Britons are facing travel chaos across the country as a 500-mile wide ‘Beast from the West’ brings a so-called snow bomb, heavy rain and severe gales.
The St Patrick’s weekend storm could pose a danger to life and threatens to cause widespread road and rail disruption, washouts, floods and blizzards.
Up to eight inches of snow and four inches of rain are expected, along with potentially destructive gales approaching 70mph as forecasters warn Britons to prepare for dangerous conditions.
In Scotland, where the heaviest snow is expected over high ground, 100 snow ploughs and 500 gritters are on standby.
RAC spokesman Simon Williams said: "Motorists should delay travel if possible to avoid the worst effects of this weekend’s snow,."
The 500-mile wide storm was dubbed the ‘Beast from the West’ by forecasters from the Weather Outlook.
Eight inches of snow on high ground and four inches on low hills is forecast, the Met Office said.
Snow will fall rapidly in heavy showers – meeting the definition of a ‘snow bomb’, which occurs when four inches of snow falls in a few hours, with quick accumulations causing immediate travel problems.
Sunday, St Patrick’s Day, sees more snow flurries, with blustery winds.
The Weather Outlook forecaster Brian Gaze said: "We’re more used to the Beast from the East – but this is a Beast from the West as St Patrick’s weekend sees whiteouts and washouts.
"A heavy fall of snow in a few hours is sometimes referred to as a snow bomb, because the rapid accumulation of snow always causes immediate travel problems.
"Large accumulations are possible in parts."
The heaviest rain is expected in North Wales, where up to four inches is possible.
Met Office forecaster Matthew Box said: "We have a developing low pressure that’s going to pass across the northern half of the UK and it’s going to bring some disruptive weather as it does so.
"That weather will be a mixture essentially of rain, sleet and hill snow for a time, and also some strong winds."
From midnight on Friday through the whole of Saturday, two warnings are in place for "heavy persistent rain" forecast in parts of Wales, and northern England.
The Met Office is warning that some homes and businesses may flood.
Mr Box said: "Given that some of that ground is already saturated, and has had quite a lot rainfall recently, this spell of further persistent rain is cause for a little bit of concern and we could see some localised flooding."
In Northern Ireland, a weather warning for snow and rain will be in place until 1pm.
In Scotland and northern England, from 4am to 9pm on Saturday a warning is in place for potentially "disruptive snow".
A warning for wind is in place for Wales, southern England, the West Midlands and north west England.
From 4am to 9pm on Saturday, gusts of 45-55mph are expected widely, with gusts up to 60-65mph possible in exposed coastal areas.
Coastal routes could be affected by large waves, while difficult driving conditions are possible and delays to public transport likely.
Mr Box said: "Obviously we’ve got a lot of travel for some of the big rugby games so people should take extra care and plan ahead."
The pressure will build into next week, with conditions turning drier, brighter and calmer.
Met Office five-day weather forecast
Strong winds and outbreaks of rain across much of the UK.
Some heavy rain in the north and west, with snow in parts of Scotland.
Mainly dry but cloudy across the southeast. Mild in the south, colder elsewhere.
Rain clearing southeastwards this evening.
Clear spells and showers will follow, locally heavy in the north and west with snow on high ground.
Patchy frost and ice.
Winds generally easing.
Sunny spells and blustery showers, most frequent in the north and west.
Hail at times with some snow on hills.
Strong winds with some coastal gales.
Monday to Wednesday
Patchy rain in the northwest Monday, fine and dry elsewhere.
Cloudier Tuesday with patchy rain, mostly in north and west.
Dry, bright for most Wednesday, some rain in the northwest.