frd

Those are wise words. Even though the Euro has the highest skill and verification numbers you have to consider , as you said, the overall pattern.

The progressive pattern and unfavorable indices argued against this. Another win for the AO / PNA guidance. Honestly I think I rather have the PNA + and have a neutral NAM state. I would not be surprised to see the follow up event go to a cutter. The cutter theme goes back to last winter as we all know.

@showmethesnow as you might have seen the 06Z EPS not agreeing with the OP. It have the primary to our NW although there are a few members with centers to our South and East. But the general cluster is Western PA and Western NY state. Maybe this will change to a degree with the afternoon run.

Rather frustrating if you ask me. Many weather pros and mets are frustrated as well. I know this has been brought up before, as a matter of fact I think Don S brought this up a couple days ago about the warming of the "warm pool "and the recent research which suggests the effects are promoting, high amplitude warm phases, over cold phases and the passage of the colder phase being faster versus the warm phases. For those of you who might state well what about earlier this Fall when we did spend more time in the colder phases, well I am talking about a longer period of time, and when that time periods occurs. To me the MJO favoring warmer phases also seems to be happening more so in the beginning of winter, as it did last year at this time. I am referring to the later part of December and in January. Another interesting observation comes form HM, he mentioned recently that the warming of the "warm pool "may be over time effecting the wave train over North America in the time period from November to the first half of January. ( The cool part here ,as you will read below, HM is proposing two effects - the first a early season cold delivery via the -EPO and then warming from a shift in OLR in the IO- Maritime. HM also mentioned that the poleward heat transport is most receptive in Autumn, and hence it sets off the wave train which at that time promotes a favored - EPO. ( Now HM did not mention this but I also think there is some November influence from the mentioned wave train and acting upon the early season Siberian High, descending NH snow cover, etc in developing a early -NAM state. - like this year ) HM mentions this really cool idea that by late December the annual cycle redistributes probabilities through the tropics and then heightens the strongest -OLR that are in the IO - Maritime. I believe HM has something here. Many of the words I used above are right form HM's feed so all credit to him. I guess now the question becomes do we move forward from this cycle to a new one late in January and through February. There are some indications we do, but to what degree in terms of favoring sustained cold and snow I am not sure. On a side note, there are some interesting trends this past decade regarding longer summers and sometimes late season blocking developing at the end of winters. The absence of sustained - NAO is one as well, the late December warm-ups is another. Here is the referencing post from HM that I focused on.

Seems to be following the CFSv2 - used for trends only of course. Possibly the current CFSv2 outlook is based on the modeling seeing colder outcomes late in the month. Trends.....

Yes, you and Anthony on the same page. Using the reliable AO and PNA indicators this was expected in my opinion. Sure, a small chance we could have worked into a failed period or set-up but the stats that Donald S and Wes posted a while ago are remarkable. I mentioned a few days ago that without a favorable AO or PNA the threats would dissipate, or degrade. Since then they have. We will have to wait until the NAM state changes, and that will be a while.

Thanks Don, great info as always ! As you and bluewave both mentioned it will be interesting to see whether the MJO has any effect down the road on the PV.

I prefer to simply use the AO as a guide to SECS events. Indices were not supportive. Of course, more to it than that, but a -AO is a money signal. And we all know the current NAM state.

@bluewave mentioned this possibility a week ago. Today @donsutherland1posted over at 33 that the IOD has indeed weakened even further . You can see here from the site http://www.bom.gov.au/climate/enso/iod_1.txt Would be great if Don could share his thoughts here. We are now below the threshold of a +IOD I believe. 20191125,20191201,1.14 20191202,20191208,0.86 20191209,20191215,0.82 0191216,20191222,0.56 20191223,20191229,0.31

That depiction is right along the time lines of @40/70 Benchmark, and @psuhoffman. The issues with the Pacific ridge and its location goes back to last winter. Nothing new to add. I don't care what others might say that there are differences elsewhere, that set-up is a HUGE issue and brings the SE and WAR to play. Combine that with a very +AO and a deeply -PNA and it is very frustrating. Maybe things progress later in the month, but I believe any change to better will be gradual and no one should except a sudden flip.

A wag that the NAO may be more conducive next year to negative phases, also we will be fully established with the QBO. I know Isotherm mentioned the NAO being more receptive to - phases after the solar min, target date 4/2020 . multi year SST lag to NAO domain would be two years. I also read from Isotherm we have an issue currently as well in regards to ozone concentration and the NAO domain. The context he mentioned it escapes me at the moment.

Thats the spirit , craft beers for all and for all a good night !

