8 May 2014

Low pressure set to linger this weekend

After a generally fine and settled spring so far, the weather has turned a bit turbulent this week, with low pressure being the main driving force.

Whilst not as active as their autumn and winter counterparts, low pressure can still have a notable impact on how the weather feels at this time of year – especially following warmth and sunshine.

The reason for the spell of unsettled weather this week has been the position of the jet stream, which has been over or just to the south of the UK. 


It has also been moving relatively quickly for this time of year, reaching speeds of around 140mph over the Atlantic Ocean. This has developed and steered areas of low pressure our way.

Unfortunately, the position of the jet stream isn’t going to change until after the weekend, which means the unsettled theme is going to stay with us for now.

This weekend

An area of low pressure will arrive in the early hours of Saturday morning, which will mean a spell of wet and windy weather for most places for the first part of the day.

Even when the persistent rain clears through, there’ll be sunny spells and heavy, thundery showers following, accompanied by a brisk and gusty wind.

The area of low pressure will then become slow-moving, only gradually drifting out into the North Sea into the early part of next week.

Its close proximity will mean that it will still deliver further showers or longer spells of rain during Sunday and Monday, making it feel quite cool – especially as the downpours move through.

High pressure from mid-month?

I tweeted a few days ago that there were signs of high pressure building from mid-month, but that there was a lot of uncertainty about the detail. This still proves to be the case.

sunrise_may_g_wpAlthough there is a trend for the jet stream to slow down and move northwards, the weather computer models are offering a variety of outcomes as to what extent this will happen.

This is important, as it not only determines how strongly high pressure will build, but also its orientation, which will influence where the wind is blowing from and thus how warm (or not) it may be.

At the moment, one of the more reliable weather computer models, the ECMWF, has high pressure building across southern parts of the UK, with a south westerly wind.

This would bring a drier trend for most, with temperatures possibly reaching the 18-22C mark later next week. However, the warmth, at the moment, looks brief, with the threat of cooler air returning after a day or two.

So, whilst there are signs of a high pressure bringing a drier trend mid-month, the temperature aspect of the weather remains very uncertain at the moment.

Don’t forget, you can get the latest forecast on the Channel 4 Weather website. I’ll also be posting regular updates on Twitter – @liamdutton

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