From midweek onwards, an increasingly cold undercut from the frozen
Continental reservoir across eastern Europe, will lead to 'bitter'
conditions being drawn towards us. Beware the misleadingly benign
850mb temperatures. Despite advertised temperatures I have seen, I
would anticipate values nearer 1-4C across central and eastern UK by
Friday. As the next set of fronts from the west engage this undercut,
snow threat is significant as we end the week.

Any 'breakdown' from the west thereafter is fraught with uncertainty,
and will inevitably lead to the risk of further snow, before milder
air erodes the block, if indeed it does.