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Wow, so how early do the " big spenders " get to see the Euro weeklies. Out already, normally I look for 6:00 PM. release. And yes, the trend is your friend ! Looking forward to seeing the progression.

Bob, if the Atlantic side improves, in terms of the positioning of the block, do you think we see the ULL in future runs dive further South and Southeast? Looks like the Pac is OK in a general sense, but the Atlantic is lacking. Move the block further South and a bit West and could see some improvements. So far ahead to have any confidence I would imagine at this point. There seems to be a lot of chaos going on up North, lots of moving parts you could say. The funniest thing of all is this entire concept is built upon the concept the GFS at 150 hours, has any clue at 500 mb.

Many times the state of the AO in December provides clues to the AO state for Jan and Feb. Having measurable snow in our area, such as DC and Baltimore during December , normally correlates to a decent snow season. Works many times, of course there are exceptions. Also, you will hear how things just are not syncing up like they use to. Some signals you look at would have you assume winter will be normal, but then the pattern head fakes and we go very warm.

All hail @Isotherm, that is his call and progression to a T . The tropics impact the higher latitudes and blocking. He and a couple others called this a month ago. Hey, but no winners yet, as it is Nov. 24 th not Dec. 24th. However, as Bob stated, the trends with the AO are very concerning. If we reverse and empty all the cold air in Canada and lose snow cover up North, it will take weeks to recover. I myself speculate, once we get to mid January, we diverge from last year and go very cold and very stormy. I might buy Tom's progression for December, but I feel there is a decent opportunity this winter for some cold powder storms and high ticket snow events.

Great update, I hope we eventually see some positive signs in the HL. Seeing some +4 to +5 AO ensemble members is a bit worrisome, and the recent 4 day trends continues more so positive. Noticing these huge bowling bowls moving across the country with that fast Pac jet is reminiscent of last winter to a degree. Alaska is set to record a fast Pac jet up there this early week. Another thing to watch, and I believe there is a statistical correlation here to our area from DC North is that having a + PNA in December is key to accumulating snowfall. Maybe more so than a -AO. That relationship probably changes in January. So difficult lately getting the PNA to go + and remaining so. I love to see the Pac and the HL align down the road. If you go HM's route there is hope in December.

There does seem to be some changes this year in the far Eastern Atlantic and the far North, but you are correct the forcing pattern is very similar. Is is true we are still suffering from a lack of coupling, or it that becoming a mute point with the meager Nino. It also seems we are losing the Modoki SST pattern in the Pac as well, the East region warms 1.2 , and the West region might be cooling soon. Also, seeing some changes too regarding the sub surface SSTs in region 1.2 ( Do you concur with this ? )

Not to mention the previously discussed Modoki Nino is fading, to a degree, and the presentation in the Pac is declining overall. We may be in for an extended period of poor Pac and poor Atlantic, on top of the changes in the HL. Seems in the last few days medium range models maybe going to route of the seasonal models. Of course this can all change, but the trends the last couple of weeks in the Pacific are concerning.

Yes, that is true. But, it is uncanny how similar to last December we look to evolve, but there are other players around that could throw a monkey wrench in the way December eventually plays out. I know some are using the MJO progression, and the standing wave, as way to maintain the warmer phases, Some are calling for the HL to become less favorable as well. Still seeing the pesky High North of Hawaii. If it were not for the - EPO we would be in trouble even faster . At least the -NAO helps us for a bit before it weakens. So hard for Decembers to work out in our favor if you love snow and cold, been that way for a long time.

What does BAMMWX refer to when they mention the CFSv-2 weeklies 2 meter temp anomaly and it is a cold run to December 17 th?

Sorry for the delay, but glad to see CAPE could help you . Kids back for the week from college, had to make an early food run . You might be interested showme that according to to Simon, during the month of November so far, the GFS has been doing a good job in verification involving the strat forecasts in the 11 day time period. Will be interesting to see how things play out, enjoyed your post above.

Do you think that changes as we progress further into time, as into late December? Aren't things still progressing in the Pac and in the NH., in terms of wavelengths and the real winter pattern developing. Some of the feedback supporting that ridge axis there may change moving forward.

Love this post by Anthony . Had to bring it here because it explains his thought process on the - NAO in regards to someone stating it was North Atlantic ridging but not a - NAO. The image is from the GFS for November 30, 2019. Of course things are evolving past this to the dates HM mentions below. From HM : Be careful here. This retrograding RW will induce upstream cyclonic wave breaking with time. The ridge between each and above each will change forms frequently, day-to-day, but the process is still a form of -NAO or blocking. The RW will arrive here 12/3-12/6. Each run will change how each low breaks and how each wave interacts with each other. Don't go too crazy here with defining what style the NAO is at a particular time. Just watch the full process and avoid the noise. In regards to this :

What is your opinion of the AO trends? A divergence here. Latest is even more so. Can not get that one to post.

