After reading today's extensive and detailed post by Tamara, it has become clear to me that there are some strong, complicated and highly significant events taking place in the northern hemisphere at the moment.
In a sentence, two strong mountain torque (MT) events are occurring in quick succession, the resulting 'global torque event' being likely to weaken the subtropical ridges (for our interests, the Azores High), then drive a substantial weakening of the jet stream as westerly momentum falls off a cliff (not literally) while also producing strong wave breaking into the stratosphere.
Some of the mechanisms involved are easier to visualise when informed that MT events are essentially air being pushed into high terrain (mountains in particular). Without going into the sort of technical detail that has left me with my head in my hands wondering what on earth I'm doing to myself on a few occasions recently, there is, in short, a big impact on the distribution of energy in the atmosphere (and also to a very small extent the Earth, though not the sort of thing you'd detect without super-sensitive equipment).
Air mass - hence energy - transport from the equator to the mid-latitudes is essentially what drives the sub-tropical ridges, so they can be strongly affected by MT events. In this particular case, they look to be dealt a heavy blow - so the Azores High should increasingly tend not to have much to do with our weather at all.
As this happens, the jet has the potential to head straight across the Atlantic to the UK, bringing a westerly regime that shoves the cold away to our east. Yet with reducing westerly momentum, it will be vulnerable to being disrupted by large blocking features such as the Siberian High, even more so in the face of cold pooling across the UK as well.
This is something that the models seem to be struggling to make a call on, and this is no surprise, as there's no guarantee that the jet will disrupt soon and persistently enough to avoid a westerly interlude, after which we'd have to wait for the Siberian High to build back west again.
If that sounds like more 'jam tomorrow' talk, I say fair enough, we have had to put up with a lot of setbacks this winter so far, this coming week very nearly falling to the same fate.
This time around, we look to have in place the vast Siberian High that was missing when we last went through similar motions back in December. Combined with a strong poleward ridge via Alaska being modelled to initiate some 7-8 days from now (sound familiar?), and more favourable (or at least, less unfavourable!) MJO/GWO behaviour (GWO is linked to the MTs... no need to worry about details I think), theodds are stacked more strongly in favour of the Atlantic jet - hence troughs - disrupting frequently, with lows sliding SE to undercut the Scandi/Siberian High. Those familiar with typical progressions will know that this tends to lead to either a stalemate situation in which the mild/cold boundary offers snow events, or a backing further west of the pattern to develop a -ve NAO (blocking to our NW).
Tamara was cheeky enough to describe the latter as a real possibility... with the required 'shameless ramp disclaimer' 
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So who knows, next week could just be stage one in something bigger.
I would certainly like that to be the case, given how persistently the various model output presents most of England with little better than sleety rain for Tuesday, followed by Wednesday still struggling to deliver this far south (but I am a long way south, so be fair).
Admittedly Thursday looks like the most sufficient day for snow down here in nearly two years, but by then the English are chasing areas of what look to be increasingly light precipitation, and over the past few days, the models have been underestimating the extent to which precipitation has been diminished by cold air mass (which is inevitably drier).
I realise that the models may have the parameters a bit wrong, with Fergie suggesting that they're unlikely to be entirely on the mark, but it looks like a real stretch for the closest of those days to deliver for much of England away from high ground. The potential is far improved on Wednesday so good chances for much of England and Wales on that day - I just hope I get to join in either that day or Thursday 
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All eyes on the 12z runs to see if ECM and/or GFS hold the pattern any further west than on their previous runs.
A weaker jet 6-7 days from now, with less progress of the LP developing N of the Azores, is a key target as that keeps the Scandi/Siberian High closer to our shores. A continued signal for that strong Alaska-Pole ridge is also vital.
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T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
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