Geordiesnow

It's going to be difficult not too read into the details too much at times especially when it shows charts which would suggests sods law. As others have said, the 18Z is an improvement on the ridging but not as good on the end result. Still many more runs to go of course and a weaker northerly flow can't be ruled out but nothing is nailed at this stage.

It's not a good NH profile, no blocking on our side of the Arctic, Alaskan/Pacific ridges are overrated and as others alluded too usually more negative for winter cold for us. The frustration for me it looks like shortwaves are going to rear their ugly head again in terms of stopping Greenland ridging which makes things harder for the cold to arrive.

Yep perhaps so but the shortwave developments is something we have seen lots of times over the years unfortunately when it comes to Greenland ridging. It's no surprises to me the UKMO are not showing these shortwaves, never been a strong point but whilst details wise the ECM is not the best, the overall pattern is similar to other runs and slight changes can and will alter the outlook, whether that is for positive or not is another matter.

Yep ECM picking up on the shortwave activity now so I do feel the ridge into Greenland is quite unlikely now although no surprises from me. Of course the cold can still come but it does make it tougher and more complicated.

Yep it gets there despite the shortwave drama but as I said yesterday, I do find the GFS model the best at picking these up and the UKMO model least likely. Until that is sorted then I'm always skeptical on any potential of decent ridging into Greenland. That said all the models are consistent with the broader pattern of cold easterly followed by anticyclone gloom NE'ly and then the floodgates potentially opening. The uncertainty will remain how much cold air ends up flooding southwards and how long it lasts for a while yet.

Will be a brief window but the possibility is there for sure and with not alot of wind around then any PPN won't be moving too quickly either I would of thought. What the 18Z does show is what some posters have mentioned is the Pacific ridge does have an influence in terms of potential longevity of any blast from the North and heights around Greenland. It is one to keep an eye on and of course still subject to change. The shortwaves are the main concern for me though, just got to hope if they do develop and reload ridge can occur like the 18Z has shown.

It gets there but that shortwave that develops under Greenland is a heart in mouth moment. It does look like the ridging into Greenland is getting less likely now but these shortwaves popping up is going to make the situation more knife edge I feel.

Would be nice too see those set ups again but for whatever reason, it seems alot harder to get such a set up these days. Got to try and not get sucked in what each individual runs are showing and see the trends and they are showing for the UK a largely dry spell with an increasing snow risk mid month. How that set ups remains to be seen, it's just too far out at this stage.

Lol you were the one that was writing the GFS off earlier! Okay a little disappointing the Greenland high signal has faded but it does not mean we can't remain on the cold side of the jet, as can be seen though, it is more slower but things are not too bad on this evening runs. Of course the signal could come back again and that can't be ruled out

I never said that either. Going from experience, GFS tends to pick up on shortwave activity first(can also overdo them but I don't think it's as bad as it used to be). ECM tends to over amplify but can also pick up shortwave activity. Used to be UKMO model was the least likely to pick up these situations because of it's resolution but now we got access to the higher resolution, hopefully it can pick up shortwaves if they do occur. All I'm saying we can't dismiss any model run and it's always subject to change in anycase.

But we have seen over the years how one little shortwave can ruin ridging into Greenland, it's why I'm always skeptical of seeing a Greenland high being modelled until it's in the medium range(120 to 144 hours) at the very least. No doubt theres going to be a attempted ridge and at least a mid Atlantic high but full retrogression to open the floodgates potentially is far from certain. It could well be gone from the next run but it's always one to watch I feel.

Where have I said that he can't have an opinion? Of course he can have an opinion and he might be right but it is the classic technique we see on here. I've seen all too often shortwaves popping up which alters the outlook significantly and that shortwave alters that particular 12Z run for sure.

That's the classic, it's not showing what we want too see so let's throw up some skeptism at it. Effectively the run was looking more favourable than the 06Z run until some energy from the Azores low created the shortwave which has had a major impact of what the rest of the run is showing. Whilst both GFS and UKMO are both similar looking for our part of the world, there is noticeable differences over Svalbard for example. Keep saying it, I'm skeptical when it comes to Greenland highs because the models don't pick up shortwave activity well and it is usually the GFS that tends to pick up on them first so it is something to bear in mind.

Heart sank when I saw that, shortwave drama could be on the way I feel on this run!

