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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 ?

I may be wrong with the date but one analog tossed out was 69 -70. Was that the winter which did not produce until March ? Maybe there was a blizzard in early March that year, whether we shared in it I am not sure, recall reading a post from Uncle in the NY forum.

Possibly, but we have had periods where it appeared the blocking would couple and did not, or we would experience a longer cycle of a -NAO and then it became only transient , or the MJO would proceed more normally and not spend more time in the warmer phases and then rapidly pass the colder phases. Ah, but what you said does have merit , because if everything lined up perfectly all the time our average snowfall climo would be much higher. The general warming base state the last few decades is also a bummer as well. And for the record, my perception is also clouded somewhat by frustration at times.

Exactly, keeping in mind this is my personal perspective, but have you noticed how difficult it has become the last several years in achieving a state of cooperation between the indices. You see it in the West Pac with the MJO, you see it in the Pac and the Atlantic where they never work together, you see it in the high latitudes when we do not achieve coupling. Either a string of random bad luck, or a change in things, where everything is out of alignment .

Interesting post by Simon :

LOL that is hilarious - over the weekend he posted one of the American models showing a dramatic cold flip, but everyone calls him out now on social media that the Euro at the same time has very warm temps and exposes his cold bias. Too funny reading the replies. I just happen to stumble upon it . As I normally don't read his feed for these very reasons. Also, Earthlight said buckle up, well, I am still waiting. Weather is so humbling and frustrating at times. Another winter with complexity off the scale. I mentioned weeks ago about sudden model flips but even these long range changes are rather remarkable to me. I am jealous, was just there recently and it was awesome. Have fun ! So many great craft beers to sample. I love greenman in Rehoboth - so cool for breakfast and juicing. https://greenmanjuicebar.com/

Of course seasonal models looking correct at the current time, in regards to the HL. Courtesy 33andrain - I enjoy Snowy's post, here is a little regarding EAMT and the Siberian High . Snowy's thoughts seem to echo the modeling at this time. << Posted 12 hours ago Just a few notes about the East Asian Mountain Torque, we will start with the current status. We are currently in a negative EAMT. I expect a positive EAMT to develop in the next few days to counter the current negative trend for a brief moment. This would add some momentum for the first 10 days of January for the PNA domain. But it won’t last. However from about the 1st to 3rd of Jan, we will see another -EAMT come into play, and this one could be sustained for a while. This is going to reduce momentum in the North Pacific basin, and increase the forcing of Aleutian ridging, and therefore Western US troughing and Eastern US ridging. As you can see in the model guidance, the troughing over Siberia early in January weakens the Siberian High, which weakens our chances for a stronger North Pacific jet stream pattern, and for a strong Aleutian low. Based upon this, I’d forecast Aleutian ridging for much of the month of January, barring an extraordinary constructive interference. The weak Siberian High and Aleutian low also means that any forcing towards a SSW is unlikely in the foreseeable future. Hope everyone here had a good Christmas, and wish everyone a happy New Year. >>

Yes, I tend to agree, good observation. We really need something to re-set the entire SST pattern out there. Wonder what would happen if we had a moderate Nino or even stronger. We seem to be stuck with the recurring issues.

bluewave, that is an interesting concern. I have read, from a couple mets, that the desire for colder outcomes in the East eventually rested in part to a weakening of the record +IOD. I did not come across any mentions of weaker IOD influence leading to more amplified forcing in those unfavorable phases. Unless, I misunderstood what Webb posted, I thought that when the IOD weakened it would enable more traditional and assertive West Pac forcing to arise, and even the possibility of increased -NAO phases. I would appreciate why you feel the weakening + IOD might be a concern. Honestly, I was happy to see the + IOD weaken, now you have me concerned. For reference, here is one of Webb's posts regarding the weakening IOD. Please take note, this is from back on December 10th, simply inserting it here so you can get a better idea of what I was referring to .

