EasternLI

10 hours ago, bluewave said:

Great post. The quick reversal from -AO in October to +AO in November is something that we normally see during an El Niño. This may be related to lingering neutral to positive IOD which is also more Niño-like. The IO standing wave the models have for November was implicated in the very strong PV and +NAO +AO last winter. The current +PMM with near record SST warmth north of such a strong La Niña cold tongue is also a first for a La Niña.  A very warm November has also been associated with El Niño’s in the past. Several times this warm November during an El Niño carried over into December. So such an occurrence this year would be different than the typical front loaded La Niña winter progression. There have also been several very warm La Niña Novembers followed  by warm Decembers. On the other hand, a warmer PMM was present for our most recent La Niña warm November in 2016. That was a near record warm winter. But it may have been the +PMM allowing occasional poleward extensions of the North Pacific Ridge into Alaska. Those were also accompanied by short -NAO -AO episodes for respectable seasonal snowfall despite the record warmth. There are many factors this year which could interact. We may just have to wait and see how things look in another month or so. But even beyond  the specific ENSO conditions and interactions, we have just seen the warmest 5 winter stretch on record. 

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

 

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.

46 minutes ago, CAPE said:

That oddity in the regular cycle in 2016-17 really stands out. Makes one wonder if that sort of thing will become more prevalent. I suppose it could have simply been related to the strong Nino during that period, or maybe a sign of things to come.

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.

7 hours ago, uncle W said:

Looking at oni only 1995 and 2005 and 2007 are the best fits imo...

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

21 hours ago, raindancewx said:

One thing that concerns me this winter is that record cold in the orientation that occurred in October 2019 has occurred with the same blotch of warm waters in the Pacific in previous winters. I'm defining this blob as 150-180W, 30-60N, as opposed to 2013-14, which was 135-165W, 30-60N. See the heat shooting up to Ohio with the cold over Montana and the whole west cold?

Look at this. 30-60N, 150-180W right? Both cases. Both periods, record cord in the West (cooler ring by Western North America around the warmth, with cold south of the equator too.)

That 2013-14 setup was east of this year, and so the cold was centered east. The distance from where the cold is centered and where the blobs are centered is about 15-20 degrees E-W. So it makes sense that the blob in 2013-14 would feature severe cold in the Lakes, while the current one has focused more on Montana and Wyoming. This all assumes these warm patches matter, and that if they do, the current one will persist.

If we look at the 2 October's from your example and compare with this October from your post. One is a little more interesting. 

6 minutes ago, Dan76 said:

Dunno...somebody's going to pay for this sublime weather

Yeah, hopefully we'll pay dearly come DJF.

8 hours ago, SandySurvivor said:

We lucked out with Sandy a few years ago.  Two days later and it landfalls on Halloween and the impact is much worse. 

Pumpkins everywhere!!

Didn't feel it 

Happy Thanksgiving folks 

3 hours ago, psv88 said:

People freaking out over models showing blocking in mid-November is insane. New England may even see rain from these threats. We have had great patterns in June, but it doesnt mean it will snow. 

I dont take any threat seriously until after December 1. Yes, i know we have gotten snow in October and November a few times in the past thirty years, but those are the exception and not the rule. If the models look the same in 2 weeks i will get more intrigued, as of now its fantasy.

I agree with your main point here. It's November, right.

The thing is, seeing blocking show up for the end of Nov. like this, is kind of what you want to see in a la nina. The ratter years, for the most part, didn't have it. That's what it's all about right now, at least for me.

7 minutes ago, SnoSki14 said:

Those decadal averages really show just how much of a snow haven we've been in since 2000. 

Those 80s must have been putrid. 

They were.

3 minutes ago, IrishRob17 said:

Has rooting for any particular outcome ever affected the actual outcome?  Please advise.

Yes...

Oh wait you mean the weather.