frd

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.

More possible support for a -NAO down the line from Matt.

If Webb is honking and HM backs him up, well, that sounds like music to my ears. Webb did mention to keep an eye out for this as a clue to the next big time - EPO 20m Replying to When this MJO wave finally begins to dislodge from the low frequency Indian Ocean/+IOD forcing, that's probably when the next big -EPO is coming

Sounds good, I am bored. And it appears the Southern stream will be a player as well. So hopefully we snow.

EPS may be correct, but too far out to know. The default pattern bluewave speaks about has been a real issue the last couple winters and you can see it here yet again on the 240 hour EPS. The Pac I believe has a hand in this set-up and a weak -NAO will not help us unless it is really very negative, otherwise the Pac rules. So many reasons could be at play in the Pac from certain ENSO regions to the Hadley cell, I simply don't know the real reason. But, this pattern for us here in the East has been a snow and cold killer that is for sure. Might work out well for North Dakota , but not the Northern Mid Atlantic. Here is bluewave's post: I am just weary of the Pacific defaulting back to its multi-year Niña-like base state. Notice how the EPS has the ridge north of Hawaii and SE ridge holding on with the weak -NAO near the end of the month. My guess is that the warm western Pacific and cold Niño 1+2 has a hand in this pattern of the last few years.

Not every winter in the 1960's were super awesome, but many winters were above average snowfall. A good time to be a snow weenie !

This is why to a degree.

Interesting @Isotherm spoke about Canadian warming today at 33, and here Anthony is bringing this up in his post . Some have used a couple 1960's based analogs for this coming winter despite the climate being warmer now, versus then. Of note is one analog, believe 65 or 66 possibly that featured a warming and then all hell broke out in mid Jan.

This is a great thread to read further. Ventrice and BammWX added comments here. Always so much to consider, the IOD, the standing wave, VP forecasts and the MJO progression.