Both the GFS and the ECMWF models are promising a change of type between Christmas and New Year reversing the zonal westerly into a cyclonic easterly. Both models take a low southeastward across the country, in the case of the ECMWF model this is a deep 955 hPa low just off the Humber as early as 12 UTC on the 27th, with a strong northeasterly flow following on behind it. The GFS does something similar but not as intense and slightly slower. Temperatures don’t look particularly low but given time this kind of scenario must introduce some colder air. This agreement between both models does add some credence that this could actually come about, even though the forecast is for eight days in the future. How long the change will last is anyone’s guess, but it does seem that there’s something in the air over this Christmas period.