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Great model watching at the moment. Momentum products are generally neutral - but the key here is that the GWO hasn’t descended (yet) into a Niña style orbit, meaning the kind of forcing that would help produce a flat pattern isn’t in process. Instead the GWO is holding in a high enough orbit to suggest amplification will continue. Meanwhile we have rising mountain torque once again, predicted on the back of frictional torque that started to rise a week ago. Resultant pacific jet energy is very evident at the moment, not just for today but for the next 10 days or more if gfs is to be believed. In addition wave 1 energy has surpassed forecasts of a week ago, now running significantly above the levels predicted then. As a result we have split vortices remaining split in the lower strat, preventing downwards reinforcement of westerlies. And wave 2 forcing is returning - at low levels admittedly for now. And finally we have a good bit of convective activity around the maritimes suggesting the MJO is entering a condition more conducive to supporting ridging Sum total? We have an unhappy vortex, I’d suggest the origins of which can be traced right back to the semi permanent ScEuro High that was being cursed in November. It’s unhappiness is being sustained by strong forcing from the pacific side, and it could become extremely unhappy when forcing kicks in from Scandy again. What will cause this? We have another +EAMT helping sustain wave breaking momentum, and a GWO profile and MJO context that at the very least are not in opposition and at best are providing support for ongoing amplification. And the timing is good. Trop led amplification is going to work to hit the vortex just when the vortex is ripe for being hit. There is nothing bad here, and no driver I can see that portends the return of a flatter pattern this side of New Year. By the time we get there the vortex could be in shreds. My pre season guess at an SSW on 23rd January looks conservative now. Amy Butler, boss of Strat knowledge, might be spot on with the 9th. We need the Ural High to remain in play so that we get a split SSW....and then the rest of winter is wide open for fun. Glosea can go swivel........

Why are you a member on this forum then, or even reading this mod thread, what do you hope to get out of it? Some really strange posts in here today, and the irony is they come out in greater number when things actually look interesting for once. Remember guys trop vortex all over place so blocking is more likely to feature than normal, big +EAMT which I don’t understand totally but this has kickstarted potential SSW and enhancing blocking as we move into late December / early January.

If anybody wants to take advantage of this busier than average period we're experiencing at the moment, but trying to make a name for themselves by being contrary for the sake of it, or a little bit snappy or otherwise just trying to spoil what should be a nice harmonious discussion about the weather....good luck!

A cold Christmas followed by a NH pattern promising a prolonged cold spell,what more could Winter lovers wish for? Yes signs now that a chunk of the vortex is going to transfer across our north towards Scandinavia in the mid-term as we see a second amplification upstream post Christmas. GEFS mean day 10 Both suites have the same idea just slight variations on the ridging,Obviously it would be good to see it drive as far north as possible to swing that cold to the ne more directly our way. I wouldn't be concerned with snow chances yet.Let's see this pattern firm up and get the cold established then we can start to see where the surface features develop. What a nice change to see these charts now where we have plenty of time to get the best out of this developing cold setup.

Afternoon All- Im sure there will be some Euphoria from the 12Z GFS A couple of interesting points * Watch out for a shallow trough from the North on Christmas eve bringing Snow to Scotland. * If we do get this amazing jet profile at 168 the its Greenland high all the way... A GH profiled at just 7 days > Will need Euro support...

Get it a rest. In your constant desperation for this to all go wrong (which it absolutely may well of course), you have clearly now started hallucinating

Yeah, imagine people being excited when seeing charts like this: How shocking.

Have to go to work but events in the strat could well become the story of the day .... and a quick look at the ecm op strat data reveals unusually strong support right up to 10hpa for the scandi trough at day 10

Jeeze.. over the years I have pondered if you’re simply a glass half full chap or a troll. What we are seeing modelled at present and within the mid term are once in a decade Synoptics and the most hearting thing was that gfs and ecm were aligned at 192. we Might be taking different routes but the outcome is positive for coldies so with all that being said you’re not going to clutter and litter my enjoyment and knowledge gaining anymore. You’re number 5 to the block list...goodbye.

Really? From the 27th until the 29th at least, - there are hard frosts predicted and daytime temps struggling to get above zero - 528 DAM line far south of the UK - Low pressure domination - 500hpa temps below -35c -850hpa temps below -5c -Dew points below 0c Thats all on "that" model run you "dissed" , to suggest theres nothing "significantly snow or cold" is not how those figures look to me! Now you are quite right of course, it is a long way off and may well turn out to be less wintry, but this is the model discussion forum so discussing what the current models show is surely appropriate. However, all models are singing from a similar hymn sheet, plus the anomaly charts for that range support that general synoptic pattern. So broadly, id have thought that theres a strong chance of it turning cold and unsettled, there will be snow in the forecast.

