]

23 hours ago, Snowstorms said:

I guess it depends where you're geographically located. A strong El Nino is an almost guaranteed torch especially now with climate change and we can see that radical shift after the 70's. 82-83, 91-92, 97-98, 15-16, and 23-24 all blowtorches.

El Nino's are great in offering big storm potentials. However, most moderate-strong Nina's that were preceded by El Nino's can offer a lot of storm potentials and we saw this with 2007-08, 2010-11, 2016-2018. Most weak Nino's are great at keeping a weak Aleutian low present allowing for good cross polar and blocking patterns to emerge.  

Similarly, La Nina is great if its dominating the pattern which allows for a poleward Aleutian ridge which can either morph into a -EPO pattern or allow for cross polar flow with a -AO/NAO. It may keep the centre of cold near the Plains and Midwest, but it's good for allowing strong gradient storms to develop or coastal storms when the trough displaces east. This also helps keep a longer lasting snow cover. 

I prefer mod-strong La Nina's and weak Nino's. Weak Nina's (ONI <= -0.9) or strong Nino's can go either way. Mod Nino's are okay, if we have good blocking. 

Merry Christmas 

 

Weak ninos can be ok, but strong ninos have always, always sucked here. It's not even a contest. If it's not neutral, I'll take any kind/strength of Nina over a strong Nino.

[LibertyBell]

2 hours ago, snowman19 said:

Even if we were to see a SSW, I’m not sure that would stop a canonical La Niña response (-PNA/trough in the west) in the NPAC. It may modulate the AO/NAO states, but I can’t see it stopping a -PNA from forming or altering the Niña progression or tropical PAC convection/MJO 

It might still be okay for snow in the east come March because of shortening wavelengths though.

[mitchnick]

Euro AI was a little drunk for the past day or so but sobered up at 12z.

[so_whats_happening]

2 hours ago, snowman19 said:

Even if we were to see a SSW, I’m not sure that would stop a canonical La Niña response (-PNA/trough in the west) in the NPAC. It may modulate the AO/NAO states, but I can’t see it stopping a -PNA from forming or altering the Niña progression or tropical PAC convection/MJO 

Depends on what type of SSW takes hold and what pattern should evolve from this event. If we get a solid wave 2 potential that shows up it could reshuffle the pattern in our favor a lot better than a large wave 1 response like we saw last year. Of course a wave 2 response doesn't always mean ridge west/trough east. The propensity of the atmospheric pattern to not fully revert back to the constant deep -PNA has been a nice change-up for this year even with a La Nina starting to actually build properly.

The SSW (which this one I actually consider significant) that came in the beginning of January 2024 I think just linked up in the wrong spot for us. We had a fairly strong 500mb ridge in SE Canada already in place leading into that strong wave 1 response so it locked the pattern up rather quickly and we just could not shake it we also did not see the breakdown of the SPV fully so once the warming was done it started to gather itself together again. Talk about unlucky. Now if we get significant wave 1 or wave 2 (preferably) with an atmospheric pattern of ridging into Alaska and retracted Pacific jet like we have been seeing off an on I wonder if the results would be different, I mean they should just not sure how it would translate yet.

2 hours ago, BuffaloWeather said:

Buffalo NWS says we had a SSW 10-14 days ago? Their morning discussion.

Looking further ahead into the start of 2025...

A BIG change in our weather can be expected immediately after the
New Year. The relatively low amplitude Pacific based flow that will
have dominated the Lower 48 the past week or so with above normal
temperatures will be replaced by a high amplitude, coupled +PNA/
-NAO pattern that will feature our first cross polar flow in at
LEAST two years. Boiling this down, it simply means that there is
HIGH confidence that our temperatures will plunge back to well BELOW
normal, with the potential for this change to persist at least a
week.

The first signal of this dramatic change back to mid winter weather
was a fairly significant stratospheric warming event that took place
some 10 to 14 days ago. Sudden warming above 10mb usually results in
a change in the arctic jet that translates into significant changes
to the Arctic oscillation along with the corresponding North
Atlantic oscillation. Within two to three weeks, this change in the
high latitude flow will lead to an impressive surge of cold air that
will make its way across eastern Canada and the northeastern portion
of the Lower 48. Supporting this compelling change to mid winter
conditions is agreement among many of the ensembles that anomalously
strong ridging will be found along the West Coast (+PNA) while broad
ridging will also build across Greenland and the North Atlantic (-
NAO). This coupled pattern has a very high correlation to below
normal temperatures throughout the Great Lakes region.

The proverbial `icing on the cake` for this event is that many
ensembles also suggest that a cross polar flow will develop. This
will allow arctic air to settle southwards across eastern Canada
where H85 temps in the -20s C will be common. Fortunately, the
source region for the air in this event does is not especially cold
at this time, or the event could be more noteworthy.

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/flux/vtn_10_2024_merra2.pdf

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/temp/t60_90n_10_2024_merra2.pdf

We had a heat flux but not a significant stratospheric warming event that took place. It was at best a displacement event that happened to work a little bit in our favor instead of roasting us like what typically happens in a Wave 1 response. I don't want to discredit that it was a stratospheric warming event but it was nothing noteworthy. Maybe it was because the SPV was already well established and strong that we didn't see a significant rise in temperature other than to near average? 

