Geordiesnow

Still not going to get too carried away with the details, they will still change(for better or worse) but one thing I would like too see from the GFS 18Z run is not have that Iberian low coming into play and sod off basically like the 06Z run did. Also better ridging into Greenland and hopefully all that will end up it showing the UK getting into the significant cold air quicker than the 12Z run did. Still mindful with what the UKMO shown also, if the main northerly flow too far east and high pressure from Greenland has not established itself correctly, we could be left with a weak northerly flow therefore a struggle to get significant cold air. That is still my concern with this, I think the northerly in some form is nailed, it's just whether it will be potant enough.

Nope they are similar but the details are different. Quicker northerly flow followed by slack low cyclonic pressure, this run is really not all that far away from this mornings run(which if you went on some comments you think it was a really poor run which it wasn't) but because the pattern was a bit further south and east it meant the mixing of the cold was not as noticetable as this mornings run. Like I say, the ECM feels more high risk but its more reward quicker.

Only if it's get its amplification into Greenland right, if not then maybe we will see something closer to the initial GFS/UKMO projections of the northerly thrust being further eastwards. ECM definately feels like high risk but high reward as you don't want things too far west otherwise you end up with scraps but it's the same if things are too far east also but you probably got more room for error as the GFS shows(e.g the significant cold does eventually arrive).

I think there is similarities between this run and this mornings run, it's a good run though because you get the initial proper cold blast followed by slack low pressure with the potential for some nice frosty weather. Obviously if you want something more long term, the initial northerly needs to be further eastwards but amplification to remain as good as the ECM shows and not like the UKMO run for example.

Not as amplified as this morning run, it's a very good run upto 144 hours and because its not as amplified then I don't think we will see thing go as far west as this mornings run!

ECM looking identical so far with the earlier run, hopefully that's where the similarities end. Be an interesting next few frames.

A polar low are not usually modelled until 24 to 48 hours. That is a nuisence shortwave which usually scupper cold set ups! If its over the UK it could bring more prolonged PPN but we need a clean flow before all of that.

That's a real head scratcher of a comment there, certainly no polar low on the UKMO run even at 168 hours, shortwave maybe but not a polar low. Like too see on the upcoming ECM run another decent ridge into Greenland seeing as the UKMO and to a lesser extent have back off the ridge hence the less clean northerly flow. If anything it was too good on this mornings ECM run hence the output after 168 hours but it had by far the strongest initial plunge so at least no messing around unlike the GFS run.

I think he means the more significant cold and I do get what he means to an extent but we are still at a range where slight adjustments could still being the more significant cold in quicker. The potential northerly has not been pushed back but if we get a situation where its too slack(as per the UKMO) or the cold takes a route via scandi like the GFS then it feels like will the UK see the significant cold air or not. Interesting but not at all crucial ECM coming up!

Initially the Iberian low delays the easterly somewhat(we pick up more of an ESE'ly) so somewhat a delay to the colder air and we all know we don't want to see delays! UKMO is better in that aspect but the attempted stopping of the ridge into Greenland means the main northerly thrust is further eastwards which could moderate the cold. Its a decent run though and I await too see what the 168 hour chart shows. Either way neither the GFS or UKMO is backing this mornings ECM run so far.

This afternoon runs are showing why I don't believe in a true Greenland high set up as we are getting into the time frame where spoilers pop up and we do see that on the UKMO in particular. The GFS spoiler seems to be the Iberian low once again, still room for upgrades though but not quite the output that will get this place celebrating.

I don't think a northerly flow of some kind is in any huge doubt, its just whether we will get enough cold air far enough southwards for snowfall. My main concern is will the flow be strong enough to help get the coldest air down. Of course there is the threats of a west based NAO but it will be hugely dissapointing if we go through all these wonderful snyotopics and the air just has not been quite cold enough.

The ECM is not even a poor run for cold weather fans, snow potential there also. You think it was showing a Bartlett high something like that!

Oh goodness, that's a model classic quote there. There is nothing crucial about the 12Z runs. Just another set of predictions, that's all. Anyways better 06Z run, again not worried about uppers as details like that will vary, I guess initially the ECM had the perfect set up to get the coldest air down but the trend is important and its a good run imo.

Yep if anything, the ridge into Greenland is too well done, I'm not overly worried as it still trends the right way in the short term, the longer term charts will always vary from run to run. That said, it does show nothing is cut and dry and whilst we are likely to stay cold, obviously its the cold enough to snow set ups people want too see.

Just caught up with the output and yes the GFS is frustrating and there is always a chance it could be right but its still got the main feature that I want too see which is Arctic air dropping down from the North. All models showing a Greenland high aswell, I'll still remain some caution on this but its a pretty strong signal for it and we are getting closer to the medium range. As for uppers, yes they might not be as cold as 2010 but I would not be worrying too much about the details you don't want a weak northerly though as getting significant cold air could well be a struggle.