Seems the difference between the GFS and the GEFS strat forecasts have narrowed recently. Looking at the various models nothing seems to indicate a SSW is imminent. As some experts have mentioned having a SSW so early is very rare. Having one might also disrupt any current HL blocking in place. A lot of chatter recently on various other weather boards regarding the evolution of the troposphere and the stratosphere as we move through December. The recent and medium term attacks on the vortex, according to some strat experts, is expected to decline. Some are referencing momentum ( AAM, GLAMM , etc. ) and that is a very complex subject. What appears to be evident is the early state of the vortex which was interim strong for the date a while ago, has weakened. It is expected to continue to be perturbed. Some of the precursors that lead to the weakening and the drop in zonal winds are forecasted not to be as robust as they were a month ago. There again are two schools of thought on this mater. One that states the vortex will keep getting attacked in December and the other which states they expect the vortex to get stronger as we loose all HL blocking. Hence, the implications for this on the January forecast, as there is a significant lag effect in a warming, not so much in a simple displacement or favorable elongation. Isotherm goes for the breaking down of blocking with his winter best window later in the season. while HM seems more optimistic. There is seems to be a battle going on behind the scenes as to what techniques and science will yield a correct forecast this year. I follow about 12 strat experts whom specialize in this area. Currently this is the most disagreement I have come across in several years. There is no consensus out there and maybe that is a good thing. Also, keep in mind, when there was almost 100 % consensus the outcomes were still incorrect last year. According to these strat pros the science behind the evolution in the troposphere and the stratosphere will guide the weather models. These guys I believe using modeling in predicting the long term weather to a degree, but rely mostly on a host of other data, such as drivers and the evolution of the HL to derive what they think will drive the long range models. Some do not even look at weather models, a fascinating topic that continues to evolve.

Does the nature of the EPO block wreck havoc on the previous NAO block? . I read the Pac block will aide in the destruction of the NAO. You can not have both that extreme for such a long duration. Any thoughts on that. I know Isotherm had mentioned the NAO block would be transient . I mention these things understanding I am referencing a Day 11 to 16 forecast. However, pretty sure last winter might have touched on this topic. If am interpreting HM's postings correctly than I am guessing he is anticipating possibly more -NAO this winter. And, he did say recently the weeklies are "useless " !

Weeklies are trash, but I find this look very ironic for the period, especially in view of the regular post 12/20 warm ups recently, right in time to mess up my eternal hopes of a White Christmas!

I hope some of this is white.

@psuhoffman very interesting thread here if you read all the replies from HM. Over at 33 Isotherm and others talk about the atmosphere's , AAM, momentum budget , GLAMM, etc. and why they foresee a warm up in December while reading between the lines here it appears Anthony has other ideas. This stuff is awesome to read about.

Fascinating data by HM. Need to read the replies and further answers by Anthony to appreciate it it fully. There is more than meets the eye just looking at the chart.

Not sure about early December. Depending on the location of the block and the set up in the Pac we may revert back to what we had last winter with cutters as one of the primary storm tracks. After the block breaks down, if the Pac does not improve the SE ridge will grow more prominent ( High North of Hawaii ) and we will warm. I mean the NAO is transient and then we enter the warm MJO phases Here it can last a while before moving on. So, in the end we waste the NAO block and enter the typical December Nino warm up, only to transition to colder by the end of December or early January. Could be totally wrong, time will tell.

Well, it is not all about the block, you still have to look at the flow across the Pac as it enters the country and how it interacts with the block.

Not sure if strat folks would concur, but yeah, it is very quiet. Also, I read there is other data used to determine the bottom of the cycle. But this low point can last months and maybe even drop further.

There was a post 3 months ago that indicated a very cold and stormy December based on the record positive PMM at that time. However. maybe the record + IOD is interfering some how to achieve that outcome next month, or simply the correlation may work, but occur later in December. Some some research indicated increased odds of cold an enhanced sub tropical jet during December based on the +PMM association along with increased odds of phasing along the East Coast. Some of those things are already happening if you look close enough. There are indications the STJ is picking up steam and there have been ample coastal storms this Fall season as well.

Imagine if the -NAO has legs. I admit, I am happy to see this because at least it provides an indication that maybe we will be seeing more -NAO episodes this winter. That is all we can hope for at this point as we near the end of November.

The look back and trends do support the idea here that the EPS, as it gets closer to real time, is indeed sensing the -NAO more so.