The current AO sums it up. The numbers and history don't lie. From Don S - here is a portion of his recent update courtesy 33andrain: << Based on the forecast strongly positive AO to start January, the probability of a significant (6" or greater snowstorm) for the major cities of the Middle Atlantic region during the first week of January is low. Since 1950, the biggest snowfall for that region when the AO was +2.000 or above during the January 1-15 period occurred during January 14-15, 1954 when Philadelphia received 3.0" snow and New York City picked up 2.0". Boston has had numerous 6" or greater snowstorms during such cases, including one 10" or greater snowstorm. Therefore, the risk of significant snow would likely be greatest over New England assuming this relationship holds (no significant offsetting variables). 　 Some of the newer AO forecasts keep the AO at +2.000 or above through January 10. If so, that development could adversely impact Mid-Atlantic significant snowfall prospects beyond the first week of January. >>

On a simple " indices only cause and effect " relationship, I will be interested to see whether anything really does materialize between Jan 7 to the 9 th or even slightly outside of that window. @usedtobe research on the - AO and its relationship to significant DC snowstorms is well known and has merit. It would then not surprise me to have various models lose the threat. Whether the threat re-emerges I am not so sure. Again, as simple as it may sound, simply basing this on an unfavorable AO phase. I know it can snow without a -AO, but it will be interesting to see how things pan out for us. Right now the AO looks horrible. If the AO trends downward then I feel the threat has more merit. Also keep this in mind form HM and Hugo

Appreciate your thoughts Wes. Wonder if the EPS reaction to pulling the ridge back again towards the end of its run is a consequence of where it thinks the MJO progression will be at that time. But, as you said, too far off to consider anything serious. Right now the highest ROI might be focusing on the period between Jan. 7 to 9 th. By that time there should be much more clarity for the second half of Jan.

Looking forward to the afternoon Euro op run today to see whether there is consistency with the robust -EPO forecast. Again, this is in the time frame of interest near Jan. 9 th.

From Ventrice regarding the high amplitude ridge set to build over the North Pac into the Aleutians. Keep in mid this development, and the progression from there is way out in time.

Will be very interesting to see if we get the afternoon Euro run to maintain the -EPO signal. As Don posted recently, we really need to see either a -EPO to develop in early to mid Jan., or a more favorable MJO progression. However, modeling has been struggling with the MJO progression for weeks. Seems this winter so far is following the variability theme, just when you think you have it figured it only changes again.

Some good mets and pros are thinking we really do not achieve any long lasting + PNA from here on out. As 40 70 Benchmark points out he feels it is mostly -PNA tendencies. That might work for areas North of us in a cold gradient pattern but I don't put much faith into snowfall for my area in a pattern such as that. One could speculate, with everything evolving we could morph or transition into a better Pac pattern with corresponding tendencies for a period of a +PNA, but my guess would be later versus soon. Any favorable window for cold and snow most likely would be transient in early Jan. One concern at the moment is figuring out the MJO progression for later in the month. That and the EPO will most likely guide the sensible weather here in the East after Jan 17 th in my opinion. If we were hoping for a strong West based NAO that has a real impact in our area, I would think later in the season. We may see a convoluted North Atlantic, along with continued wave breaking, but based on the NH pattern I simply feel a true West based block is a better bet in Feb. or even later. We still have a ways to go to get any cooperation from the descending QBO as well. New data will be out early next month that may shed some light on how quickly it is descending. .

Well, two things I came across that you are aware of, but cool to mention, per BAMWX. 1 GEFS is too robust in its HDD forecast at the end of its runs, at least in the last couple weeks. 2 EPS has forecasted a declining EPO several times in varying degrees, but corrected back.

The theme of post 12/20 warm ups the last few years is remarkable, almost as if the MJO knew the time of year. Also, it seems in this day and age any monthly negative departure has to be really extreme and significant to stand up to eventual warmth that hits us almost every month, including the higher min temps as well. The calls for an above normal December in the temp department were good calls. However, looking back at the last 10 years persistence forecasting would have been correct without ever considering the models, or fundamental meteorology. Thought for a brief moment winter was going to start early this year, but it was simply a head fake, part of the possible new trend of warm Octobers leading to colder Novembers and then the eventual warm up after mid December.

I will save my dessert for later today when you post it. I am looking forward to it. How far back in time did you go psu ?

It is a proven fact the EPS first identified this warm-up evolution a while back. Some thought the EPS might have been incorrect this go around, as it had previously reversed course to a colder GEFS outcome earlier in the Fall. However, the GEFS, CFS and other American models all trended to the warmer EPS solution. No surprises here, as alluded to by psu and others.

Thanks for the clarification psu. I would love a blizzard though .

Two years in a row it has been there I believe, or at least in the December to Feb months ...... You agree ?