1 hour ago, mitchnick said:

One caveat on the possible SSW. We have had an extremely anomalous PV; hat tip to Snowman banging that drum. Notwithstanding, the shape/trajectory has not precluded the cold, and possibly enhanced it, idk. But if we get that warming as progged, that may alter the trajectory but not be enough to help the threat of cold/snow in the east. I have no control over it, obviously, but I  think I'd prefer leaving 10mb alone at this point. Lol

This warming event we just had helped relax the SPV and bring it back to what is typically average for this time of year so any further attacks will start to impede in the strength much more, if we do see these attacks come to fruition. As for the snow/cold possibilities that come along with it I think the important thing would be to have much more wave 2 response, this means help not only from the Alaska region (which is the typical location of the 10mb ridge) but also over northern Europe. We need poleward flux/ wavebreak events (negative tilted troughing leading to large blocking highs) to happen and that seems to only be on the Pacific side right now, the Atlantic has been having more equatorward wavebreak events which still helps to keep the SPV intact. We had a very strong wave 1 response last year that gave us a blip of winter weather hopefully it is not a wash rinse repeat scenario.

This was last years wave 1 response compared to this years (seen above). Of course the SPV was a bit weaker last year so it helped to rock the boat a bit more compared to this year. Angle of attack is also extremely important as to the proper effects into the mid latitude maybe because the Pacific jet was a bit stronger due to a deep -PDO state that was not changing caused it to have a different location for the atmospheric ridging location? May be something worth looking into down the road.

[so_whats_happening]

Just now, so_whats_happening said:

Depends on what type of SSW takes hold and what pattern should evolve from this event. If we get a solid wave 2 potential that shows up it could reshuffle the pattern in our favor a lot better than a large wave 1 response like we saw last year. Of course a wave 2 response doesn't always mean ridge west/trough east. The propensity of the atmospheric pattern to not fully revert back to the constant deep -PNA has been a nice change-up for this year even with a La Nina starting to actually build properly.

The SSW (which this one I actually consider significant) that came in the beginning of January 2024 I think just linked up in the wrong spot for us. We had a fairly strong 500mb ridge in SE Canada already in place leading into that strong wave 1 response so it locked the pattern up rather quickly and we just could not shake it we also did not see the breakdown of the SPV fully so once the warming was done it started to gather itself together again. Talk about unlucky. Now if we get significant wave 1 or wave 2 (preferably) with an atmospheric pattern of ridging into Alaska and retracted Pacific jet like we have been seeing off an on I wonder if the results would be different, I mean they should just not sure how it would translate yet.

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/flux/vtn_10_2024_merra2.pdf

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/temp/t60_90n_10_2024_merra2.pdf

We had a heat flux but not a significant stratospheric warming event that took place. It was at best a displacement event that happened to work a little bit in our favor instead of roasting us like what typically happens in a Wave 1 response. I don't want to discredit that it was a stratospheric warming event but it was nothing noteworthy. Maybe it was because the SPV was already well established and strong that we didn't see a significant rise in temperature other than to near average? 

This warming event we just had helped relax the SPV and bring it back to what is typically average for this time of year so any further attacks will start to impede in the strength much more, if we do see these attacks come to fruition. As for the snow/cold possibilities that come along with it I think the important thing would be to have much more wave 2 response, this means help not only from the Alaska region (which is the typical location of the 10mb ridge) but also over northern Europe. We need poleward flux/ wavebreak events (negative tilted troughing leading to large blocking highs) to happen and that seems to only be on the Pacific side right now, the Atlantic has been having more equatorward wavebreak events which still helps to keep the SPV intact. We had a very strong wave 1 response last year that gave us a blip of winter weather hopefully it is not a wash rinse repeat scenario.

This was last years wave 1 response compared to this years (seen above). Of course the SPV was a bit weaker last year so it helped to rock the boat a bit more compared to this year. Angle of attack is also extremely important as to the proper effects into the mid latitude maybe because the Pacific jet was a bit stronger due to a deep -PDO state that was not changing caused it to have a different location for the atmospheric ridging location? May be something worth looking into down the road.

Mind you scale is different between the two years but here was the temperature anomaly that occurred between the two events. Similar placement as far as warming goes (again fairly typical location) this years was a bit weaker than last years that took place in the beginning of December. Now will be the interesting part of what comes of it. We saw another attack that occurred, a much more significant one, about a month later so if timing is similar we should see a significant warming event after the first week of January. We should start to see it on models by the end of the month as the first 10 days will be within view for January, 10th day being about the month mark after the first strike took place.

Reminder the atmospheric pattern is much different this year so far leading into the potential second strike onto the SPV than what we had last year. Just something to keep in mind. I say potential because nothing is set in stone this far out but it is nice to see the models are trying to pick up on something.

[LakePaste25]

3 hours ago, BuffaloWeather said:

Buffalo NWS says we had a SSW 10-14 days ago? Their morning discussion.

Looking further ahead into the start of 2025...

A BIG change in our weather can be expected immediately after the
New Year. The relatively low amplitude Pacific based flow that will
have dominated the Lower 48 the past week or so with above normal
temperatures will be replaced by a high amplitude, coupled +PNA/
-NAO pattern that will feature our first cross polar flow in at
LEAST two years. Boiling this down, it simply means that there is
HIGH confidence that our temperatures will plunge back to well BELOW
normal, with the potential for this change to persist at least a
week.

The first signal of this dramatic change back to mid winter weather
was a fairly significant stratospheric warming event that took place
some 10 to 14 days ago. Sudden warming above 10mb usually results in
a change in the arctic jet that translates into significant changes
to the Arctic oscillation along with the corresponding North
Atlantic oscillation. Within two to three weeks, this change in the
high latitude flow will lead to an impressive surge of cold air that
will make its way across eastern Canada and the northeastern portion
of the Lower 48. Supporting this compelling change to mid winter
conditions is agreement among many of the ensembles that anomalously
strong ridging will be found along the West Coast (+PNA) while broad
ridging will also build across Greenland and the North Atlantic (-
NAO). This coupled pattern has a very high correlation to below
normal temperatures throughout the Great Lakes region.

