And they were both glorious!!

Yeah a more interesting 06Z GFS synoptic wise with high pressure extending further north, hopefully this theme will continue and not disappear. Ironically a weakened Azores high (which has been the feature for most of December) bodes well for any potential blocking to form once the high pressure moves away from Central Europe. Its just a shame its taken this long.... and consequently we have had a month dominated by a mild SW flow becuase high pressure has remained pretty much stationary here.

Therefore it hasn't been a typical 'zonal' month, the Atlantic has been rather weak with low pressure  remining pretty much stationary to our immediate WNW (ie low pressure systems havn't quickly moved from west to east), as a consequence the persistant SW flow has been unabated drawing up this exceptionally mild air from the sub tropical Atlantic.

I sense a disturbance in the force.

Even at 192hr the polar vortex is under attack; note how the cold pool at the 500hpa level in danger of being split in two? It isn't much but there has been a consistent weakening of the polar vortex at all levels from 500hpa to 1hpa on the GFS. It won't be enough to bring us a cold spell before xmas, but it may be enough to bring something interesting before 2016. 

Yes, no need to panic yet. The mild conditions may well still hold on!  

It would be hugely disappointing if a coolish Sceuro block were to scupper the record in the final days of the month. May the blowtorch continue until 23.59hrs on 31st December. 

Bring in proper cold at 00.01hrs on 1st January. 

If the height rises over Scandi, of which there are signs of, don't get far enough N or W then we could get stuck in a further very mild SWly/SSWly flow, possibly very wet too. But I suppose it's something. 

Don't see much sign of the vortex becoming disrupted tbh.

NAEFS 324hrs. Intense area of vortex centered near Greenland.

Yes but we have to think this in a wider context; is anyone going to disagree with me that any hopes of a cold Christmas are gone? Anyway, I agree with you but the point is that we are seeing disruption to the polar vortex in the reliable time-frame with a high degree of consistency. The time it takes this moderate disruption to propagate down from >500hpa to the surface could take weeks, and even then its not a huge disruption. Nevertheless I think there is something to be optimistic about that the probability of a pattern change after christmas or early January is being hinted at.

We're also seeing signs of the strat cooling after some mid term warming! 

Again, I think we need to look at a broader scale. 10hpa is only one level, further up there is a more significant warming; also despite being a fairly modest affair the polar vortex is left weaker than it was at 0hr and that has to be a good thing for the prospects of cold spells in Early January. 

To be honest, didn't see much to be optimistic about in the EC ens out to day 15 if it is harsh winter weather you are looking for. Some ridging over eastern Europe is progged beyond day 10 but with cold uppers on the east side of the ridge tending to advect eastwards, rather than southwards, it remains to be seen if this ridge can grab a firm hand north of the 60th parallel. Early days and all that..

Sure, but I think there is potential for Early January if not the end of December.

sadly even Aviemore is in the mild for this Christmas so looks like a lot of the mild callers were on the money big time

I agree, but considering that early January is one of the coldest periods of the year on average, the potential for cold spells to develop around that time must be greater anyway.

Sadly, there is no kudos for calling a depressingly mild winter in the UK, since that is the depressing business as usual.

Now someone who calls a cold winter and is vindicated - that is special and impressive.

So in betting terminology, you don't get a plaudits for backing the odds on favourite, but you do if you back the 100-1 rank outsider and it comes in first.

I think Ian Brown has called it spot on even though I am very disappointed he could be right. 😠😠

Based on what we know regarding the current meterolical pattern, is that this pattern is very hard to Change😕😕

Yes, i was actually inferring even the Highlands which looked like they had a chance with the rinse and repeat cycle, but that is looking ominous now as well. 

Actually it isn't.

In fact the Highest, 95th, 90th, average, 10th and 5th percentiles are actually all on the rise from early january until early february when they drop to reach the seasonal low in mid February. This will be because early january is generally a very active period in terms of the atlantic, whereas the late winter the Atlantic eases off so its no surprise that it is on average colder.

There is one exception. The lowest record despite having a noisy signal for obvious reasons reaches a low in early or mid january not mid february like all the others. The reason? Because for a cherry pick of the most severe synoptics the sun becomes the dominant factor not the synoptics themselves. I made this point last year, the theoretical coldest possible time of year should be much closer to the winter solsdist then we normally think; the reason it isn't is because truly extreme synoptics are far less likely at this time of year. However keep in mind the coldest months ever have always been Januaries not Februaries. Basically 1947 was actually nothing compared to what it could have been if it had happened a month earlier. 

Sorry for this tangent people, but not that much is happening wrg to synoptics anyway!   

Ok, fair point. Regarding the CET, this is an interesting comment on the yearly singularities.

"Using the mean daily Central England Temperature (CET) series [ 1961-1990 ], the curve dips to a first winter 'minimum' around the end of December or within the first few days of January, i.e. the 'turn' of the year. There is then a 'false' recovery in mean temperature, before the series minimum is reached in mid-February. In both cases of course, these minima occur after the point of shortest daylength - in the case of the lowest (mean) temperature, a good 7 weeks after this date. The main reason for this marked 'lag' is again a function of the fact that sea temperatures in particular do not reach their lowest values around our islands until well into February or even early March. There are other factors though, such as a greater tendency to northerly or easterly types as the winter progresses and the increasing likelihood of anticyclonic 'blocks' allowing night radiation to become fully effective."

Yes exactly, and keep in mind that the 850hpa temps are relatively static now in the arctic and will not really fall that much more (on average), obviously the SSTs will continue to fall but lets say we got a feed from the SE that brought a -15C pool at the 850 level to our shores. Were it to happen in February then initially it might be colder at the surface given the warmer SSTs, however a January case would catch up and exceed the February case. Let's be honest we only have about a 5 week window left to get a truly severe winter (CET <-1.5C).  

Looks like the jet is going to start digging south next week, could be some stormy wet weather across southern parts around the Christmas period.

UKMO +144hrs

Weakening of polar vortex not as obvious as in the 6Z though by 10 days things are getting interesting.

Note the wavy pattern beginning to emerge, if any of these lobes get cut off it would cause LP to move quite far south and possibly even introduce the risk of Easterlies for the beginning of Jan. Like I say just a possibility, but the weakening of the polar vortex remains very consistent.  

Polar vortex continues to weaken by 264 hours

Shape becoming more distorted, one lobe looks really close to breaking off in SE Europe. 

Yey, here we go

Took longer than on the 6Z, but here we see a chunk of the polar vortex being chipped off and moving towards Turkey. I'm sure it will bring plenty of cold and snow there! 

By 336hr the polar vortex actually splits into two in the arctic

One bit is sitting over Greenland and the other bit is sitting over Alaska. Arguably there is also a third over china, although I don't think this is is part of the 'true' polar vortex (need to look at higher levels).