Thursday forecast chart from the GFS looks quite dramatic (fig 1), particularly over Scotland, as Arctic air sweeps down across the country. Thicknesses like these should ensure snow showers down to sea level across all areas of the country I would have thought.
Down here in the sheltered southwest, it might be the secondary lows on Sunday or Monday that could finally break the snow drought (7 years here in Bradninch since we’ve seen a covering) and finally bring a touch of Winter.
If this forecast is correct for midday on Sunday (fig 2) the timing couldn’t be any worse for snow at any height in the southwest, although as the cold air digs in behind the low on Sunday, it could turn the rain to snow on it’s back edge as the frontal systems clear away southward into France.
A bit of a repeat performance just 24 hours later, but this time the colder air has entrenched itself a bit more (fig 3), and as this much more intense low slips southeastward across Cornwall, the southwest could be perfectly placed to catch a lot of snow in this scenario, but more especially the high ground of Dartmoor and Exmoor. I’m not holding my breath at this range, but there are possibilities.