2024-2025 La Nina

[bluewave]

1 minute ago, snowman19 said:

It’s thermodynamics 101. The atmosphere is going to fire the strongest and most persistent convection over the warmest SSTs (MJO 4-6). That’s where the global heat budget is centered. And even despite the rise in the PDO last month, it was still record strong at over -3 as @GaWx pointed out yesterday. I honestly fail to see any change from last year in the PAC other than ENSO. This La Niña is finally, at long last starting to really take off (EWBs, +SOI, 3.4 cooling, AAM slowly falling) and it is entirely central-based/Modoki now too

 

 

 

 

Yeah, the nearly doubling of the Indio-Pacific warm pool has become a major climate driver especially for us in the East.

 

https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global

[jconsor]

19 hours ago, GaWx said:

 

 Nov NOAA PDO just came in about where I expected (based on adjusting WCS’ PDO) at -3.24 (rise of 0.54 from Oct). This compares to the WCS’ Nov of ~-2.10. So, this is only the 2nd time since 1851 with three sub -3 PDO months in a row. The other time was in 1894 (6 months earlier that year than 2024). We actually only barely missed 7 months in a row of sub -3 as the last 7 have all been sub -2.90:
 

-2.99 -3.16 -2.99 -2.91 -3.54 -3.78 -3.24

https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

 Current daily NOAA PDOs are likely in the low -3 range.

@snowman19

Per Eric Webb, the PDO has limited influence and limited usefulness for subseasonal predictability (especially in a winter like this with a strong Indo-W Pacific warm pool).

https://x.com/webberweather/status/1864088518886322455

https://x.com/webberweather/status/1864091992386605400

https://x.com/webberweather/status/1864095069449699705

https://x.com/webberweather/status/1864150597710369022

Also interesting comments on PDO's limited usefulness as a teleconnection here:
https://x.com/_WxPhil_/status/1864148237403263157

[snowman19]

8 minutes ago, bluewave said:

Yeah, the nearly doubling of the Indio-Pacific warm pool has become a major climate driver especially for us in the East.

 

https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global

The background La Niña state just keeps chiving on unabated. The recent changes in the ENSO genre and constructive interference from the -IOD are just going to reinforce the whole process going forward

[GaWx]

27 minutes ago, snowman19 said:

It’s thermodynamics 101. The atmosphere is going to fire the strongest and most persistent convection over the warmest SSTs (MJO 4-6). That’s where the global heat budget is centered. And even despite the rise in the PDO last month, it was still record strong at over -3 as @GaWx pointed out yesterday. I honestly fail to see any change from last year in the PAC other than ENSO. This La Niña is finally, at long last starting to really take off (EWBs, +SOI, region 3.4 cooling, AAM slowly falling, -IOD) and it is entirely central-based/Modoki now too

 

 

 

 

-RONI for SON just came out at -0.80. So, on a RONI basis this event will end up with at least a solid weak La Niña peak.

-ONI for SON: -0.24

-So, difference between RONI and ONI in SON was -0.56 (difference between -0.80 and -0.24)

- Difference between RONI and ONI:
MJJ: -0.60
JJA: -0.55
JAS: -0.52
ASO: -0.54
SON: -0.56

 So, when I see an OISST and want to very roughly estimate the equivalent daily RONI, I’m currently subtracting ~0.55. The Dec. 1st OISST was -0.35. So, I have the current equivalent Dec 1st RONI near -0.90**(**Corrected for typo).
 

[bluewave]

22 minutes ago, snowman19 said:

The background La Niña state just keeps chiving on unabated. The recent changes in the ENSO genre and constructive interference from the -IOD are just going to reinforce the whole process going forward

Yeah, we were discussing the issues with the much faster Pacific Jet and inability to sustain -EPO patterns. All the guidance has been underestimating this influence beyond a week out. This recent +AAM driven Pacific blocking pattern reverses fairy quickly. The forcing near the Maritime Continent accelerates the Pacific Jet, weakens the -EPO, and leads to a Southeast Ridge.