I do understand some people's 'concern'. But I live my life very glass half full and have no intention of changing that any time soon, but each to their own I suppose. Better to have loved and lost and all that... There is a consistency here, an 'all routes lead to cold' feel about the current chart output that isn't usual at all. We may have to wait another 10 years+ to get this sort of potential again during a Xmas period, just enjoy the ride folks. It's not just bad luck that we struggle to see a white festive period, late December into January is a traditional period for mild wet and windy. The strat vortex has usually ramped up to Tornadic F5 speeds, coupled with the trop and has become a horrible purple beast. Meridional jet streams are all but a pipe dream. But... this is not the case at all as we head towards Christmas. We have a fair chunk of factors on our side for a change. And just wow, what timing if we get a decent cold spell (a cold 'snap' is already 95% nailed on) could a toasty strat warming be? That is starting to become quite consistent as well. I wouldn't fancy the deck getting a reshuffle right now with a strong warming but if we could get one early - mid Jan just as tropospheric forcings may be waning, it could be just the tonic for more fun and games heading into Midwinter. One thing at a time though, come on 2020, YOU OWE US!

May I be forgiven just once in 15 years? If its snow you want, watch this, or go on to the N America link

You do know where Greenland is don't you.

Yes. The very best of the options that were on the table a week ago modelled in that one chart. It’s nearly time to hide behind the sofa and watch each run come out with only one eye open.............

Just showed this to my good friend and newsagent mr singh.. he has-now withdrawn all the adult magazines that I used ta buy from he’s shelves!!

Not only that, but some of these things are also needed when viewing the outputs @Hullsnow87 Welcome to Netweather

Evening all! Hope you are all well! Exciting times for a cold/snow lover! Lots of chat about late December/early January and rightly so! However - wee bit of naughty cold sneaking into the semi reliable timeframe of 120 hours/day five. UKMO 120: 13:00 UKV snapshots for 120: 15:00 Precipitation type & sea level pressure: 850HPA: Wet bulb freezing height (m) Dewpoint temperature (C) Thickness (dam) 23/12 to 25/12 at least has chilly days, risk of snowfall/wintry showers for some and frosts for many on current output - lovely seasonal/festive weather! Not to be sniffed at. Merry Christmas and a Happy New Year to you all when it arrives! I shall see you all again in January when the BFTE arrives! Cheers!

What a brilliant day the best of the winter! And no it’s not just day 10 the ball is rolling few days before that...

I was about to post something similar, so odd! Anyway, back to the models and another delicious GFS today and not the manky old 6z or pub run either. The Control also very much on the same page, now to 240 And yes, this is at day 10, but was set by day 7/8. Then there's the Strat profile for 29th December. If this doesn't get your weather juices racing, then really there's no pleasing you.

Those of us around here long enough, will remember the winter of 09-10 where the models, nearly in unison, counted down the days from 12 days out with northern blocking, coming in with every run! This has the same sort of feel about it, consistent and all singing from the same hymn sheet. That said, we've been bitten before, at 96 hours out, but that happens mostly with Scandi highs. GHP's are that bit more reliable IMO. My advice would be, enjoy the eye candy charts, and if they come to pass, then super. If they don't, then so be it. This year has been horrible for hundreds of thousands of people across our islands, this comes as a nice distraction to us weather enthusiasts. Enjoy it, try not bicker, and pray to whatever God or deity you follow that they do come to fruition!

12z ECM @240... It's happening lads... I've even changed my profile picture

Corrected it for you, M4 snow shield and all that

UKMO 12z 24th Dec A bitterly cold Christmas Eve if the UKMO 12z is correct

Wow,have I missed something Firstly those 12z ens are pretty encouraging moving forward, and I'm aware the ECM earlier was a peach. I'm gonna bring you some positive news from Jon Hammonds updated blog this week.. Brief cold snap Xmas! Weather systems perhaps being blocked by colder air to the East..the jet carrying these systems having a tendancy to split rather than dive across us. There is a very real chance colder air lurking to the East will re assert itself,and this looks increasingly likely as we enter 2021.. Its been pointed out that many Long range Models were writing off Winter before it began earlier on, now most of the long rangers are indicating the atmosphere will continue to be blocked.And most definitely signs the Vortex will significantly weaken in the coming weeks. Its been a long time since I witnessed snow and I tell you what if and when it comes I will be running naked through it..

You’ve got to be kidding me, I knew there would be someone moaning.

Moved house today. Chaos. Popped in now for a quick look at various bits of data to see this GFS chart for Xmas day. Not much needs saying other than - Yee Haar! It’s still too far out to be served with clotted cream and a dollop of jam....but it’s a damned tasty looking setup for sure! All the key elements are there. Siberian High edging to the Urals....trough dropping into Eastern Europe, obvious open door up into Greenland, clear wave break eddy effect on the back of the next momentum spike producing a highly amplified pattern. And the Berlin charts have renewed wave 2 impacts arriving at day 10. There is a long road yet to travel, but it would be great for all amateur weather watchers and snow hunters if the best computers running the highest powered seasonal forecasts could be put to the sword. What will happen to our fun if NWP output starts to nail every season? A split style SSW is very much on the cards for January. If so, somewhere in the northern hemisphere will be staring at some extreme cold conditions inbound. In the shorter term our coldest tropospheric led output for many a December is looking likely. Happy days.

early evening observations a week is a long time in this place - go back to last Friday evening in here if you don't believe me! ICON is sometimes right when it is persistent against the other models - its the only model not positively tilted around greeny day 6. but at day 7.5 it looks like it would still go down the route of nw/se jet and diving trough finally, we seem to be honing onto the nw/se axis with the amplifying atlantic ridge responsible for dropping the trough close to or over us ..... what if upstream isn't modelled correctly and that amplification doesn't come (remember the xmas ridge is now fairly flat). with different clusters on the ens i would urge caution - for the time being. lets see where the eps clusters go this evening and tomorrow morning. at the moment, each suite brings more clusters ! and the strat developments look v interesting as we look forward to jan/feb.

