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A bit limited in time, however, I recommend this article, as it talks about various pieces of the puzzle. Here is a small section of the article . ( The article has decent images as well ) The stratospheric polar vortex shows quite a bit of day-to-day variability. This variability is caused by weather systems or large-scale waves that move upward from the troposphere into the stratosphere. In the left image (9 January 2010), we see some undulations along the edge of the polar vortex, but the vortex is generally centered on the North Pole. Two weeks later (center image on 23 January 2010) we see the center of the polar vortex pushed away from the North Pole. On a constant latitude circle, PV values are high in the eastern hemisphere and low in the western hemisphere. This is referred to as a wave-1 pattern (a wave-2 pattern can be seen in the vortex breakup section below). The wave-1 pattern develops in the troposphere and moves upward (propagates) into the stratosphere. These stratospheric waves are forced by the large-scale mountain systems and the land-sea contrasts between the continents and oceans. During the northern winter, these waves are continuously forming and moving upward into the stratosphere. The waves can “break”, much like the waves on a beach. These wave-breaking events erode the vortex and keep the polar region warmer and ozone amounts higher. Often, parts of the polar vortex are pulled away from the main vortex. The image on the right (28 January 2010) shows this, where a large piece of the polar vortex was pulled away from the main vortex (green colored material at the bottom of the image). A comparison between the middle and right images also shows a slight contraction of the polar vortex because of these waves. link https://ozonewatch.gsfc.nasa.gov/facts/vortex_NH.html And here is another good read https://www.sciencedirect.com/topics/earth-and-planetary-sciences/polar-vortex sample section from above link Wave-2/vortex splitting type The most dramatic major warmings involve a complete split in the polar vortex, followed by a rapid breakdown of one or both of the two cyclonic vortices that result from this split. The growth of the Aleutian High is accompanied by the development of a second anticyclone in the vicinity of the Greenwich Meridian at 0° E. An unusually symmetrical example of a ‘wave-2’ major warming occurred in northern winter 1984/85. Its evolution is illustrated in Figure 7. There are two developing anticyclones: the Aleutian High near 180° E and another (nonclimatological) anticyclone near 0° E. The polar vortex was split in the ‘pincer’ formed by these anticyclones, which then merged over the pole, as shown in Figure 8, bringing warm air over the polar cap. Subsequently, both of the cyclones weakened rapidly as they were stretched out around the strong anticyclone over the pole. Often, vortex splitting events are preceded by a ‘preconditioning’ of the vortex in which it is displaced from the pole and elongated. This preconditioning has a strong signature in the wave number one geopotential height field meaning that separating vortex displacement and vortex splitting events purely on the basis of the amplitudes of the wave number one and two geopotential height field can be difficult. Instead, alternative methods, which focus on examining the two- and three-dimensional structure of the potential vorticity fields have proved a useful complement to traditional methods in classifying and understanding SSWs in recent years.

The idea is it could interfere with the base state if it occurs too early. Just because you get a SSWE does not mean the outcome for cold and snow in our area is guaranteed. Many times a simple disruption and keeping the PV on our side of the pole is good enough. As @WxUSAF mentioned a SSWE later in the season is probably good for us. This year with a descending QBO that should help us with blocking. I read that currently wave 2 activity is/will taking punches to PV , but I believe we do not have significant wave 1 activity. There are some precursor patterns that show up and you can look to these to place stress on the PV. Lastly, I read that the set up for this winter does not favor an official SSWE happening. In that context I am happy with the way things are proceeding without a SSWE messing things up. I know Isotherm is releasing his winter outlook soon, I respect his work and I am sure he will focus on the strat and the NAO domain.

I came across an interesting read a few days ago that showed a very close correlation between October's SAI and the following winter's AO, which revealed a -_AO in the winters following robust October snowfall in the Northern Hemisphere and below 60 degrees North. This correlation came in the time period 07 to 11 the post mentioned. Problem is since then the correlation has been a erratic at best, and the ensuing winter's AO was not predominantly negative. The overall results were mixed. Whether this has to do with the recent sea ice losses, later starts to winters , I am not sure. That is why after 2011 the magic was lost to a degree. Judah did get a lot of press during the winters of 13-14 and 14-15 with the PV visits but by then folks were questioning the validity of the SAI.

Just checked out the Euro Northern Hemisphere look, really stunning . Thanks for the tip, I had no idea about the access there.

I believe Judah's second follow up post was directed at @psuhoffman as a disclaimer of sorts ..... Always good to say, not a forecast, not everywhere will be cold. Hey, at least we have snow cover that' s all I am after. Here is my disclaimer psu - I am a not a Judah supporter, this post was paid for by the Alliance of Snow Advance Index Members, all 3 of them.

Pretty crazy look forecasted around mid November and the implications for the strat.

Continued trends downward with the AO and trending up with the PNA

The MJO has gotten my interest as of late . Also of note, the lack of the MJO going into very high amplitude. Also, seeing the signs of more favorable phases for us here. There is a lot more to the MJO as well as certain phases aid in strat disruptions. I see today the SOI making a big move down as well 4 Nov 2019 1008.28 1010.80 -34.36 -4.51 -7.07 Keep this in mind as well

Many folks share this view. Some concerns are increasing the odds that the holiday period will be very warm, such as recent years, also that the cold air mass is wasted because snow climo itself is still too early and hostile. However, some areas of the country I have seen in the past do start early, with cold and snow, and remain so during the heart of winter. I hope this is not a head fake. I believe there are plenty of reasons to expect cold and snow in the NE this winter.