New run faster Pacific Jet weakening -EPO block and leading to Southeast Ridge several days later

Old run

[40/70 Benchmark]

2 minutes ago, 40/70 Benchmark said:

Strongly agree with all of this. 

https://youtu.be/OdBnQZCFcQM?si=o9E18FO-SuFdihKq

 

[bluewave]

7 minutes ago, GaWx said:

Chris,  
 At what latitudinal range are you saying the forcing near the MC warm pool is accelerating the Pacific jet?

I posted the Pacific Jet correcting much stronger in the above post. The JMA site has the MJO jet composites. Just select the options for 200mb zonal wind anomaly. The jet increases across large swaths of the North Pacific when forcing is in the 4-7 regions. We are currently near a 4 composite for December with the jet pushing through the -EPO block this weekend.

 

https://ds.data.jma.go.jp/tcc/tcc/products/clisys/mjo/composite.html

 

[bluewave]

1 minute ago, GaWx said:

Thanks but I need to restate my question.  What is the latitudinal range of this warm pool that is leading to the stronger Pacific jet?

It’s described in this story that I posted above.

https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global

[GaWx]

8 minutes ago, bluewave said:

It’s described in this story that I posted above.

https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global

So, would you agree that the warm pool is between 15N and 15S latitudinal range? I want to make sure I’m properly following along with you on the waters you’re focusing on.

 So, does this mean that the marine heatwave E of Japan is having minimal impact on the atmosphere?

[bluewave]

5 minutes ago, GaWx said:

So, would you agree that the warm pool is between 15N and 15S latitudinal range? I want to make sure I’m properly following along with you on the waters you’re focusing on.

 So, does this mean that the marine heatwave E of Japan is having minimal impact on the atmosphere?

Yeah, close to those areas around the equator. The warm pool east of Japan to north of Hawaii raises some interesting questions. I suppose you can make the argument that the forcing from the WPAC warm pool near the equator leads to stronger 500mb ridging across the North Pacific which warms the SSTs below. So the -PDO signature could be a result of the tropical forcing in the WPAC. When it aligns with the tropical forcing perhaps the subtropical -PDO marine heatwaves can lead to feedbacks which help to strengthen the pattern when in alignment. 

[GaWx]

1 hour ago, jconsor said:

Per Eric Webb, the PDO has limited influence and limited usefulness for subseasonal predictability (especially in a winter like this with a strong Indo-W Pacific warm pool).

https://x.com/webberweather/status/1864088518886322455

https://x.com/webberweather/status/1864091992386605400

https://x.com/webberweather/status/1864095069449699705

https://x.com/webberweather/status/1864150597710369022

Also interesting comments on PDO's limited usefulness as a teleconnection here:
https://x.com/_WxPhil_/status/1864148237403263157

 

56 minutes ago, bluewave said:

Yeah, close to those areas around the equator. The warm pool east of Japan to north of Hawaii raises some interesting questions. I suppose you can make the argument that the forcing from the WPAC warm pool near the equator leads to stronger 500mb ridging across the North Pacific which warms the SSTs below. So the -PDO signature could be a result of the tropical forcing in the WPAC. When it aligns with the tropical forcing perhaps the subtropical -PDO marine heatwaves can lead to feedbacks which help to strengthen the pattern when in alignment. 

 So, I want to make sure that Webb, jconsor and Chris are on the same page. Jconsor said this based on what Webb said:

“Per Eric Webb, the PDO has limited influence and limited usefulness for subseasonal predictability (especially in a winter like this with a strong Indo-W Pacific warm pool).”

