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Key point indeed... and you'll notice today that teleconnective comments are absent because we await exactly what you ask for here - real data rather than forecast data. A few things we do know for sure - the GWO orbit is holding up and the CPC report on the MJO published today (it is updated each week) is quite bullish about the current renewed and observed MJO cycle and observed enhanced convection over the western pacific. The same report also suggests a slow moving MJO cycle from here, at the lower end of the expected rate of transition, so probably holding longer in the 7/8 orbit. We can also see from NH charts that a trough/ridge pattern close to the Himalayas is currently in place and is likely to provide a spike to east asian mountain torque in the next few days... a point made earlier by Masiello on twitter. We know we have an ongoing wave 1 moderate level hit on the vortex keeping it pushed over towards the Asian side with no great coherence to vortex influence currently on tropospheric patterns. We also have a fast climbing temperature over the north pole at 30mb - an old fashioned tool over on JMA that has always seemed to me a handy guide on the state of things over the pole for those (like me) who struggle to visualise the entire complexity of the many layers of stratospheric vortex activity. We know also that ensemble forecasts from both EC and GFS have swung in the last few days towards a flatter pattern, elimination of the mid atlantic ridge but also an increase in height anomalies to the NE. What more would I like to know tonight? I'd like to know exactly where the AAM budget sits... the trend over the last few days... and the actual situation regarding frictional torques. This data has not updated today. Conclusion? Today's bullish MJO report from CPC and visible east asian torque with associated lag has me firmly fixed to a strong belief in the return of amplification in the medium term. Lack of vortex intensity supports this. Tie into GP's key knowledge on composite data (something I have as a 2018 target to improve on myself....) pointing strongly at a Scandy ridge evolution on the back of the observed GWO orbit and current observed state of the MJO moving slowly through 7/8 and it seems a very good bet that this amplification will produce the aforementioned scandy high. Timing? Well - not for the first time of stating.... there's the thing. Lag impacts are uncertain - and I wouldnt want to make a timing prediction at this stage. Our atlantic is not being driven by a rampant vortex this year - indeed I am beginning to wonder if the vortex is going to remain weak for a sustained period now especially with IF tweeting about Metoffice sense of ongoing warming and disruption. A sluggish atlantic makes it difficult to predict how much westerly momentum might gather through next week. Are the models built around a westerly bias that may overcook this signal based upon "normal" climatogical impact of the winter vortex? The models continue (by observation) to underestimate the orbit and direction of the MJO - underestimating first of all the impact of the 5/6 transition but now equally underestimating the move to phase 7... and as such are they failing to pick up an amplification signal for Xmas week? Laying my cards on the table (admittedly without the data update today...) I think amplification will return more quickly than the ensembles are seeing following a short to shortish period of westerly influence of around a week.

A quick look at how GFS,EC modelled the 0-10 days approach to the Dec 10 snow. The black isobars are what actually happened i.e. 0 hour: EC240: GFS240: Both models have the right idea at 240h. The EC is already hinting at an undercut but has Scandinavia as anticyclonic whereas GFS correctly has cyclonic. Both models have a low centre too close to Iceland. EC216:GFS216: EC gets the Greenland/Iceland/Norway cyclonic pattern broadly correct, but GFS has Greenland/Iceland high pressure too far east, and GFS has North Sea low pressure not extending far enough north. I prefer EC here. EC144:GFS144: At +144h both are good. EC seems a bit slow in its evolution though, showing a still well-defined 'slider'. EC96:GFS96: At +96h the EC still has the 'slider' at a too-sharp angle, whereas GFS is picking up on the flattening as the low starts to move E rather than SE. EC72:GFS72: At +72h EC has rectified any problems and is now close to perfect. GFS has the cyclone/anticyclone centres in the right place but the isobars deviate a bit more wildly at times. EC24:GFS24: At +24h, EC is such a good match that the black isobars are often covered. This 'perfect matching' occurs less with GFS. Finally, here are the full 10 day GIFS: EC:GFS: Conclusion: EC had the clear edge at < 72h. GFS spotted the trends at longer timescales fairly well however. GFS is a bit like the American personality: It broadly answers the fundamental questions but is too brash and impatient to be bothered with the finest details.

Am' suprised theres not a lot more members/comments via 12z Ukmo/gfs: Some decent evolutions across suites. Block holding up very well' and certainly cool-cold preety much throughout(reliable) Zonal IT ISN'NT!!!

Well, according to the Gfs 12z the less cold midweek blip shows snow spreading from the west later on wednesday and there is another very cold spell towards the end of this week with further snow showers and severe frosts continuing into early next week..I would call that an upgrade..hope it continues!

