A snow warning has been issued for a large part of Wales as cold air moves in across the UK. The warning has been issued for Thursday and Friday this week. BBC forecaster Derek Brockway says that Wednesday will be the "driest day" of the week with low pressure bringing the risk of snow in the north from Thursday.
The long-range forecast is showing that cold air will "extend to all parts" of the UK by next weekend with the risk of "significant snowfall" for parts of the UK. The yellow warning starts at 3am on Thursday and runs through to 3am on Friday.
The forecasting agency yellow warning says there could be as much as 20cm of snow in some areas. For the latest Welsh news delivered to your inbox sign up to our newsletter
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Temperatures will drop to below average for the time of year, with an ongoing chance through the week of ice overnight, which could result in further warnings.
The warning states in full: "A band of rain, sleet, and increasingly snow, will push north on Thursday bringing up to 2cm snow at lower-levels, 2-5cm on ground above 200m, and perhaps as much as 10-20cm above 400m. The snow will ease later in the day, and may turn back to rain or drizzle, especially in the south and east of the area. There is some uncertainty with respect to the rain/snow boundary, and the northern limit of the snow, and so details may change in the coming days as confidence increases in these aspects."
The areas covered by the warning in Wales are: Carmarthenshire, Ceredigion, Conwy, Denbighshire, Flintshire, Gwynedd, Isle of Anglesey, Powys and Wrexham. The long-range forecast for the UK from the Met Office says that the cold air established across northern parts of the country will "extend to all parts" next weekend.
It adds: "As it does so there is a risk of some significant snowfall for parts of the UK, perhaps central areas most prone to this but this aspect is very uncertain at this stage. Across the north cold throughout with snow showers tending to focus on northeastern areas while for the far south the period may start of with some rain and near average temperatures, before the cold air reaches here by the start of next week.
"Windy at times, especially so in some eastern areas where a notably wind chill is expected. Temperatures ranging from rather mild in the south at first, to cold, perhaps very cold in the north."
Met Office deputy chief meteorologist Chris Almond said: “While the early part of this week will see some rain, at times heavy, gradually sinking southwards, there’s an increased signal for wintry hazards as we move through the week as cold air from the north moves over the UK.
“It’s from Thursday that the snow risk becomes more potentially impactful, as mild air attempts to move back in from the south, bumping into the cold air and increasing the chance of snow developing on the leading edge. While there are still lots of details to work out, the initial snow risk looks highest in northern England and Wales from Thursday. 1-2cm is possible to low levels, with 10-20cm possible over the highest ground within the warning area. This snow will likely gradually transition to sleet and rain later on from the south.”
The Met Office says that with a developing weather situation, it’s likely warnings will be issued and amended through the week, with an ongoing chance of ice warnings for some. Temperatures could drop as low as –10°C in rural parts of Scotland on Wednesday night, though it will be less cold further south.