This is what Webb said:

“Most people misunderstand the direction of forcing. Extratropical SSTs are mostly forced by atmospheric circulation anomalies, not the other way around. I.e. the -PDO’s contemporary correlation with things like the -PNA is more of a reflection of the -PNA pattern forcing the -PDO on interannual scales, not the other way around”

 
 Chris, do you agree with jconsor and Webb that the PDO actually has limited influence on the atmosphere? So, does this mean that the record -PDO we’ve been having, itself, has been having only minimal impact on the atmosphere?

 There seems to be a lot of disagreement about this among the meteorological community, which has been confusing to me over the last few years. I‘m just trying to learn. For example, I used to think that -PDO, itself, including the W Pacific marine heatwave E of Japan, tended to help force a -PNA/stronger mean Aleutian ridge/stronger than avg mean SE ridge. But in reality it appears that the 15N to 15S warm pool in addition to La Niña is what drives that pattern and not also the marine heatwave to the north/-PDO. Chris and Yaakov, do I have this right?

 So, if so, does following the PDO, itself, have much usefulness for seasonal predictions for, say, the US and the Atlantic tropics? If not, what’s the point with regard to forecasting mean seasonal atmospheric circulation in following the PDO index and the E of Japan marine heatwave?

[michsnowfreak]

15 hours ago, FPizz said:

You can have a wealth of knowledge while also cherry picking and having a bias.  

1000%. There is plenty of knowledge AND bias by the frequent posters in this thread. In nearly every post, as a matter of fact, from some.

[jm1220]

1 hour ago, snowman19 said:

The background La Niña state just keeps chiving on unabated. The recent changes in the ENSO genre and constructive interference from the -IOD are just going to reinforce the whole process going forward

Perma-Nina. It’s so prevalent that it was noticeable even in the strong Nino last year. It just added a lot more moisture to the perma-Nina so the East had a near or record wet winter but zero cold other than short couple day periods where it was cold enough for snow IMBY. 

[40/70 Benchmark]

35 minutes ago, michsnowfreak said:

1000%. There is plenty of knowledge AND bias by the frequent posters in this thread. In nearly every post, as a matter of fact, from some.

I wouldn't include Chris in that....when it looked colder early month, he reported that. Its important to observe the behavior of a contributor during an instance in which the overwhelming perponderance of evidence goes against perceived bias.

[MJO812]

1 hour ago, 40/70 Benchmark said:

 

This is excellent.  He put alot of thought into this forecast .

He thinks a brief break and then winter comes back in early Janaury.

[michsnowfreak]

10 minutes ago, 40/70 Benchmark said:

I wouldn't include Chris in that....when it looked colder early month, he reported that. Its important to observe the behavior of a contributor during an instance in which the overwhelming perponderance of evidence goes against perceived bias.

Oh I dont mean every poster...just some. Sorry if it came across another way. I just think overall there is a huge difference between having a preference and a bias. I usually have general thoughts for my area and keep it vague like that; getting in too deep increases the chance to get burned. Im kind of a mix between BAM and Don Sutherland on my thoughts- a variable winter.

Had snow on the ground when I cut down the Christmas tree Sunday and should have a little bit of snow on the ground at an event Im going to Friday. Those were my 2 "outdoor" holiday events planned, so while Im never a fan of the up and down, Im actually fine if it warms up sooner rather than later, as it increases the chances of another turn colder by Christmas itself. 

[GaWx]

2 hours ago, 40/70 Benchmark said:

 

My opinion on this:

-Michael Clark clearly presents his thoughts in detail with solid reasoning, especially regarding the MJO and TPV. Well done. He’s hinting at a strong possibility of a cold Jan in the Midwest to interior NE though he didn’t know about the coastal NE and said (virtually) nothing about the SE.

-Per his history, I don’t put him in the Bastardi category of being a strongly cold biased hypester by any means (exhibited by him talking about warmth Dec 10-25/30….Bastardi would unlike Michael gloss over the warmth and skip to the cold potential)..so a big positive vs JB

-Per that same history though, my feel is that he’s probably still a bit cold biased though not as much as a few years ago when I first followed him.

