Isotherm

The MJO will certainly be an integral aspect of the entire momentum budget. As I noted pre-season, there were many variables likely to be fundamentally unfavorable for most of the season. Some of those background indicators should improve late-winter [e.g., the QBO]; however, the amelioration in the pattern may only be into a fair/mediocre one [though this would be improved versus the Dec-Jan mean pattern]. Many (not all) of the analogs I examined pre-season would tend to indicate a MJO circuit through 5-6-7, with diminution in 7+ beyond. As an aside, sometimes the background state overwhelms even a favorable MJO circuit. For example, last winter, we did have a 8-1-2 passage late winter, which improved the pattern, but not significantly so. The momentum transports have been unpropitious this winter, and we would need a quite significant vicissitude in that. All said, late winter should *improve* versus Dec-Jan as I've said.

I am uncertain whether I ever recall seeing such an expansive (or any) area of 32C coverage in that part of the world. These are 90 degree F water temperatures to the north of Australia. For such an anomaly in the deep tropics, it yields a significant impact on the energy budget as you know, and concordantly, it isn't surprising to see the modeled high amplitude in phases 4/5 of the MJO. This is akin to throwing gasoline on the proverbial fire. Ambient SST's of 32C/90F are very impressive. This will further serve to enhance the MJO in its unfavorable [from E US perspective] octants.

Here's a temperature departure composite of every January since 1990 that featured a MJO phase 4 RMM amplitude of > 2.0 in January: The ensuing February composite -- the resultant was rather mixed -- by my count, 4 warmer than normal, 3 colder than normal, and 1 near normal.

He utilizes the GFS guidance. The forecasts are not his own. The reason for the alteration from the prior day is b/c the GFS guidance prognosticated a high closer to 50F yesterday at NYC, but the resultant was closer to the ECMWF guidance in the lower 40s. Hence, the change. Regardless, most of NJ and the Northeast are finishing slightly warmer than normal for December.

Exactly +1.0 here through this morning. After today and tomorrow, likely near 50F, I expect that will be a bit higher. Departures about as I expected nationwide; slightly warmer than normal in the NYC-metro region; a little lower than I had for Dec, but good overall. Snowfall here was 3.7". How much do you both have to date?

January 1978 featured a much more atmospherically engaged Nino signal than is extant presently. Pre-existing blocking over the high latitudes, in concert with a fairly coherent GWO circuit 7/8 enabled sufficient momentum induction to produce a conducive downstream synoptic. So, the MJO-4 and concomitant NPAC decay didn't totally extirpate the set-up. Finally, the southern stream/STJ was quite/more active than normal, again, reflective of much improved Nino engagement. Blocking already in place across the AO domain: STJ active: Auspicious GWO circuit:

Very nice article, Chris. The sea surface temperature profile projects onto the negative PDO paradigm to a certain extent, so we end up with a quasi Nino/Nina esque signal emanating from the Pacific. Warmer SST anomalies in the West Pacific, adjacent to Japan, and across the spatial domain around 150-60W longitude tend to promote these patterns. November PDO value was -0.36 per ERSST: https://www.ncdc.noaa.gov/teleconnections/pdo/ The tropical forcing pattern experienced last winter, also mediated in part by z50 QBO modulation. See this study: https://www.researchgate.net/publication/309099921_Impact_of_the_quasi-biennial_oscillation_on_predictability_of_the_Madden-Julian_oscillation

Chris: nice post. In my post mortem analysis last winter, I noted that the z50 negative QBO in concert with robust BDC and protracted SSW length, likely enhanced the intraseasonal-MJO signal, aiding in deceleration, and thus the resultant anomalous warmth across the East [Dec 2018]. 2018 arose quite a bit in my 'differential diagnosis' of this present winter's factors. One difference is the z50 QBO state, which I think, via that indirect pathway, allowed the MJO to remain a bit less coherent this month versus December 2018, and thus, not as warm on the East Coast. However, many of the precursor variables extant last winter are once again present this year, and so, these largely unfavorable storm tracks are concordant with those variables.

In addition to your veracious comments above -- 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.

@frd, thanks for your comments. Yes, I think the probability remains lower than normal for a SSW this season, although, if there is one, the most likely window would be February. Later winter SSW events are more prevalent in low solar/+QBO backdrop. The tropospheric structure for the next few weeks is largely unfavorable for potent wave driving/trop-strat energy transfer. However, it's possible we might be able to achieve more auspicious torque forcing and momentum uptick later in January via tropical engagement. Nonetheless, even if a SSW were to occur, that doesn't guarantee surface impacts as you know.

