11/02/2016 Weather for the Week Ahead

We are going into a colder spell which could last a week or so.

There will be some frost

and there will be some snow for some of us, too.

We start Thursday on a chilly note,

that's for sure, with wintry showers

pushing down across Scotland,

some rain showers for parts of Wales

and the West Country, particularly round the coast,

pretty heavy ones, too.

But most of us will actually have

a lot of dry weather through Thursday,

sunshine hopefully, where you are.

The wind is not too strong, it shouldn't feel too bad.

A bit of a nip in the air, but not desperately cold.

5 degrees in the north, 8 or 9 across

some southern counties of England.

As we go into the night-time,

frost returns for a good few of us.

There will be wintry showers knocking about

across parts of northern England for a time

then this area of low pressure

glides across the far south-west,

bringing more persistent rain

and throwing some showers up across

other southern counties through Friday.

Another band of wintry showers

then pushing down across Scotland,

but again, many of us -

the vast majority of us, actually -

will have a lot of dry weather through Friday,

light winds for the most part.

4 degrees in the north, 7-8 degrees in the south.

Now, what about the weekend?

It is causing us some problems here at the weather centre

in terms of getting the detail right.

Quite a challenge.

We do think it'll be predominantly cold,

some rain in the south and the chance, or the risk,

depending on your point of view,

of a bit of the white stuff.

The first ingredient to the puzzle is

this area of low pressure pushing in from the west.

That will bring wet weather, we think,

to southern and western parts of the UK on Saturday.

Trying to push milder air in as well,

but coming up against a block of cold air.

Now, the dividing line between the cold and the mild

is quite important,

because as that rain tries to push northwards,

encounters that cold air, there is a chance

some of it will turn to snow.

At the moment, we think that is most likely

across parts of Wales and the Midlands,

especially over the high ground,

but this could change.

It could be further north, it could be further south.

What we are more confident about, actually,

is what happens next.

Later on through Sunday, and into early next week,

cold air will flood southwards,

quite a stiff northerly wind.

It will feel distinctly chilly, we think,

through the early part of next week.

There will be some wintry showers,

sleet and snow showers,

particularly where you've got exposure to those winds,

so northern and eastern coasts in particular.

There could be a few centimetres of snow over the high ground.

A lot of sunshine, though, further south and west.

Feeling cold in that wind.

So, yes, this could be a typical scene

through the early part of next week -

bright and crisp to cold, with overnight frost

and a dusting of snow in some places.

Now, how long does the cold spell last?

Certainly through the early part of next week,

those northerlies should prevail.

There are weather fronts trying to come in off the Atlantic,

but they are being held up by this ridge of high pressure.

So through the early part of next week,

we've got this block of cold air in place,

mild air trying to push in.

We think it will succeed -

the motion of everything is west to east.

But there is a catch.

The catch is that the jet stream

is getting all kind of...well, tangled up.

Look at the huge great ripples in the jet stream.

It's a bit like a crumpled carpet,

and if you try to iron out a crumpled carpet,

it's not easy, is it?

It's trying to do that -

it is coming up against this block.

The question mark is how quickly

that block will get shifted.

The computer models often

have difficulty in nailing down

the detail and the timing of that change of type,

so later next week, eventually,

it might turn milder and potentially wetter,

but watch this space.

Sarah will update you again tomorrow.

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