I think the GFS outputs do show what happens if we don't get a true ridge into Greenland. I said it yesterday I'm always skeptical when models long range wants to take a successful ridge into Greenland because they are exceptionally rare these days in wintertime and secondly shortwaves/spoilers pop up. And yes, if we don't get a successful ridge, it does mean the chances of the exceptional cold charts are less likely. I do find the GFS is usually the best at picking up the spoilers first, the ECM usually remains more amplified but it can switch back hence the up and down emotions from run to run. Either way the output has not changed all that much, still a cold dry and for some frosty outlook which eventually will become a cloudy anticyclone. How much ridging will we see towards the Greenland region remains a uncertainty but it is creeping towards the medium range now.

Again the trends remains on the 18Z run for ridging to develop into Greenland at the 192 hours range. It looks too me a shallow shortwave may of developed from the Hudson Bay area which crosses over to Greenland which scuppers our ridge somewhat but a new ridge develops however too far west to affect our weather in a positive sence. Really do need to emphasize any snowy weather is far from nailed at this stage but I really won't get too hung up on every details of each run. The weather for the UK at the moment is one of turning drier, colder with a cold wind in the south before some anticyclonic gloom takes over with milder temperatures. What happens after that is very much up for debate.

I think there will be too much wind for freezing fog down south, air probably will be quite dry aswell. That said in terms of any unexpected snowfall, down south is the place to be albeit it's a low chance. It is worth keeping an eye on those cold pools though as they may create that bit of instability which could change an outlook of what looks on paper quite a dry set up to something more unexpected, the models are struggling just how cold the easterly will be but the further south you are, the colder the 850 air is likely to be.

Not really, you can see main player which is what we want too see consistent at this stage is the ridge into Greenland(which going by those charts is more pronounced than previous runs). Everything else is less relevant at this stage.

Would be nice if things work that way but it never does and we all know each run will be different. What I do see at 192 hours is the start of the ridging into Greenland and that's my main focus/concern at the moment. Maybe the models can pick up on something like the GEM which may bring the more convective set ups quicker but that looks the least likely at the moment in terms of timing.

Aslong as we get the high to retrogress properly into Greenland then yes your right it won't remain a dry stable set up. If the high gets blocked off by shortwaves then we remain in the reminicents of sub tropical air and the anti cyclonic gloom will continue for longer. Certainly will take a few days of anti cyclone gloom if it guarantees a cold set up later on. Your right on the details of each run though, we do have to emphasize that anything cold and snowy is a long way off and subject to change.

Whilst it's understandable that people can get sucked in what each individual run is showing, when you constantly see charts getting posted at such a time range then of course the reality could look different. As others allude too, we have seen it so often before how shortwaves especially seem to kill any prospect of a Greenland high so whilst there is no denying a Greenland high signal as we head into mid January is quite strong, unless it's in the 120 hour range with full support then I'm always skeptical of it. And also, no Greenland high means those charts we are seeing on this thread are unlikely to verify. So the usual one step at a time which starts in a couple of days with high pressure developing. Some uncertainty how cold the initial easterly is going to be. It's one of those where whilst the easterly won't be the classic sunshine and big shower clouds type of easterly in general, if there is a shallow area of low pressure mixed in within the flow, that could lead to some surprises but the models probably won't pick up on this until almost radar watching I feel and it's entirely possible it remains a relatively stable flow with drizzle/snow flurries at best. Then it's the question of whether the high will fully retrogress into Greenland and it's just too far out to be sure.

That's always the danger if an easterly develops more and thicknesses are too high. I will take a few days of anti cyclonic gloom if it means the high retrogress into Greenland but unless that happens at the short range(and we are a long way off from that) I would remain quite cautious of a Greenland high developing despite the strong signal in the output.

I doubt the easterly will be convective in anyway, I think thicknesses and pressure is too high for that. Just hope we don't get too much of an easterly wind as that will mean even the frost will be more limited but I am loving the drier trend, long may it last.

Not really, just an evolution on what may happen. The main trend is the potential for the Greenland high to develop is there but I'm always skeptical until it's at short range due to short waves being picked up nearer the time.

I actually can't believe just how close the UK is to tapping into some pretty cold air right in the here and now and it's all being blocked off by that low pressure system just to the NW of Scotland. If more of that cold was allowed to slip further south and west then we may of seen some snow risk from when the trough finally sinks southwards but alas rather sums up this winter with cold air always flirting with the far NE of Scotland but never cold enough to bring a snow risk. Either way delightful charts of a nice big high developing and some drier weather on the way. Time will tell whether the high can retrogress into a position which increases any snow risk but a welcome break from the rainfall is on the horizon thank goodness.