The proverbial `icing on the cake` for this event is that many
ensembles also suggest that a cross polar flow will develop. This
will allow arctic air to settle southwards across eastern Canada
where H85 temps in the -20s C will be common. Fortunately, the
source region for the air in this event does is not especially cold
at this time, or the event could be more noteworthy.

They might just be referring to a sudden weakening of the PV. For an official SSW, these winds need to drop below 0 m/s which only has a few ensemble members doing so near the end of January into February.

[so_whats_happening]

28 minutes ago, LakePaste25 said:

They might just be referring to a sudden weakening of the PV. For an official SSW, these winds need to drop below 0 m/s which only has a few ensemble members doing so near the end of January into February.

Major SSW cause a reversal or winds dropping below 0m/s as well as warming. Minor SSW weaken the SPV and typically these are induced by a Wave 1 response.

Here is a good read for those interested in the MJO response to the SPV and potential SSW events that take place.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053144

[EasternLI]

7 hours ago, so_whats_happening said:

Depends on what type of SSW takes hold and what pattern should evolve from this event. If we get a solid wave 2 potential that shows up it could reshuffle the pattern in our favor a lot better than a large wave 1 response like we saw last year. Of course a wave 2 response doesn't always mean ridge west/trough east. The propensity of the atmospheric pattern to not fully revert back to the constant deep -PNA has been a nice change-up for this year even with a La Nina starting to actually build properly.

The SSW (which this one I actually consider significant) that came in the beginning of January 2024 I think just linked up in the wrong spot for us. We had a fairly strong 500mb ridge in SE Canada already in place leading into that strong wave 1 response so it locked the pattern up rather quickly and we just could not shake it we also did not see the breakdown of the SPV fully so once the warming was done it started to gather itself together again. Talk about unlucky. Now if we get significant wave 1 or wave 2 (preferably) with an atmospheric pattern of ridging into Alaska and retracted Pacific jet like we have been seeing off an on I wonder if the results would be different, I mean they should just not sure how it would translate yet.

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/flux/vtn_10_2024_merra2.pdf

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/temp/t60_90n_10_2024_merra2.pdf

We had a heat flux but not a significant stratospheric warming event that took place. It was at best a displacement event that happened to work a little bit in our favor instead of roasting us like what typically happens in a Wave 1 response. I don't want to discredit that it was a stratospheric warming event but it was nothing noteworthy. Maybe it was because the SPV was already well established and strong that we didn't see a significant rise in temperature other than to near average? 

This warming event we just had helped relax the SPV and bring it back to what is typically average for this time of year so any further attacks will start to impede in the strength much more, if we do see these attacks come to fruition. As for the snow/cold possibilities that come along with it I think the important thing would be to have much more wave 2 response, this means help not only from the Alaska region (which is the typical location of the 10mb ridge) but also over northern Europe. We need poleward flux/ wavebreak events (negative tilted troughing leading to large blocking highs) to happen and that seems to only be on the Pacific side right now, the Atlantic has been having more equatorward wavebreak events which still helps to keep the SPV intact. We had a very strong wave 1 response last year that gave us a blip of winter weather hopefully it is not a wash rinse repeat scenario.

This was last years wave 1 response compared to this years (seen above). Of course the SPV was a bit weaker last year so it helped to rock the boat a bit more compared to this year. Angle of attack is also extremely important as to the proper effects into the mid latitude maybe because the Pacific jet was a bit stronger due to a deep -PDO state that was not changing caused it to have a different location for the atmospheric ridging location? May be something worth looking into down the road.

Great post. I've done a fair amount of reading on this topic over the last several years. I think your thoughts are right on the mark as far as lining up with said reading. One thing I remember seeing, and I don't remember where, is that if one is looking for an ssw to deliver a colder pattern. There's a higher probability of that occurring from one that initiated during an already colder pattern. Which sounds like it lines up with your thinking on the phenomenon and kinda makes sense to me. 

[40/70 Benchmark]

Anyone see DT's latest video? Not sure why he portrays Modoki La Nina as being more favorable for east coast cold and snow...its the total opposite. Common theme I have seen with that guy is that he is absolutely inept in terms of ENSO. He was dicounting La Nina prospects all fall, and is now so shocked that the CFS was correct about La Nina developing late. Its not a suprised to anyone that researched the subsurface, dude.

[Terpeast]

1 minute ago, 40/70 Benchmark said:

Anyone see DT's latest video? Not sure why he portrays Modoki La Nina as being more favorable for east coast cold and snow...its the total opposite. Common theme I have seen with that guy is that he is absolutely inept in terms of ENSO. He was dicounting La Nina prospects all fall, and is now so shocked that the CFS was correct about La Nina developing late. Its not a suprised to anyone that researched the subsurface, dude.

IIRC, the difference between this year and 2022-23 was that the 2022 nina peaked early and slowly faded through the winter. This year seems to be a late peaker. Off the top of your head, which analogs are similar to this late peaking nina, or have we never seen a nina strengthen this late in the game?

[40/70 Benchmark]

Just now, Terpeast said:

IIRC, the difference between this year and 2022-23 was that the 2022 nina peaked early and slowly faded through the winter. This year seems to be a late peaker. Off the top of your head, which analogs are similar to this late peaking nina, or have we never seen a nina strengthen this late in the game?

