That doesn't look like a "Euroslug" high to me, Beast?

Also, I don't see much if any indication going further forward from the models of such a set-up developing.

I believe the impact of SSWs on the troposphere have been researched since at least the 1960s

If I'm being honest, I knew absolutely nothing about SSW events until one took place early in 2010, which IIRC actually came after our coldest weather of the 09/10 winter. I have no recollection of them even being discussed on this forum prior to then, but as the olsd saying says, one lives and one learns!

i agree the majority suggest this but there is enough uncertainty to keep an eye on the models for gory term developments given the year and how dominant HP has been. Look at 144 on ECM and UKM would not take much for some cold to impact UK and then that might alter the whole pattern

By day 10  on all models, pressure is rising over Europe and is low to the NW. The GEFS remain very poor for cold weather.

I think Brian made reference earlier to how a few weeks ago, the MetO were at one stage predicting colder weather around or just before Xmas. From what I remember there was brief suggestion from the models that this could have ended up happening, as some GFS runs a couple of weeks ago indicated at one point that the HP that has been sitting just to the south of the UK since Christmas Day could have been futher north. Had it been further north, I imagine that Xmas would have seen rather colder weather than what we have actually had.

The biggest stumbling block there has been to getting cold in recent weeks from what I have seen has been the almost permanent HP cell over or near to Iberia. Until that moves out into the atlantic to some degree, not much will change.

At a guess things will remain mild with low pressure to the south before becoming much more unsettled from the north, and then colder (with hill snow in the north from the end of the first week in January). This could change of course.

What I meant was the idea that a SSW means that cold weather is on the way for the UK, or the idea that without a SSW we won’t get any cold weather. It seems to have been grossly oversimplified by some. 

Yes it looks poor! So why is it that all seasonal models go for big blocking feature or above average heights over Iceland and Greenland in Jan/Feb?

I have watched Gav;'s weathervids and ECMWF, B.C.C, Met Office Glosea 5 seasonal, CFS, MeteoFrance etc show blocking north and low pressure to south through central Europe?

-it's either they are wrong or we really do need to start seeing some cold GFS runs soon by mid month to back up the above, including backing up what the Met Office have been saying! I also see that the GFS HAS BACKED AWAY from the extreme cold air to hit the NE states too. - NYC, DC, Phili and Boston hasn't seen much in the way of snow either...?

Meanwhile ! What is it with Pizza slices this winter:

*cough*... aside from ECM, that is, which runs out to 15 days via its ensembles. For what feels like the millionth time, you can see the full output every 12 hours via weather.us.

https://weather.us/model-charts/euro/england/snow-depth.html is one way to access those charts .The Switch Member button allows you to see every one of the 52 members each run!

You should have mentioned that before Darren 

Heh! You'll note I linked the snow depth charts, too, albeit other variables (and other parts of the UK) are available. An eternal optimist? Not really, it's left over from March when I last hammered that site every 12 hours!

An important point. 

The most intense cold in some winters preceded the SSW - 1963, 1979 and 1987 included. In the first two, further very cold weather did occur afterwards; but if we consider the even colder weather before, it becomes slightly more difficult to attribute the latter cold spells to the SSW events listed.

Others (Jan 85; Dec 81) occurred very closely ( a few days) before the cold set in- too close to be SSW induced?

This all suggests to me that it is still worth watching the models for all the other signals we usually focus on in non-event years- persistent trends in clusters in the ENS included.

I feel a new study coming on “Sudden Stratospheric Warming: A cause or consequence of cold weather”? 

You are aware that there are dozens of members that use the term ' UK pizza slice?' - where Else would I have got this term from??

Anyway sorry for the irritation caused! 

 You've already got your doctorate; let someone else take it on!

 I’ll wait until I retire, with a bit of luck we may have had another cold spell by then to add to the data. 

On a different note it will be interesting o see if the 06z GFSP run persists with the FI  (2nd week in January) cold unsettled pattern when it comes out within the next hour.

There is a general recurring theme in these Forums and it is the tendency to jump on the latest magic answer that supposedly solves the puzzle of how the atmosphere will behave.

Over the years we've had teleconnections, sunspots, El Niño/La Nina and now SSWs.  It is never ever that simple, as many recognise.  If it was the professionals would have worked it out by now,

There are lots of pieces to this jigsaw and it seems to me that no single one determines the outcome, and certainly not when it comes to our tiny part of the globe.

I think this rather excellent summary should be pinned to the start of each MO thread.

I’m starting to think if we are to see continental cold post day 10 we need to keep the EC solution and to move it’s high north. A two week zonality ‘reset’ a la GFS is not very appealing TBH.

I confess I had expected to see some reaction in the GEFS suite to the reversal now due 1st Jan so in that respect it’s dissapointing today. On the plus side the EC46 look good for HLB in the right place longer term so it’s a waiting game.

Those ensemble graphs have been indicating snow for me since early November. All part of the idea of course, given they include all 50 members, but the reality is I haven't seen a flake since March! 

Do the models start their runs with the data that is available to them at that moment in time? Another words would the reversal be factored in to the ensembles or only when it actually happens. Sorry if this has already been explained..

Spot on. At least SSW has validity and isn't a hoax like one or two other ideas. Nonetheless it remains true that long range forecasting in the UK still has a very long way to go.