UK weather latest: ‘Significant snow’ expected across country – as baby dies after crash in icy conditions

Analysis by Joanna Robinson, weather producer

Forecasters have been talking about weekend snow for a few days now, and as we get closer, details are beginning to become a bit clearer.

But in reality, forecasting snow in the UK can be a big challenge.

There is often a fine line on whether the precipitation reaching the ground will be rain or snow.

Temperatures of 2C or below can bring snow, but just a slight change, by perhaps just a fraction of a degree, can mean rain is seen instead.

Some other things forecasters look at when determining whether snow will be seen are location and altitude, including distance from the coast, and precipitation intensity.

Temperatures in cities will typically be higher than in rural areas due to urban heat.

There is also a drop in temperature with height, so high ground is often more likely to see snow rather than low levels.

Frustratingly difficult

In winter, the relatively warmer waters surrounding the UK typically keep temperatures a little higher at the coast than would be seen further inland.

Finally, prolonged rain can also turn to snow, with evaporative cooling helping to lower the air temperature around it.

The heavier the rain, the more evaporative cooling that takes place and potentially the greater chance of snow.

Usually, the UK’s most significant snow events happen when warm, moist air moves in and meets cold air, but getting the detail right can be frustratingly difficult.

Snowfall could peak at 40cm

And that is exactly what is forecast to happen this weekend; rain will move in from the South West, which will turn to snow as it moves into cold air across us.

It looks like there’ll be a spell of snow for much of England, Wales, and Ireland on Saturday evening and overnight, but as milder air pushes in from the south, it may be limited for some southern parts.

That said, disruptive snow is still likely across Wales and central England for a time, with the heaviest and most prolonged snow expected across northern England.

The Pennines could see up to 40cm of snow by the end of Sunday.

The threat of freezing rain

There is also the added concern of freezing rain, a rare type of liquid precipitation that – when it falls to the ground – will freeze almost instantly on cold surfaces.

Wales and the West Midlands look most at risk of freezing rain bringing icy stretches.

Scotland will see a few snow showers on Friday and Saturday, with more general snow expected there on Sunday.

Northern Ireland will see a wintry mix of rain, sleet, and snow.

Weather warnings have recently been updated by the Met Office and Met Eireann, but they may be tweaked over the next 24 hours so.

It’s worth keeping an eye on the forecast.