My primary ENSO analog of 2008-2009. This is why I have been arguing all winter against the idea that La Nina would  a no-show.

This is an excerpt from my November outlook:

 

ENSO 2024-2025

Primary ENSO Analogs: 2021-2022, 2020-2021, 2011-2012, 2008-2009

Intensity & Structure Discussion

The October update of ENSO guidance from the International Research Institute reflected a significant reduction in the forecasted peak intensity of La Niña with a -.6 NDJ peak. 

 

 

 

While this is in better agreement with the -.4 DJF peak suggested by statistical guidance, the remaining difference still implies uncertainty with respect to whether an official La Niña will be declared. This is especially true given the paltry ASO ONI of -0.2 in conjunction with the fact that the weekly reading in region 3.4 was down from -0.5 on 10/23 to -0.2 as of 10/31. The reason for this is attributable to the behavior of the subsurface in conjunction with the zonal wind pattern during latter portion of the month of October.

The trend in the subsurface since mid October has been for the cold pool to shift east and even intensify.

 

 

 

However, during this same period of time, the trade winds have also shifted to the east and completely abated and even reversed to westerlies over region 3.4 

 

 

This has triggered a warming over region 3.4 with a burst of cooling over the eastern flank of ENSO. Note the sea surface temperature anomaly profile as of September 17th with the max anomalies focused in region 3.4

 

As compared to the max anomalies having relocated to region 3 on November 4th.

 

 

 

These changes have cooled the eastern flank of region 1.2 from -0.1C on October 16th to -0.5 on October 30, while both region 4 and 3.4 warmed from 0.1 to 0.2 and from -0.3 to -0.2, respectively. Although the trade winds are anticipated to re establish over the western flank in region 4, the forecast moving forward is precarious. There is uncertainty as to whether or not the occasional flirtation of the eastern extent of the trades with the western periphery of region 3.4 will be able to colocate with the western periphery of the subsurface cold pool to foster the development of an official La Niña event per ONI. The dynamical guidance suite, as stated, remains at odds with the statistical guidance. The former, albeit weaker, insists on the development of La Niña, and the latter has been steadfast on the ENSO neutral scenario.

 

 

This recent trend for the trade winds to be relegated to the east is already reversing, as they have to die died off and redevelop over region 4, which has halted cooling for the entire eastern half and likely even induce some warmer fluctuations. In fact, as of the November 6ht update, the region 1.2 has already warmed back up to -0.2 from -0.5 on the 30th and region 3.4 is back down to -0.3. Despite this, the notable absence of a subsurface cold pool beneath region 4 will prevent this event from becoming a full-fledged Modoki event, and it should instead remain central-based in nature. 

 

 

Guidance affirms this central based assessment, but like most hybrid events, there will be variation and mixed elements of each.

 

 

The convective forcing that has been redolent of the mixed type La Nina pattern should remain as such in the aggregate seasonal mean, however, expect it to assume that of a Modoki during warmer times, and that of an east-based event during the anticipated period of deviation. 

 

 

Note the positive precipitation anomaly beneath this area of maximum convective forcing  on model guidance.

 

The El Nino Modoki Index (EMI) forecast for the Japanese Meteorological Society confirms.

EMI analogs include  2008, 2010, 2011, 2020 and 2021 and the EMI forecast is between -.5 and -.7

Overall, while it may still appear somewhat muddled as to whether or not La Nina will officially come to fruition due to its recent stagnation coupled with the discrepancy between statistical and dynamical guidance, analog data offers support to scenario depicted by dynamical intensity guidance.

 

Analog Data Confirms that Official La Nina Designation is Likely

Eastern Mass Weather has identified five ONI analogs, three of which peaked as cool ENSO neutral and two with a weak La Niña designation. The three ENSO cool neutral seasons are as follows:

 

1996: -0.4 ASO ONI, -0.5 peak ONI, 10/30 3.4 weekly reading of -0.1, 12/25 weekly peak of -0.8

 

2001: -0.2 ASO ONI, -0.3 peak ONI, 10/30 3.4 weekly reading of -0.5, 11/21 weekly peak of -0.7

 

2013: -0.3 ASO ONI, -0.5 peak ONI, 10/30 3.4 weekly reading of -0.1, 2/5 weekly peak of -1.3

 

And the two weak La Niña analogs:

 

2005: -0.1 ASO ONI, -0.9 peak ONI, 11/2 3.4 weekly reading of -0.4, 11/18 weekly peak of -1.1

 

2008: -0.2 ASO ONI, -0.8 peak ONI, 10/29 3.4 weekly reading of -0.1, 12/22 weekly peak of -1.0

 

Here is the subsurface and zonal wind juxtaposition for later October-early November 2024 for comparison with the rest of the dataset, as measured against the appropriate climate period.

 

2024:

 

 

Weak La Niña members:

 

2005:

 

 

2008:

 

 

Cool ENSO Neutral Members:

 

The glaring discrepancy between the ENSO neutral portion of the dataset and 2024 is that the sample from 1996 is completed devoid of any trades and has a very weak subsurface cold pool.

 

1996:

 

 

The years 2001 and 2013 have neither a cold pool nor any semblance of trade winds, which is why neither of these years featured the development of an official La Niña per ONI.

2001:

 

 

2013:

 

 

The recent descent of the Indian Ocean Dipole (IDO) into negative territory represents a nod towards the La Niña analogs is thus also supportive of a marginal cool ENSO event crossing the threshold into official La Niña designation as an added measure of confidence.

