13 Mar 2013

Winter just doesn’t want to let go

Last week’s brief burst of spring-like warmth gave many of us hope that winter was finally going to be banished to the freezer and temperatures would head upwards and onwards.

However, it wasn’t to be. Winter has bitten back hard during the past few days, with major wind chill and freezing temperatures that would be impressive even for mid-January.

In addition, there was the snowstorm that gave the Channel Islands, northern France and the far south east of England wintry weather that would be more at home in the mountains of Scotland.

Snow drifts of up to two metres formed in places as the dry, powdery snow was whipped up by the strong to gale force wind. Transport chaos ensued and some people spent the night stuck in their cars.

Whilst snow isn’t uncommon in March, it has to be said that the scale of the snow in terms of persistence and severity was pretty remarkable.

Residents of the Channel Islands that I’ve spoken with on Twitter say that this is worst snow they can remember in at least three decades.

Why has it been so cold?

Once again, it’s all down to the position of the jet stream – the fast-moving ribbon of air high up in the atmosphere that determines the weather we experience at the surface.

The jet stream also acts as the dividing line between cold air to its north and warmer air to its south – effectively separating winter and spring.

Normally at this time of year, the jet stream should generally be sitting across Scotland, with most of the UK lying on its warmer side.

This would bring typical mixed spring weather, with sunshine, showers and rain, with temperatures reaching 10-15C and just occasional colder interludes.

However, at the moment, the jet stream is much further south than normal, sitting across Iberia and northern Africa. As a result, the whole of the UK lies on the cold side of the jet stream, under a huge pool of cold air.

Is the jet stream going to move anytime soon?

Over the next few days, the jet stream will temporarily move further north, bringing a spell of less cold weather with higher temperatures and rain more likely than snow.

However, early next week, it dives southwards again, putting us back in the colder air and increasing the chance of wintry weather returning.

Whilst next week doesn’t look quite as cold as it was on Monday, temperatures are still set to be well below average at around 2-6C by day and dropping to around -3C at night with widespread frosts.

Falling temperatures will also mean the risk of further snow next week, although at this stage, the detail is uncertain.

As March progresses, it does become harder for snow to stay on the ground for long as there is enough strength in the sunshine to melt the snow during the daytime – unless the air is extremely cold.

So winter isn’t done with us just yet and there could well be some more snow on the horizon. As ever, you can stay updated here on my blog and also by following me on Twitter – @liamdutton

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