Hi, @psuhoffman -- regarding your inquiry. The modality of the AAM, as in, positive or negative, is not most integral - but rather - the distribution and transport of angular momentum through the hemispheres. My analyses pre-season indicated unpropitious transports, that would likely countermand the development and maintenance of significant/sustained high latitude blocking structures for much of the winter season. There's more to the entire methodology as well, so, what is stated in the outlook is only a skeleton of what I've analyzed. But, as said, the AAM distribution in concert with other variables, such as QBO timing/diminution, Hadley, Walker Cell behavior, among other factors, were all utilized. We'll see how the rest of the winter progresses. However, the present model/NWP trending in recent days largely comports with my expectations.

It's a steeper climb for interior New England, but for coastal stations, like BOS, they're at -1.1 for the month, without accounting for today's 60F. So they've essentially neutralized, with half-month ahead. The departure distribution again evinces the storm track propensity.

Yes - and the month has not yet finished. We'll see how it looks in two weeks.

Incorrect. This is a misinterpretation of my forecast. First, I do forecast for the entire nation, but provide specific departure values for the NYC metro region. Both the AO and NAO have been positive to strongly positive so far this month, pursuant to the forecast. See CPC data. The rest of your first paragraph is speculation with respect to the remainder of the month. Temperature departures for December are presently normal to warmer than normal in the US, except for New England; and the jury is still out re the final numbers. The overall storm track so far has been similar to last year, favoring the interior Northeast for snowfalls, and coastal rain events particularly NYC southward. @bluewave has also been correct on this matter, to date. I realize that people become quite emotional regarding snowfall, but at the very least, wait until the verification period is over before impugning others' forecasts, and exercise greater care in interpreting those forecasts. Not entirely correct, and there are material omissions here. I called for aperiodic injection of polar/arctic air into the Rockies-Plains-MW c/o poleward NPAC ridging, and near normal snowfall in NNE. The nation has been milder than normal to date, save for New England. It remains to be seen how the month finishes, temperature and NAO/AO wise.

@40/70 Benchmark - the board I posted that on is geared toward NYC metro, so the 1-3" forecast was specifically for PHL-NYC corridor. @frd and @Ralph Wiggum, thanks for your comments. And Ralph, that is generally an accurate description of my thoughts. I expect February will be the most conducive, compared to Jan/Dec.

@40/70 Benchmark, great, detailed work as per usual. You are colder and blockier than me overall, but we concur that late season has the highest probability of inducing such action centers.

There were quite a few strong similarities to last autumn/preceding period in the objective data. As far as the major drivers, the disparities are not significant, though there are a couple notable differences. For example, the momentum budget tended a bit more positive last winter, which aided in the DC area occasionally striking luck with snowfall. With a stronger negative momentum signal this year, the snowfall regime may be less favorable than last through the first half. However, the descent of the easterly shear stress is an improvement over last year, which should, a priori, yield a more conducive regime for those on the East Coast south of Boston for February-March compared to last year. So there is a bit of balancing of positives/negatives of this year vs. last year.

Thanks for your comments. Re November, most of them showed an amplified Pacific ridge w/ some Arctic assist, and a cooler pattern across the North/east, not too dissimilar from this year. The November amplification is quite common within a backdrop of more negative AAM.

Much thanks for the kind words, @frd. I realize this is not a popular forecast, and as much as I would have 'wanted' to forecast the alternative, the objective data simply did not allow it. In my opinion, the case is a robust one for the statements opined in the outlook. As usual, it will be interesting to watch evolve.

My outlook can be read here: [also posted on the main board] http://www.lightinthestorm.com/

@frd. Below is the latest proxy data on the QBO. Easterly shear stress has propagated slightly below the z20 level at this point. My estimation, given slope and pace of decline in this particular cycle is that neutralization will occur mid-winter. Not much time right now, but I'll have more detailed thoughts on my NAO/AO forecast in my winter outlook, posted in about 10 days. Just waiting on a couple more pieces of data to incorporate into the final formula. Here's the image:

Thanks, @WEATHER53. Should be in approximately 2-3 weeks.

A strict construction of the ENSO-oceanic analysis may reveal neutral tending toward weak nino, but inclusion of the GSDM into the analysis yields a different conclusion. The total sum of momentum additions/subtractions evinces an apparent deficit/easterly momentum dominating the tropical/sub-tropical domains, and as such, retrogressive features will be the mainstay of the short to medium term. Whether the GWO neutralizes, thereby comporting more with the oceanic appearance remains to be seen.

Yes, I agree. The cool down is unimpressive. Only when juxtaposed with the recent week's heat does it seem more dramatic; however, average first frosts are nearing for most of NNJ in suburbia. As far as drought, my local area is still fine, due the excessive rains we received this past summer.

Station indicates a high of 93F for my area today. Today was the hottest October day I can ever remember. There have been memorable days in the mid-upper 80s, but they had a much more "summer in autumn" type feel. Today, to me, was indistinguishable from mid July, if I didn't have a calendar handy.