 

 

 

 

Given the congruence of 2024 with the weak La Niña composite of 2005 and 2008 in conjunction with continued support from the dynamical ENSO guidance, one last concerted cooling of region 3.4 between mid November and mid December should be sufficient to ultimately achieve a weak La Niña designation, with a peak DJF ONI of between -0.6 and -0.8. This range is slightly more aggressive than suggested by the current consensus of guidance out of deference to the ongoing severe cold phase of the Pacific and its tendency to constructively interfere with and reinforce episodes of cool ENSO. This is reflected well by the Multi ENSO Variate Index (MEI) and Relative Ocean Nino Index (RONI).

Relative Ocean Nino & Multivariate ENSO Index Expected to be Indicative of Moderate La Niña Peak

In addition to the absolute intensity analogs (peak ONI) of 2005 and 2008, the strong 1973 La Nina event will be considered as a relative ENSO analog, due to the fact that it may inform the degree of additional development from this point forward considering that this year also featured a robust El Nino transitioning into a La Nina during a deeply negative PDO regime. This is precisely when the RONI is more critical than the ONI for assessing the overall intensity of ENSO. The reason why that is the case is because the RONI attempts to remove the trend due to global warming in an effort to produce a measure that is of more direct relevance to changes in tropical convection driven by SST anomalies, rather than the general warming around the globe. This in conjunction with a lack of appreciation for the Maritime forces competing with ENSO were the primary sources of confusion with respect to the inaccurate diagnosis of last season's El Niño. When used in conjunction with the MEI, which combines both oceanic and atmospheric variables into a single index as an overall assessment of ENSO, a more accurate measure of the true strength of the interface between land and sea that is represented by ENSO can be made. The ASO RONI values for the aforementioned three seasons and the subsequent peaks are as follows:

 

1973: -.1.54 ASO RONI and -1.95 peak.

2005: -.02 ASO RONI and -.93 peak.

2008: -.27 ASO RONI and -.89 peak.

 

 

What is apparent when examining the data is that the residual, baseline cool ENSO influence that is being reflected by the RONI is enhancing the current La Nina, as opposed to when it was competing and in conflict with El Niño last year. These analogs support a peak RONI range of -1.2 to -1.4, which is of course a significant, moderate cool ENSO event. An analysis of the ground truth can be completed for the atmosphere to confirm what an exhaustive analysis of the data has suggested.

The evolution of the Walker Cycle dictates that it is the upwelling of cooler subsurface waters via the enhancement of easterly trade winds that drives the development of La Niña, as touched upon previously. This is evident by the robust trade winds that are evident when viewing a composite of strong La Niña events.

 

The contrast between this composite and that of weak La Niña events is clear.

 

When viewing the May-August zonal wind anomalies for 2024, it is obvious that the meager strength of the trades winds thus far in the mean spanning the last several months has inhibited the development of La Niña. This corresponds with the earlier analysis citing the collapse of the trades in conjunction with some nuances concerning the subsurface cold pool as the reason for the recent stall in the development of La Niña.  

However, there are a multitude of indicators that are suggestive of a cool ENSO event that is appreciably better coupled with the atmosphere than the meager ONI value would imply.

 

 

 

This configuration is clearly more representative of the a stronger La Niña, such as the 1973-1974 event, rather than the weaker 2005 analog.

 

 

This represents a splendid illustration of why having the North Pacific in phase with La Niña, as it is now during the current deeply -PDO, results in a RONI that is stronger than the ONI and very likely a cool ENSO event that is well coupled with the atmosphere. Last season, this was not the case with El Niño, as it usually is not when the PDO is so deeply negative. Having climate change enhance the West Pacific warm pool that is a staple of an already record powerful Pacific cold phase only accentuates this phenomenon further. This is clearly evinced when comparing October composites of Pacific pressure anomalies during weak and strong La Niña events to October 2024.

Normally in a healthy La Niña event, the abundance of convection fostered by warmer waters over the western Pacific MC result in low pressure anomalies, which result in sinking air across the eastern portion of the basin and higher pressure. 

 

 

Note how diffuse this dipole is in the weak la Nina May-October composite.

 

 

The dipole is comparatively much more pronounced in the strong La Niña composite.

 

However, its even more well defined in 2024, despite the paltry ONI reflection to date.

 

 

Prior to this recent intensification of the pressure dipole, its initial slow response over the summer was at least partially attributable to the influence of the Southern Oscillation Index, which had been lethargic to respond to the burgeoning cool ENSO event given the magnitude of the strong El Niño event that preceded it. This resulted in a lag due to the extensive recovery necessary for the atmosphere to switch phases and couple with the ocean. However, during the middle to latter portion of summer, and then again in October, the SOI finally began to elevate and the MEI tumbled more precipitously, which is now fueling a faster intensification of the cool ENSO walker cycle.

 

The notable lack of a Pacific pressure dipole during the early portion of the summer season was also present during the relative ENSO analog season of 1973, which like this event, was transitioning from a strong Pacific cold phase El Niño to La Niña.

 

Now here is the May-August pressure pattern prior to strong La Nina events.

 

 

Note that the pressure dipole during the summer of 2024 was still rather disjointed in comparison to the strong La Niña composite.

 

However, as of the last update for the JA bi-monthly period, the MEI had already descended to -0.7.