Okay, I think we may be seeing hints of ‘let’s not get ahead of ourselves’. I’ve been saying about this Atlantic Ridge with attendant northerly mid month/next weekend for sometime. Indeed in my LRF I have forecast it to generally be in place up Christmas so I am looking now for changes in the output beyond day 7 to come away from zoneality. The less cold midweek is becoming a blip and won’t be imo classed as mild either. I think we might be seeing early signs of us coming away from the Atlantic zonal dominating. Interesting to see where we are come Friday. Mighty cold tonight folks, keep an eye on the vulnerable near you BFTP

Good olde La Nina, Its funny how this place changes from WESTERLIES EVERYWHERE! to cold in a matter of hours. One thing ive noticed year on year is that the models hate having to deal with any form of blocking or long term cold. Anything further out than a few days and they always seem to point to a warmer west and the Atlantic taking control. The models just cant cope with any other setup. hence the tendency to constantly push back towards it. Granted, there are signs of extremely brief milder days but they seem to keep getting push away.

Hello, first post for a few days as I have been away Looks like we have a pattern change coming this weekend and I’ll describe what I think may happen based on the model output. However first, lets have some context… why is the pattern changing? Well a big part of the change can be attributed to the Pacific North American pattern (PNA). What is this?, well here are some basic diagrams to show its effects. The top two panels show the synoptic pattern and the bottom two show the temperature anomalies. The synoptic pattern over the USA when the PNA is strongly positive is one where we have high pressure over the western USA (like recently). That is the main thing and usually there is lower pressure over NE Canada or the NE USA. Positive PNA - SLP Negative PNA - SLP Positive PNA - temperature Negative PNA - temperature So its probably little surprise that this pattern has contributed to increased wildfire activity in this region. The downstream effects (North Atlantic) are that the Azores high is more likely to ridge North which is what we have been seeing. Due to the cold air from Canada being deposited over the SE USA, low pressure systems over around the coastal areas where cold continental air meets the warmer temperatures of the North Atlantic. Low pressure systems typically move NE off the Eastern seaboard and some of these get trapped in the far NE Canada or USA. Thus encouraging ridging of the Azores high. However we are seeing a transition to a more negative PNA which is shown on the right hand panel. Often the high Pressure over California is not as strong allowing the jet to dive further west in the USA instead. The SE USA is often under warm air from the Gulf of Mexico. Areas of low pressure zip across Canada and carry cold Canadian air into the North Atlantic. We therefore see a region of rapid deepening of low pressure due to the cold Canadian air meeting the warmer Atlantic. Low pressure moves past Greenland and warm air from the SW Atlantic hits us instead. Now there are some variations over the PNA but a somewhat similar kind of pattern change explains why there is a stronger chance of mild westerlies coming into play over the UK. Though how this Atlantic energy is split will determine how mild the UK gets. So here is the basic scenario on Sunday. Now we have mild air racing across the North Atlantic but a slightly displaced Azores high close by. From here three scenarios could develop within the following couple of days. Sunday Scenario 1: 15% Scenario 2: 35% Scenario 3: 50% The first is a Scandinavian high which has a fair chance of happening but it probably wouldn’t occur that quickly due to the amount of energy in the North Atlantic jet. Also there is the issue of that low over Scandi blocking its Eastward progress. The second is an anticyclonic outlook. Here the Azores high ridges across but a lot of energy goes over the top. Many parts of the UK would still be cold because of the short days. Slack winds and weak solar heating means temperatures can’t recover during the day. In these situations T850 ensembles can be misleading because it can be cold at the surface despite warmer temperatures higher up (known as a temperature inversion). Warm air will likely affect NW areas though and a slight modification could see either the whole of the UK cold or mild. The final scenario is one where the Atlantic wins out over the following few days. This could lead to either mild SW winds if there is a pressure build to our east as well or a more alternating mild/cool pattern with westerlies. Finally a Scandi high could develop later from the other two Scenarios. The middle panel wouldn’t be that bad if some blocking could develop from the high pressure. Overall these are just a bunch of scenarios that I think will develop from the model output. Lets see what the 12z’s bring.

Having read some of the posts from last night and this morning, if you don't mind me saying some are in denial. No evidence as mentioned last night of the jet continuing to run NW-SE. Little evidence of any significant height rises to our NE. The return of a milder pattern was obvious to me as I mentioned a few days ago. What we are likely to see is a rather typical UK winter weather pattern of a flat jetstream with low pressure systems tracking NE to the N of the UK. Milder SW,lys with the weather more settled further S and rather more unsettled and windy for Scotland. If we do see pressure rising then it is more likely to occur over the UK bringing settled conditions and cold nights. The last thing I see is any cold, snowy E,ly whilst heights remain low to our NW/N. Sadly I would be amazed if any of the above changed before xmas. My punt is a dry, settled Xmas but at least we should wake up to frost which is better than wind/rain.

