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Speculation could be because of the weak Enso state we remain in a rather volatile and variable pattern the duration of the winter. Speculation, of course, but until a certain pattern driver takes hold and is able to provide a repetitive pattern ( feedback loop, etc ) maybe it is more of the same. Hard to say right now. Will the driver be blocking in AO domain that goes negative for a period of 30 to 45 days, will the MJO become more prominent and work in our favor, aka the Webb progression, or will it be more of the same. Interesting times ahead.

Maybe forcing will shift as the + IOD weakens and takes on more favorable phase(s) for cold as we go through January and enter February. So much more than the phase of the MJO, as you are aware and pointed out. Volatility reigns in the model world. There have been some prior significant changes in the EPS this fall. But, no idea how this will turn out.

The general idea that run to run model changes would be frequent, and at times significant, is really holding true so far. I would not want to issue a 30 day forecast because the swings in modeling are really extreme. I really feel many mets are even at a loss. Of note, the same theme the last two weeks, pretty subtle yet significant changes on the modeling, ie. the -NAM state for example. Overall trends up top in the last 72 hours are not very good as you know. A lack of cooperation in the drivers at play, maybe the seasonal models had a clue, although that determination is still yet to be determined. I really don't like the looks of the TPV and its location out in fantasy land. Unfortunately I believe the progression to a more conducive winter pattern that can reload and has real snow potential will have to wait possibly, although there is a window as the PNA goes + near days 8 to 12. Funny thing is with the reasoning of the two camps , as we discussed before, one warmer less snow and then the other more seasonal and maybe snow potential, well the momentum seems to change with the modeling. There have been some set backs in terms of real threat window, and so far Philly and the surrounding areas have had multiple low end snow events, but every one has under-performed. Certainly not a positive trend, even HM admits to the trace phenomenon. Another thing I was looking for was the occurrence of a "significant "snow event prior to December 15th to aid in providing some support for an above seasonal snowfall potential. These may or may not be clues as well as to the future. Another observation from the NE forum, from Tip. He mentioned how cold air was not holding on and was surprised how certain events up North trended warmer. Sounds like our area right, LOL . He posted that he felt we needed to establish deep cold air source with a -EPO and then intervals of + PNA. ( Of note on or near Jan 2nd to the 4 th we do enter a forecasted period of + PNA. ) I like to see what happens then. Wondering if the best pattern does go down in the second part of the winter. There are several analogs/outlooks that support that idea, along with a few Nino winters starting after Jan 15th in terms of snowfall and colder outcomes. Whether they prove useful in this day and age and background state , hard to say. Things are still progressing in terms of forcing and continued developments up top. Bottom line, very hard pattern to predict and just enjoy the holiday season and treasure those in your life Very bottom a post by Don S courtesy 33andrain - my take away (I think we all know this , but ) from it is the importance of a - AO and a + PNA. Those are your clues to Jan to March IMHO. Some interesting posts below regarding the IOD and the HL. From Don S courtesy 33andrain Dreams of a white Christmas for the Middle Atlantic and southern New England regions will have to wait for at least another year. Milder air is now pushing into the region and will likely predominate through the much or all of the remaining days of December. Through December 21, snowfall amounts for select cities include: Allentown: 2.1" (1.6" below normal) Atlantic City: 0.5" (2.1" below normal) Boston: 11.5" (4.9" above normal) Bridgeport: 5.5" (1.9" above normal) Harrisburg: 0.2" (3.5" below normal) Hartford: 21.1" (14.8" above normal) Islip: 4.3" (1.7" above normal) New York City: 2.5" (0.5" below normal) Newark: 4.2" (0.7" above normal) Philadelphia: 0.1" (2.1" below normal) Providence: 8.0" (1.0" above normal) Worcester: 25.3" (13.5" above normal) Despite the warmth, which could take monthly departures toward and perhaps even above normal across many parts of the region, dreams of a snowy January persist. Perhaps a key to whether those dreams are realized will be the state of the Arctic Oscillation (AO) and Pacific North America (PNA) pattern. Since 1950, 52 snowstorms brought 6" or more snow to at least one of the following cities: Boston, New York City, or Philadelphia. 60% of those storms had an AO-, 64% had a PNA+, and 38% had an AO-/PNA+. From among the 18 storms that brought 6" or more snow to at least two of those cities, 83% occurred with an AO-, 83% occurred with a PNA+, and 67% had an AO-/PNA+. From among the 11 storms that brought 6" or more snow to all three of those cities, 91% occurred with an AO-, 91% occurred with a PNA+, and 82% had an AO-/PNA+.

To go with the above from @Bob Chill this is a another fascinating animation regarding the NW Atlantic, Check out the second image loop from Anthony.

Another kudo to HM for stating this upcoming period would bring model uncertainty along with significant run over run changes. Having the EPS, CFS, GEFS, analogs etc all pointing in the same direction for once is a huge morale booster.

OMG

I would speculate these storms off the NE coast continue to possibly add wave breaks to the NW Atlantic reinforcing the good vibes there while various S/W traverse under the block way out in fantasy land. Maybe the EPS will show this.

Bob, would you say when you look at Canada and the HL the progression resembles the GEFS for this time period. To me it looks close in certain areas.

