phil nw.

I have been watching Nick. A colder trend, good to see.Been noticing more runs easing the mean jet further south. It's all we can expect at this early stage I guess, perhaps a promise of the main course in the new year.

Indeed the forecast chart i showed was of course just a snapshot for the coming weekend.Anomaly charts can make things more stark and i am sure even with those i wouldn,t wish to be outside in shorts and tee shirt in Siberia. The 2m anomaly chart i posted earlier. I just thought it stood out and worth showing as it was quite a switch around from 2/3 weeks ago when if we recall there was a big area of quite cold anomalies across Scandinavia and much of Siberia. Of course there is cold air around it is just that what we see are the effects of the current NH pattern where the shape of the pv across the pole leaves NA and Siberia short of a their normal colder feed with the Arctic airmass confined to higher latitudes at this point. This will change in time i am sure as the NH pattern evolves when we see another injection of amplification around the globe which would help to release some more cold somewhere into mid-latitudes.

Remarkable warm 2m temperature anomalies over continental areas by the end of this week.

The modeling of the short term developments along the polar front are proving key to how far south the cold air gets around the Christmas period. The latest fax for Friday show the wave depressions out west which will run along the boundary over the holiday period. A small change in the track and movement of these will affect where the final boundary lies.Currently Scotland looks the best bet for snowfall but a small adjustment south on the track of the low feature could bring more areas into it. i would give it another couple of days before expecting the final verdict on the Christmas weather.

Morning Nick, Here you go Index of /kort/ec-ens/ SPAKORT.VEDUR.IS Be aware these do not appear some days.

Yes indeed maybe light at the end of the tunnel with the first signs of amplification in the pattern later on. Something a number of us were hoping to see eventually once the mjo entered the colder phase and momentum picked up. The pv is already displced with zonal winds weakening so let's hope this is the start of an exciting new trend for the new year.

Ok people a whole raft of posts have been hidden,many of them have been reported,can we stop the bickering please. This is a Winter thread so please leave Summer views out of posts. Thanks all

As the saying goes Nick this could go down to the wire. Upstream there looks to be a sharp gradient developing so tricky for modeling to work out where any wave appears. We could see this micro feature not being resolved until later in the week. It does make a difference to how far south cold can get and of course any possible snow event.

Oh yes I realise that Nick just find them easier to view

I know Mike Poole posts the ecm clusters regularly but it is good to get the Icelandic ones back again and they do seem to show the start of a slow down to the Atlantic train and a confirmation of a cold north westerly setup for Christmas. Christmas day T360 The later clusters showing a trend to raise height anomalies further north with only a minority for holding on to a south westerly setup. These are only a guide of course but a promising trend, probably reflecting the forecasted reduction of zonal winds and the displacement of the pv towards the Siberian sector going forward. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4977684

I know Mike Poole posts the ecm clusters regularly but it is good to get the Icelandic ones back again and they do seem to show the start of a slow down to the Atlantic train and a confirmation of a cold north westerly setup for Christmas. Christmas day T360 The later clusters showing a trend to raise height anomalies further north with only a minority for holding on to a south westerly setup. These are only a guide of course but a promising trend, probably reflecting the forecasted reduction of zonal winds and the displacement of the pv towards the Siberian sector going forward.

All looking very interesting for Christmas.The boundary between the cold and milder air masses fighting it out across the UK.GFS/GEM bringing the cold south with ECM also looking to bring the cold further south on this run. This will continue to change back and forth until models get into near time as those little wave depression develop and run along this boundary. The trough doing its best to flatten the Azores high but quite a battle between these 2 main features..

The 06z Gfs shows again the jet running through the UK, something I alluded to yesterday. It keeps the possibilities open for a short wintry spell on it's northern side. With polar air so close by it only needs a small ridge to ease it south. I think given the mobility it's the best we can hope for.It is down to luck with timing to see this happen over Christmas.Of course models won't pin this down for a number of days yet.

Just a brief roundup of where we are heading into next week.The pattern developing now is very much +NAO/AO with the pv feeling at home to our north and the Azores high, a bit fidgety, moving around towards our west and south west. UKMO T72hrs After its short stay nearby it looks like the first north westerly push squeezes the high further south with cold air getting into the north of the Uk around day 5. From here out until Christmas we see the mean jet path running across the UK with it rippling a little south and north,polar air to the north and the milder to the south.So its very much battle lines drawn during the holiday period with detail still to be pinned down. gfs 06 mean jet around day 8 A very fast moving setup after the high sinks with possibly secondary low development along the boundary which could give a surprise snowfall to its north. Gefs 06 ens graph Not the usual dreaded south westerly zonal set up but of the cooler variety,cyclonic and quite stormy at times. Perhaps not the widespread white blanket many of us dream about for Christmas by the looks but plenty of interesting weather to come.

