16/03/2017 Weather for the Week Ahead

I know a lot of you like it

when we talk about the jet stream in this broadcast.

You might reconsider by the end of this.

There's a lot of jet stream coming up,

but hopefully it's worth it.

I want to show you a picture

from glorious sunshine

across much of Wales and England

during Wednesday, 18.8 Celsius in the sun

at London's Kew Gardens,

the highest temperature the UK's had so far this year.

That 17 in Hawarden in north-east Wales

the highest that Wales has seen so far this year

and you might be surprised to see

this big dome of mild air across the UK.

Of course, the highest temperatures are realised

when we get some sunshine

and it's high pressure across the UK as well

that's kept our weather pretty similar

as we've been through the past few days.

No great change.

The jet stream is to the north of us

at the moment, not severely impacting our weather,

and if you are new to the jet stream,

here are a few key facts about it.

There's a ribbon or a stream of strong winds up to about 200mph

high in the atmosphere, up to nine miles above us,

and it's along the jet stream...

Well, it impacts and influences weather systems and steers them,

particularly across the Atlantic towards us.

We haven't been getting anything

because the jet stream has been to the north of us

and it's a looping,

we call this meridional jet stream

across the Atlantic right now

and when you see that,

you know the weather isn't changing very quickly.

Weather systems, either high pressure

or low pressure, stick around for some time,

but fast forward to Friday and, look,

these weather systems are queuing up

right across the Atlantic to come into the UK

on a jet stream which is no longer

looping up and down,

but it is taking a more direct

straight line towards us.

It is a zonal jet stream -

it is stronger and on it,

there are more active weather systems

and they're coming right for us so, for Friday into the weekend,

well, things will look and feel very different out there.

Let's take things day by day.

We will start with Thursday's weather

and there is a band of rain

pushing through Scotland and Northern Ireland,

heavier for a time before clearing in the afternoon

as sunny spells and scattered showers follow,

some of that rain heading into

northern and western England into Wales,

the far south-east staying dry until after dark,

not as much sunshine, not as warm

and by Friday morning,

it's quite chilly out there.

Northern Scotland fares reasonably well

on Friday, but for the rest of the UK,

rain pushing south-eastwards,

but then again, you might want something on your garden

after it's been, for some of us, quite dry.

And then this is the picture going into the weekend,

I showed you it again a second ago.

You can follow this weather system

all the way back almost to North America

and all of that is coming our way.

It won't be raining all the time.

I think some of the heaviest rain

will be focused on western parts of the UK,

into the hills and maybe Wales, for example,

will see quite a lot coming down into the hills.

Another spell of rain sweeping eastwards on Sunday,

showers following on behind.

Sunday looks like the windier of the two this weekend

and it's in the wind, particularly,

things are feeling cooler.

Then into the start of next week,

still low pressure close by

so it's still looking unsettled.

Another push of cooler air

looks like it will come in,

but as we get to the jet stream,

look at this.

It's no longer right across the Atlantic

towards us, it's doing that looping thing again

so it looks like the mobility is slowing down

so pressure systems hang around longer.

Low pressure at the start of the week,

but looks like later in the week,

there'll be a gradual progression to high pressure

coming back into the UK

and the influence of that will be

to settle things down for many of us,

turn things drier once again.

It could be pleasant by day,

but there is a risk of some cold frost overnight.

So, a weather pattern at the end of next week

pretty similar to what we have at the moment,

in between something much more changeable,

for which, of course,

we can blame the jet stream.

The psychiatrist was a figment of his imagination.