Quite the turnaround from the models with the dip into the 'circle of death' almost eradicated and much better amplitude into 6/7 from GEFS and 7/8 from ECMF. Both are good for boosting HLB starting a week or two later in time from onset... so around 10-18 days from now. Question is whether we can achieve the 'almost' situation of recent GFS runs in the 7-10 day range, or end up with more work needing to be done to rescue things as per recent ECM runs. With the near-term reduction in MJO forcing removed, there may even be additional amplification on offer in the 6-10 day range so that's something to watch out for. Maybe.

Well - don't despair too much folks, the GEFS 06z do show a cool down towards Christmas with some beautiful runs appearing. Notice the improvement from 00z to 06z (to add to Karlos's post above). Who wouldn't love to wake up to a 1962/63 Christmas like this? Obviously a very unlikely scenario but at least it has a few supporting runs.

With Christmas Day in range of the EC clusters, are there any patterns? So far I'm seeing: - Azores High slightly held back west but amplifications to be temporary if at all - No clear direction on Euro heights but unlikely to see a strong trough there like we have so far this month - Small chance of ridging to the north but generally too far away to influence the UK greatly - Most likely outcome ATM: a changeable or unsettled WNW flow, possibly drier in the SE. White Christmas likely to be limited to high ground in the N and W. Cool but not cold. - Being at D14/D15, subject to serious change!!

I can understand the despondancy but the charts certainly do not scream endless zonal to me. +PNA hints in a week or so time will be worth watching. Also, P5 pulls out an absolute belter of a run this morning on the 06z and shows HOW and WHY we should not rule out looking to the E / NE, as a few others seem to have already done. All a bit soon though probably. Edit: Ha ha, I can see P5 caught they eye of others as well

I don't mean to sound too much like a broken record, but there continues to be massive scatter in the GFS ensembles. There's a staggering 25C difference for Christmas Eve and near enough 15C difference just a week away. Those are pretty colossal scatters. It means there are a number of possible and perhaps plausible perturbations in the forecasting models. Perhaps worth bearing in mind, alongside the various upstream signals.

Looks to be a fair few easterlies on the ecm ens for debilt

The plume for de Bilt still very uncertain after the 17th, it has been like this for 4 days at least but I think we see more and more members choosing a cold solution

According to a recent poster in the Southwest regional thread. Fergie quoted as saying Glosea going for blocked Jan and the model is also keen on strat warming event late December/early Jan.

This is what I'm clinging to this evening as I'm sure are all the coldies.

Seems that at the moment in order to see temperatures anything above the long term average you have to look out into fantasy land. The opposite of our norm. And there is still no certainty that this long foretold milder spell will last very long, if indeed it happens at all! Also the northerly at the end of the week seems to be getting more pronounced too. It seems to be generally considered here fait accompli that a mild spell will commence after this weekend, but I am still not fully convinced of this and still think we may yet see some interesting developments in the models as the cold air holds on longer than currently suggested, and perhaps even fights back.

well. a day of sleet, turned to what could be classed as wet snow for a while but just light rain/sleet now. however... the cloud is clearing from the west, so we should be getting clear skies over the region just in time for getting dark. it will be still wet on the ground though. the roads cant be gritted wet, so conditions are ripe for some very dangerous ice conditions on the roads and i've just seen a met office warning out for just that. i would imagine there are many younger drivers out there who have never experienced driving on ice. i've been driving for nearly 30 years in all sorts of conditions and all sorts of vehicles including HGV's. i've owned land rovers for several years and been off-roading a few times but the one thing i am most wary of is black ice. you cant see it and no matter if you have 4 wheel drive, winter tyres, ABS, traction control, you still have to be extremely careful. my land rover has all of the above but if i lose it on black ice, it becomes a 2 ton uncontrollable missile. so if you have never driven on ice, BE CAREFUL!! better still, if you dont have to, dont drive at all.

May lead to nothing but the Atlantic pick up at the weekend doesn't look straightforward looking at the clusters from the latest gefs. First of all a look at the 850hPa temps showing the mean rising around the 17th but the op staying cold along with a few other members.Looking at the jet stream patterns for that time a lot of splitting and signs of trough disruption around the UK with some energy leaking south. The favoured evolution for week 2 is still for the flattening upstream to release enough Canadian energy to push the Atlantic through but maybe as we get closer the higher resolution of the operational runs may ease back on the amount of strength in the northern arm. Just putting it out there for something to monitor over the next few runs.

From the latest GFS run, heights remain over the pole beyond T240 and from history whilst they remain in that unusual locale, I have found that cold spells often pop into the forecast without much notice as they often struggle whilst heights remain oop North. A bit of hopecasting, yes, a bit of viewing experience yes, but I'm not ready to churn out the Vardy, just yet.

