19/12/2016 Weather for the Week Ahead

Hello, there's a major change in our weather coming our way

later this week and just in time for Christmas.

If you were hoping for something white for Christmas,

it looks like another W will be a bigger player and that

is wind. All very different from what we have at the moment.

With light winds and scenes like this

in South Wales on Sunday with fog.

Problematic at times, but the sort of thing you get with high pressure.

That's what we have at the moment and that's what we've had

for much of December so far. As a result, most of the UK

has been drier than average, it's been quite mild too, in fact,

if it carried on this way, could well turn out to be in the

top-ten mildest Decembers on record. But yes, there are changes coming.

We can look to North America for origins for that change,

we've seen bitter cold Arctic air spreading out of Canada into

the USA, meeting the warmer air further south.

Strengthening the thermal gradient,

the change of temperature over a smaller area.

And that's what the jet stream thrives off and strengthens

from and that's what we're getting this week,

a stronger jet stream roaring across the Atlantic towards us,

carrying deeper areas of low pressure, turning our weather

wetter and windier. Not at the start of the week,

high pressure still close by, influencing our weather from

Continental Europe, but then look - the first deeper area

of low pressure coming out of North America will come close

to us later this week, as we'll see. We'll take it day by day,

this is Monday, still high pressure, still some quite dense fog

across parts of England and Wales to start the day. Bit of patchy

rain coming into the east and south-east of England,

bit of patchy rain spreading southwards through Scotland

and Northern Ireland turning a bit brighter behind that -

single-figure temperatures. Clearer to start Monday night

in Scotland and Northern Ireland, some more of us picking up a

frost - going into Tuesday, still a weather front, a weak one,

close by western parts of England and Wales. So, some us here

seeing a bit of rain but actually a bit more sunshine coming through

further east across England and then look to the north-west,

here comes the first weather front from our first deeper area

of low pressure and that brings some gales and some heavy rain,

and that spreads its way south-eastwards, weakening as it

does so on Tuesday night and into Wednesday as it runs into

high pressure. So maybe for England and Wales on Wednesday,

not a huge amount of rain left on this.

Sunshine and showers for Scotland and Northern Ireland and

a colder flow.

Some of those showers turning wintry and giving some snow, at least

on the hills into Scotland, but a few spots to lower levels too.

Now there's a pulse of energy running along our

weather front affecting England and Wales on Wednesday night

that could give some heavier rain for a time.

Bags of uncertainty about that, so we're going to follow it

and keep you updated. Thursday, that clears, then we're all in this

sunshine, showers, brisk west-north-westerly colder flow

and again some of those showers wintry, maybe not just on hills

across northern Britain. Thursday night - high pressure starts

to try to build in to southern areas, touch of frost, maybe a few

fog patches once again, but then, look - another area of

low pressure quickly coming in from the Atlantic on that jet stream.

May start fine on Friday but the further west you are, you'll

notice the wind picking up. Towards the north-west, gales

or severe gales developing. More heavy rain coming to parts of

Scotland and Northern Ireland later in the day.

Now, the start of Christmas weekend - that drives

south-eastwards and then we're watching this area of low pressure.

This could potentially turn things quite stormy on Christmas day.

Not set in stone, still a lot to play for -

we will follow that and keep you updated

but it could be an unwelcome visitor for Christmas.

After that, leading up to New Year, further spells

of wind and rain but there are gaps between the weather systems,

when we get something a bit drier, brighter, colder,

with a chance of getting something wintry and white,

especially on the hills of northern Britain.

But at the moment, Christmas is looking more windy

than white and do keep watching this week for regular updates.