EasternLI

Agree with the warm IO. It's problematic. Exasperating the situation is the QBO this year it looks like. Being westerly, coupled with a la nina, it's just not an ideal situation. All of these things combined looks to keep forcing "trapped" in the IO for the most part. It's why the euro weeklies have been showing the awful pattern moving forward. (Yes, the weeklies have been abysmal at times. The problem is, there's research to support them in this case.) Combined effect of the QBO and ENSO on the MJO https://www.tandfonline.com/doi/full/10.1080/16742834.2019.1588064 The QBOW phase, however, will suppress the MJO intensity over the Maritime Continent through enhancing the diurnal cycle; plus, there is no reinforcement of the MJO over the western Pacific because of the cold central Pacific of La Niña. Thus, the MJO rarely reaches the western Pacific during the La Niña/QBOW phase (Figure 3(d)).

Nice post. It could be a part of a Vortex Intensification event (VI) as is described in the following paper. If so, would be terrible news for any -AO prospects. Here's a couple of relevant quotes from the paper. The life cycle of such events, if that's what is indeed occurring, can be up to 80 days. Stratosphere‐troposphere evolution during polar vortex intensification https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JD006302 Reduced poleward planetary wave heat flux occurs as the circumpolar wind becomes strongest and pressure anomalies penetrate toward the surface. Descending pressure patterns project strongly onto the positive state of the Northern Hemisphere Annular Mode (NAM). Between days −20 to +20, reduced poleward heat flux is observed as the vortex becomes strongest; increased poleward heat flux is observed as the vortex recovers. [41] In our preliminary examination, the anomalous vortex intensification seems to occur preferentially during La Niña conditions.

It's a great question. I'm quite sure the answers are much more complicated than what my current understanding is. I am aware of a few things though. I don't have the data to back this up right now, but there is some relationship with the Indian Ocean and ENSO. Through Ocean current and rossby waves also I believe. Not sure about the Atlantic. I haven't seen anything about a relationship there. Why is it important in regards to the NAO? Mainly, because forcing there strengthens the PV, as it pertains to this year specifically. The following paper describes why that is an issue. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL084683 The state of the stratospheric polar vortex has a clear impact on the NAE (Scaife et al., 2005) weather regimes (Charlton‐Perez et al., 2018). NAO− is most sensitive to this stratospheric state, occurring on 33% of days following weak vortex conditions but on only 5% of days following strong vortex conditions The same paper also goes into what to look for if we're hoping for an increased opportunity for some -NAO. As it relates to MJO activity combined with different ENSO states, La Niña for this year. Naturally, other factors are always at work as well to determine what the end result is. In any event, it would seem that we would really like to see the MJO be active through phases 7+8. We find that the MJO–polar vortex–NAE pathway is strongly active during La Niña years (Figure 3c), particularly for the weakened vortex following MJO phases 8 (corresponding to the third pentad after phases 6–7 in Figure 2), associated with the low in the northwest Pacific following MJO phase 7, increasing vertical heat flux to the stratosphere. There is also a weakened vortex closely following MJO phases 7–8 during neutral years. These contribute to the increased NAO− occurrence around phases 7–8 during neutral and La Niña years (Figure 1).

Published: 12 November 2020 An earth system model shows self-sustained melting of permafrost even if all man-made GHG emissions stop in 2020 https://www.nature.com/articles/s41598-020-75481-z In this paper we report that in the ESCIMO climate model the world is already past a point-of-no-return for global warming. In ESCIMO we observe self-sustained melting of the permafrost for hundreds of years, even if global society stops all emissions of man-made GHGs immediately.

A potential for a shift away from the IO down the road a bit. Maybe. Could shakeup things a bit hopefully.

As far as I can tell, there just wasn't that much research on global effects in the past. There was a lot of research on more localized effects. It's gaining more attention more recently though. Probably because it's identified as an area with anomalous warming trends.

As was brought up earlier in this thread, research says Indian ocean convection will strengthen the PV. The following 2 tweets are related. You can see anomalous negative VP in the Indian ocean first. Signaling anomalous convection. Secondly, the strengthening PV. Quite impressively actually.

Nice outlook Isotherm. I think it's even more optimistic than what I was thinking. Hopefully it verifies.

Some great points. Makes a lot of sense. Perhaps a good cautionary tale of using any older analog years. The arctic sea ice issue is interesting. Something I would like to do some more reading on. I think it's one area that is gaining popularity in research. The QBO has had a good amount of attention recently.

Oh I am in full agreement on your point here. My post was in reference to the tropical pacific warm pool. Which can drive a favorable winter pattern for us. Instead, the models are locked in on the Indian ocean. Which can drive a terrible winter pattern for us. But the current state of the QBO gives support to what the models are showing IRT that. As far as the North Pacific warm pool. My thinking is that it's more of a indicator of what the pattern had been. Not necessarily a driver of much. Maybe more of a modulator? I just feel like those anomalies can be bullied around by what the tropics are doing as that is where the most energy (heat) resides. I feel like this winter is going below average snow maybe way below, much above average temp. Not seeing much for winter fans to be excited about TBH.