Yes that would be quite a shock

Yes good point.Looking at t72hrs on GFS shows where the mild air is coming from. A conveyer of warmth from the sub tropical Atlantic.It will be quite an up and down period temperature wise over the coming week or so.

We are looking at a very mobile pattern next week so any cold will inevitably be fairly short lived before the next Atlantic system comes in.We could be lucky with this north westerly landing around the holiday The charts do a show quite a cold shot of polar maritime air approaching Christmas so i am sure places higher up and further north stand the best chance of lying snow ,for a while at least.Current timing shows we are still in the Polar air at Christmas but of course at 12 days out its subject to change . Probably not worth picking over detail at this range but if this pattern verifies it may well be worth a bet for a snowflake falling on Christmas day in some Northern stations.

Yes I think that's a fair summary.

Understandable disappoint in current outputs but please try to include model discussion in posts. Let's not take the thread off topic. Thanks all.

Just a glance at the European situation currently and we can see the effect of a stronger phase of the Atlantic jet pushing into Western Europe and the UK. The cold being pushed back further east towards Poland as the milder air filters in. It looks like we have a few days of this wet and unsettled regime before the High starts to build later in the week. Day 6 . Looking at that projected jet pattern there is still plenty of energy running over the ridging on this run limiting any traction a high will get. Beyond that and onto the lead up to Christmas it doesnt look an Arctic block will show up in this time scale but we perhaps can still achieve a consolation and get something seasonal,at least for a short while.This is whether we can squeeze a colder north westerly or even northerly but it does rely on any further amplification of the ridge and less energy going into the northern arm of the jet flow. Upstream over North America some model runs handle the split flow differently and i think this where the variability comes with regard to the Atlantic ridge and placement over our locale towards Christmas week. A north westerly has shown up on a few later charts so cannot be discounted but at this stage just something to hang our hats on.

Given time lags of a week or two(we can never be precise on this)of mjo phases it may be nearer to Christmas before nwp factor in the cold phases. Current ens guidance for week 2 suggests more of a retrogression of a mid latitude Atlantic high rather than any amplification at this stage. We may squeeze a colder north westerly out of this. I think if we are to get the main course(Arctic cold) from there it will be likely post Christmas As ever it's a waiting game and following the trends in the ensemble suites is usually the way to keep expectations grounded.

I would think they don't see the high getting enough traction to cut off the Atlantic in the far north by the looks and that is supported by current ens charts today. As for later I imagine too far away for them for confidence of a cold pattern as beyond current nwp. modelling. They do give a cursory mention of a possibility probably based on the mjo.They do refer to the mjo from time to time in their YouTube videos.

i have been watching with interest over the last few days as speculation rises over a return to cold towards Christmas. Certainly plenty of hints showing for a pattern change towards mid-month as the Atlantic is halted from a build of high pressure somewhere around our shores. Beyond that imo is still to far away to be confident of this developing into deep cold by the holiday .We can see the GFS op is a bit too ambitious leading into Christmas,although nice to see what could develop perhaps a little later on. The 2 sets ecm/gfs ens graphs looking a little colder for sure but viewing the extended charts on both ens suites it can be seen the pattern looks like evolving to a north westerly type as the high regresses somewhat into the Atlantic and a trough digs se into Europe in week 2. I think the amount of amplification we get into the Atlantic pattern has still to be figured out from developments upstream and also the timing wrt lag effect .I remain cautiously optimistic though.

Just looking at the here and now we can see the start of the Atlantic influence trickling into parts of the UK and Western Europe today. These are the images at 12noon of European temps. and current ecm 500 pattern Interesting to note the sharp temperature differences north and south of the Alpine region here . Anyway the coming change to less cold is nothing unexpected as the blocking is set to fade in the coming few days. Looking further on at T144 Encroachment very slow as we still see trough disruption into Europe the Russian block still influencing things. This week then nothing really mild but certainly less cold with for much of the UK but that block of cold air still lurking very close to the north east with the Northern Isles likely to remain quite cold.

Yes looking good.What is also noticable is the dramatic drop off in the mean zonal winds leading up to Christmas. A much weaker and preturbed tropospheric vortex looks likely in a couple of weeks or so.All in line with the expectation of Arctic heights building later in the month.