In a general sense, I see the same issues as last year, but slightly varied. Still Pac issues persist...... Modeling not seeing the SE ridge beyond day 6 but it shows up due to the crap Pacific pattern, as mentioned earlier today by bluewave Warm and wet then cold and dry - cutters, etc. West Pac SST structure not conducive, hence effecting the MJO behavior ( related to the study done on warmer phases lasting longer and colder phases lasting shorter time periods ) Fast Pac jet - continued records being set across NA and the NH Ridging and High pressure North of Hawaii - same as last year. Then downstream effects for us. Again, nothing new. Warmer SST profile too far off the West Coast of NA. - Never really looked that good, even earlier in the Fall. Nothing remarkable is evident so far regarding this December, except the continued above average rainfall. However, the AN precip is simply a consequence of the above factors. But, maybe things will change later in January. Not loosing any sleep about this winter, not worthwhile in my opinion, as I learned to lower expectations and be more rationale after last year. However, still feel a window of significant winter weather will occur in Feb and even March. Here is a recent post form Tom. From @Isotherm Note ozone concentration propensity, which is highly reflective/comports with the mean z500 structure hemispherically. Increased ozone residence over the WPO/West EPO domains will continue to promote higher geopotential heights, whilst lower ozone concentrations in the means near the North Pole/Greenland will promote the overall +NAO paradigm maintenance, prospectively. When one considers the forthcoming AAM cycling, that too, comports with the NWP's modeled Nina-esque z500 structure in the medium term.

Wondering the impacts of the declining +IOD for Feb and the first half of March. The last update, from two days ago came in at +0.6 C. Pretty decent drop continues from October when it was 2.2 C. Hopefully this will impact the Pac forcing and eventually lead to a more traditional and assertive West Pac/date line event. I see you mentioned the warm WPAC SSTs and amp up of the unfavorable MJO phases. Do you feel the declining +IOD will effect this area of SSTs, or whether it might mute the effects ? Eric Webbs stated recently, as well as others, that we should begin to see a more favorable pattern for cold deliver into the East later in Jan. As you know model error and forecast uncertainty reigns this early winter. A continuation from December really. If we can achieve a more coherent MJO progression maybe more faith can be given to the models beyond day 6. And truth be told there is more to the global drivers than just the MJO, but here I am focusing on MJO behavior.

Also of note, SE Canada maintains snow depth and the fantasy land GEFS does have a somewhat colder look for us originating from the extreme cold air mass pooling near Alaska and the NW territories and then SE towards the Tennessee Valley, NE and the Northern Mid Atlantic.

Was waiting on this update, released today by http://www.bom.gov.au/climate/enso/#tabs=Overview I am not an expert on this topic but I am surprised we have gone from 2.2 C. in mid-October to +0.6 C. as of December 24, 2019. Even further weakening is expected according to the various climate models. The + IOD threshold is +0.4 C. Now the question is how soon will the atmosphere react, so we can revert to a more conducive and assertive Pac forcing regime, not all of these weak, multiple areas of convection that continues to throw off the various MJO models. New release- issued December 24, 2019 Positive Indian Ocean Dipole weakens: The positive Indian Ocean Dipole (IOD) continues to weaken, while the El Niño–Southern Oscillation (ENSO) remains neutral. The IOD value has fallen from a peak of +2.2 °C in mid-October, to the latest weekly value of +0.6 °C. Warmer than average waters persist near the Horn of Africa, but waters in the eastern Indian Ocean are now near-average. While the index is still above the positive IOD threshold of +0.4 °C, most international climate models surveyed by the Bureau indicate the positive IOD will dissipate in January. The rate of current weakening would suggest a return to neutral is likely by early January. Positive IOD events in spring (as happened this year) are often associated with a more severe fire season for southeast Australia in the summer months. In the tropical Pacific Ocean, while most indicators of the El Niño–Southern Oscillation are neutral, warmer than average sea surface temperatures in the far western tropical Pacific may be contributing to some changes in local weather patterns over the region. International climate models forecast ENSO-neutral until at least autumn 2020. When ENSO is neutral, it has limited influence on Australian and global climate.

