http://www.wetterzentrale.de/maps/GFSOPEU12_207_1.png 

So, the story so far today is that change to unsettled conditions midmonth is is still on track with colder interludes in the north and then possible more widespread beyond then. Irrespective of any cold, what looks most probable is the switch to more mobile cyclonic conditions, and I’m not really using the term zonal for a good reason.

http://www.wetterzentrale.de/maps/GFSOPEU12_201_1.png 

The switch has been very clear but what winter weather fans will be looking for is to see if the next stage develops as hinted at by the GFS/P runs.

The PV split is beginning to show in the closer time fram which is our potential to the cold developing showing nicely on the GFS run now where it leads for the UK who knows

All starts to kick off again on the 19th very consistent from the GFS Op . Only 12 days to go what can possibly go wrong?

From what im seeing. The GFS is presenting its usual winter stuff. No cold for UK within say 7 days. Typical FI Blue colours presented in all sorts of imaginative ways.

However because there is a SSW about it seems everyone is a little bit on edge with whats being presented. Ive gotta say, nothing that the GFS has produced during this SSW has been consistent or that severe enough for me to sit up and think - ey up, maybe this is the SSW impacting the charts.

If you presented the current charts last year or any other year - i doubt anyone would give it a second glance. From my perspective theres nothing of any interest in the charts this year. I wouldnt be surprised if this year ends up being the year we measure other SSW's against as a warning to get excited.

It just seems like maybe this year will be remembered for the mid atlantic HP rather than anything else. And also - how vastly different the LRFs have been to reality (So far)

Hopefully Im wrong.

Gfs12z keeps the trend going post t192 albeit it loses its way I think towards the end. With forcing from the strat getting stronger by the day (down welling) high latitude blocking should become much more prevelent in the coming days. 

We are still talking post 17 -18 Jan therefore detail will vary run to run but theme will remain.

The change to more unsettled conditions  which started off a couple of weeks out about a week ago is now about a week out. The potential for cold has not changed, nor has the timescale (in the models not the forecasts). The cold is neither nailed on nor is it shown with lots of consistency but it is being hinted at. 

I'm not sure we will see a clear dip in the majority of ensemble members for a few days yet if it is to occur at all. It is certainly an interesting period for watching the output.

It wouldn't be that much of a surprise to see colder charts appearing  at an earlier time frame as the models get to grips with the forcing from above.  We shall see.

Accurate assessment but the last sentence is still a strong possibilty with two months or so to go.

Lovely GFS Control   goes cold as early as the 18th and stays very cold to the end of the run.

The first effect should be a definitive raising of heights over the pole and then a dislocation of the splintered PV segments into mid latitudes. Two or three of the ‘gaps’ created will act as conduits for cold surface air to flood south below the Arctic circle.

This in very simple terms is what I’m expecting and we should see a steady rise in the number of extended EC and GFS members showing this as the week progresses.

A very reasoned post, let’s hope it pans out like suggested. ENS watch it is then 

GFS Para also goes cold on the 18th stays blocked to the end

Looking at the latest GFS 12z ensembles there is now a slight cluster developing after the 20th well below the mean which still sits at -4C. Those above the mean are more spread and if they are eliminated as outliers in the next couple of days the mean is going to drop below -5C.

The control and op are right at the bottom though and the control is a cold outlier, but hey it is -12C !

Nothing dramatic in the near enough future but more signs of things going in the cold direction I would say.

My previous concerns were clearly unfounded with snow now "guaranteed" for my Birthday!! 

Interesting in the ECM tonight to watch the west to east movement grind to a halt at 216 and then the Russian high pressure build at 240. One to watch.

Martin

The ECM is still a progressive chart at day 10 and could easily have us on the wrong side of the PFJ. Good troughing into Europe though.

Interesting end to GFS looking at the Jet - I'm assuming you'd expect a very disorganised jet following the impacts of a SSW but happy to be proved wrong on that

That is a nice looking weather chart. I don't mean synoptically, but more for its uncluttered simplicity. Less is more and all of that. 

ECM still only covers the transition phase and the charts are in line with the Met Office forecast of a more changeable period. I doubt you were expecting much else.

Nonetheless the 12z run ends with cold uppers over the country.

T+216

We could start to see Cold NW flow by about Wednesday the 16th January, but by 17th January only the North and NE UK remains with the low T850 hPa air.

On next week Tuesday the 15th we should see a spell of rain across the UK with scattered blustery showers following behind during the morning and early afternoon.

Upto this coming Monday the 14th, the UK is affected by the Bartlett High, and it keeps us mostly dry and less cold in general, mild WNW winds at times over the Weekend on Saturday hmm, Bartlett Conditions again on the Sunday as well.

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The flow is still Zonal in the North and NW Atlantic, with the less cold air meeting very cold air from Canada and these short wave Low Pressure areas move over the North Atlantic and Iceland areas etc.

Norwegian Sea and East Europe and NE Europe often seeing lots of very cold weather and cold arctic NW and NNW winds etc, wintry snow showers and longer spells of snow for some.

On the todays 12z ECMWF and GFS Models, at T168 and T192hours the prediction appears to differ in a big way from what I have seen...

That Low Pressure for 12th to 15th January 2019 is very interesting as it shows WAA in North and NW Central N Atlantic, and it turns Cyclonic very cold as it hits the very cold air from Canada Low Newfoundland and it's journey through Greenland bring a brief spell of less cold but as it moves off from Greenland to Norwegian Sea, to Svalbard and Norwegian Sea and then to NE Europe and Northwest Russia, it is featuring Cyclonic flow and very cold Arctic Air spreading out in it!!!.

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Indeed - and I think it's worth looking at two thing in the FI sections of the NWP at the moment:

1. Relatively weak MLB/MHLB blocking is still resulting in colder scenarios in the longer term (cf GFS Op/Para low-res continually going cold),
2. "Progressive" trends in terms of Atlantic influence can work in your favour for snow when a cold airmass is about. A clean GH or SH is not always the holy grail - you sometimes have to dance with the devil to hear the best tunes.