This week so far has been a shock to the system as mild air has returned with temperatures reaching double figures across many parts of the UK today. However, A cold front on Saturday will introduce cold air from the NW. This will first bring a band of rain followed by clearer and colder conditions and this could lead to the back edge of the rain turning wintry in places. This Metoffice fax chart below shows the cold front moving through the country on Saturday.
By Saturday evening, 850hPA temperatures across the Northern UK will be in the -8 to -10 region which will result in any precipitation being wintry in nature and at low levels. Heavy wintry showers will follow behind this cold front and Scotland, Northern England and West and North West Wales will be at the greatest risk of showers. Currently, some sleet and snow showers are likely and some snow accumulations are possible. However, how much precipitation that is associated behind this cold front is still uncertain as if high pressure builds from the West too quickly, then showers will be limited.
These GFS charts show where showers are more likely and how they will be wintry on Saturday/Sunday. The first chart is for Saturday at 12:00pm and the second is for Sunday at 12:00pm
So a return to colder conditions is likely at the weekend but looks short lived with mild conditions returning next week.