weatherguy

Bank the 168h ECM all the way! Brutal cold coming from the north, quite rare in that regard.

If you live on the summit of Ben Nevis, perhaps! Let's not overblow this; the potential is there for a decent snow event, but it's no battleground scenario.

And how many of those GFS super storms actually come off? Interesting to note the presence of HLB in FI though, always a promising sign at least. PS - Amidst the FI talk I've neglected to discuss the shorter term output! Well, it ain't that bad for snow (in the north in particular) and cold lovers

Except they aren't...Generally speaking, you'll find that the models predict the longwave pattern pretty well. You have to remember the UK is an absolutely tiny area when you look at the NH bigger picture.

It's exciting to see the prospect of some good cold weather on the way (albeit tentative signs this far out), but I will echo what others are saying... Barring exceptional circumstances, no cold spell is going to be anything special in terms of severity/longevity, not while the stratospheric vortex is in such good shape. I wrote this about a week ago: And it seems to have been a reasonable forecast. Let's just hope we can continue to eek out these cold snaps as we progress through December, until we start to see some more favourable teleconnective signals as we head into Jan/Feb. And hey, no sign of anything (mild) zonal yet, so I'm sure us coldies can be thankful for that

Is that not just a surface high, mind?

RE the model verification, it's important not to forget that it's not as clear cut as pitting mild v cold and seeing which model gets it right...If for example the ECM is gunning for cold while the GFS backs a relatively mild set up, it's quite easy to jump to the conclusion that the GFS has got it right. Well, not necessarily, as of course there are many variances in a mild pattern that still lead to mild, while often very minor changes in a cold pattern can lead it to being mild.

I recall a poster, chio or lorenzo I believe (if someone else remembers so I can give proper credit), talking about the relationship between the stratosphere and troposphere being like a dance, where they take in turns to influence the PV. Well, it seems that with the stratosphere continuing to cool rapidly and the PV becoming gradually more organised, the impact of MLB "buckling the system" seems to be becoming reduced and the state of the stratosphere is playing a greater role. In my opinion, I can't see any sustained cold for at least the next 2 weeks. At the same time, it certainly doesn't look zonal, with positive HP anomalies centred near to the UK. As a result, natural wobbles in the PV will leave us in with a chance of receiving topplers, so wintry weather is possible. By no means a "winter's over" post, but my view with regards to pining for anything substantial/sustained

WOAH! Huge flakes falling now!

Looking out the window at snow is much more enjoyable than looking at endless high pressure in the charts!

Can report snow in Sheffield

While it's looking more likely our weather will be more high pressure dominated, that doesn't necessarily mean a rise in temps is inevitable; an anti-cyclonic set up drawing in cold air off the continent is still the form horse in my book for at least the next week or so. Here is the upper profile for the second chart you quoted: Pretty chilly, with plenty of cold pooling starting to build up in eastern europe! If the HP cell remains in play and holds off the atlantic (this is all way into FI, there's no real way of telling what will happen in this regard yet), we're well placed to tap in to that air somewhere down the line. Edit: The main concern I have though is how that PV lobe off greenland interacts with the ridge...It could simply flatten our block, but it's simply a case of wait and see for now.

ECM shaping up well so far, energy going under... (runs to the nearest tree to touch it)

Indeed! And on that last chart the LP is perfectly orientated to reinforce the block - Potential for it to undercut as well

Hmm mixed feelings so far, it's a huge upgrade short term, but long term there's no WAA really heading up to Greenland, and on the other hand the shortwave is certainly sliding south east by +105h...Not quite sure how this will end up, a short lived easterly of sorts I imagine.

18z looking more amplified at +72 hours edit: oops, realised I haven't really added anything to what has already been said

What's wrong with the UKMO? Shows energy undercutting the block to my eye.

Gav: UKMO sees the high moving over the UK at t144 (accidentally removed the proper quote oops, apologies) I think that has energy going under the block too Gav, certainly seeing some trough distruption, and that euro trough is well placed to prop up the high and prevent zonality

It's almost always good news for us if the PV segment over greenland decides to go on holiday to Siberia, as is being modelled. Makes any potential beast from the east a mouthwatering prospect, while also reducing the threat of any successful attack from the west

Everyone knows the GFS control is the most reliable chart to follow...Right, right?

Feel like a broken record each undercutting low scenario, but briefly... Cold air with atlantic moisture added is never going to bring record breaking minima, but it does provide ammunition to see snowfall rather than a bitter HP dominated scenario. Remember: easterly airflow with uppers below 0C is usually good enough for snow, so need to worry about us ending up with cool and damp conditions if that's the case! The ECM does look marginal in this regard but would still be just cold enough in my opinion, perhaps not so for the far south mind, and perhaps not cold enough for snow throughout, but cold enough all the same for most places to see snow at one stage or another. However, reload inbound after +240

I think it may be time to dust off my ramp

Remember that colder uppers easing towards the end of the run doesn't matter in the slightest: the "wet" northerly airflow is replaced with a dry continental airflow...We saw what could happen last March with any upper temps below 0c off a continental feed. Dew points will generally drop by T+0 anyway so no need to worry about those uppers at this stage, we see the same worries every year Cracking run from the ECM, and it appears the models are starting to reach some sort of agreement as to the evolution, UKMO and ECM in particular. Another thing to add: As we suck those "warm" uppers in eastern europe away, we help our long term prospects as those deeply cold uppers from that segment of PV which moves to siberia should rush to fill in.

To the more learned posters here, regarding the PV: What are the background signals, if any, causing the trend over last week or so to model a deeply disrupted PV? With no SSWs taking place and PV disruption appearing to be more than you would expect in terms of "wobble" in shape/organisation, any idea as to the cause? Edit: Weathermaster appears to have beaten me to it! The answer appears to lie with the state of the stratosphere again, perhaps.

Holy mother of God...If that came off... Aaaaand the GH vanishes. Illogical in my mind at that stage of the run. Still looking to see the GFS come more in line with the ECM anyway; I always back the ECM over GFS when it comes to northern blocking. Remember the jaffa cakes poor attempts to steamroll the atlantic in every god damn run last March, when in fact the block to the NE held for what seemed like an eternity?