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This conversation is too good to pass up . Webb makes a good reasoning for us to have a warm December and if we get the ENSO 1.2 to warm well it could get ugly. For every action there is a reaction. @bamwxcom · 41m Replying to @webberweather Things are a lot different this year though. I don’t think we’re looking at the traditional Dec torch. Reasoning is winded but just looking at the PV alone, tropical forcing and QBO/solar cob argues this year has legit chances at atleast slightly colder than normal. BAMWX @bamwxcom· 38m No denying the risk and general climo of course but if I were to bet against all that it would be this year. If ENSO 1.2 can stay cool that will help too along with generally -AAM. That’s our idea atleast hope all is well! -Michael Eric Webb @webberweather· 35m Oddly enough, when you remove the strong NINOs w/ huge NINO 1-2 anoms from that subset, the warm signal gets stronger in Dec. I have a hunch we're probably going to hit a brick wall at some pt once the tropical forcing shifts back into the Indian Ocean. http://atmos.albany.edu/facstaff/roundy/waves/RMMphasecompslp500ht.html… BAMWX @bamwxcom· 32m That is certainly interesting. The correlations since 2000 argue an Eastern Us Trough. The EPS/CFS weeklies also stall the MJO in 8-1-2 largely for DEC. If we torch this year I think it may never be possible to get cold in DEC again Eric Webb @webberweather· 24m MJO phases 8-1-2 are cold at lag = 0 in the east-central US, but w/ positive lag in NDJ, we're often mild or torching. I also have reservations about NINO 1-2 staying negative for too much longer. Eric Webb @webberweather ·22m Interesting forecast nonetheless, I hope I'm wrong because I've gotten completely sick & tired of warm Decembers around here, 8 in a row and counting in NC.

Brilliant ! Bring on the ice age baby ! Its about time Snow Miser gets his damn revenge !

Well now, I see HM mentioned the rubber band theory. I know he reads these boards. I also know for a fact Joel Myers from Accu Weather really did talk about this as a theory way back in the day. Not sure if HM's post means a moderation and change in the weather is a natural process, or whether he believes we can continue cold, or simply the most obvious might be there is no real support for the rubber band theory. Who the heck knows sometimes with Anthony. But, I love his insights ! I imagine eventually a pattern runs its course.

Maybe even the South gets involved. Goes to show you the extent and degree of the cold air mass. However, as Webb mentions, it is still early November, and what is a week among friends.

@poolz1 So much to look at these days, very exciting times. The Strat takes a back seat to sensible weather and real time events but this is worth mentioning. Speculation on my part, but maybe this either decreases any moderation period ( even though the outcome is uncertain and lag period as well ) and potentially increases risk of more significant weather events here. As Tip in NE forum mentioned any strat helped - AO outcome may simply get lost in a season of naturally occurring -AO tendencies. So far, so good.

Hearing the spread of NAO solutions are larger in this update , going by what Matt posted. I have not seen it first hand. Sounds like the Pac remains good, which makes sense and increase my confidence in colder risks/outcomes. Will be interesting tracking what the PDO does, according to Bob's recent posts, maybe going more positive. A + 1 PDO in December ( from Don S ) certainly makes a colder December outlook more plausible based on his research. I am still riding the +PMM for a cold December , even though it is not as high as 3 weeks ago I believe.

A follow up from John regarding the collapse of the Chukchi Sea ridge. A combination of factors leading to a very cold and active period down the road. Awesome animation too !

Bring it !!!!!

