That was still a better winter if you want wintry weather than most winters from 1987-88 to 2007-08. The January was colder for the CET than any January from 1988 to 2014 with the exception of 2010. 

Thoroughly depressing output at the moment. More rain. Great.

I agree. I remember the 1979-80 Winter quite well.  There were actually quite a few snow events during that Winter, in my location anyway.  There were regular frontal snow to rain events, especially in January, as Atlantic fronts pushed into quite a strong Continental High Pressure area at times.  There were some heavy snowfalls too, a very impressive heavy wet snowfall on January 14th, and another heavy fall in mid March, followed by a vicious cold easterly just after that, bringing a lot of snow showers in.  February 1980 was disappointing, mainly mild, but other than that a pretty decent Winter for snowfall.

The meto outlook till the 20th Jan basically covers just about everything so can't really get too excited 

On a different subject has anyone noticed that it's stayed light to later this winter? yesterday it was about 4.25 before it got dark here, not complaining but as for the shortest day, it wasn't like it use to be 

Very dull today here though.

Can't say I've noticed, sunset has been the same time as usual! Most likely there have been a few more clear evenings than normal, which you'd notice as heavy cloud can make it look like it's getting dark at 2.30pm...

Do you mean in rural West Northants? Or on TWO?

Still potential for fairly cold January/February based on current models and hints from MO outlook and others  

Part of me would like another mild winter (no need for gas central heating most of this year always a good thing ) and helps keep the pressure on Putin's Imperial/Mafia Russia (off topic but true!)

Are you trying to get me into trouble? 

The failure of this high to hold north is not unexpected.  The resultant resetting of a flattish westerly pattern with some cool Pm air at times interspersed with chunks of Tm and accompanying wind are a predictable but poor outcome for those hoping to see lowland snowcover for a day or two after this spell is over.

My feeling is that January will see its usual absence of northern blocking and it will again fail to deliver its considerable cold potential, with the possible exception of the last week.  I am very happy for this to be wrong, but its my take as things stand.  February offers more hope at this stage, but a milder winter overall than the 1981-2010 average is looking likely to me.

The events of 2012-13 offer some hope for a change.   I will continue to hope my Dec 1st LRF is wrong for January.  Enjoy your model watching!

WI

I have been taking a look at what has happened to the CET in the period after significant past SSW events to see if there is any trend worthy of note. Of course it is important to point out up-front that there are many factors that influence temperature and so any consideration of just one or two variables cannot in and of itself suggest that those variables may be the key influence of temperature differences.

In order to identify significant SSW events I made use of the following article from 2007 by Charlton and Polvani. This has a very handy table of SSW events on page 453 covering the period 1958 to 2002.

Charlton and Polvani article

I then turned to other online sources to identify SSW events since 2002. In particular this site by Patrick Martineau was very helpful. I have only used events that, on his index, are -2.9 NAM or less.

http://p-martineau.com/ssw-animations/

This gives me the following table of SSW events since 1958. The first column shows the central date of the SSW (or in the case of events since 2002 the date of the weakest Polar vortex state). The next column indicates whether the SSW caused the Polar vortex to be merely displaced or actually caused a split in the vortex. The third column shows whether the SSW event was a relatively weak one or a relatively strong one.

At this point it is worth referring back to the Charlton and Polvani paper. If you go to page 463 and refer to diagrams a) and b) these show the 1000hPa geopotential height anomalies for the 60 days from the central date of the SSW event. Chart a) is for vortex displacement events and b) for split vortex events. What we see is a clear positive height anomaly over the Pole and a negative anomaly over the Azores suggesting an anomalous easterly flow for the UK. The anomalies are higher for split vortex events. The data seems very clear on this.

So if we then go back to my table I was interested to see what effect this anomalous easterly flow had on the CET. So I compared the actual CET for each of the 60 days following the central date of each SSW event to the 1971-2000 mean temperature for each date. This gave me an average CET anomaly for the 60 days which is presented in column 4 of the table. Column 5 then gives the number of days within the 60 day period where the CET was more than 2C below the 1971-2000 mean.

The results show that the CET mean is, on average, about one-third of a degree below the 1971-2000 mean in the 60 days following an SSW event. This is not a very large anomaly but is still interesting. There seems to be no difference in the temperature anomaly between vortex displacement and vortex splitting events.

There is, however, a larger temperature anomaly with strong SSW events compared to weaker events. For these purposes I define a strong event as one where the temperature anomaly in the final column of the table on page 453 of the Charlton and Polvani paper is +8 Kelvin or greater. For later events I take SSW events shown in the Martineau paper with a minimum NAM figure of more than -4.  

I have also analysed the temperature impact by the month in which the SSW occurs. What we see here is that the earlier in the winter the SSW occurs the higher the temperature anomaly on average. For those SSWs that occurred in March (of which there are not many) the temperature anomaly was in fact on average positive. The vast majority of SSWs occur in January and February. In recent times almost all have occurred in January.

I then got to thinking about what other factors might significantly influence the temperature changes that might be triggered by a SSW. An obvious factor is the QBO. As noted above, a SSW typically results in an anomalous easterly flow over the UK. If this occurs during a westerly (positive) QBO phase then the easterly flow that the SSW attempts to trigger may well be offset partly or entirely by the westerly QBO effect. Conversely during periods where the QBO is easterly (negative) this is likely to be enhanced by the anomalous flow resulting from a SSW.

