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The hunt for cold is hotting up..so to speak..I'm hoping the Ecm is on the right track and that all roads lead to cold..and snow during early winter!❄❄❄

So, how are we doing here ? The tropical wave evolution identified has been slower and that shifts any comparative analysis back by 2-3 days. Suspicion that it may continue to be slower than forecasts currently advertise. That places GWO in a likely tilt towards phase 5 around 12th December For 12th December, GEFS vs original vs GWO composite phase 5: So a continued indication of anomalous ridge development to our NE for this time scale. Regular readers will understand the value of this approach, particularly in view of the volatile model output in the last few days and particularly back end of last week. Looking ahead, the tropical wave development has week 2 and possibly into week 3 as most favoured for the GWO to be in phases 5 and 6. For high amplitude phase 6: That suggests we're looking around a week's to five days worth of blocking ridge to our NE mid month, trending towards ridge transferring to our west and NW in the lead up to Christmas, troughing into Scandinavia. That I think gives us a first proper opportunity to pull some genuinely cold air into Europe, although the for Western Europe I suggest that this continues to mark a skirmishing phase of the winter which would be typical of similar ENSO events. The real interest lies in the final week of December into January given the stratospheric vortex will be under intense pressure and may well have collapsed. Synthesising the GWO attracted to a phase 6-7 evolution suggests a proper episode of Greenland blocking (and more identifiably from the composites distinctive -ve height anomaly in the North Atlantic) and impacts of the strat warming being overlaid with that pattern.

Running the EPS just now ensemble means are good all the way. Transfer of heights from the Azores to Scandy ending in this I dont tend to spend that much time now dissecting every set of runs (it can drive you completely and utterly insane) - but there is nothing at all wrong with this. Ties in with next pacific cycle and fits the well advertised timescale of winter starting mid month - will try and do a more detailed analysis later. EDIT - and note this is an absolutely corking pattern if an unhappy vortex is what you are after. Signals for this winter continuing to get better all the time...... (if you like it cold.....)

OK - starting to get interesting now. Where are we on the shape of things to come? Fairly strong MJO has passed through the 8/1 orbit and looks set to reignite in the indian ocean into week 2 If you like looking at a few composites the phase 8 December weighting from the JMA looks a fairly decent fit for the pattern upcoming given lagged impact And as this pushes on to phase 2 we see a signal for pressure rises to the east which then pull back west as the MJO enters the indian ocean once again. I've come to realise that these composites are far from gospel, but we have perhaps a sense of the MJO forcing that will impact the pattern over the next 2 weeks. Meanwhile we await the next pacific cycle to see how much AAM can be injected via torque or convection activity. It would appear that frictionals have now reengaged and we await subsequent impact of mountain torque activity that will follow. I am hoping to see a spike in east Asian activity in particular that can extend the jet over the pacific and provide the momentum to encourage a more meridional pattern at 55-60 and further north. Given frictionals are now climbing we can expect to see this in the next 5 days or so. Conclusion? MJO activity setting up the north atlantic pattern nicely for pressure rises first to the NW and then more particularly the NE.....and at just the right time we get an engagement of the pacific jet to help reinforce those eddies over the north atlantic still further. I see an easterly of sorts at mid month with an undercutting flow....perhaps then a relaxation into a more cold omega UK pattern towards month's end and then into early January another impact from the pacific. Where will the vortex be by then given the signal for the scandy high and ongoing north pacific low? Hopefully on its knees and ready to pop. Anyone like to take a guess at what would happen if a renewed MJO cycle through phase 7/8/1 were to combine with the next pacific cycle at just the time that the vortex comes under major stress? Homer would know what to say. Hmmmmmmmmm. But a lot of water to flow under the bridge yet. Important that the MJO maintains decent amplitude over the medium term (and given the Nino background this is not a given by any means because in a Nino year the MJO is supposed to fade through winter....) and that we don't get a sudden solar spike. And vortex stress is not destined for sure to sit pretty for the kind of epic impact we got back in March either. A lot of macro and micro scale analysis lies ahead. But these are, in general, very good signals at present.

