Cold air versus mild air – let the battle commence
On Monday, I wrote a blog about the weather turning colder this week across the UK – something that is still going to happen.
However, what I did emphasise was the huge level of uncertainty about how cold it is going to get, with the weather computer models having difficulty getting to grips with the forecast beyond this weekend.
During the last 24 hours, there has been a somewhat clearer and more consistent signal from the weather computer models that a spell of very cold weather is likely, starting this weekend.
Although the chance of very cold weather has increased, there is still a lot of uncertainty about how long it is going to last and how much snow there will be.
The reason for this is that the UK will effectively become a battle ground between mild air across the Atlantic and very cold air lurking over mainland Europe.
As they tussle around through the weekend and early into next week, the temperatures will fluctuate, with the coldest weather most likely across eastern parts of the UK and places towards the west a little less cold.
Temperature trend
During the next few days, the temperature will continue on a downward trend – both by day and by night.
By the end of the weekend and into the early part of next week, temperatures across much of the UK will be around 0 to 2C during the day, widely falling to -2 to -6C at night with a widespread frost and icy patches.
Northern Ireland, south west England, along with the far west of Scotland and Wales will always tend to be a little less cold. With the milder air close by daytime temperatures here will be around 3 to 6C.
Chance of snow
There is no doubt that snow is going to be the hardest element of the forecast during the forthcoming cold spell.
I mentioned in a blog I wrote a few weeks ago that snow is really challenging to forecast in the UK, often because the conditions are so marginal. Also, because there are so many different factors to take into account.
I think that the first chance to see some light snow will be later on Saturday, as colder air undercuts a weather front across England and Wales. At this stage, it looks like hills and mountains are most likely to see any sleet or snow, but there is a lesser risk down to lower levels too.
Into the early part of next week, the uncertainty is huge, but given the weather setup, the nature of the snow risk will depend on where in the UK you live.
For eastern parts of the UK, any snow is most likely to come in the form of snow showers, as cold air becomes unstable as it moves over the relatively warm North Sea.
For western parts of the UK, any snow is likely to come from weather fronts that try and move in from the Atlantic, bumping into the colder air and producing more persistent spells of snow.
The caveat to all this is that with daytime temperature in the range of 0 to 2C, getting the snow detail right, even 24 hours ahead, will be difficult.
Don’t forget, you can get the latest five day forecast for your location on the Channel 4 Weather website and I’ll be posting regular updates on Twitter – @liamdutton