Further to Chris's post above it shows that the last two years and this
year's cold spells have shifted the emphasis on cold further west. As I
recall these spells have largely come from, especially snowfall, Arctic
derived cold air entrained in low pressure systems. Once again, although
sometimes shown in the models, there has not been a Scandinavian or
Siberian HP positioned such to bring long track Easterlies or N.E from
Siberia and Northern Russia for long periods. The blocking has been to
the North or in the Atlantic not from the continent. Continental air has
been relatively mild as can be seen at the moment. These were the text
book cold spells which lent said books to quoting East Anglia as cold in
winter (I think Norwich used to be the snowiest)and the SW having mild,
wet winters.
There are not many contributors here from Suffolk and Norfolk but I
wonder if that is there perception.
Londoners and further west have seen these as exceptional spells. There
is no doubt that this one in particular has been cold and lengthy here
in Essex, and exceptional for December. But it would only beat those
since the early eighties. The snow depths are such that not once have I
driven down a lane where the snow is piled as high as the hedgerows and
walked in fields with thigh deep drifts, a relatively common experience
in East Anglia through the 50's to 80's. (Although I was shorter for a
good deal of that period!)
So for this part of the world this spell has been exceptional,
especially so early, but not historic although the winter has only just
begun so plenty of time to make it so!

Dave (S.Essex} 1.6C DP 0.3C