Like last winter I would keep an eye on the ENSO region 1.2 If region 1.2 were to warm significantly I believe it could overwhelm the pattern for us here in the East in a negative fashion, and lead to warmth and a poor storm track. There are many favorable elements that are pointing to cold and snow, but I prefer we remain in the SST profile that we have basically have maintained the last several months in Pac. If BAMMWX is bringing up the potential warming of ENSO 1.2 as a possible concern it gets my attention. This of course goes with the notion that most of us here know that region 1.2 is prone to wild short-term fluctuations.

Taken with a grain of salt , but nice to see the AO negative and staying negative. I think the Euro Ensemble index more likely to be correct. ( last image )

Great Lakes to cool off and snow in SE Canada. Very impressive forecast map. The question later in the month is whether there is a whole sale pattern change, or just a relaxation , even a version of an Indian summer if you may. I remember Joel Myers saying in the old days , 1970's and 1980's you can only pull the rubber band so much before it pulls back or snaps. In this case keeping a highly anomalous winter like pattern for an extended period of time makes you wonder the implications for the first 1/3 of the meteorological winter. Of course, there are things that argue after a brief to moderate relaxation we go back to what the base state may want to provide, which is an active storm track(s), and penetrations of cold air. this takes place as wavelengths continue to lengthen.

@showmethesnow I brought up the record +PMM a month or so ago. Rolling forward from Sept. to November and then December a very high +PMM gives a decent signal for a cold November in the East , and a even more robust cold signal for December. I even recall it has, in December, the ability to help in phasing and in introducing a more active and present STJ stream, through longer wavelengths, . Not saying it is going to work out, because about 90 % of mets are going with a warm December this year. I feel we can go normal with colder risks and stormier as well. BAMMWx so far is on a roll.

Nice seeing some pressure being applied on the PV to keep it from rapidly getting stronger. As HM stated, you simply can not go by the last days of October and early November, in regards to the PV strength, as a proxy to the implications for the ensuing winter. Also seems we are taking a different approach this late Fall with the location of the PV and the general behaviors in the HL. Some similarities later next week if we get a significant snow storm to our North, but feeling that does not gloom the winter coming up. Also, looking back at the summer in the Northern Plains and continuing even now with the placement of the coldest anomalies, well they seem to want to take shop on our side of the pole. Not seeing any red flags so far with the MJO. and nice seeing the + PNA kick up.

A most interesting set-up in terms of the warming origins.

Low of 31 degrees here this morning. Heavy frost almost like a covering of light snow.

Maybe the early November cold has legs.

This makes a lot of sense and goes along with some of the mets I follow. The talk from some of them, including HM here is that "if" the seasonal models are indeed getting the winter NAO signal from forecasting and anticipating a strong to very strong PV, well, if the vortex if weaker, or more prone to shifts and elongations then the seasonal call for a mostly + NAO during December through Feb. might be very wrong. Taken a step further would potentially equate to a very different sensible weather outcome for some folks. Please keep in mind HM is talking about the AO and I am inferring the association to the NAO domain and the relationship of a not so strong PV.

If the UKmet couldn't forecast the seasonal NAO last winter, even after doubling down in November, how the hell can this trash model even attempt a seasonal forecast and for 4 months in a row as well of a + NAO ? Wait, persistence is modeled into the physics. It does have company, but many models last Fall called for a -NAO average during the winter. I don't buy it yet.

Difficult keeping the coffee hot this morning, with this chill in the air. Nice to hear from you, and looking forward to your insights as the season progresses.

So far, so good with the MJO.

Incredible winds last night estimate near 50 plus near midnight, many limbs down . Huge area under a freeze warning from Mount Holly. I put the hoses and sprinklers away, debating whether to cover the annuals, but the mums should still be OK I imagine. 930 AM EDT Fri Nov 1 2019 ...FREEZE WARNING REMAINS IN EFFECT FROM 2 AM TO 10 AM EDT SATURDAY... * WHAT...Sub-freezing temperatures as low as 30 expected. * WHERE...Portions of northern, northwest and southern New Jersey, east central and southeast Pennsylvania and northeast Maryland. * WHEN...From 2 AM to 10 AM EDT Saturday. * IMPACTS...Frost and freeze conditions will kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing. PRECAUTIONARY/PREPAREDNESS ACTIONS... Take steps now to protect tender plants from the cold.

Not to jinx us, but love seeing the orientation of the PV combined with the location and from there tons of snow will be put down just to our NW and a breeding ground for some very cold air delivery, eventually a direct discharge. We did not have this last year. Also, it seems the atmosphere, at least so far, is conducive to showing ( and delivering ) a good pattern. Hopefully any turn to the milder later in November is just a reload, or a brief moderation. Still like a normal December with snowfall opportunities.

QBO looking good so far

Cold and active Novembers correlates with March the best. Cold and snowy Decembers I read correlate better with the period Jan 1 to Feb 28 th. Of course as we know there are exceptions. If you believe the notion that this will be a back loaded winter, combined with a possibly colder and more active November leads me to think this March will have higher odds of snow and cold. With the exception of last March, we have trended to winters lasting longer, and starting later in this decade. @MountainGeek This is interesting Granted October 2009 was much colder , then November turned warmer in time