 

 

The MEI calculation has unfortunately not been updated since last summer due to the immense flooding in the aftermath of Hurricane Helene, however, it is safe to expect given the above data and recent trends that a peak MEI value between -1 to -1.2 is to be expected. Having a sound conceptualization of the ultimate peak intensity of ENSO, especially one that incorporates the degree to which the ocean-atmosphere interface will be established, is vital to any seasonal forecasting effort. Not only is ENSO instrumental in the configuration of the Hadley Cell and MJO waves that dictate the hemispheric long-wave pattern, but more recent observations suggest that the intensity of La Nina may play role in determining the duration and frequency of any deviations from the baseline Maritime continent (MC) forcing that has been so prominent over the course of the last decade.

[LibertyBell]

5 minutes ago, 40/70 Benchmark said:

My primary ENSO analog of 2008-2009. This is why I have been arguing all winter against the idea that La Nina would  a no-show.

This is an excerpt from my November outlook:

 

ENSO 2024-2025

Primary ENSO Analogs: 2021-2022, 2020-2021, 2011-2012, 2008-2009

Intensity & Structure Discussion

The October update of ENSO guidance from the International Research Institute reflected a significant reduction in the forecasted peak intensity of La Niña with a -.6 NDJ peak. 

 

 

 

While this is in better agreement with the -.4 DJF peak suggested by statistical guidance, the remaining difference still implies uncertainty with respect to whether an official La Niña will be declared. This is especially true given the paltry ASO ONI of -0.2 in conjunction with the fact that the weekly reading in region 3.4 was down from -0.5 on 10/23 to -0.2 as of 10/31. The reason for this is attributable to the behavior of the subsurface in conjunction with the zonal wind pattern during latter portion of the month of October.

The trend in the subsurface since mid October has been for the cold pool to shift east and even intensify.

 

 

 

However, during this same period of time, the trade winds have also shifted to the east and completely abated and even reversed to westerlies over region 3.4 

 

 

This has triggered a warming over region 3.4 with a burst of cooling over the eastern flank of ENSO. Note the sea surface temperature anomaly profile as of September 17th with the max anomalies focused in region 3.4

 

As compared to the max anomalies having relocated to region 3 on November 4th.

 

 

 

These changes have cooled the eastern flank of region 1.2 from -0.1C on October 16th to -0.5 on October 30, while both region 4 and 3.4 warmed from 0.1 to 0.2 and from -0.3 to -0.2, respectively. Although the trade winds are anticipated to re establish over the western flank in region 4, the forecast moving forward is precarious. There is uncertainty as to whether or not the occasional flirtation of the eastern extent of the trades with the western periphery of region 3.4 will be able to colocate with the western periphery of the subsurface cold pool to foster the development of an official La Niña event per ONI. The dynamical guidance suite, as stated, remains at odds with the statistical guidance. The former, albeit weaker, insists on the development of La Niña, and the latter has been steadfast on the ENSO neutral scenario.

 

 

This recent trend for the trade winds to be relegated to the east is already reversing, as they have to die died off and redevelop over region 4, which has halted cooling for the entire eastern half and likely even induce some warmer fluctuations. In fact, as of the November 6ht update, the region 1.2 has already warmed back up to -0.2 from -0.5 on the 30th and region 3.4 is back down to -0.3. Despite this, the notable absence of a subsurface cold pool beneath region 4 will prevent this event from becoming a full-fledged Modoki event, and it should instead remain central-based in nature. 

 

 

Guidance affirms this central based assessment, but like most hybrid events, there will be variation and mixed elements of each.

 

 

The convective forcing that has been redolent of the mixed type La Nina pattern should remain as such in the aggregate seasonal mean, however, expect it to assume that of a Modoki during warmer times, and that of an east-based event during the anticipated period of deviation. 

 

 

Note the positive precipitation anomaly beneath this area of maximum convective forcing  on model guidance.

 

The El Nino Modoki Index (EMI) forecast for the Japanese Meteorological Society confirms.

EMI analogs include  2008, 2010, 2011, 2020 and 2021 and the EMI forecast is between -.5 and -.7

Overall, while it may still appear somewhat muddled as to whether or not La Nina will officially come to fruition due to its recent stagnation coupled with the discrepancy between statistical and dynamical guidance, analog data offers support to scenario depicted by dynamical intensity guidance.

 

Analog Data Confirms that Official La Nina Designation is Likely

Eastern Mass Weather has identified five ONI analogs, three of which peaked as cool ENSO neutral and two with a weak La Niña designation. The three ENSO cool neutral seasons are as follows:

 

1996: -0.4 ASO ONI, -0.5 peak ONI, 10/30 3.4 weekly reading of -0.1, 12/25 weekly peak of -0.8

 

2001: -0.2 ASO ONI, -0.3 peak ONI, 10/30 3.4 weekly reading of -0.5, 11/21 weekly peak of -0.7

 

2013: -0.3 ASO ONI, -0.5 peak ONI, 10/30 3.4 weekly reading of -0.1, 2/5 weekly peak of -1.3

 

And the two weak La Niña analogs:

 

2005: -0.1 ASO ONI, -0.9 peak ONI, 11/2 3.4 weekly reading of -0.4, 11/18 weekly peak of -1.1

 

2008: -0.2 ASO ONI, -0.8 peak ONI, 10/29 3.4 weekly reading of -0.1, 12/22 weekly peak of -1.0

 

Here is the subsurface and zonal wind juxtaposition for later October-early November 2024 for comparison with the rest of the dataset, as measured against the appropriate climate period.

 

2024:

 

 

Weak La Niña members:

 

2005:

 

 

2008:

 

 

Cool ENSO Neutral Members:

 

The glaring discrepancy between the ENSO neutral portion of the dataset and 2024 is that the sample from 1996 is completed devoid of any trades and has a very weak subsurface cold pool.

