1 Oct 2014

Five reasons it’ll feel like autumn next week

After a somewhat extended summer, with September being the driest on record for the UK, as well as the fourth warmest, autumn is finally going to arrive in the coming days.

The luxury of leaving the house without a jacket, scarf or umbrella will be taken from us, as the weather at last catches up with the fact that it is October.

Whilst we have been enjoying the sunshine and warmth, retailers have been taking a hit in sales.  

autumn_tree_g_wp

John Lewis reported a rare dip in sales on Friday, saying that shoppers were delaying purchases of winter clothing because of the unseasonable warmth.

However, autumn is definitely on its way, and here are five reasons why it’ll feel like autumn next week.

Jet stream heading south

jetstream_uk_WZ_wpDuring the next week, the jet stream is not only going to pick up speed, but it is will also start to move further southwards.

It’ll dip down across Scotland and Northern Ireland later this week, before dipping south of England and Wales early next week.

This will see the balance of power shift from high pressure to low pressure, bringing a change to weather that is much more akin to autumn.

Low pressure getting stuck over us

The jet stream acts a conveyor belt for low pressure systems that form over the Atlantic Ocean – not only developing them, but pushing them towards us.

One such area of low pressure is going to form to the north west of the UK this weekend, before drifting over us early next week and getting stuck.

This will lead to the weather turning much more unsettled than what we’ve been used to for quite some time.

Temperatures falling

The low pressure that will get stuck over us next week will bring cool, returning polar maritime air across the whole autumn_mist_g_wpof the UK.

This cool air will have originated over Greenland, travelling via the north Atlantic, before dipping southwards and heading towards us from the west or south west.

Temperatures will therefore return to average for this time of year, reaching just 10-15C by day and dropping to single figures at night.

Cloud and rain

The presence of low pressure means that air can more readily move upwards in the atmosphere, leading to air cooling and condensing, forming clouds.

This rapidly rising air, know in the meteorological world as an increase in instability, will therefore bring showers or longer spells of rain at times, which could be heavy.

The combination of cloud and rain will also result in a reduction in the amount of sunshine, making it feel even cooler.

Brisk wind

wind_turbine_g_wpLow pressure is synonymous with unsettled weather, as well as an increase in wind speed, as air rises up from the surface and air rushes in to replace it.

The movement of air over our skin will also cause evaporation of the moisture on its surface, leading to the same cooling effect that evaporation of sweat has during summer.

This means that when the wind is brisk, as it will be at times next week, it will add to the chill.

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

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