ECM is being very consistent in digging the Scandi trough far south enough to bring snow streamers across large areas of the UK following on from a little back-end snow from the frontal system.
It then shows a shortwave running south in the flow, which would bring a classic snow event for some.
GFS is being less consistent, varying the extent to which the energy digs south. We must always be wary of such possibilities, even if it is the over-zonal GFS that we're talking about.
It's good to have UKMO supporting ECM regarding the trough digging south, but unfortunately the day 6 chart from UKMO has the Atlantic energy positively tilted so we'd be looking at the initial cold plunge being swiped aside, although there would be some potential for heights to our NW to drive a new bout of cold across the UK behind the low pressure system, which some GFS runs of late have showed.
Longer term, I'm seeing strong suggestions that we might see some energy dropping down to the eastern Mediterranean or thereabouts. With the PV energy towards Siberia driving a lot of cold air into the continent in the shorter term, we'd only need a bit of a ridge over the top of the east Med. trough to generate a reasonably cold easterly. The 00z GFS op run illustrated that fairly well, and the 00z ECM op is not without it's potential at day 10.
Overall, very interesting model output, with a real chance of some widespread snowfall within the 7 day range, although I'm not going to say lying snow for most at this early stage 
Originally Posted by: Stormchaser