Brought it up in the context of a somewhat similar occurrence, a few years ago when a extremely powerful cyclone went up into the NE Pac. Was all over the media and social feeds. Sorry for not including the reference. Was thinking about it and forget to include it in my post. Anyways, there was talk that winter that it could have messed up the AO domain because of over pumping the heights and messing things up in general. However, IF it was the Fall of 2015 and it was the Bering Sea Bomb then that following Jan we had the spike down in the AO and the Blizzard in an otherwise crap winter. https://www.ncdc.noaa.gov/sotc/national/2016/01/supplemental/page-5 So take from that what you may. Overall speculation about any future outcomes pending the recurve as Webb mentions. Oh, just to mention in 2014 there was Nuri https://en.wikipedia.org/wiki/November_2014_Bering_Sea_cyclone I found this link https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/12/14/bering-sea-bomb-cyclone-ties-record-for-strongest-storm-in-north-pacific/ Dec. 14, 2015 at 2:51 p.m. EST The Bering Sea west of Alaska hosted a whopping storm system over the weekend, with sustained winds equivalent to a Category 1 hurricane and gusts up to 115 mph. Having dropped 49 millibars between Saturday and Sunday, the incredible Aleutian cyclone constitutes a meteorological “bomb” — a storm that drops at least 24 millibars in 24 hours — more than twice over. Early Sunday morning, the storm’s central pressure finally bottomed out at 924 millibars, tying the record for lowest wintertime pressure in the North Pacific Ocean since records began in the winter of 1969-1970. The previous strongest storm in this region occurred just one year ago.

Well................................... this might empty the clip .......j/k

Back - trajectories - pretty cool. For this Sat AM.

Week 44 N Hemisphere Snow Cover just updated, and we are very high compared to previous week 44 over the past 20 years. Yesterday we gained positive anomalies on both sides of the pole ( link below ) Southern Canada did very well over a large region. If anything the Siberian high should be aided by the vast snow cover over there. Row Year Week N. Hemisphere Eurasia N. America N. America (no Greenland) 1 2019 44 31.89 18.41 13.48 11.33 2 2019 43 28.69 16.50 12.19 10.04 3 2019 42 23.49 14.29 9.20 7.05 4 2019 41 18.05 9.66 8.39 6.24 5 2019 40 14.63 8.16 6.47 4.32 6 2019 39 8.91 3.52 5.39 3.24 Wow, positives on both sides of the pole. Looking great so far ! https://climate.rutgers.edu/snowcover/chart_daily.php?ui_year=2019&ui_day=307&ui_set=2 More to come for NA

Don't see this every day. https://www.naturalgasintel.com/articles/120102-cold-pattern-shows-staying-power-as-natural-gas-futures-continue-climbing

From Don S. taken with the notion that we are not really sure about the next three weeks and how the PDO might change along with possible blocking, as Don mentions. I personally feel that the record IOD , + PMM , less sea ice over vast areas North of Alaska and other factors point to possibly normal December temp wise. but only speculation at this point. However, as with the upcoming extremely cold and anomalous air mass we could snap the rubber band and go in the opposite direction resulting in warmth returning for a while in December , the extent and duration is again pure speculation. From Don S recent post ( just a section of it ) from the NYC forum : <<< Since 1981, approximately one out of every seven December cases involved a neutral ENSO. In general, a neutral ENSO in which Region 1+2 had a cold anomaly and Region 3.4 had a warm anomaly (as has been the case in the 6 week moving average) saw a warmer than normal December. Such neutral ENSO cases accounted for about 27% of all neutral ENSO December cases during the 1981-2018 period. This data does not consider blocking, as it is too soon to be confident about that factor in December. However, the greatest warmth coincided with a negative PDO while the coldest outcome coincided with a strongly positive PDO (+1.00 or above for December). Therefore, the first part of winter could start off milder than normal in the Middle Atlantic and southern New England regions. >>>>>

There are signs that the PDO region might become better established and grow more + in the next several weeks. Also, you have to think that we are deviating to a degree from the warm West Pac , Cold East by nature of the extreme +IOD and very cool ENSO 1.2. Also, the lack of sea ice North of Alaska and other factors as well suggest, at least the possibility, that after a moderation we may not be destined for a torch December. The record IOD is a huge player and even the PMM has my attention.

Valid point. There are however several good reasons to to be hopeful for an averaged winter -AO. I am most interested about December, but you have to love seeing the atmosphere cooperate with the early season cold delivery, Seems if we maintain no negative surprises we roll into December and then hopefully rock and roll near the holidays, none of that post 12/20 warm up crap this year please.

