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The GFS is looking very much NAD Shutdown over the North Atlantic Ocean, from day 7 to 10 is very interesting to look at, with some very cold air and Cold North Europe Low Pressure as well as Blocking High Pressure in NE Atlantic and NW Europe SW and Western Norwegian Sea.

With WAA and Deep SW to NE moving PV Low far NW Atlantic through Greenland and skirting Iceland as well, those Diverted PV Jetstream Low Pressures are pointing straight through Greenland and the Central Arctic Sea etc etc.

We'll have to get more support from ECMWF, as now GFS is showing a very good chance of a cold NE and Easterly blast of air across North Europe and the UK.

This needs more careful checking particularly once we get to Friday and Saturday 7th and 8th December and by then we shall hopefully know if the Negative AO and NAO will produce what we want to happen..

Some wet and windy weather to go through to upto and including Saturday 8th December, with UK in the firing line from Low Pressure pushing eastwards to North Europe via the UK from the Western North Atlantic Sea...

This is one run and we must expect more flip flopping about as the models explore and test these potential outcomes, but it is not a surprise to see the switch back yo cold and blocked, and it may yet prove that the mild outcome was an outlier extended by the GFS bias to the weight of data for normal zonal weather. There have always been more than the odd token cold run, indicating an underlying potential. There were always signs of this year being a little different, with more chance of old fashioned blocks developing. This was so much more common back in the 60s and again at times in the 80s. When I was at school age, in the 60s, you could hang your hat on at least 2 x 2 week long blocked periods Dec - Feb,  some colder than others, but I remember one just like this GFS evolution, with the temps dropping by 1-2 degrees for 5 days, (1969 perhaps - not totally certain but around then), sunny by day, frost lasting longer in the shade - then all day, then a cloudy start and frosty, snow starting at 12.00pm and a 3" fall on low ground in Sussex, really deep frozen and dry. This lasted over a week on the ground, with the odd snow shower at night,  sunny and 2-3 degrees by day, but low humidity, so the snow stayed around. Bright, frosty, sunny by day...and this was sparkling diamonds on white tracery of twigs and trees - cold blue skies and a joy to be alive...and I have craved this type of weather ever since...  But you get years, and clusters of years with a greater propensity for such blocked patterns, and back then Bert Ford used to talk about this patter being a common pattern. Of course it became far from common in the nineties and naughties; well ever since really. The return of the Scandi-block dry polar continental cold spells is as welcome as a forecast of a sweeping snow front by Bill Giles!!

JMA goes for the Scandi theme too on the 12z!

Today's trend may well not be there tomorrow but GFS 18z is doing its best to set up a Scandi too!

The real cold slips to our south and east on the 18z.  Different outcome to a similar trend!  Where will it sit in the ensembles I wonder?

ECM 12z ensemble for London:

A significant lurch to colder conditions from day 8 with the dominant cluster now giving maxima of 3c and overnight slight frosts. The operational was within the spread of the cold cluster on day 10.

LOL.  The ensemble says otherwise.  It may be wrong but as we're discussing the output that represents a clear and strong signal for a sharp cooling. Eight days from now we should be seeing below average temperatures; the only issues are just how cold and the longevity of the pattern.  Detail will remain unclear for some days, particularly how far north the surge of warm air advection gets and that will dictate what weather we get.

18z OP run collapses the ridge in FI. Where is the two Winter forecast which was due to be issued yesterday? - As announced on homepage!?

That's what I'm wondering as it's not like Brian to not fulfill a promise like that, although I'm guessing that something else probably cropped up there.

However, I will be looking forward to Gavin P.'s winter forecast later on this morning. I know that he always bases that on the winter updates which he has done throughout the autumn leading up to that, the NAO forecast which he did back in the summer and of course, all of the various model output which has shown us on a monthly basis during that time. it will therefore be interesting to see what he comes up there as his forecast.

But for the south east at least it’s a remarkably cold run at the surface from 11th.

Encouraging to set up something interesting for later in month

A lot of flip flopping going on in the past few days with each day showing almost the opposite of the previous day.  The models are obviously struggling with something and I don’t think they can be taken too seriously. 

It was issued yesterday. 

2 words. And one of them is Uncle....

http://www.wetterzentrale.de/en/topkarten.php?map=1&model=ecm&var=1&run=0&time=240&lid=OP&h=0&mv=0&tr=24#mapref 

Morning Brian, thank you ...is there a link to find it please? 

Thank you 

Is the other one acompletelydifferentscenariocomparedwiththepreviousrun? 

The direct link is: 

https://www.theweatheroutlook.com/forecast/uk-seasonal-weather-forecast 

Pretty good agreement now for  +ve heights over the UK by day 8. 

Going forward from there depends where the Atlantic energy goes and if we can get some lower heights into Central Europe.

The ECM op might have a very mild spell around the 11th but it's got no support from the ens

Interesting also that the control is sticking to its plan:

https://www.theweatheroutlook.com/twodata/chart.aspx?chart=///www.theweatheroutlook.com/charts/gefs/0_384_850tmp.png?cb=548

Prolonged near -10C 850s, and if you look east, something more intense starting to mass forces.

Yeah, arguably cherry picking but I think the persistence of the control in recent runs is worthy of note.

Yes all we're looking for in the longer term is the signs of a consistent pattern or signal developing, and it is encouraging for the control run to highlight the very real potential for a colder regime developing mid month  Hoping the trend continues and the ensembles to back it up soon!

It's a no to the southerly tracking jet on the 6z but a yes to the Westward march of low heights into Europe, so interesting to see what subsequent runs show.

The general idea of a back-ended Easterly spell looks credible to me, which means cold fans might have to be patient.