Something to keep an eye on for early 2020. The modeled storm at 917 versus the Braer storm of Jan. 1993 .

@Isotherm Do you continue to favor the idea that a SSWE is not favored this winter season ? I can see a way to a better pattern without such an event, as I almost worry about the consequence should we experience a SSWE, although I put the odds of an official SSWE as rather low myself. However, outside of a SSW I would certainly like to see some disruptions to the vortex in January though, along with improvements in forcing, and as you mention above, AAM and the distribution and transport of it. Seems your progression is looking good so far Tom. Still feel we have ample opportunity later in Jan. that may go into March. Time will tell.

I am very skeptical myself. Just when I thought I had a logical progression things turn the other way. When I read about the delayed atmospheric response to the weakening + IOD I started to worry a couple weeks ago, but felt the HL may bail us out. Now that seems a no go. Until proper Pacific forcing becomes more prominent and assertive we have to wait. The opposite of last year at this time in regards to the SSWE. Several mets ( not here at American ) have reversed their position only to reverse it again and then again. Wonder what BAMWX energy clients are saying? . No one has the hot hand currently. More on topic - Another interesting long range observation, and I believe also mentioned by Isotherm, was the - NAO was verifying not as negative the past 3 to 6 weeks. When you actually look at the readings ( yes debate over what is a - NAO verus blocking acknowledged ) ) we really have not experienced a deep NAO state except on one occasion. Certainly everything has been rather progressive. The wave breaks have been beneficial and I would guess have helped those further North. Looking back a bit further, it was hard to keep the previous decent NAO drop going when we had that robust - EPO I believe. psu I also can't help but feel all our cold air outbreaks from early November to mid December were caused by mostly HL and strat related events ( wave 2 etc. ) such as displacements and elongations including one event that was barotropic related. Losing the HL and vortex disruptions and elongations are a real bummer. I felt early in the season the HL and elongations may be favoring Eastern North America but now it seems that mechanism is fading. Of course we could return to it later, as a consequence of an improving Pac and increased attempts to weaken the vortex, a.k.a the Isotherm seasonal evolution, or as is typical in some Nino years. One final note about the HL is the fact that the QBO might become a bigger player by mid Feb through March. I know folks refer to shear stress as well with the QBO at 30 and 50, but those references are above my pay grade. Hopefully an improving Pac will coincide with an improved NAM state later in the season via the descending QBO including seasonal vortex weakening. We shall see.

Looking back at the last 10 days of November for the CFS it was remarkable how it changed so quickly. I use to read it was in its wheelhouse 15 days before the start of the new month, but after looking at the past 6 months and combining that some notes posted by a couple climate/seasonal mets the CFS is not really stable and in its wheelhouse until the month is almost over. ( forecasting the next month ) So, I say what good is it ? Maybe for trends, as I have noted times that it is incorrect even when it is in the existing forecast month. I expect it to warm up for Jan in the next few days. I believe the trend to warmer has started already. Whether it is, or will be correct is difficult to determine.

Admit I am a little surprised but not totally. Yes we had the good wave 1 and 2 events but nothing timed up correctly and lasted long enough. I am sure there is more to it than than that . When the vortex was in a state more prone to further attacks , it was like , is that all you have ? And hence the bounce back.But not worth the time to even figure it out. I have not read about the latest forecasts regarding the precursor pattern that was posted last week from Ventrice. This strengthening is more camp two of Isotherm and stating the atmosphere and drivers were not conducive to weaken the vortex this season until later or not at all. If so expect the HL to continue to look poor. In terms of retrogression and blocks and just because this post by HM is interesting . He posted it just because it is cool. Seems there is always a monkey wrench thrown into the winter. Of course with the run to run changes it is silly to worry. Everyone so far has been proven incorrect at least in some form or fashion about this December, not surprising given the abundant weak signals.