14 Jan 2013

How long will this cold spell last?

Much of England and eastern Scotland woke up to a slight covering of snow today, only to be followed by a heavier band of snow across eastern parts of England during Monday afternoon.

Confidence in the change to cold weather has been high for around a week now, but getting the forecast spot on for snowfall has been difficult.

Although predicting the snow has been a challenge, the parts of the UK that I highlighted in my blog at the end of last week are the areas seeing the more significant snow today.

Just to illustrate how varied snowfall has been over short distances today, over north London, the inner zones 1-3 have seen have seen snow falling but not settle, whereas the outer zones 4-6 have had a full covering.

The urban heat island effect fading towards the suburbs and the slight increase in altitude of 60-100 metres up makes all the difference in marginal situations.

Once today’s snow in eastern England fades away tonight, there’ll just be a few coastal wintry showers around northern, western and eastern coasts of the UK.

The primary concern tonight for all areas will be sub-zero temperatures and ice. Any moisture from rain, sleet or snow will readily freeze, giving slippery surfaces – especially on untreated roads and pavements.

Temperatures in towns and cities will drop as low as -4C, with -7C possible in rural areas where snow is lying on the ground.

How long is the cold spell going to last?

I’m quite confident that the cold weather is going to continue across the UK for the rest of this week, although milder air will try to creep in from the west at times, turning things a little less cold here.

However, for much of the UK for the rest of the week, daytime temperatures will struggle to get above freezing, with ice persisting all day in places. Northern Ireland, south west England and western parts of Wales and Scotland will be the exceptions, at 3-6C.

Widespread, hard frosts will be common at night, with temperatures down to -5C in towns and cities, but as low as -10C over snow covered ground in northern areas midweek.

The next big question mark is for this weekend when some of the weather computer models try to bring less cold air in from the west. The problem, however, is that cold air can be hard to shift and there’s no guarantee that the less cold air will win the battle.

When could there be more snow?

There could be a band of wintry showers moving southwards across eastern England tomorrow, giving a few centimetres locally, but for many, it will be a dry and cold day.

From Wednesday to Friday, the snow risk will depend on which part of the UK you live. For eastern coastal counties of England, there could be some snow showers moving in off the North Sea.

For Northern Ireland, and western parts of England, Wales and Scotland, Thursday and Friday could see rain try to move in from the Atlantic, which would turn to snow as it meets the colder air.

As always, the snow detail is uncertain and I’ll keep you updated during the next few days. In the meantime, if you have any pictures or weather reports to send me, please get in touch on Twitter – @liamdutton

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