Jason M

Although the opp is okay in the short / medium term, looking at the GEFS out to 144 I'd say our northerly next week is in the emergency ward! Everything looks like its going west based, so the fish are about to get an icy blast. In response its evident that we are seeing increased height rises to our SE (which nearly always happens with the west based set up). Based on that I'd say its time to sell out of firms producing anti freeze and buy into those producing BBQs. As the saying goes, more runs needed.

Well, according to the pub run we are on track for what is becoming a traditional barbeque Christmas.

It can do, but 9 times out of 10 it usually it produces non descript weather. Certainly it wouldn't produce what people want on here. Anyway, its not worth fussing over as I may be right, but like every other prediction on here its more likely I'll be proved wrong!

Because if we get a mid latitude high temps won't be sub zero! You would likely end up with slightly below normal temperatures. I'm not sure who is talking about sub zero temps? Once we get to the weekend and beyond there is currently nothing to suggest we will be seeing sub zero max temps any time soon?

Depends exactly where it decides to set up. Form horse though would be cool and dry? Still a long way out though to Xmas so all subject to change.

Still a few stragglers amongst the GEFS that don't want to remove the cold air at weekend. Bit surprising tbh as I thought tonight's runs would just drive the final nail in on that score. Remains highly unlikely though that south doesn't lose the cold. Based on current output it looks then like a very brief warm up on Sunday / Monday before a brief but cold NW'ly and then I suspect we will be looking at a mid latitude high in or around the UK for the Christmas period.

Probably an 8 now on the Voldemort scale . Heaviest snow here for years.

Things are not terrible by any stretch. West based set up has been a real prospect all through this episode though and today that looks more and more likely. In my experience, once you go that route its usually a mild weather pattern for us and NW Europe. As mentioned earlier, I'll be back in time for the 00Z runs and I expect we will see if it's a blip then. It just feels today that the trend is a negative one.

Absolutely, plus once you get into the west based set up with a huge Atlantic low, heights building rapidly into Iberia is almost always the end result. Poor day today but I think it's worth just waiting until the morning as the models are struggling a bit. Heart says the morning runs will look different, but head says that were now just looking at a few days of cold weather with a transient snow event as it breaks down.

Looking through GEFS at 132 there are still lots of decent charts and most have us under a slack easterly. Its very messy though and all just looks a bit unlikely. Models seem to be struggling big time.

Agree with this. Despite being a maritime airmass this northerly is going to be very established and being December the sun will do little to moderate it. Any fronts moving up from the SW should readily turn to snow.

Absolutely. The one big positive though is that at the point the ensembles all go in different directions the control appears to follow the opp.

I was just thinking that. A northerly on or around the 9th of that month followed by Channel lows. Could still go horribly pear shaped though especially in the south and southeast and there is still lots of uncertainty about the front on Thursday, let alone what happens after.

Now that is a cold chart!!!!!

Thats my understanding as well. I tend to regard anything after 192 as largely pointless anyway. By the time we get to 240 hours the charts are not worth the electricity used to load them on my screen.

Looking at the GEFS out to 192 and it's a mess tbh. Lots of uncertainty in the forecast. My advice is to ignore the 'mean' charts from this suite because they will be worthless looking through the individual ensembles. More runs needed .

Extreme yes, but mean is now at -3 and between the 10th and 12th not one run has 850s below -5. That said, it may look different in the morning. A west based set up has always been well in the mix and the trend has been towards that solution.

It's the same every year. The first chase goes shaped and then people remember that at day 10 the charts are a waste of pixels.

I think then we just disagree on 'big picture'. To me, if you replace a massive high to our NE with a massive low that feels like big picture. We can all have different views though which is fine .

The big picture has changed though. We were looking at massive heights over Scandi and an easterly, now we have lower heights over Scandi and a northerly. As it happens, both are cold patterns, but they are 'different'. You often see confusion on this forum in times when all the charts are showing cold but from different synoptics. In truth the signal just means that nothing is nailed on, and we then normally end up with SW winds!! That's not the case here though as whilst the big picture has changed most of the models are broadly on the same page. In summary, its highly probable that it will get colder. It's not looking like anything dramatic at present but some will see snow.

Agree with this. In fairness this is what has been on offer from the start. Other than a few very cold charts yesterday (but fairly dry) we have never been looking at anything more than a bog-standard winter cold spell. It will be cold, some people will see snow but right now there is little IMHO to suggest anything severe. This won't be 2010 or 1981 based on current output. After next weekend I suspect we still have a ticket to the lottery for something more punchy but that's too far out to be worrying about.

Yep, we would basically generate a homegrown cold pool given the time of year. Very cold, but not the snowiest set up (albeit would be some around)

In many ways yes, but it's interesting in this set up because that snow distribution chart would be very much what you would expect to see. The lack of wind promotes cold but isn't particularly helpful for generating lots of snow. In summer months this set up would bring huge storms but at this time of the year, its very cold but fairly dry. This would also be a nightmare for energy companies as it would really hit wind power.

The problem with northerlies these days is often twofold. First problem is the source is not as cold as it used to be (that will be true here) and secondly northerlies in recent years have been fleeting. The first point about source matters a fair bit less where the airflow stays in place for longer (which looks likely here). A third point which actually helps us is that we are rapidly approaching the shortest day so solar input will be low. So, whilst -5/-6 uppers are a little bit meh for a maritime airflow, we will probably be okay for snow. Are we looking at subzero days and deep snow? Doesn't look like that to me. Decent winter cold spell looks increasingly likely but nothing severe (at least at the moment ). If we do manage to get a covering of snow on the ground over the next few weeks that will really impact daytime highs.

True, could happen. No two scenarios are the same, so I get where your coming from but more often than not, west based set ups just lead to a long period of mild weather for us. Hopefully it won't be an issue here but if it does go pear shaped, west based would be my guess.