20/12/2017 Weather for the Week Ahead

Hello. I can't see the weather having too much of an impact

on your travel plans to your Christmas break,

but on the way back after Christmas it may be a different story.

For the time being things are pretty quiet out there

because the jet stream, the winds high up in the atmosphere,

driving weather systems around the world,

is well up to the north. That means the active weather

is well up to the north and what we have at the moment

is an area of high pressure dominating the scene.

However, it is not a nice, clean, sunny high. We've got this

weather front slung across the middle of it, which is

essentially polluting the high, bringing a lot of cloud,

mist and murk, some hill fog and during Thursday a band

of patchy rain northwards across Northern Ireland

and into northern England. Best chance of any

brightness across northern and eastern parts of Scotland,

here on the chilly side but very mild down to the south,

11 or 12 degrees.

During Thursday night, remember that frontal system will

continue to wriggle its way around, bringing some outbreaks

of rain, perhaps some heavier rain for a time across the

south-west into the early part of Friday.

A very mild night once again for most of us but perhaps

a touch of frost across the north of Scotland

but we'll keep hold of clear skies.

Into Friday this frontal system still with us, but the

high pressure all the while will be squeezing it out of the

picture, so after a very cloudy and in places damp start,

particularly in the south, again with some mist and murk,

there is a slightly better chance through the day of

seeing some brightness, particularly across eastern Scotland

and down the eastern side of England.

Again, quite chilly up to the north-east, 5 degrees

in Aberdeen but 12 there in Cardiff. Now, Saturday

should be a milder day in Aberdeen because we'll start to

pick up more of a south-westerly wind, a stronger wind,

so if that breaks up the cloud across eastern Scotland

we could get to 14 degrees, but equally we'll start

to see some rain into north-west Scotland courtesy of

this next frontal system. Now, this one is going to be a part of

the weather story, really, right through into Christmas.

On Christmas Eve it will continue to bring outbreaks of rain

across north-western parts of the British isles, the rain

just wriggling around in the same sorts of places,

and to the south it'll be quite windy, less in the way

of fog and less in the way of low cloud because the winds

will be that bit stronger. And for the big day itself,

still rain into the north-west, still fairly windy

but largely dry to the south, little bit of brightness

in eastern areas. Notice, though, temperatures beginning

to dip away in the north. As we move out of Christmas Day

there is some uncertainty about the timing of this

but it looks like we're going to bring this area of wet weather

southwards and eastwards and as it moves southwards

and eastwards it'll start to introduce some colder air.

In fact, some places in the north could even see a little bit of snow

for the end of Christmas Day.

But it's cold air on the other side of the Atlantic that's going

to drive our weather. Beyond Christmas we're expecting a real

plunge of cold across North America,

bumping into some very mild air being drawn up from the tropics.

In fact, very warm air, and that clash of air masses

is going to supercharge the jet stream.

It'll strengthen the winds high up in the atmosphere,

it will also bring the jet stream further south,

so not only will areas of low pressure drift towards our shores,

some of these areas of low pressure, because of the powerful jet,

could be very deep indeed, perhaps even troublesome.

So, as we move beyond Christmas,

briefly it looks like turning colder and then deeper into the week

some heavy rain at times, the risk of gales, so there could be some

disruption for your travel plans after Christmas.