Forecasters still disagree on how much snow we will get in Wales this weekend and when. The majority of Wales remains covered by a two-day warning for snow and ice starting at midday on Saturday and lasting just before midnight on Sunday evening.
Weather maps show the Met Office now expects the weather front to move into Wales from about 2.30pm on Saturday. By 4pm the Met Office forecasts hail, rain and snow will be falling across much of south Wales and moving in a northeasterly direction.
By 8pm on Sunday maps from the Met Office show the forecaster expects a significant amount of snow to be falling across much of west, south and mid Wales. By midnight on Saturday it’s predicted the whole of Wales will be covered by the white stuff. Get the latest Welsh news headlines delivered free to your email inbox
But there is a big difference between the BBC and Met Office forecasts. The main difference with the BBC’s prediction for this weekend is it expects much more of the weather moving across Wales on Saturday to fall as rain rather than snow. The maps from both forecasters show the BBC also expects far less snow on Sunday. Here is what they say.
Met Office
Met Office weather maps show the first snow forecast for around 6pm on Saturday. The Wales forecast says: “Largely dry on Saturday but rain, preceded by snow, likely arriving later. Disruptive snow possible but probably turning back to rain Sunday.” Below are the maps from the Met Office for 4pm, 6pm and then 8pm. The map for midnight on Saturday shows more snow for northern parts.
The weather front is predicted to move into Wales on Saturday after 2.30pm. This is the prediction for 4pm from the Met Office
(Image: Met Office)
The grey areas show where snow is predicted to fall
(Image: Met Office)
This is the forecast for 8pm on Saturday from the Met Office which predicts by then much of Wales will be covered in snow
(Image: Met Office)
This is the forecast from the Met Office for midnight Saturday night
(Image: Met Office)
By Sunday morning, for most, the snow is predicted to turn to rain which is likely to continue throughout the day. Maps show that by Monday morning the snow should be clear, according to the Met Office. You can see the maps for Sunday and Monday morning below.
This is the forecast from the Met Office for 8am on Sunday morning
(Image: Met Office)
By midday on Sunday rain will takeover, says the Met Office
(Image: Met Office)
By 9pm on Sunday it is predicted the weather front should be clearing
(Image: Met Office)
The front should be all but cleared by Monday morning, according to the Met Office
(Image: Met Office)
But the BBC weather forecast for Wales for Saturday has changed and predicts significantly less snowfall than the Met Office. The BBC forecast reads: “Tomorrow (Saturday), it will remain dry through the day, with variable cloud and some hazy bright spells. Cloud thickening into the evening, with spells of sleet and snow approaching.”
The outlook from Sunday, according to the BBC, reads: “Very unsettled conditions on Sunday with cloudy skies and blustery showers moving in. Windy with a band of heavy rain moving in from the north-west overnight. Monday will start cloudy and wet. It will be turning drier in the afternoon with a few sunny breaks and the odd shower moving in. Cloudy with showers on Tuesday morning but turning drier and brighter in the afternoon.”
The maps below are from the BBC and show a bleak rainy picture for the weekend for most with snow for some in the south and mid Wales.
This screenshot of the forecast for 6pm on Saturday shows the BBC predicts rain for most with snow for some in the south and mid Wales
(Image: BBC)
The BBC predicts snow for south Wales and parts of mid Wales by midnight
(Image: BBC)
The BBC isn’t predicting much snow for Sunday in Wales. This is the screenshot for 9am
(Image: BBC)
The Met Office has explained why it is so difficult to forecast snow. They say: “As it’s so cold high up in the atmosphere most precipitation either starts off as snow or supercooled raindrops. As it falls to earth it moves through warmer air most of the time and melts. Depending on the temperature of the air near the ground we either see rain or sleet or hail. However the freezing level (usually the boundary at which precipitation will fall as snow rather than rain) doesn’t just stay the same every day or even within a day. Sometimes it can change hour by hour, across the country, or even a few miles down the road.”
They say there are several things forecasters look at to predict how low down the precipitation will fall as snow:
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Where the air has come from: If the air has come from a slightly different direction, say for example if it has spent a slightly longer time travelling over mild water, then the air can be ever so slightly warmer and therefore the freezing level would be slightly higher.
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Very heavy precipitation: Even if the freezing level is quite high up in the air it turns out that really intense precipitation can drag the “freezing level” nearer to the ground and keep any precipitation falling as snow lower down too. Prolonged heavy rainfall can therefore turn to snow.
When warm air meets cold air: This is the most difficult situation to predict snow. Weather fronts mark the boundary between cold air and warm air so when a weather system moves in there will be warm air and moisture wrapped up in it. While we need the moisture for snow to form the warm air makes it very tricky to forecast if it will be turning to rain. As the warm air bumps into the cold air it slides up over the top (warm air rises). The precipitation falls into the colder air lower down but in time the air mixes together and makes the cold air slightly warmer and the warm air slightly colder and so then rain becomes more likely. You’ll often find that there’s a fine line between who sees snow and who sees rain. Sometimes a fraction of a degree is the difference between rain and snow. That’s what makes forecasting snow difficult.