I love the animation, pretty cool to see things reverse/ retrograde.

psu, are you aware of how the CPC develops its 30 day forecast ? I have not seen many issued over the years that go cold and above normal precip in our area for Jan. Is it a combination of fundamental long range forecasting along with modeling or a specific modeling program? There does seem to be growing support for colder risks and storminess this Jan., based on the HL progression and tropical Pac improvements, including several analogs. I have no idea the eventual outcome of the descending QBO for Feb and March. I believe though we broke the 2009 record for sunspots, as in spotless days last week for 2019 versus 2009. .

@psuhoffman @WxUSAF Do you recall the sensible weather in this area during the period mid Jan to early March of 1987. Regarding the strat evolution as a basis for the question. Thanks

psu, this is right along your lines of thinking I believe and others. I need to study the area of Pac forcing in detail, as there is so much more to it than stating just phases of the MJO. HM mentioned some other factors to consider as well on a global level. Enough to make your head spin a

The depiction of precip there generally matches the CPC 30 day precip outlook for January. Another confidence builder for the STJ to continue moving forward. If I can get those positive precip anomalies combined with the recent, day after tomorrow, cold on the CFS Jan forecast I would be pretty happy. Side note, the SOI although not overaly negative is behaving different than last year at this time, another plus for us down the road.

from psu "Only thing I feel confident in is that we should ignore JB tweets. The only thing worse than his social commentary is his weather commentary. " @psuhoffman wanted to respond in banter but a few weeks ago he tweeted that Twitter was blocking him from posting a climate post when the real reason was simply a technical based within Twitter. I hardly ever read JB these days. He has a great memory for previous patterns and outcomes but he does more social commentary and even the weather tweets are more biased it seems these last five years.

Did someone from here hack the CPC site? Not very often do I see light blue over my area. OK, its a low % forecast, but still, I like it!

True, going to a more Nino-ish look, and poolz as you know, the developments in the HL which Ventrice posted about are somewhat typical of a classic Nino background state / progression as mentioned today by HM. Hopefully then the good results up top continue for us, along with a conducive NAO domain. I propose, maybe the best looks in the HL may still be ahead of us.

The HM storm. Courtesy 33andrain from HM < You've got a few things happening that are signals and not just model noise: 1. Retrogression through early Jan before momentum is added from an East Asian +MT then. 2. Coherent transient wave train across the North Pacific begins in a week which will amplify things then and beyond then. 3. Split flow with retrograding RW across the North Atlantic Early Jan is a time when the RW reaches our longitude with potentially enough beforehand to bring the baroclinic zone to the coast. So while we're coming out of a milder period, the right timing could work with this. Climo would favor interior vs coastal plain, however, with a retreating TPV and lack of big cold shot. I'm hoping for another lucky trace just after xmas, haha. The Northeast will not "torch," in this pattern but the variability will continue of course. >

In the COD, but still kind of blah. Slight trend noted below.

@psuhoffman something else for you to ponder. As a connection to the record + IOD ( Also note the SH SWE also had implications - see Amy's post below ) Maybe we need to look to Australia for clues to the long term changes in our weather here, ( focus on Jan , Feb, and March ) regarding the + IOD and the progression of the Pac, including the MJO. Speculation that maybe we need to see the current pattern there start to change. Just a little speculation on my part. Some locations there are forecast to have their hottest temp for ANY time of the year, that is really remarkable. Again, another piece of the puzzle. http://www.bom.gov.au/climate/iod/ https://www.washingtonpost.com/weather/2019/12/18/australia-has-its-hottest-day-record-sydney-residents-brace-heat-fires-smoke/ The heat is forecast to peak Friday in Adelaide, where the forecast high temperature is 113 degrees (45 Celsius), as well as Melbourne, which is predicted to reach 109 degrees (43 Celsius). The BOM is also forecasting that many locations will break monthly records for the hottest temperatures in December. In fact, some places in New South Wales could see their hottest temperature on record for any time of the year, particularly Saturday, according to BOM meteorologist Blair Trewin.

So true , I long for snow cover and cold temps near the holidays and the solstice. Up next is the complexity of early Jan to mid Jan.and what the sensible weather is going to be around here. Time for some cheesecake to ease the pain, but seriously, I am still hopeful though that we get our snow and cold. The idea from @psuhoffman that we get a brutal several week onslaught of winter is one such possibility that I see. Hopefully some clarity will arrive soon.

I believe you also have to re-visit what was posted a week or so ago, the up coming period, and even beyond, has a very high level of model difficulty in terms of forecasting. Many competing forces, and changes abound in certain areas of the NH.

Stir the pot in Jan possible. - AO is all I ask for. Looking at that depiction seems different from recent years, I believe. Ventrice states the ECM depiction below matches up to his precursor SSWE composite. Looks fairly close to me. Just another thing to monitor in fantasy land.

I can only guess this might be related to what @tombo82685 posted earlier that the GEFS might have this outcome because of implied coupling from the previous event in early December. Funny thing is that the GEFS is biased, I believe, in being too aggressive at times with things such as HL warming events, etc. So, maybe it is wrong in its outcome, however, as you posted psu it still accelerates the pattern flip. There is always too the possibility the GEFS has the right idea this time. IMO the environment for coupling may have merit, even if for a short duration. However, caveats apply , as stated earlier by HM with the NWP.

Will be interesting to see how things continue to progress this month and next. Two things : Granted the visual look is still warm neutral enso state. However, I believe the takeaway is more favorably placed tropical forcing is ahead , combined with a weakening + IOD and slow warming spreading East in time, along the lines of what Webb stated, hence an improving pattern .

Back to the West Pac and the Nino