A plunge of cold air from Greenland will jolt the Atlantic jet stream bringing warmth and sunshine across Britain. Temperatures will rise after the weekend as high pressure builds to the east of the UK drawing in mild, southerly gusts. It will, however, follow a chilly weekend which could bring up to 10cm of snow to the hills of Wales and Scotland, forecasters warn. But a ‘shift’ in the weather into March will deliver a boost of joy of Britons holding out for a sunny start to the meteorological spring. Met Office meteorologist Annie Shuttleworth said: “Through the early part of next week, ther…