-My biggest disappointment is how much emphasis he puts on the typically highly unreliable CFS. He focuses on the 12/4/24 0Z CFS 4 member ensemble run. Although that’s much better than just showing a control run (something JB often does when it is very cold), it’s still highly unreliable.

-Besides it being typically highly unreliable, the CFS (though it has backed away slightly) is still calling for a record rate of Nino 3.4 cooling of -0.8C from Nov to Dec to -1.0C and then -1.25C in Jan! No other model is anywhere close. That potential huge error makes me wonder if it is affecting the CFS in Jan.

-I also don’t like to see his displaying WxBell CFS US 2 meter temperature maps. They’re usually several degrees colder than what the NOAA CFS maps show on avg in the E US and are messed up. He showed the very cold WB 12/4/24 0Z ensemble run for Jan, which is almost definitely colder than what that actual CFS  run has. Also, the maps he showed had the ever-present cold spot in S Lake Michigan and warm spot in N Lake Michigan.

-My overall feeling is to take this with a grain but hope he’s generally right for Jan and hope that the cold includes the SE/Mid-Atlantic/coastal NE with no blocking mean SE ridge.

[GaWx]

16 hours ago, GaWx said:

 I just emailed my Maxar contact to see if he’ll give me an update on the latest ensemble biases based on internal analyses. I hope he responds. He (Brad) really is fantastic with this kind of analysis.

This is from pro-met Brad’s email response:

“Your ideas about model biases are generally true. The CAN EN (GEPS) is often cold biased, and this is especially the case in the West as you have noted. The GEFS is often cold-biased as well, but this has not been the case more recently. I think the maps and graph from DTN make sense from what I remember this fall. With that said, model performance in the fall can vary more than other times of year. This might be a function of tropical activity, which peaks in the fall, but also the changing of seasons itself. So in that respect, I probably wouldn't consider the biases from this past fall to be an indication of how models will perform going forward.”

“While I can’t say for sure what caused models to be too warm this fall season, their handling of soil moisture might be a theory:”

 So, in other words, Brad is suggesting that we not count on the net warm EPS/GEFS E US day 6-15 model biases of this past autumn continuing into this winter.

[bluewave]

6 hours ago, GaWx said:

Chris, do you agree with jconsor and Webb that the PDO actually has limited influence on the atmosphere? So, does this mean that the record -PDO we’ve been having, itself, has been having only minimal impact on the atmosphere?

The SST -PDO is a reflection of the predominant atmospheric 500mb state over extended periods of time. But this -PDO era is much different from past instances in that it’s being defined by the record warm pool from east of Japan and to the north of Hawaii as defined by the historic 2nd EOF values I posted a while back. My guess is that the SST -PDO is being driven by forcing closer to the equator such as the MJO getting stuck in phases 4-7 as has been the case for the last 10 years. The SSTs are just the reflection of the 500 mb atmospheric pattern. When the SST -PDO aligns with the atmospheric -PDO a feedback loop can develop and sustain the pattern. But sometimes when the forcing shifts like Jan 22 into MJO 8 we can get more of a +PDO atmospheric look even if the SST is still in negative mode. This is why I mention mismatch patterns when the 500 mb goes against the SST. Such a pattern tried to get established this week but the warmer MJO forcing is working to shift it quickly. If the +AAM could have had some assistance from a MJO 8 instead, then it could have been a more extended pattern. That’s why I will be tracking the MJO heading into January. If the WPAC warm pool slows the forcing there then we could see renewed warmth following the start of the New Year. But if the MJO can push strongly enough east of the Dateline closer to 8 than we would be able to revisit the first week of December against the colder January climo with improved snowpack for better Arctic air production. 

