West is Best

Reasonable prospects of a 2 - 3 day colder spell to coincide with Christmas. Nothing seismic and my big worry is that these northerlies have a nasty habit of downgrading at the last minute which is what I expect to happen again. This is all the more the case given the evolution of the ECM which looks very likely to me going speedily from: to this: The ensembles are pretty mixed. Quite a bit of scatter and the 0z operational definitely on the colder side in the key period: There continues to be one cold outlier which was insane on the 18z: I don't think I've ever seen -15C 850hPa reached on an ensemble member before. Generally though it looks like something more festive for the key two or three days. It's bizarre how often that happens. I would however urge some realism. Nowhere is going to 'get buried' by snow next week. Well, nowhere in Britain anyway. (Sleety was referring to a chart two weeks away rather than next week)

They are almost identical GFS / UKMO / ECM are all of one piece with a very vigorous Atlantic out to reliable timeframe of T144. The Christmas Eve to Boxing Day period remains in unreliable timeframe. There is still evidence of considerable cyclogenesis off the eastern seaboard so until or unless a proper upstream block develops the best we can hope for are occasional north-westerly incursions. There may be one over Christmas itself but at the moment it looks like being short lived before the Atlantic reasserts its currently powerful presence. Meanwhile, a case of battening down the hatches here tonight. It's going to blow a hoolie.

It's quite amazing how often, even in mild winters, we've seen a cold snap around Christmas. I have twice had festive snow in north Devon and once posted a pic on here of me dancing in a snowstorm on Christmas Day The 0z operational though definitely headed colder than most members and in far flung FI was a brief outlier. The 6z continues the festive cheer but I'm wary about the height rises shown over continental Europe right at the end. It's a fine line but if we get one parking up over northern Germany then it's a problem as that puts us in mild south-westerlies and anything but cold over the UK. To be frank though ever since summer I've stopped paying any real notice to the GFS past T168. It is so erratic.

I'm cheekily quoting myself because the 6z is a case in point where mobility can be a good thing. The storms showing up on the 16th, 20th and then 23rd pave the way for the north-westerly / northerly incursion just before Christmas: Obviously that's in FI but it is quite extraordinary the number of times we get something around Christmas. I can remember two occasions of snow at Christmas in north Devon, relatively close to the coast. I also would like to repeat the point about realism. I know that this isn't the Armageddon blocked scenario some wish to see (a la 1947 / 1962-3) but these types of cold incursion can still be potent even if they are more short-lived. I personally would take that any day over an arid high pressure.

I like that bowling ball metaphor. It's a good one. A case in point here: Nevertheless, it's surprising to see 'winter's over' posts appearing on December 11th. Yes we are back to fairly full-bore Atlantic zonality (it certainly felt that way overnight here on the Cornish cliff-top) but even so it's far too soon for cold lovers to throw in the towel. I can recall two other occasions that Steve Murr declared a departure. One was a long time ago when a Bartlett High took up residence in southern France and he basically decided to come back in a month The other was iirc in a November/December around 2004 again when a mucky high pressure settled over the UK. The point is that when patterns are mobile there is more opportunity for change than if they are static. A resident HP over Southern Europe or Germany is about the worst outcome. We don't really have either at the moment. Yes it's zonal. It could be pretty stormy at times and that can be a dramatic experience for amateur meteorologists. Perhaps, dare I say, just a little greater realism would be good. We live in the British Isles, warmed by the Gulf Stream and fed by the Jet which makes us much milder than would be the case at our latitude. Properly cold conditions here are rarer than hen's teeth, especially these days with climate change. That doesn't mean some cold spells are out of the question. So, chins up folks.

I can't see why tbh. I've never seen the potential that one or two have stated to be so amazing this year. So there's been an Arctic High. Well as many have pointed out, that's only one piece of a much bigger jigsaw. It's not sufficient in and of itself, especially if other upstream signals aren't helping. There's nothing coming out of the US that fills me with inspiration for cold, with the jet powering up off the eastern seaboard and a reduction in amplification. We're now moving into a North Atlantic ridging/positive geopotential height anomaly which will lead to European temperatures normal to above to above normal. And the point about the NW flow just doesn't bear out. Most of the time over the next week to ten days the UK will be back in a south-westerly and even southerly flow. And that means mild. At the moment I'm afraid it's all bog-standard UK winter weather of recent years.

Well we're in for a windy and sometimes stormy spell for a bit. All the models agree on this for the next week. Batten down.

With you 100%. I know it's not popular and I apologise for that. Case of battening down the hatches for a few days I think. Mind you, I am on the north coast of Cornwall so I guess I tend to notice when the Atlantic re-awakens .

Yes and I see no convincing evidence that an Artic High is any bleeding use for the UK. In fact, iirc, the best scenario is displacement of the polar vortex, not its static placement under a high pressure. An Artic High is zero use if, as seems the case, the jet drives like a coach and horses through the eastern seaboard. We need a proper Greenland High, or a mid-Atlantic block. At worst case a Svalbard High. Anything else is not sufficient for the UK to have a sustained cold spell.

I totally agree. The GFS has been shocking in FI for months. I started studying it carefully in the summer, really so that I was prepared in case of let-downs this winter. In the words of Rowan Atkinson, it's up and down more than a whore's drawers

Is that this winter's myth? Seems so to me. We're back into zonality. By all means hit that ignore button but there's no point pretending otherwise.

That really is a case of straw clutching I fear. The GFS 0z ensembles have a couple of wildly cold members, although in the interest of balance it needs to be stated that they also have the opposite. However, the ECM doesn't show anything other than an Atlantic-driven scenario with temps heading above average for the time of year. Moreover, there's no cold pool in Europe. This place is going to go bonkers if we get some properly cold FI runs as has happened from time to time even in recent years. So far there hasn't been an operational to make me sit up.