 

1996:

 

 

The years 2001 and 2013 have neither a cold pool nor any semblance of trade winds, which is why neither of these years featured the development of an official La Niña per ONI.

2001:

 

 

2013:

 

 

The recent descent of the Indian Ocean Dipole (IDO) into negative territory represents a nod towards the La Niña analogs is thus also supportive of a marginal cool ENSO event crossing the threshold into official La Niña designation as an added measure of confidence.

 

 

 

 

Given the congruence of 2024 with the weak La Niña composite of 2005 and 2008 in conjunction with continued support from the dynamical ENSO guidance, one last concerted cooling of region 3.4 between mid November and mid December should be sufficient to ultimately achieve a weak La Niña designation, with a peak DJF ONI of between -0.6 and -0.8. This range is slightly more aggressive than suggested by the current consensus of guidance out of deference to the ongoing severe cold phase of the Pacific and its tendency to constructively interfere with and reinforce episodes of cool ENSO. This is reflected well by the Multi ENSO Variate Index (MEI) and Relative Ocean Nino Index (RONI).

Relative Ocean Nino & Multivariate ENSO Index Expected to be Indicative of Moderate La Niña Peak

In addition to the absolute intensity analogs (peak ONI) of 2005 and 2008, the strong 1973 La Nina event will be considered as a relative ENSO analog, due to the fact that it may inform the degree of additional development from this point forward considering that this year also featured a robust El Nino transitioning into a La Nina during a deeply negative PDO regime. This is precisely when the RONI is more critical than the ONI for assessing the overall intensity of ENSO. The reason why that is the case is because the RONI attempts to remove the trend due to global warming in an effort to produce a measure that is of more direct relevance to changes in tropical convection driven by SST anomalies, rather than the general warming around the globe. This in conjunction with a lack of appreciation for the Maritime forces competing with ENSO were the primary sources of confusion with respect to the inaccurate diagnosis of last season's El Niño. When used in conjunction with the MEI, which combines both oceanic and atmospheric variables into a single index as an overall assessment of ENSO, a more accurate measure of the true strength of the interface between land and sea that is represented by ENSO can be made. The ASO RONI values for the aforementioned three seasons and the subsequent peaks are as follows:

 

1973: -.1.54 ASO RONI and -1.95 peak.

2005: -.02 ASO RONI and -.93 peak.

2008: -.27 ASO RONI and -.89 peak.

 

 

What is apparent when examining the data is that the residual, baseline cool ENSO influence that is being reflected by the RONI is enhancing the current La Nina, as opposed to when it was competing and in conflict with El Niño last year. These analogs support a peak RONI range of -1.2 to -1.4, which is of course a significant, moderate cool ENSO event. An analysis of the ground truth can be completed for the atmosphere to confirm what an exhaustive analysis of the data has suggested.

The evolution of the Walker Cycle dictates that it is the upwelling of cooler subsurface waters via the enhancement of easterly trade winds that drives the development of La Niña, as touched upon previously. This is evident by the robust trade winds that are evident when viewing a composite of strong La Niña events.

 

The contrast between this composite and that of weak La Niña events is clear.

 

When viewing the May-August zonal wind anomalies for 2024, it is obvious that the meager strength of the trades winds thus far in the mean spanning the last several months has inhibited the development of La Niña. This corresponds with the earlier analysis citing the collapse of the trades in conjunction with some nuances concerning the subsurface cold pool as the reason for the recent stall in the development of La Niña.  

However, there are a multitude of indicators that are suggestive of a cool ENSO event that is appreciably better coupled with the atmosphere than the meager ONI value would imply.

 

 

 

This configuration is clearly more representative of the a stronger La Niña, such as the 1973-1974 event, rather than the weaker 2005 analog.

 

 

This represents a splendid illustration of why having the North Pacific in phase with La Niña, as it is now during the current deeply -PDO, results in a RONI that is stronger than the ONI and very likely a cool ENSO event that is well coupled with the atmosphere. Last season, this was not the case with El Niño, as it usually is not when the PDO is so deeply negative. Having climate change enhance the West Pacific warm pool that is a staple of an already record powerful Pacific cold phase only accentuates this phenomenon further. This is clearly evinced when comparing October composites of Pacific pressure anomalies during weak and strong La Niña events to October 2024.

Normally in a healthy La Niña event, the abundance of convection fostered by warmer waters over the western Pacific MC result in low pressure anomalies, which result in sinking air across the eastern portion of the basin and higher pressure. 

 

 

Note how diffuse this dipole is in the weak la Nina May-October composite.

 

 

The dipole is comparatively much more pronounced in the strong La Niña composite.

 

However, its even more well defined in 2024, despite the paltry ONI reflection to date.

 

 

Prior to this recent intensification of the pressure dipole, its initial slow response over the summer was at least partially attributable to the influence of the Southern Oscillation Index, which had been lethargic to respond to the burgeoning cool ENSO event given the magnitude of the strong El Niño event that preceded it. This resulted in a lag due to the extensive recovery necessary for the atmosphere to switch phases and couple with the ocean. However, during the middle to latter portion of summer, and then again in October, the SOI finally began to elevate and the MEI tumbled more precipitously, which is now fueling a faster intensification of the cool ENSO walker cycle.

 

The notable lack of a Pacific pressure dipole during the early portion of the summer season was also present during the relative ENSO analog season of 1973, which like this event, was transitioning from a strong Pacific cold phase El Niño to La Niña.

