The contrast between this extremely cold air mass and the much softer air further south will “supercharge” the jet stream. Winds at the core of the plane are forecast to exceed 418 km/h (260 mph) over the Atlantic.
This huge injection of energy high in the atmosphere will cause an area of low pressure to deepen rapidly as it heads towards the UK and it is this that brings the threat of gales and disturbances on Friday and Saturday.
In this range, several days ahead, there is some uncertainty about exactly how strong the winds will be and exactly where the strongest gusts will occur. At the moment, the north-west of the UK appears to be most at risk, hence the Met Office yellow warning covering this area.
Outbreaks of rain are also expected and although it will be milder for some, especially in the south, it will still be cold enough for snow to fall on the hills in Scotland, northern England and Northern Ireland.