An upper air feature, low pressure disturbance, that move out of far W/NW Canada going SE ( quickly ) and passes over the province of Manitoba, Canada. These features can at times drop far enough to our South and Southeast to spawn cyclogenesis. If they drop far enough to our South and the pattern is conducive they can develop into powerful East Coast snowstorms. Sometimes these storms can even stall or loop as they move NE along the Eastern Seaboard dropping feet of snow. This diving system out of Canada shares common characteristics with Alberta clippers and even Saskatchewan Screamers. The name given simply implies the location they pass over. Great link https://www.9and10news.com/2011/01/03/alberta-clipper-saskatchewan-screamer-manitoba-mauler/

So, then for me after looking at this beautiful meteorological artwork is, what about the eventual flip, and do we go back to a favorable pattern at some point ? I think any relax is minimal, but has to happen. The ensemble mean, as Maue points out, is remarkable. Lets not forget in the process of all this cold is the building snow cover extent and depth to our North and Northwest. I did read one thing from HM about N Pac ridging. However, I assume if that were a huge concern for December in the East Anthony would talk about it more. Here is the snippet from HM I was referring to: << . Too much ridging in the N PAC and you end up with a 1990 situation--big +AO next month. >>

Here is that time period John was mentioning in his post earlier today. I would say you have to consider this as a potential snow event window as well, even though it is way out there. Of course this potential event may favor regions North of us, but plenty of time to work that out. One thing of note, the continuous anomalous cold air from NW Canada feeding down the next 10 to 14 days. On a side note, I have heard from several respected mets that this winter will feature a few robust clippers and even Manitoba Maulers. I would love an exploding clipper to bomb out off the Va Capes and then doing a loop off Ocean City, MD for say 24 hours. As John stated : " Another threat for winter weather could evolve in the Northeast states from 11/11 - 11/13. As the closed ridge near the Chukchi Sea collapses, increased momentum/amplification could occur. The evolving waveguide could support a storm threat a few days later."

Cool animation John created here. Certainly seems there is potential in this time period.

@poolz1 This is a cool post I brought over from @Typhoon Tip in the NE Forum Someone asked about whether there would be a warming event by the end of November , here is what Tip wrote. To me the image and the time issue involved is very interesting. And, as Tip mentioned, in this upcoming winter we may not even need a warming to get a - AO. Sounds good to me . Here is the post <<<< If there is one, keep in mind that there is a coherent time-lag in the statistical correlation. Any subsequent forcing on the Arctic Oscillation lags by as much as 20 to 30 days. Few know this, or, demonstrate very readily via turns of phrase and deliveries of prose where they've beautifully ( otherwise ) fused the sudden stratospheric warming sciences into their speculative, and I'm like " ...you do realize the effects of SSW are outside your forecast range, right?." There is a particularity that needs to be observed, else ... whatever is being observed is more likely to fail coherent forcing on the AO outside of coincident index numerology. The warm plume has to propagate downward in time ( i.e., 'downwelling' ). In every case of SSW graphical layout back to 1979, this downward motion appears to 'spiral' away from a central axial point that begins near the axis of PV rotation, at a very high beginning SIGMA level - typically between 5 and 30 hPa. As it descends, it will first appear to weaken, before the next node comes in warmer, then fades slightly ... then warmer, each node gaining x-coordinate distance upon each emergence. That growth in the x-coordinate is a representation of gaining distance from the axis of rotation. Notice the ending node is almost faded/indistinquishable in anomaly relative to the surrounding features of the ambient field ( nearing 150 hPa SIGMA) there bottom right along the nodal curve. That is tropopausal mechanical absorption/ increasing stabilization and suppression of the depths ensues, and that weakens the PV ... "pancaking" and blocking in the mid and upper troposphere ignites. This entire translation of events, as you can see took ~ from Jan 15th to the end of February ... and we can see in this case a very clear and coherent AO correlation taking place: 2013 -0.610 -1.007 -3.185 0.322 0.494 0.549 -0.011 0.154 -0.461 0.263 2.029 1.475 ... Bold is March. SSW don't really value-add like the popular mantra of the day has it in their mind(s) and bandy about. If one did take place in the last week of this month... We may be hearing about an AO response some time after Christmas.. which is fine. But, I also offer that this particular year we may not have much trouble with AO being negative anyway, so it could be lost in the din of a -AO complexion hemisphere anyway. >>>>>>>

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.