Thanks. There's certainly a risk of a very warm winter ahead. I'm not overly fond of anything that I'm seeing at this time. The Pacific warm pool (associated with the PMM) could help us out, but will it? That's one area of very warm water. The other is the Indian ocean, which is what models are keying on right now. Interestingly, the MJO to -NAO connection is strongest in La Niña years. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL084683 The NAO− regime teleconnection via the stratosphere from MJO phases 7–8 is most enhanced and occurring latest during La Niña years, while it is suppressed during El Niño years. Unfortunately, it seems that the QBO is working against us here being westerly. Suppressing convection where we would prefer to have it. https://journals.ametsoc.org/mwr/article/147/1/389/103189 As MJO events propagate eastward over the MC during boreal winter, static stability anomalies increase in magnitude over the eastern MC and WP. That is, static stability anomalies decrease during QBOEM and increase during QBOWM, corresponding to a less stable atmosphere and increased RMM amplitudes over the eastern MC and WP (RMM phases 5 and 6) during QBOEM, and a more stable atmosphere and decreased RMM amplitudes over the same region during QBOWM.

This is what the GEFS and EPS is showing for VP200. The new EPS weaklies today continues this look right into December. Research says that Indian ocean convection will drive a strong polar vortex. Last year is a great example of that occurring. I didn't give that enough respect. So expecting a ++AO La Nina as of now unless something changes here and quickly.

The west pacific warm pool is of some interest this year IMO. It's something that I will certainly be paying attention to in looking at the sst trends in that area in the month ahead. This relates to the discussion of the PMM in the discussion thread. There's potentially some optimistic outcomes that could (or could not lol) stem from this as it relates to the winter ahead. Some recent research has shown that forcing in this area can actually drive an Aleutian low +PNA pattern during winter. Which in turn can act to cause a weak SPV. It should be interesting to monitor this area moving forward. Nonlinear response of Northern Hemisphere stratospheric polar vortex to the Indo–Pacific warm pool (IPWP) Niño https://www.nature.com/articles/s41598-019-49449-7 During boreal winter, anomalous SST warming associated with IPWP Niño can excite NH extratropical teleconnections that project onto the positive phase of the Pacific–North America (PNA) pattern in mid–high latitudes, intensifying the upward propagation of planetary waves into the stratosphere and, in turn, warming and weakening the NH stratospheric vortex41. Note that the wave pattern excited by IPWP Niño is located further west than the PNA pattern, a fact that may be related to the different wave source locations from that of ENSO.

@bluewave That's very interesting about the PMM October pattern. I didn't even think to look at that for some reason. I remember we discussed that in the past. I found that particular pattern interesting when it was first showing up on ensembles. So I dug into some Nina years to look into it a little. I had some difficulty finding anything. Which I guess suggests the rarity of it. I see 1995 was brought up a few pages back. That was actually the closest match I could find. Albeit, it didn't happen until the end of the month that year. Therefore the composite for the month as a whole looks different. Interestingly, it's almost a mirror image of the PMM pattern composite you posted.

Yeah, I've seen a couple papers that attributed it to the super Nino. A more recent paper goes into some greater detail. I can't help but wonder if the powerful +IOD event last year played some role in the odd behavior of this year. https://acp.copernicus.org/articles/20/6541/2020/ In addition to the anomalous behavior in the tropical lower stratosphere in 2015/2016, we explored the forcing of the unusually long-lasting westerly zonal wind phase in the middle stratosphere (at 20 hPa). Our results reveal that mainly enhanced Kelvin wave activity contributed to this feature. This was in close relation with the strong El Niño event in 2015/2016, which forced more Kelvin waves in the equatorial troposphere. The easterly or very weak westerly zonal winds present around 30–70 hPa allowed these Kelvin waves to propagate vertically and deposit their momentum around 20 hPa, maintaining the westerlies there.

Interestingly enough, the qbo that year actually was westerly below 30mb to the tropopause. This year actually looks to do that as well albeit with a thicker vertical profile. Also interesting in that 2007-08 was completely different then this year. Merely a couple observations. Cheers.

Worked this up for October 1970

Here's a newer paper on the MJO - AO connection. But also how the QBO modulation plays into it. For anyone who is interested in a little reading. It's open access. https://www.mdpi.com/2073-4433/11/2/175

These blasted 3 part ridges are always the kiss of death. Or are they?? I found that particular pattern to be interesting. So I did a little digging. Only instance of this that I've found in a nina thus far. Doesn't mean jack, just something interesting. At least I thought so. Seemed appropriate to post it here now.

In a MEI sense, 2007 looks like the best fit.

My girlfriend lives in Branford. She says trees blocking roads everywhere, and a tree came down in front of her on the way home from work. Took her 3 hrs for a 20 min trip. This was somewhere on Rt. 1

Merry Christmas

I guess congrats on relocating to a different area are in order.

This has really been an impressive +IOD event. I was looking through the fabulous JMA charts and the only one that looks similar was 1997. The super Nino. I know that they mostly coincide with El Nino, but not always. Interesting to see one so robust without an El Nino. I didn't see any other years that looked quite like this.

That's a good point, and a nice observation as usual. I strongly agree with the bolded. It's exceedingly difficult to have ridging in both locations simultaneously. That's been documented in the research as well. It makes sense too, when you think about it. Like when we see a trough on the west coast and ridge on the east coast. Maybe part of the story of the ++NAO during those years with the --EPO. Interesting.