If you analyse NAE, what it's done is shrunk the size of the 0c area in the center of England and enlargened the 1c area. It's changed snow to rain in these area that it's now put up 1c. It seems to think it's very cut and dry. Those areas that remain freezing remain in snow (like ours, right in center of england), those that increase to 1c it's turned it all to rain. It may be coming to that conclusion on more than those variables, but it would seem that is what is the deciding factor.
In my opinion, it seems a little bit unrealistic for it to change to totally rain with just a 1c rise in temperature above 0c. Could happen I suppose.
It's changed the size of the snow area from most of midlands during late Friday afternoon to only very central parts and very north mids being snow. Precipitation amounts over all have varied a little, some places less, some more. Still a lot coming so don't worry.
As for the changes in areas that it thinks will be raining, read above. Thats my take on it. Probably wrong, but never the less