Decent runs this afternoon, even with the GFS trying to drag it heels to get there, it's showing the trend I want too see of Arctic air heading southwards. It's ashame we slightly downgraded on the initial easterly though, seems like too much of an ESE'ly and I'm guessing the continent is not cold enough to bring in lower dew temperatures.

It is a huge irony that there is too much blocking, too much yellow and oranges and very little blues and purples. Especially as some of the blocking is not ideally placed like the 1050MB high over western Russia, you want the centre more over Scandinavia. As for the Greenland high how many times we seen over the years a Greenland high becomes more of a mid Atlantic high due to shortwaves being a spoiler,far too many times and I'm always a little dubious when it comes to the ECM model wanting to over amplify things. So it feels unless something develops as a surprise in the initial easterly flow, a snowy set up still feels a bit of a way off.

Unfortunately I think some were expecting the GFS to look like the ECM and obviously that is not the case hence the mood. It is some bizzare charts we are seeing from all models in this set up, I don't think I've ever seen so much blocking yet so little troughing and that is the issue here. Only the ECM this afternoon offers that hope it could change but previous GFS runs have suggested the same. The initial easterly is still touch and go in terms of hoe cold the air will get, there's been some slight upgrades in this but because of the weak troughing, it all seems to point towards a stable easterly but details are still hard to pin down. Ironically there would be a snow risk if low pressure did come up from the south and the cold air managed to filter enough but on paper it does not look 'sexy' and the cold air would very much mix out as per the todays GFS runs.

There has been some GFS runs showing similar at the 300 odd hour stage in previous days though. Obviously now we are in the 216/240 hour range so Arctic air flooding southwards is a fair possibility although by no means a certainty.

ECM continuing the trend of trying to push Arctic air southwards, the details are irrelevant at this stage mind. Ironically it's the GFS run that has the most potential for snowfall with the shallow low set up whereas the ECK/UKMO do look a bit drier in terms of the easterly, still quite hard to pin down the details unfortunately with the easterly because slight changes could be the difference between fairly cold air and something more modest.

Whilst I am concerned about climate change, we must point out that throughout the second half of November, the arctic has actually been below average(with the exception of the Pacific side of the Arctic) and Siberia is also below average as a result(and when I say below average we have seen temperatures of 20 degrees below normal but that won't make the headlines). The modest cold is nothing to do with climate change. Its down to the Russian High originally being in a position which scooped up milder air into Scandinavia but now its settled down in a more favourable position, the models are developing the cold pools again which has got gradually stronger, how much cold ends up in the UK is uncertain but we are definately trending more towards - 6 to around - 7 on some runs with the - 8hpa being more noticetable in the North Sea. Yes its still scraps because in the short to medium term, there is no PV coming from the Arctic basin but hints longer term this could be different. As for the 06Z run, it has the continental air winning out quicker than the previous run(that shortwave on the 00Z run is further westwards again). Still be interesting to watch if we can upgrade the cold although it still depends how it sets up. Would not rule out the - 8hpa at least briefly ending up in the UK from the initial easterly.

To emphasis my point about the delay of the continental air, on the GFS 00Z run the deep low under Greenland at the moment actually ends up over the UK as a shallow shortwave which initially delays the cold but then ends up helping to bring in the colder air, ironically it does actually bring a snow risk but its very risky to go down that road! The UKMO and ECM does keep it further westwards but only just about and even those runs delay the cold somewhat. Be ashame if the initial easterly gets scuppered whilst the cold pool is gaining more depth.

Little mixed feelings for me on todays runs, noticed the trend of the colder air for this week struggling to make inroads northwards and westwards, Atlantic air is really trying to cling on to Northern Ireland and Scotland especially but yet the depth of cold has again upgraded which makes the delay frustrating for me. By the first of December on previous runs a few days ago, the whole of the UK was in the continental airmass, that's not the case now however when the colder air does arrive, it is slightly more potant(definately seeing the - 6hpa more widely across the UK). As for the talk of Greenland highs, its always the same thing for me, longer range models got no issue in producing a Greenland high but closer to the time, it ends up being stopped by shortwaves and we end up in a half baked cold set up.

Yeah slight differences in thicknesses certainly helped but I've noticed from the last cold pool that just missed us that the models did seem to closer to the time just slightly strengthen the depth of the cold run by run, not consistent albeit and there be variations but it's something I watched closely on this run and it's subtle but the depth of cold did increase in the short term. The reason why the UK did not see more in the way of the - 6hpa on this run because the flow was more ESE'ly instead of ENE'ly like the 12Z was which shows how a subtle shift can make a difference!