Joe Levy

Quite a nice chart on the ECM 12z at 192 hours!

That was what I thought! I don't think I said it was perfect, but better haha

Better ridging northward from the European high towards Scandinavia and beyond

Better heights in Scandinavia at 120

Not saying that this chart will verify, but I am meant to be catching a train back to London for the holidays that day. It will be Friday 13th I guess...

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=185&y=179 (South West England) http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=254&y=2 (Northern England) http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=357&y=78 (East Anglia) Whilst there is not too much in the way of deep cold shown in the 18z ensembles, bar the odd run here and there, there is a notable cool down towards the end, marked by an increased spread. If this trend is maintained, we may start to see the colder runs emerge as a more significant part of the ensemble, but equally we may not. All part of the fun! EDIT except there is a more notable presence of cold runs in Eastern England, which does support the Scandi high idea

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=188&y=177 (South West England) http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=256&y=3 (Northern England) In addition to the spread in 850 temps in a few days that I mentioned earlier, more significantly for long term trends is the shift towards a more blocked outlook and some significantly cold runs later in the set. One or two runs bring back cold 850 temps quicker than others, so based on the spread, there are many options available still but plenty of interest in the run up to Christmas at this stage.

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=190&y=176 The spread on the 850s is still quite considerable for only a few days away, especially in the south (as shown here for Exeter) where the depth of cold is most uncertain.

Because southern England is a very small area of the globe, and a relatively sheltered region at that! I share your disappointment, however when severe snowy weather does hit us it is far more exciting, because it is so rare!

Considering the small adjustments westward on the 12z so far, whilst I would say that any major changes are unlikely, there is still certainly some room for improvement in the extent of the cold and possibly the precipitation as well, but much of this is coming down to last minute corrections

They didn't back the GFS, they backed a particular run of the GFS and only elements of it. They took a blend of UKMO and Mogreps, supported by GFS, GEM and their own GME, if I remember correctly. This run could be taken completely differently by forecasting professionals. Also it is quite notably different to the previous run, so some caution is required

They're much easier to view that's for certain haha! I think ensembles are very useful for looking at broad trends, but in the high res sections of the ops, you are right, they are more useful as they pick up details better. That is where our key issue is at the moment - the detail of the low that exits the Eastern Seaboard and its tilt!

Yes but that is an average once again - when there is a broad spread, the mean tends to default to average. But if one of the colder ensemble runs were to be closer to the correct value, then the ensembles could change at a later date. Equally the same applies to a milder ensemble run. Always value the mean for what it is - an average.

With regards to the ECM ensemble, I think it's worth bearing in mind that the shifting of the cold air at 192 will be down to many of the members removing it early, whilst many may continue the cold much later, as is always the case with ensembles. By the way Summer Sun I hope you realise I am not criticising your analysis, I am just drawing attention to the fact that it is only a mean of the ensembles and so must not be taken at face value

Yes I appreciate that but I more meant that it's not worth thinking about the end of the cold spell before it's even begun!

Right, but after 3 full days of cold... 3 days is plenty thank you very much and it will feel very seasonal! Also, that chart you have posted is not mild, not at the surface and even the uppers aren't very high. They're within the expected range for the time of year

I love reading the writing of the NOAA as the fact that everything is in capital letters makes it seem so much more urgent and official for some reason. Excellent news. We are within a timeframe now where many of the changes upstream are already beginning to happen, so it is reassuring to have that sort of guidance being issued.

I am unsure whether it has shifted eastward by much though. Remember that in terms of timing, the 12z from yesterday is a more accurate comparison due to the fact that ECM is released twice daily, but I am sure you are right that there is some shift

ECM at 120 hours. Very much in line with what it has been showing so far. Let's hope that those verification stats remain true and that the ECM is right about this.

At 72 hours and so far the ECM is behaving itself, but stay alert and stay patient as we know things could change in either direction at any moment! Such pretty colours with such evil tendencies, a sort of nightmarish meteorological rainbow...

I think that some excellent posts have been made on this forum over the last few days explaining the effects of the upstream pattern on our weather. I know that I wouldn't be able to understand the importance of shortwaves and lows exiting the Eastern Seaboard without them explaining it, so in amongst all of this ramping and ranting that belongs elsewhere, those who look at the broader picture certainly deserve a round of applause

It's only one run from the ens, but number 9 is the sort of thing we want to see from future op runs if we're looking for deep cold. In terms of longevity I think that's not something we need to focus on right now, as getting the northerly in place at all is proving somewhat complicated. As some of you may comment, it doesn't last very long on this run, but it does give us a good depth of cold and early, which is what I am currently looking at.

Can we please focus on charts we can see, rather than debate what we can't see, especially since this is a model output thread. Based on the output produced over the last 48 hours, there is an extremely fine line between whether we get deep cold and whether it misses us, but that is why we look at the models, so we can ascertain it. Patience is required here, and there is no point being personal or angry over something which ultimately is out of our control and is not worthy of spiteful or aggressive remarks!

We're not actually in winter... that's tomorrow... and there are three months of it...

GFS is not the main model if we are going on verification stats. Look at some of the posts on the previous page, which show quite clearly that the ECM verifies better. That does not mean that it will this time for certain, but it's a fallacy to say that the GFS is the main model, when really we need to be looking at all the main models in conjunction with each other, as well as expert advice from the Met Office. Your expectations are without substantiation methinks.