Hastings/St Leonards on Sea

So thanks to my FB memories notification this morning this is what we were facing 1 year ago 12 months on

I might pop back in this thread sometime, hopefully the topic by then will have returned to the actual weather ? Sheesh.

Our favourite Weatherman is unable to play in here but said I should pass on the following message. The message to pass to the regional folk is keep across stratospheric evolution into late Dec-early Jan. Glosea keen on strat warming Jan; hints *perhaps* as early as late Dec. Either way, we suspect blocked, colder wx likely into Jan (as being progged now by GloSea) and clearly any SSW changes goalposts (70% chance it causes blocking NW Europe). Watch this space.

All I will say about the Ecm 12z is I hope the Gfs is right!!!!

Fascinating chart that one....that could lead towards the deep freeze with pressure ridging towards Greenland and imo would block any further Atlantic inroads and the block to ene backing west. Hmmmm, I am interested in the major block to ENE at that point and it’s influence just not enough....at that stage. Anyway pure FI but interest neartime remains definitely. BFTP

What about a potential ice-day next Sunday?

In regards to my post above, definitely musings rather than predictions!! I would add that the EC clusters had a period at the end of November when they suggested a return to a flatter pattern around about now - we all know that did not happen!! So they could be wrong this time, too. But if one took all of the model output today and studied it mathematically, they would not conclude an easterly to be the preferred option for Christmas. However, if someone things they can see signs of how the models might have got this wrong, that's a different matter - blooming good luck to you and I hope you are right

With this set-up pretty much all of us in the UK would likely benefit at some stage - and no it wouldn't be sleety marginal stuff

i think you are correct, my kids school has just been closed in felsted! mrs not happy though its caused murders with her eyebrow appointment lol

Suns come out now, stunning:)

Well first real sign in the 15 Day ensembles of swinging back to colder, from less cold conditions toward the end of the month.

Iconic Beachy head in a blizzard

Settling snow now on South coast. Windows blasted by a NE Gale.Blizzard conditions.

Current scene in East Grinstead 109m asl

Now that todays snow event is finally over and tomorrow looking a bit too marginal I can safely say...

Some of the individual flakes falling yesterday afternoon in the garden.... must have been very cold aloft for these to fall... but yesterday managed a couple of inches eventually.... -5c dew -7c cold.... got woodburner on

Ac few post ago I referred to the lovely sunset - it so happened that my daughter was equally impressed and took photos - great minds think alike! However the one to really drool over is the third one which I believe is a scene from Finland.

Polar Low? 500mb temperatures are cold enough you need them generally lower than -35C. I notice the fax chart for the same day Friday, has the same low feature coming S down East Coast.

One last 'arty' shot of a South coast snow day. Hard pushed to remember 70mph gusts one day and a blizzard that sticks the day after!

Well well, even out to T+180, no Atlantic intrusions to speak of are on offer. Yes the odds are in favour of this happening (I'm not in denial), but we can't say the output this season and today isn't without interest again. Gripping stuff!

Yes day 6 as some of the 06z suite suggested- picking up a signal for some resistance to an Atlantic breakthrough energy heading se -cold air more resistant against a weaker Atlantic jet.Eventually it does flatten but the delay shows uncertainty for next week. UKMO unfortunately still has too much energy over the top I wonder if the ECM later will start to hint at a slower Atlantic.

The scenarios add up to 115%?

I'm glad parts of the southeast got some snow today, especially higher parts of surrey. Tonight looks bitterly cold with severe frost, especially over the snow fields with minus double digits celsius for some!..needless to say tomorrow looks cold after such a bitter night and then we have a midweek less cold blip before colder air returns from the north with wintry showers to exposed n / e areas and overnight frosts and ice.

* Put's sledge away and get's out the rubber dinghy *

Kids very happy at the sight of falling snow! It’s not sticking and it certainly won’t do, but its a pretty good way to start Monday!

I haven't had much chance to look at the outputs this morning but there is nothing surprising about the ecm contours and anomalies. And I can confirm that SIdneys cockles are warming nicely

Not had a look at the models in a while but certainly intriguing with the eagerness to build +ve heights to north / east, perhaps this is the lag result of high amplitude MJO phases and there’s room for models to play with more amplification - we could enter something much colder before Xmas. I for one think that is plausible, model watching this year has taken a decidedly different turn to what we have been used to.

Even if we do have a milder, more cyclonic spell in the latter part of December, that wouldn't necessarily be bad. A lot of famously (or infamously) cold winters have had milder, even stormy periods at some point during December. I'm staying hopeful and so should you lot!