It’s bad, very bad. No Easterly with -35*C 850 hPa temperatures covering the country. Not even any -35.1*C 850 hPa’s. I mean seriously ECMWF, what are you playing at? I have never seen such an outrageous chart before... PS: Welcome back Frosty!

Today has been a good day in terms of modelling of what may well be a great Scandi high- Cold in place over the UK @150 now but the ridge developing about 132 - so beginning to get better agreement The 06z is better because the initial ridge has uninterupted movement Ne where as the 00z tried to push energy through eastwards into the block impeding it-I remember this occuring a lot in 2012 Easterly only to be ushered away nearer the time... The run up to christmas looking very festive - note the return of ridging straight away if the first one collapses day 10- The atmosphere is primed this winter !!

Looking at tonight's Ecm 12z ensemble mean @ T+240 hours, it certainly ain't mild!!..let's hope the power of positive thinking can darken those shades of blue on subsequent runs!..nobody will be more delighted than me if we can get some entrenched cold..and hopefully SNOW in the run up to christmas!

Hi all, looking back at the analysis from the above post a week ago, I can confirm that the single model our portal forecasting experts use has been rock solid in its outputs .One week on and nothing really changes in the medium term. Strong ridge development over the British Isles at 168t and development of a fairly long wave trough further east with a possible upper low ( now showing on their latest run ) at the base of the trough. Reasonable high confidence now of Scandinavian High at 240T. I ask what are their thoughts on the longer term outcome for days ( 10-15 ) with specifics to the British Isles? Difficult that one , but at this instant ,50% (prob) attack from the West but with a bias to some kind of undercut possible. 30% attack from the east as generated from the Upper Low being shown on their model. So in a nut shell, it could go milder again after a short cold spell or you could go under a more potent flow from the East. Tomorrows 144t runs will throw some daylight as to where we will be heading. Hope this helps, fairly rock solid out to 240t , C

Fergie has tweeted about this winter being colder than average according to the met

Morning all from a cloudy but mild Austrian Alps. 24 hours on from yesterdays post and the same consistency on route to cold being shown on most models now at 168t as shown on the latest GFS control run. Remember , I did mention there will be variations on the more frequent op runs as shown this morning with GFS against ECM at 240t. The former with the high sinking and the other with an undercut . Tomorrows comparison at 144t will be important as to determine the type of cold spell now likely to develop next week for many in Europe and decrease or increase the probability of a sustained cold spell. A crucial 24 hours coming . I will talk to the team over here in a hour or so as they will have a update on their singular NWP model and will get back with specifics for you lot back in blighty.

There is some meat on the bones starting to apear(as in cold prospects)in some of the charts/models/graphs/anomoly's etc lets have a wee gander:- the latest outlook from cpc 6-10/8-14 day outlooks shows the Azures ridge develope into Scandi with trough extension in the atlantic with possible trough undercut on the 8-14 day eps/gefs height anomoly's at day ten,the eps is a lot better in regards to the positioning of the height anomoly's over Scandi with lower height's on the southern flank of the high De-built ens temps/dewpoints getting colder each day and the wind direction is starting to show more easterly members in there now 30/10hpa from jma although not significant at this stage but it's a start and will see how this progresses over the next few days a recent tweet from Mr.Hugo so at the moment,things are looking good for a cold snap/poss cold spell,i just hope that i do not have to wait too long before i get my ski's out P.S. nice to have you back Karl/Frosty,you have been missed xxx

Here's a chart for the zonal lovers out there! That's as zonal as it gets, it's just in reverse