You can count recent cold christmases on the finger of 1 finger..but I think we will add to that this year according to tonight’s ECM 12z ensemble mean!..and whisper it but I think between crimbo / new year could deliver something even more wintry..watch this space!

Ha ha, there she blows

I’m in no way convinced yet that a decent cold spell will come off considering how many times the models have backtracked from decent synoptics. However, I do get the sense that some people in here could be staring at a blizzard unfolding outside their front doors and still be on here moaning that the uppers won’t be cold enough for snow.

Let's keep to sensible Model Output Discussion please in here, Nothing wrong with a little humour within a post related to the topic. The forum is obviously getting busy now because of the interesting synoptics so we don't want good posts getting lost amongst the noise.. Thanks all, please continue

I don't think COBRA meetings get called for wet snow over the hills. Ridiculous exaggerations from posters in here, as usual. There's nothing significantly snowy or cold for the majority of lowland UK in that model run, and it's academic at this range anyway. Nice synoptically, but talk of snowstorms is such nonsense. People never learn and set themselves up for a fall when future model updates show less wintry potential.

The first properly exciting model run of the winter. The first one to make me sit up. Notice the all-important Greenland High. Upstream blocking is the key, which wasn't present in previous flashes of cold. It doesn't have great support but neither is it an outlier. Something to watch.

It's always a good sign when all routes appear to be leading to cold.

The Viagra run.

If this is the PV setting up shop in Greenland then I’m the Pope.

ECM mean and spread T240: Very good. And the uncertainty on the spread chart is now twofold, probably related to heights at the tip of Greenland, but more related to the low pressure across the UK related to the (hopefully) snow storm. We’re getting closer.

The government should be praying for a cold snowy festive period . Far better for people to either be stuck at home and not mixing or as in members here outside playing in the snow !

Since we are on page 63, I'll keep the above going with this lovely chart from the control at Day 10.

I didn't think it looked at all likely. Why so? Because there was no upstream blocking: people were relying on the high pressure in Russia / Scandinavia to turn into sustained blocking here and that's a fraught pathway to cold in the UK. Looking east not west is like beginning a book on the last page and reading backwards to the start. It can be done but it's sub-optimal . This time there's upstream blocking showing up: a proper Greenland High which is very different. Doesn't mean it will happen, mind you (so I agree about that), but at least the starting position is on much firmer ground. Damn the flow upstream first and watch the results. This is a cracking chart:

I'm resisting to throw caution to the wind on potential between Xmas and New Year, looks nice from the 12z runs of GFS, EC and GEM, but can we trust them with how they handle the breakaway vortex heading from Greenland to Europe? Already Xmas day has gone from cold northerly to mild northwesterly on GFS, some spots may even reach double figures east of high ground. With the breakaway trop vortex heading SE, ideally don't want it to grind to halt over the UK, or too far west. Moving SE or S best into mainland Europe best - but we need ridging to build to the north at the same time, not a trough extension from Greenland.

The big wins tonight are: - The Xmas day Northerly has been sharpened up and will bring 60million people in this country not to mention NW Europe some frosty and *possibly* snowy cheer on a year in which they’ve been battered to oblivion - The major models have not gone flat with the post Boxing Day Atlantic amplification, they have all gone for variations on the today’s broad GFS theme, the details of which are unknowable yet. On the negative side - They have still not decided upon the fate of Wednesdays low (or not to low). Fair play @nick sussexyou said it wasn’t relevant to the overall pattern and you’re right but it’s still Important in forecasting terms for the sodden south west. However should that Wednesday low come to pass, some back edge snow for Northern England looks possible: I reckon the ECM would show something similar, hopefully someone can rustle up the charts! Oh... I just saw the ECM day 10 WAT GIVE IT TO ME. I don’t care that it’s an outlier (it will be). I just want it to happen

Probably best in the moans thread then!

Who ordered the 1070mb block then - own up !

I think most people on here know, the second part of any GFS/ECM run isn't to be taken so literally otherwise the word CAVEAT would be used in every sentence. People are allowed to get carried away and have a bit of fun with the second half of a run, it's part of the enjoyment (for most anyway).

This is the big problem though...its been so long since we last experienced proper cold,some just won't have it..Even if it comes up and bites em on the ar@e they still won't be convinced. Even if we had cross model agreement for a significant cold snap starting tomorrow,some would still stay...ill believe it when I see it...we have to start somewhere.

Here is this mornings very promising GFS (0z) evolution from Boxing Day to New Years Eve.... 500s. 850 VERY seasonal! Quite a few wouldn’t need a lockdown to make them stay at home if this happened. Pity it’s in the land of make believe...