Geordiesnow

Or the classic of radar showing the PPN over us but nothing falling because the air is too dry and then when PPN does fall it's too marginal.

You on about the first northerly or the second because they are both quite short lived and the first one, the thicknesses and pressure to an extent are too high. The second one is better thicknesses wise and lower pressure but it's a blink and you miss it before developments to our south come into play. Still cold and dry is better than wet and mild and it will be good too see the sunny skies again after this anti cyclonic gloom clears but it all feels a tad underwhelming for me sadly on a snow point of view.

The fact yet again we can't seem to get a sustained Greenland high is proving to be very frustrating. Is it climate change or something else, can't really blame the shortwaves on this one really! I bet in the 70s and 80s that would produce an epic northerly/NNW'ly with instability all over. Now it's just a glancing blow albeit the air under it is still quite cold but becoming a blink and you miss it affair. More hints the Atlantic is coming into play also but that's still a long way off but hopefully the details can improve again because barring the threat of frontal snow and maybe some snow showers in northern and eastern Scotland, the snow risk does look fairly minimal so far.

I got to say I'm dissapointed with how things have manifested especially with the initial northerly. Going to be a dry stable northerly as high pressure to the west is too close so no instability but it should be crisp and sunny. I did thought this was the most likely but yesterday's UKMO did briefly promised something a little better. This also means less room for error for the cold hanging on as winds switch to a WNW'ly as the northerly collapses which whilst this was going to happen seems to be happening a good 12 or so hours quicker too me. Can we get the reload, I have my doubts but this would be my preferred choice over the threat of frontal snow which going by the ECM may not even bring frontal snow as the air is too warm. Just kinda feel alot of chasing for an outlook where snow looks quite limited for our region so far.

Apart from a few minor differences, the GFS 12Z run is pretty identical to the 06Z run. Going by the models, an indicator what might happen with the frontal snow event is if the initial northerly is not as strong(in terms of wind flow) then it's makes it easier for any Atlantic front coming up from the SW but if it is stronger like the UKMO then the second push of lower heights will push that attack from the front further southwards. So still some minor disagreement on the first northerly which of course leads to consequences down the line.

That's not true at all, the initial cold blast is still on for the 14th/15th which is the start. That initial northerly has always been forecast to collapse via a shortwave and this may bring slightly less cold air before perhaps a renew push of cold air down from the North. That's not a certainty but certainly a possibility.

As I mentioned in the model thread, upon further examination, I don't think the UKMO run is actually all that far off from the GFS run. From what I'm seeing, if any of the PV enters Greenland from around the Arctic/Svalbard area then the true blocking will collapse quite quickly. Maybe we would just about get away with it on the UKMO run because it occurs a day later so there might be enough forcing to stay in mostly cold air. I guess for us in our region, the messier it gets, the better as northerlies are unlikely to bring snowfall to 95% parts of the region but if we get enough cold air then that would make it more interesting. The GFS just mixes the cold air out too much for my likening but sometimes charts that don't look interesting can spring a few surprises so who knows.

If the PV enters Greenland from the Arctic, then the GFS will be more accurate, if it's wrong on that, we could see more something like the ECM. Despite me saying the UKMO is not like that, on second thoughts it's not far off and arguably occurs around a day later hence the 168 hour chart although there might just be enough height rises/forcing to get more cold air mixed in again. This is real knife edge stuff unfortunately albeit as I said earlier the northerly will occur in some form, it's just how long it lasts and can we stay in the cold air when it does collapse(which it will as that is what is being modelled).

I get in those wanting a long spell of cold and snowy weather might be dissapointed in this run but it is slightly better, brings the cold in a tad quicker, quite a potent northerly at that, snow showers packing into northern and eastern Scotland possibly eastern areas of England also for a time. I looked at the low heights between Svalbard and Greenland at around 108 to 120 hours and the blues(PV) enters Greenland which just collapses the block like a balloon and the consequence of that is to collapse the northerly very quickly. It's a small detail but the UKMO/ECM does not do that, it's something that could go either way I feel. Hopefully we can get some upgrades with the initial northerly and get the cold in even quicker if we can.

Rubbish!? -10hpa into Scotland, plenty of snow showers in favoured spots for a time. Do accept in terms of longevity it might not be as good but there is hints the colder air is being further forward and the transition day could be the 14th.

I have to say I don't think the ECM is that far from what the GFS is showing(and the same vice versa). It's going to be a minor tweek here and there and the outlook could look totally different. The cold set up is the favourite as that has got the most support but a tweek here and there and we could be looking at something different. Even the GFS does goes cold but it gets rid of the cold quite quickly. I'm not doubting the northerly flow happening but what happens after that is uncertain. Questions still remains just how far south that cold air gets before the northerly topples and any attack from the SW.

Well it's not the beeb that shown it, it's cold/snow enthusiast Chris Fawkes that has shown it. I do agree though, it will only fuel the media and especially social media and could end up with egg on your face type of thing. I do like Chris Fawkes as a forecaster though especially with cold/snow on the horizon.

Not sure it's as bad as it looks. Most runs do suggest the initial northerly will collapse but aslong as the cold air is strong and far enough southwards then when it goes messy there will be some snow chances for sure.

So those GFS runs which some dismissed of the Azores low coming into play is now being suggested by the Met Office? I mean somewhere could get lucky but it's playing with fire, much prefer the cold air properly establishes itself before any attack from the west/south west. The main thing is we get a strong enough northerly to get that cold air as far south as possible and for the northerly to be as potent as it possibly can be.