Nice charts, super nice charts. My concern is this though, and it is nothing to do particularly with the GFS... NE block is an absolute cert. Great but I wonder if it is going to end up too far north, allowing undercuts with us on the wrong side. High pressure will then ridge up from the south. Still cool but no snow for the masses.. Perhaps the far North. Not like me at all to be this cautious but I just feel this nowhere near a done deal. Now is not the time for a December 2012 style solar spike! But... how brilliant is it we are in the game for an imminent decent cold spell on only the 3rd day of winter!? This is what winter chart viewing is all about! And either way, absolutely stunning prospects later on. If the vortex thinks its struggling now, it has a nasty surprise coming its way in the next few weeks. We would have to consider ourselves very unlucky if we haven't had a good cold spell by the end of January

Sensational developments this evening....EC is a ... Winter coming soon?....

Superb UKMO wintry showers moving over to snow showers filtering through scotland into the ENE - Great blocking signal as well-

Very happy with EC mean tonight... And happier still Darren Brett is ramping up a big scandy anti cyclone next week..

Absolutely and that is why we should be taking any tropospheric output beyond a few days with some caution right now The Wave 1 displacement, if coupled in the troposphere, would, you would think, give a period of stronger westerlies across the Atlantic in the 10-15 day period. But we'll see how that plays out. Either way, as we head towards the second half of December, this looks pretty exciting....especially if we can get a secondary warming into the core of the vortex while (if!) it resides in the asian sector, as has been hinted at at 10mb in several recent runs

FV3 not interested in the GFS 12z solution- We all know the GFS energy seperation issues hopefully the FV3 has sorted it out!!

FWIW, UK Met model showing a full on warming event for end of the year, as is CFS (which has continued to do so for the last few weeks). That's not wholly surprising given long lead thoughts of stratospheric behaviour and this plot which, if verified, would be signalling a stratospheric warming within 9 days:

UKMO 168 looks tasty!

Yes just seen bbc weather outlook going for Easterly winds it’s getting very interesting .

Predicted warm US build up to Xmas, should bode well to Atlantic running out of steam and massive cold spillage to our side of the NH. BFTP

Ecm 12z.. Bungs us in winter proper... And with given evolution...those 850's could improve.. As the time elapses!!!.. Peach run...with cream to boot....

192 is an utter BOOM chart. Best run of the evening. GFS on it’s own..

How about this for a MEAN at the back end of FI Big signal for Scandi heights there.

UKMO still looking v good +144 this afternoon. Good start.

I bet there are some who'd still find something to moan about with this chart.

Watch the GEFS go more wintry now... People shouldn't be surprised if the GFS is on the money here- we've seen it before. In the long run, I still maintain it won't make a lot of difference. We're still looking latter December/January for the core of this season's winter weather... And that hasn't changed.

^ Yes, we've now got to the point that 2/21 of the GEFS are showing a technical SSW by 19 Dec, this needs watching!

And the best thing? The best thing is it could just be the curtain raiser

GFS 18z the fruit machine that keeps on paying out, T216:

Really going all in now, T168: I think we can say GFS has joined the party!

sorry ........ fell asleep .......did i miss anything ....... encouraged by the ec spreads from the 12z. im currently a little nervous that we could see the ridge get way north and phasing occur further north as has been the case on a couple of gfs op runs recently ... after all, going back to the beasterly from last winter and the cold pool from last month, both involved the low heights accelerating across the meridian east to west in a way not seen by the ops at day 10/9 but picked up by ecm around day 8/7. the dncroaching undercut has become the theme of the day .....that fits with many recent eps control runs and presents the largest risk/largest reward route to snow events the scandi ridge seems secure but how it affects the uk remains uncertain .... will certainly go cold but how cold and will it go snowy??? I’m afraid we’re gojng to have to wait another day or two to know for sure what theme the continental flow will take - then we can begin to look for detail

EPS day 8 actually signalling quite a major block across Scandinavia and a strong signal for low heights across the med too, very very good EPS suite this evening. Clusters will be more telling of course

EPS day 6 in line with ECM Op & UKMO. Heights extending up through the UK and into the Griceland region.. No support for GFS Op.