It has vanished on the GFS 0z. It'll be interesting to see how the 0z ensembles shape up in FI. The 18z had some really cold ones, the first time there's been a properly cold cluster: The problem is that imho anything past T168 is next to useless on the GFS these days. I've been monitoring it for months and it's all over the place with constant yoyo-ing. I'm not sure if the word 'zonal' is inflammatory, although there's no reason why it should be especially given where we live, but let's just say that in the reliable timeframe we are in for a week of more Atlantic-influenced weather ... it certainly felt that way to me yesterday with the wind sweeping across the clifftops here in Poldark country.

Undoubtedly true & something I've mentioned on many occasions in my very amateur way down the years. Because of the prevailing westerly flow over the UK and the upstream drivers to our west of the weather patterns coming off the US eastern seaboard, we are heavily dependent on upstream blocking, or at the very least significant amplification of the jet stream. Searching to our east for UK cold is like fool's gold. It often promises but rarely (almost never) delivers. Only when there is a sufficient buckle in the jet with concomitant upstream blocking does it become significant for sustained cold. Nothing much doing at the moment anyway. The ensembles yo-yo in FI, sometimes mild, sometimes cold but in the short to mid term it's pretty zonal fayre.

Good consensus now in the GFS ensembles out to T144 (roughly Dec 13th). As the header on NW homepage states, a chilly start then gradually rising temperature profile. Into FI and cold lovers will be hoping that the yellow line is the one that comes off I'm afraid the return to zonality was inevitable. Despite being told that the synoptics were amazing and wonderful and quite the best thing for years, they really weren't. Look to upstream blocking for UK cold. Concretely that means a proper Greenland High. Otherwise no amount of high pressure out to our east will be able to resist the Atlantic onslaught. Sorry if that's unpopular. It just happens to be true.

The record isn't mine, it's the prevailing westerly flow under which the UK sits. So 19 / 20 it's the record player which plays the same disc. Have a good day all.

This is completely untrue. I can ramp like the best if I think there's something worth ramping. The synoptics are far less dramatic and exciting than many I've seen in FI over the past decade. I can recall FI eye candy with -10C 850 hPa uppers all across the UK and true deep cold pooling over Europe. We have neither. Some transitory blocking occasionally showing. Meh. I've been watching the ensembles carefully and the GFS operational have been on the cold side, sometimes by a long way, over the past 4 runs. However the 0z has bucked the trend. The most interesting thing about this, however, is the amazing scatter at Day 5. You see this often in FI but for just T120 it's amazing to have a 25C scatter. Quite incredible. It's a long time since I've seen such divergence at such short range: This helps explain why the UKMO may have appeared to have altered its tune, why their 0z model output diverges so significantly from their Fax chart at the same T120 point and why the ECM is having none of it: As I say, 19 times out of 20 in these situations always bet on the Atlantic winning. Once in a while it won't but generally it does.

I was referring to England. Scotland is sufficiently far north for the same rules to be a little less rigid.

You do need cold uppers for snow. What was 'produced' yesterday was mostly rain and sleet, especially at low levels. Many of us on here remember the days when snow would fall consistently out of the sky and pile up sufficient snow to wade through and sledge in, even in early December. That's snowfall and you roughly require -5C 850hpA for it to occur in the UK at low altitudes.

Well it will be interesting to see if the ECMWF also backtracks. If it does then I'd be more inclined to agree but I'm also awaiting the GFS 0z ensembles. For the last 4 runs the operational has been below the mean, even an outlier at times, with far more ensemble members taking the Atlantic pile through route. That's also what the T120 Fax chart shows and it's a brave person to bet against that at this range. Generally speaking if things appear to be on a West vs East knife edge then 19 times out of 20 you need to bet on the Atlantic to win out. It's the prevailing condition and it requires several upstream and downstream cards to fall right for a proper block to occur. I don't really see it happening at the moment.

So here's the 12z UKMO at T144. This is not a set up that screams cold to me? The best thing about it, is that it's very early winter.

Yep but that highlights another danger which is that when snowcasting people have a tendency to root out the most obscure and esoteric model charts they can find, which suddenly became the gold standard. The ECM did show something more promising but it has backtracked. It's been very erratic of late. The GFS in FI is in my opinion next to useless. The UKMO performs well and I don't take much notice of anything beyond T144 these days. The Fax charts are always good value.

There are multiple examples but here's just one: we keep being told how 'exciting' things look this year compared to others. There's nothing particularly out of the ordinary in the models so far. It's true that we're in a lull from the Atlantic battering but there is no extended blocking, no significant or consistent height rises over Greenland or Svalbard, no mid-Atlantic blocking. There is a bloody great high over Siberia where it always is but to be frank the FI charts aren't all that tasty. We normally expect to see the GFS throw up some wild easterlies and deep cold pooling in FI (which never come to anything) but they're largely absent. It's going to feel cold being on the polar side of the PFJ but we've been getting this a lot in recent winters. I think a lot of people will settle for this over a stagnant HP because it seems to offer more hope, and I get that.

No you're not and yes it is. Ludicrously so. I blame it on Covid, so it's understandable but in the end it's causing more pain.

If by 'interesting' you mean cold and wet, okay. There's nothing particularly exciting or special in the current synoptics despite the attempts to make them seem so. Weather is coming in off the Atlantic, albeit not belting in just yet, we're on the north of the PFJ so it's going to feel cold and that's about it. Great for the Scottish ski resorts and if you stand on top of Cross Fell you should see the occasional snow but there's unlikely to be snow at low levels for most of England. There's almost no point at which England is under -5C 850 hPa and that's pretty crucial if you want to see snow falling, as I do. Meanwhile it's going to blow a hoolie down the west coast tomorrow night.