Quite an achievement believe you me. Your not the only one of course, I mentioned it in the model thread recently how a run is not showing what they want too see, it's always this run looks iffy, or they are skeptical of it. Any run is plausible but the details will always vary on the next run and that happens with any weather pattern. It's always too easy to get sucked into seeing something and come to the conclusion it will happen that way especially if it's more of a negative run. In terms of our region, from the runs I have seen, then we could see some snow in this region especially those further south in the region, one potentially from cold air undercutting the cold front and the models hinting the northerly flow will back more WNW'ly and IF the cold air has made significant inroads down south then at least uppers of -8 could mean some convective snow showers from the Irish sea.

Always makes me laugh when people say this, it really does. You think it shows Bartlett high one run then northerlies the next. The reason for the changes are fairly simple, if the scandi trough gets too far west it interacts with the blocking over Greenland in a negative way which leads to consequences down the line, that how weather works and how an outlook can quickly change both ways.

The net weather model thread when a model(especially the GFS) is showing a 'poor' run. "GFS is clueless" "GFS is a joke" "GFS is a cannon fodder model". Always the same, I will say I think the cold reaching the whole of the UK is looking sketchy now, its what I said yesterday that there's still a chance the northerly could be quite tame. I think we got to accept it's very unlikely we are going too see a very strong Arctic blast and the trend of blocking receding is a concern. Still all runs do show some cold air making it way southwards from the 15th which is what has been consistent with but the uncertainty how cold and how far south that cold gets remains. Hoping for a bit more positive 12Z runs but would not surprise me if it goes the other way either.

Struggling!? Seriously. It's been remarkable consistency apart from the run to run variations. Struggling would be blocked run on one and Atlantic dominating on the next run. And your comparing one run to another from 2 different models, of course there is going to be differences. 18Z run is fine with me, it opens the floodgates, some snow risk also(although details are pointless at this stage). Quite similar to the 12Z run really until around the 150 hour mark where the slight differences got more notable. Of course it would be better if we get a full UK wide northerly blast with no room for error but we got to accept this is unlikely on this occasion due to a lack of a proper Greenland high. The worry is the northerly will slacken before the true cold air makes far enough southwards but the trend is clear we are going to see a northerly of some sorts, it's just whether it's going to be a convective snowy one or a more tame one.

I'm guessing the ECM 168 hour chart really does highlight how there is more to a chart than it suggest so a shortwave in this case actually becomes a friend but that only if the air ahead of it is cold enough for snow. We are gradually getting there but alot of caution is still needed, really wish it was a more simple retrogression into Greenland and we get a true proper Greenland high but that doesn't look like that will be the case.

That's a classic case of a chart not looking spectacular on the face of it actually produces quite a widespread snow event. ECM is a good run, guess we all prefer the much cleaner northerly blast in and make sure the cold arrives but most runs do suggest that it will be a slacker flow to begin with.

I got to say, I'm not the biggest fan of the mean charts because of how they are interpreted. Bear in mind it's largely based on ensembles which can widely vary then I don't think it tells us a great deal. I've seen posts on different days the mean is excellent, the mean is not so good and for me it tells me very little. As I said, the main uncertainty in the output is the strength of any northerly flow, I still favour a weaker flow with high pressure to close because most runs have suggested that so far but that's not to say it can't change for better or worse. The trends today have so far been more positive we may get the convective northerly again but it's far from nailed that is for sure.

In all honesty, the trend has been clear that we are going to see retrogression of some sorts of high pressure into Greenland which will allow the floodgates to open. What is not clear is just how strong will the floodgates open and that will determine whether we see a snowy northerly or a more tame one with high pressure to close from the west(or maybe even indeed low pressure to close to the SW if not enough cold air makes its way down). So it did looked like shortwaves could be the spoiler but now looks like shortwaves are becoming less of an issue with recent runs so it's all down to how much ridging we see into Greenland and just how much cold air makes it way south and west. We are getting to the range where the next run will start to become nail biting because some runs will be better than others because the details are far from nailed if albeit a northerly flow of some description looks all but likely.

Yep, was keep getting said the 15th was meant to be the day the floodgates get opened now it's the 17th. Yet again unless we are seeing charts in the medium term without any signs of shortwave activity I'm going to keep remaining skeptical on a Greenland high developing. Looks more and more likely too me the cold shot that was forecast for the 15th is going to end up a fairly weak affair with shower activity limited as high pressure is too close, most models are hinting at this now. Things could change but anything significantly snowy in the output is a long way off(the infamous day 10).

The shortwaves are so frustrating, some runs have them and some don't and it does make a difference to some extent. The Iberian heights are also frustrating too see. I think the chances of a deep cold northerly are low but a glancing northerly is still on the cards which will pull down the colder air and snow for some but it's not the charts most want. Can still change but we are getting towards the more reliable stage for the initial ridge into Greenland and if the shortwaves are going to be a feature, we may have to accept it may take a little longer to get any deep cold if at all. Still all fairly interesting model viewing that is for sure and some southern areas could well see some snowfall tonight and into tomorrow.

Well no wonder, look at the timeframe!! I think the models have handled this quite well and the runs have been fairly solid. The uncertainty starts how much retrogression we shall see and how strong do the floodgates open, some runs are better than others for sure but that is to be expected really. A snowy set up is far from guaranteed at this stage. For those down south, let's see what develops in the next 48 hours because that could potentially be the only snow risk that actually develops during this period.