I’m ready to jump down off the fence and hopefully Bluearmy will be joining me! I’m 60/40 deep cold into the UK next week. High pressure will build this weekend turning things colder, good support for high pressure to extend and build across Scandinavia thereafter. Lots to resolve before deep cold touches our shores, but we’re a step closer this evening. Fantastic day 8 GEFS mean.

Can we please not talk of 2012, I still have PTSD from that nightmare of a week. GFS not quite as amplified as the UKMO/or it’s previous run but it could still get there

Displacement forecast for mid December, but expectation would be for full on warming event to occur towards the end of the month. MJO wave passage through the Indian Ocean will likely delivery the knock out punch.

GFS now chasing an undercutting scenario with much better placement of the atlantic low-

Check out the end of the 00z GFS para. UK almost completely covered in snow. Just for sh***s and giggles this far out of course.

Viewing the EC clusters this morning, the general guidance seems to be: Dec 7-10: Pressure rises through the N Atlantic (consistently advertised for a week now) Dec 11-14: A split between a quick topple and a NE ridge supported by Euro trough (the latter scenario leading to a cold easterly) Dec 15-17: Where ridging to the NE had been established, it starts to lose influence over the UK - but in the meantime, positive height anomalies start to appear in the W Altantic, potentially leading to a west-based or east-based negative NAO soon after. One to watch!! My main headline would be this, though: Whatever happens in the next two weeks regarding cold/snow for the UK, it is becoming clear to me that the polar vortex is struggling - big time - to achieve a long-term influence over the weather in the UK - in a period when you would expect it to be close to its peak.

More robust upper ridge north across UK early next week on 06z v 00z GFS and also higher surface pressure over Scandi, add in more of an undercut from the Atlantic trough on SW flank of high, this is certainly more of a nod in the direction of 00z EC with an easterly T+237 deep cold knocking on our eastern door, -9c T850s across E Anglia

No idea why some people rave about February cold. It just doesn't have the same feel or sustainability as a spell in December or January. Even by mid Feb it can feel pleasant in the sun during the middle of the day.

I officially came off the fence on 13/10/18 BFTP

Yep..the wrap is on-and forming. And lets not forget the ramifications @overheads -strato-trop-... Waving doing a fine job!

ECM T168, builds a cracking block. And this is only a week away now

Stratospherically, the 12z GFS is a beauty and better than the earlier runs! It ends with a phenomenal displacement of the vortex.

Consecutive posts completely at odds with one another. Which is it then chaps?!!

Nothing is ever certain in weather....but I tend to ignore those who argue a significant warming impact on the vortex can lead to warm rather than cold. The reality is that, given an average degree of stratospheric/tropospheric coupling the loss of strong westerly circulation in the stratosphere relaxes the tropospheric vortex, and the westerlies that tend to bottle up the cold at high latitude weaken. It is true that, like a spinning top coming off its axis as velocity slows, a meridional effect can pull mild are from the south in this circumstance BUT in overall terms the global average impact is for cold air to spill out of the arctic to lower latitudes. In general terms it is a win/win despite the chances of short term variability. And a vortex disruption/displacement and maybe even a split/disintegration this early in the season under weak Nino ENSO conditions (with likely further blocking episodes ahead) could potentially spell the end of the vortex as a force to be reckoned with for the rest of winter. Perhaps someone with a nose for the archives could go back and tell us when we last had a vortex disintegration in a weak Nino year in December. Would be interesting. Having said all that, and laid the ground for snowy celebrations - the warming hasnt happened yet. Much can happen in 4 weeks of weather...........

All the warning signs are there (and have been for a number of weeks) that we're about to enter the freezer good and proper in a few weeks time. We look to be building the foundations of a potentially severe spell of winter weather...possibly at the coldest part of the winter. The strat vortex looks toast in the longer term too. All in my humble opinion of course.