When we look at the temperature anomalies split by QBO phase we see a very significant result, albeit this is not really surprising. The final column of my table gives the QBO figure for the month in which the central date of the SSW occurs.

When a SSW occurs during a month where the QBO is negative, on average temperatures in the following 60 days are above average suggesting the positive QBO is more than offsetting any impact from the SSW. When the QBO is between 0 and -8 there is a negative temperature anomaly broadly equal to the average anomaly for all SSW events.

When the QBO is lower than -10 and a SSW occurs the resulting temperature anomaly for the next 60 days is on average about -1C which is very significant indeed.

Again I repeat my earlier comment that there are many influences on temperature so one has to be very careful in drawing any conclusions. As can be seen from the data in my table even in years with a very negative QBO and a strong SSW, the CET in the following 60 days has been warmer than average in some instances (the best example of this being January 1977).

Nevertheless the data would suggest that a major SSW event in early to mid-winter during a strong easterly QBO phase does increase the likelihood of temperatures being below average in the following 60 days.

One final point to highlight is that the temperature figures in my table are averages. I am not saying that a SSW can give 60 days of bitter cold. On the contrary after all such events the temperature patterns are very variable as they always are because of the multitude of any factors that impact on our weather. So even when we have experienced spells of very cold weather following a SSW there are periods of warmer weather as well when temperatures are above average. It is just that overall over a 60 day period temperatures tend to be somewhat below average.

So if we now look at 2014/15 and try to apply some of the thinking above what do we see? Well as we know the QBO is very heavily negative at the moment (below -20 in fact). So that is obviously helpful. The models are showing a potentially significant warming event developing in the stratosphere over the next 10 days.

Major warming over Siberia has already displaced the Polar Vortex somewhat although the vortex itself is still intact and circular in nature at the moment as shown by the 18z GFS run.

http://modeles.meteociel.fr/modeles/gfs/runs/2014122718/gfsnh-10-18.png?18

As we reach the end of the high resolution section of the GFS run we see the Polar Vortex starting to split in two. By T240 the split is complete

 http://modeles.meteociel.fr/modeles/gfs/runs/2014122718/gfsnh-10-240.png?18

The 18z GFS(P) run does not quite manage a split vortex (although previous runs have). The vortex is heavily displaced though but does try to reassert itself by T240.

Anything beyond this is way into FI and in low resolution so should be ignored. A splitting vortex has been modelled fairly consistently for a few days now so it is conceivable that a SSW could occur during the first half of January but far too early to be cerain. We will need to see wave breaking as well in order for the cold air from the Pole to be displaced south into the mid latitudes. But the building blocks are there so something to keep a close eye on in the next 10 days.

Finally, on a separate point I have been looking back at some analysis I did in November on CET analogue years. The best fit now we are approaching the end of December is in fact 1984/85. The data is indeed a remarkably good fit since about 8 December.

Now of course January 1985 was very cold indeed and at the moment it seems unlikely that January 2015 will be as cold as this. But I would not rule it out, especially if a SSW does occur. The chart below shows how the daily CET for October to December in 2014 compares to 1984.

Interesting times ahead I think. This winter is just getting started weather wise and I would be surprised if we do not see some breaks in the more zonal flow during the next couple of months.

A lot of the talk of SSW (not GWs excellently well researched post above) is an attempt to gain intellectual high ground, to appear to be the bearer of "good news", to be the first to "spot" the next cold shot and therefore claim (mistakenly) some kind of credo and authority from the early observation.

Almost all talk of SSWs appears to me to come to nothing meaningful on the ground.  The acreage of cyberspace clogged up with SSW talk is hugely disproportionate compared to a meaningful understanding of the true cause and real effects, though as I say GWs post above is an exception in this respect.

WI

it may have escaped some of you but the stratosphere is above the troposphere. they are one dynamic. there may be occasions when events in the upper parts of the strat are completely unrelated to events in the trop (and vica versa given time lags) because of strong mid level vortices not allowing wave energy to make it all the way to the top/bottom. to dismiss the state of the strat and events within it?  you may as well be using seaweed!

i doubt the world meteorological agencies would have spent hundreds of millions of dollars developing better stratospheric modelling if it were just a 'fad'. of course, the modelling could all be wrong because the world might be square and flat  

December successfully negotiated without too much cold, apart from the last couple of days. The forum has wrote of January already......

By the time the parameters for cold get in place the sun will be warming the sky enough to not matter. Result then 

Aye! 2/3 of winter to go then bring on spring!

Looking at CFS LR for around the 20/1/15 looks nippy but a very long way off!

It's that interesting stage now where the Long Range Forecasts are really tested.
 
When released the models give a fair idea for the first couple of weeks, I.e a wind event, some frosts, cold and snow and most forecasters went with that plus had the me to outlook as a guide too..... Now even that doesn't always go to plan & things often change..

Now let's see how things go from here :)

Shall we have a friendly wager on who puts up a Spring Forecast first and then also commits to set dates for such events too :D

I disagree with this. A number of the lrfs went for a colder than average December and a few dramatically so. In other words they are already wide of the mark despite having the numerics and MetO guidance. 

So how are we doing?

This is where your come into your own then Brian and the cream will rise to the top, I obviously read and take note of the wrong people lol 

Have to say I take them with a pinch of salt but do find them interesting