11 Sep 2014

High pressure set to lose its grip next week

Following a disappointing August that brought a cool and wet month across the UK, September so far has delivered the goods, bringing sunshine and warmth.

However, fortunes look set to change next week, as high pressure lose its grip on our weather and low pressure tries to nudge its way across us.

During the past couple of weeks, the jet stream has split in two over the mid-Atlantic Ocean, with one branch going north towards Iceland and another going south towards Iberia.omega_block_WZ_wp

This splitting of the jet stream has allowed a big area of high pressure to form called an Omega block, simply because on a weather chart, it resembles the Greek letter Omega.

Such areas of high pressure act as a block, stopping low pressure, wind and rain from reaching the UK, allowing settled weather, warmth and sunshine to dominate.

High pressure drifting away

After a couple of weeks of this blocking area of high pressure being over us, it is set to drift north eastwards and sit over Scandinavia.

autumn_rainyleaf_g_wpAs the high pressure drifts away, this will allow low pressure to slowly move closer towards the UK from the south west, bringing a change to unsettled weather.

Low pressure means that the air is more prone to rising and forming clouds. It is this combined with a feed of moist, humid air that will lead to showers or longer spells of rain becoming increasingly likely as next week progresses.

With the wind coming from an east to south easterly direction, it will be southern and eastern parts of the UK that will be most likely to see some rain next week – probably from midweek onwards.

Staying settled for now

Despite an expected change to more unsettled weather next week, the proximity of the blocking high pressure for now will keep the weather settled.

autumn_sunshine_g_wpHowever, although the weather will be quiet in the coming days, it won’t always be sunny, thanks to the wind coming in off the North Sea.

This will bring big areas of cloud at times, as well as a little light rain and drizzle during the nights and early mornings.

Nevertheless, when the sun does make an appearance, it will feel pleasantly warm for mid-September, with temperatures in the range of 18-23C.

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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