 

Now here is the May-August pressure pattern prior to strong La Nina events.

 

 

Note that the pressure dipole during the summer of 2024 was still rather disjointed in comparison to the strong La Niña composite.

 

However, as of the last update for the JA bi-monthly period, the MEI had already descended to -0.7.

 

 

The MEI calculation has unfortunately not been updated since last summer due to the immense flooding in the aftermath of Hurricane Helene, however, it is safe to expect given the above data and recent trends that a peak MEI value between -1 to -1.2 is to be expected. Having a sound conceptualization of the ultimate peak intensity of ENSO, especially one that incorporates the degree to which the ocean-atmosphere interface will be established, is vital to any seasonal forecasting effort. Not only is ENSO instrumental in the configuration of the Hadley Cell and MJO waves that dictate the hemispheric long-wave pattern, but more recent observations suggest that the intensity of La Nina may play role in determining the duration and frequency of any deviations from the baseline Maritime continent (MC) forcing that has been so prominent over the course of the last decade.

Ray that would be a really nice winter, at least one 4" storm each month DJFM and a coastal March 1 here with 10" of snow.  Cold January long snowcover with frequent small snowfall.

[bluewave]

Looks like the AAM is forecast to drop as per the CFS forecast as the La Niña moves into the moderate range.

[40/70 Benchmark]

3 minutes ago, bluewave said:

Looks like the AAM is forecast to drop as per the CFS forecast as the La Niña moves into the moderate range.

Yes, albeit probably a lag on the pattern effect...I expect February to be more canonical La Nina like, but modified from recent versions...ie. warmth that is not completely prohibitive to at least NE. Should see some SWFEs.

[40/70 Benchmark]

5 minutes ago, LibertyBell said:

Ray that would be a really nice winter, at least one 4" storm each month DJFM and a coastal March 1 here with 10" of snow.  Cold January long snowcover with frequent small snowfall.

I'm not saying its necessarily great seasonal analog....ENSO.

[LibertyBell]

8 minutes ago, 40/70 Benchmark said:

I'm not saying its necessarily great seasonal analog....ENSO.

does it look like this could be a stronger la nina than that one was do you think? 

[LakePaste25]

1 hour ago, bluewave said:

Looks like the AAM is forecast to drop as per the CFS forecast as the La Niña moves into the moderate range.

Yep, this is progressing as expected. Hopefully the -PNA doesn’t dig to Baja and we get some blocking. 

[40/70 Benchmark]

1 hour ago, LibertyBell said:

does it look like this could be a stronger la nina than that one was do you think? 

Not really....maybe a hair.

[bluewave]

1 hour ago, 40/70 Benchmark said:

Yes, albeit probably a lag on the pattern effect...I expect February to be more canonical La Nina like, but modified from recent versions...ie. warmth that is not completely prohibitive to at least NE. Should see some SWFEs.

This winter was the strongest lagged La Niña that we have ever seen. Notice how much warmer the global SST state is than all the other La Ninas over the last 30 years. It allowed the RONI to drop well below the actual Nino 3.4s.

 

 

[40/70 Benchmark]

10 minutes ago, bluewave said:

This winter was the strongest lagged La Niña that we have ever seen. Notice how much warmer the global SST state is than all the other La Ninas over the last 30 years. It allowed the RONI to drop well below the actual Nino 3.4s.

 

 

I think the WWB may have also beaten it back for a bit....anyway, makes since given the late-blooming 2008 was a strong subsuface match late last fall.

[GaWx]

19 minutes ago, bluewave said:

This winter was the strongest lagged La Niña that we have ever seen. Notice how much warmer the global SST state is than all the La Ninas over the last 30 years. It allowed the RONI to drop well below the actual Nino 3.4s.

 

 If this daily RONI chart is pretty accurate, OND RONI would end up near or slightly cooler than -1.0. That would already give 2024-5 a borderline moderate/weak La Niña peak at the very least on a relative to surrounding global tropical waters basis. My guess for official OND RONI is at least down to -0.95. When combined with other factors including the SOI, I consider that we’re in moderate La Niña for all practical purposes although not officially (not ONI-wise).

[snowman19]

15 minutes ago, bluewave said:

This winter was the strongest lagged La Niña that we have ever seen. Notice how much warmer the global SST state is than all the other La Ninas over the last 30 years. It allowed the RONI to drop well below the actual Nino 3.4s.

 

 

Late bloomer Modoki La Niña….record, sustained strengthening on all metrics….big AAM drop projected….evidence really mounting for a canonical response late January and February 

[40/70 Benchmark]

2008:

 17DEC2008     22.7-0.2     24.5-0.7     25.7-0.8     27.6-0.8
 24DEC2008     22.9-0.3     24.4-0.8     25.6-1.0     27.5-0.9
 31DEC2008     23.2-0.4     24.6-0.7     25.5-1.0     27.4-0.9

2024:

 04DEC2024     22.5 0.1     24.8-0.4     26.3-0.3     28.3-0.2
 11DEC2024     22.5-0.2     24.8-0.4     26.1-0.6     28.1-0.3
 18DEC2024     22.8-0.2     24.7-0.5     25.8-0.8     28.0-0.4

[40/70 Benchmark]

Not sure we make it up to 1.0 on the monthly, so probably not eclipsing 2008-2009 in terms of ONI.

[40/70 Benchmark]

2 minutes ago, snowman19 said:

Late bloomer Modoki La Niña….record, sustained strengthening on all metrics….big AAM drop projected….evidence really mounting for a canonical response late January and February 

Again....EMI isn't crucial when its a weaker event.