[Terpeast]

25 minutes ago, bluewave said:

The SST -PDO is a reflection of the predominant atmospheric 500mb state over extended periods of time. But this -PDO era is much different from past instances in that it’s being defined by the record warm pool from east of Japan and to the north of Hawaii as defined by the historic 2nd EOF values I posted a while back. My guess is that the SST -PDO is being driven by forcing closer to the equator such as the MJO getting stuck in phases 4-7 as has been the case for the last 10 years. The SSTs are just the reflection of the 500 mb atmospheric pattern. When the SST -PDO aligns with the atmospheric -PDO a feedback loop can develop and sustain the pattern. But sometimes when the forcing shifts like Jan 22 into MJO 8 we can get more of a +PDO atmospheric look even if the SST is still in negative mode. This is why I mention mismatch patterns when the 500 mb goes against the SST. Such a pattern tried to get established this week but the warmer MJO forcing is working to shift it quickly. If the +AAM could have had some assistance from a MJO 8 instead, then it could have been a more extended pattern. That’s why I will be tracking the MJO heading into January. If the WPAC warm pool slows the forcing there then we could see renewed warmth following the start of the New Year. But if the MJO can push strongly enough east of the Dateline closer to 8 than we would be able to revisit the first week of December against the colder January climo with improved snowpack for better Arctic air production. 

It seems the new Euro weeklies are trying to move the MJO along (or at least kill it off into COD) and produce a trough in the east. If it pans out (a big if) this second round might work better than this week when the cold pattern was fighting against forcing in phases 4-5. Definitely something to watch late Dec - early Jan. 

[bluewave]

43 minutes ago, Terpeast said:

It seems the new Euro weeklies are trying to move the MJO along (or at least kill it off into COD) and produce a trough in the east. If it pans out (a big if) this second round might work better than this week when the cold pattern was fighting against forcing in phases 4-5. Definitely something to watch late Dec - early Jan. 

I am not buying the weakening signal on the EPS. It’s probably just losing the signal like it did back on November 15th with both the RMM and VP anomalies. The GEFS was actually much better with both the RMM and VP anomalies. Our best bet would be to have the forcing shift into phase 8 regions east of Dateline in January. Otherwise it could just reload again in phases 4-5-6 like we have seen so many times in recent winters. 
 

Euro lost the signal a few weeks ago

 

 

Verification much stronger closer to GFS

 

 

VP anomalies also verified stronger

Forecast

 

 

Verification

 

 

[Terpeast]

17 minutes ago, bluewave said:

I am not buying the weakening signal on the EPS. It’s probably just losing the signal like it did back on November 15th with both the RMM and VP anomalies. The GEFS was actually much better with both the RMM and VP anomalies. Our best bet would be to have the forcing shift into phase 8 regions east of Dateline in January. Otherwise it could just reload again in 4-5-6 like we have seen so many times in recent winters. 
 

Euro lost the signal a few weeks ago

 

 

Verification much stronger closer to GFS

 

 

VP anomalies also verified stronger

Forecast

 

 

Verification

 

 

Fair. If the MJO is gonna stay strong, then we want to root for it to get into 8 rather than going through 6 then womping into COD. Right now GEFS keeps it healthy well into 7, which is a transition phase for the east. 

[bluewave]

18 minutes ago, Terpeast said:

Fair. If the MJO is gonna stay strong, then we want to root for it to get into 8 rather than going through 6 then womping into COD. Right now GEFS keeps it healthy well into 7, which is a transition phase for the east. 

We can hope that the MJO transits into 8 so we can get some version of a Jan 22 mismatch pattern with sustained Pacific blocking. But not sure yet if that will occur. We don’t want to see it weaken in earky Jan with another 10 day cooldown before reloading in the warmer 4-5-6 phases again. 

[PhiEaglesfan712]

10 hours ago, MJO812 said:

It's only December 4 for crying out loud. Models can't even get anything right a week out let along a month out.

I had Torch January predicted back in early September. That's the one thing I haven't wavered from in my winter forecast.

December was always going to be a tough month to predict. I had a feeling it was going to start out cold, but I've waffled back and forth on when the warm-up will be.

