The Arctic SSW forecasted for the end of the last month didn't validate and it ended up as a Canadian Warming instead (resulting in a stretched polar vortex); something similar may happen again seems to be forecast for the middle of the month (although its very far out) with the vortex getting temporarily stretched again (a dip in the stratospheric winds). So at least for the NH I am speculating the second half of December will be roughly as anomalous as the first half of December.

Globally, given the medium range models are anticipating a dip in week 2, I do overall expect roughly even temps for the second half of december when compared to the first half, but more warming compared to Prophet's expectations (below) of a climatological downward trend on average after extrapolating from the dip (i.e. I expect some more reversion than shown below) ...

So overall, I'm expecting the December anomaly to be cooler than November anomaly this time... (edit2) although not official yet, the latest gistemp run I did continued to show a revised October a bit cooler than official (1.192) although this may be still due to a bit sparse data) (and expecting from ERA5 that November to be about the same or a bit warmer).

My priors for large month over dips given that the recent two months have been mostly steady, generally indicate to me that we should expect a modest dip compared to November's anomaly, so I've placed most of my initial bets based around that.

Looked at more subseasonal forecasts and indices today despite them worse than climatology usually on the whole; my interpretation is they still indicate some mild warming for weeks 3-4 of december relative to week 2, which very much still goes against the climatology... (otherwise I should be dumping all my mana in the lowest two bins)....

i.e. binning the climatology you get the following trend relative to some mid point in December (obviously not the best method)

Still looks like this year doesn't have a good analog looking at the other years indicated... The weather for North America at least should be milder than past analogs (with perhaps the exception of the East coast) and still NH anomalies overall as well as some continued Antarctica anomalies seem indicated to continue to dominate in weeks 3-4..

(Referenced ECMWF subseasonal charts as well as GEFS, CFS medium range and long range forecasts).

in short GEFS indicates NAO+, AO+, PNA- for a mild NH winter overall for December (with the exception of possibly east coast), and a continued AAO- for some more Antarctica warm anomalies)

~

In overall the justifications to go against my own (statistical and the usual dynamic medium range superensemble + Prophet) models again (by raising it slightly higher subjectively) are to:

1) rely more heavily on the priors for month to month change in anomalies from gistemp (which counterindicates such a large change, i.e. which would drop us down to 1.09 C after all adjustments for a point prediction, which would seem to be more than a 0.1C drop by my forecast for November, which if I recall should definitely be in a lower quartile if my forecast is correct)),

2) interpretation of the longer range dynamic models despite being less reliable do seem to generally agree on some warming but this is calculated subjectively in part,

3) the climate as of the last few years after the last el nino seems to have less good analogs to the past, so I do want to downplay the climatology to some degree to reflect that despite being in a la nina now...

Unfortunately this means my bets are still largely subjective at this point....

The super ensemble has shifted downwards a bit. I've updated a couple times today (now more downwards) after lastly looking at various diagnostics from only the deterministic ECMWF, subjectively this might have been caused by a change in pattern for Asia, namely a cold front/high pressure bringing a blast of Arctic air to Asia for week 3 of December (where in the 00Z/12Z runs yesterday they didn't show this). EPS isn't in good agreement about this of course so far out so its hard to say if this was definitively the cause....