[MJO812]

43 minutes ago, bluewave said:

We can hope that the MJO transits into 8 so we can get some version of a Jan 22 mismatch pattern with sustained Pacific blocking. But not sure yet if that will occur. We don’t want to see it weaken in earky Jan with another 10 day cooldown before reloading in the warmer 4-5-6 phases again. 

Long range Euro doesn't look warm at all . Gfs trended to the euro in regards to that. Maybe we will get a muted warmup.

[leo2000]

This is interesting more red showing up in Alaska pretty close to the end of 18Z GEFS. 

 

https://www.tropicaltidbits.com/analysis/models/?model=gfs-ens&region=namer&pkg=z500a&runtime=2024120418&fh=372

 

 

[Terpeast]

10 minutes ago, leo2000 said:

This is interesting more red showing up in Alaska pretty close to the end of 18Z GEFS. 

 

https://www.tropicaltidbits.com/analysis/models/?model=gfs-ens&region=namer&pkg=z500a&runtime=2024120418&fh=372

 

 

Even with GEFS being the warmest model 2 weeks out, it’s starting to bring the -epo back and with a trough south of GOA, we see it trying to rebuild a ridge out west. 

That timing is close to when it also brings the mjo to phase 7 (or almost there). For those of you who prefer VP anomalies, that takes the strongest forcing to near the dateline. From there, things can get interesting within the following 2 weeks or so. Maybe longer.

[EasternLI]

The westerly QBO theoretically could assist to temper some MJO convection in the MC region this winter. So it will be interesting to see how everything progresses moving forward. Here's some key points about this relationship. It seems like this could be a good test subject ahead of us. 

 

Modeling evidence of QBO‐MJO connection: A case study

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL089480

"The boreal winter Madden‐Julian Oscillation (MJO) is modulated by the Quasi‐Biennial Oscillation (QBO). The MJO becomes relatively strong during the easterly QBO (EQBO) winters but weak during the westerly QBO (WQBO) winters."

 

"When the lateral boundary conditions are switched with those of WQBO or strong WQBO winters, the MJO becomes weak over the Maritime Continent."

 

QBO modulation of MJO teleconnections in the North Pacific: impact of preceding MJO phases

https://www.nature.com/articles/s41612-024-00565-w

"It is found that the Rossby wave trains induced by MJO phase 6–7 exhibit greater strength and robustness during the westerly QBO winter (WQBO) than during the easterly QBO winter (EQBO), although the MJO itself is weaker during the former. This counter-intuitive dependency of MJO teleconnections on the QBO is attributed to the preexisting MJO teleconnections prior to the MJO phase 6–7. The MJO phase 6–7 is more frequently preceded by stronger MJO phase 3–4 during the EQBO than during the WQBO. The preceding MJO phase 3–4 teleconnections, which have opposed signs to the MJO phase 6–7 teleconnections, result in a considerable attenuation of the MJO phase 6–7 teleconnections by destructive interference."

 

There were recently twin TC's in the Indian ocean. Pictured below on 11/27 12z. Who's influences appear to be waning currently. It'll be interesting to see how everything trends this month. 

[michsnowfreak]

4 hours ago, PhiEaglesfan712 said:

I had Torch January predicted back in early September. That's the one thing I haven't wavered from in my winter forecast.

December was always going to be a tough month to predict. I had a feeling it was going to start out cold, but I've waffled back and forth on when the warm-up will be.

I give you credit for not wavering. I really do think you're wrong about a torch January, and even moreso I HOPE you're wrong, but props for sticking to your guns (warm Jan, cold Feb).

[Terpeast]

7 minutes ago, michsnowfreak said:

I give you credit for not wavering. I really do think you're wrong about a torch January, and even moreso I HOPE you're wrong, but props for sticking to your guns (warm Jan, cold Feb).

I think the other way around. By Feb the mjo will be back into the warm phases and has historically been a torch month in a nina.