- 2 days ago
This is an in-depth Met Office UK Weather forecast for the next week and beyond. Winter arrives early thanks to winds directly from the Arctic. Some parts of the UK will see significant snow. Many other areas will just be sunny. Bringing you this deep dive is Met Office meteorologist Aidan McGivern, with specific details of where, when and how much snow we'll see as well as how long the cold spell will last.
Bringing you this deep dive is Met Office meteorologist Aidan McGivern.
Bringing you this deep dive is Met Office meteorologist Aidan McGivern.
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00:00Winter has arrived early. Cold Arctic air across the whole of the UK during the next few days
00:06with some very specific parts of the UK affected by some very significant amounts of snow.
00:15And before I go any further, I want to emphasise that it's the North York Moors and the Yorkshire
00:21Wolves where we are most concerned about impacts from snow, particularly this coming Thursday.
00:28If you are concerned about that part of the UK, head to the Met Office website and app for the latest weather warnings.
00:35There are numerous weather warnings across the UK for snow and ice during the next few days because of a mixed wintry picture.
00:44But for many places away from those specific areas that will see significant snow, there'll be hardly any snow.
00:52And I'm going to detail which areas are expecting the significant snow and which areas we'll hardly see any during the coming days in the next 20 to 30 minutes.
01:03In this Met Office deep dive, welcome along. We do these every Tuesday.
01:08And if you enjoy watching these in-depth weather reports, please do hit subscribe if you haven't already.
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01:18In the Weather Studio Live, which is another YouTube video that we do at lunchtime on a Friday, and that's more interactive.
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01:31So send us some love if you enjoy these longer form weather forecasts.
01:35And there's certainly a lot to pack in this week.
01:38At the time of recording, Tuesday afternoon, we do have an Atlantic system crossing the UK, bringing a messy mix of rain, sleet and hill snow initially to northern parts of the UK.
01:49But that's going to be spreading south overnight and into the start of Wednesday.
01:54And I'm going to be looking at that in just a moment as well.
01:56Well, this is the mixed precipitation radar, so it shows whether what's falling out of the sky at the moment is rain highlighted in blue or sleet or snow or hail highlighted in white.
02:10And you can see this is early hours of Tuesday.
02:12We've got the system moving in, bringing that mixture of rain, sleet and hill snow to northern England, Scotland, parts of Northern Ireland before sinking south.
02:20But actually, last Friday, we were studying the radar carefully because of the rain, and that was the major talking point.
02:30And I just want to spend five to ten minutes or so looking at the system, Storm Claudia, that brought us so many impacts from rain, particularly the town of Monmouth.
02:42Of course, you'll have seen the devastating images of flooding in Monmouth because of the exceptional amount of rain that parts of southeast Wales saw in particular.
02:52And the meteorological setup, whilst devastating in some places, was fascinating in terms of how it all worked together.
03:01And I'll explain why now.
03:03Now, on Friday, this is the radar.
03:06This is through 6 a.m. Friday to 6 a.m. Saturday.
03:10And what you can see is from the word go on Friday, these bands of heavy rain moving north across the UK, but they're not clearing north.
03:17They're stalling.
03:19The northern edge isn't changing.
03:20It's across northern England there.
03:22Whilst they're bunching up, these bands of rain are bunching up across parts of Wales, the Midlands in particular.
03:27And the brighter colours indicate where we saw particularly heavy and persistent rain.
03:31So, effectively, we had this weather front moving up and stalling across this central swathe of the UK and becoming increasingly intense through the day.
03:41You can see, as we run through the day on Friday, some really quite heavy showers and longer spells of rain developing across parts of Wales, the Midlands, southwest of England in particular.
03:53And, in fact, if I skip forward to 1500, this is the picture at 1500.
03:57Now, Scotland and Northern Ireland escaping mostly dry.
04:00We've got these showers coming into the northeast of Scotland, but otherwise dry, something a little drier along the south coast of England.
04:08But at this stage at 1500, we've got some heavy thundery downpours moving into parts of Devon.
04:14In the middle, this band of very intense, very prolonged rain with the brightest colours there across southeast Wales.
04:20And the meteorological setup, as I mentioned, was really quite extraordinary.
04:25And I want to show you why.
04:27A couple of charts I'm going to show you have been shared by Matthew Lennart, one of our chief meteorologists who was on duty last week and did an amazing job at forecasting the setup and the impacts from it.
04:40But I also shared these charts with colleagues and I just wanted to show you what was going on because this is showing the same time, 1500, on Friday.
04:50And it shows where the air was coming from across two extreme parts of the UK.
04:55So here on the left, we've got Scotland, Northern Scotland, where was the air coming from?
05:00Back trajectories show the air came right away from the North Pole on Friday across Northern Scotland.
05:06So the Arctic air was in place already across Northern Scotland, directly from the North Pole.
05:11This on the right shows the source of air for the south of England.
05:16I think it's pointing to Exeter there.
05:18And the source of air for the south of England was North Africa via Spain and some bits of air coming from the Mediterranean, but a lot of the air coming from North Africa.
05:29So we've got this clash between air coming up from North Africa on the one hand into the southern half of the UK and air coming all the way down from the North Pole for the northern half of the UK.
05:40And when you get these two air masses colliding, that causes some significant impacts because of the enhanced, what we call the thermal gradient, the enhanced difference between cold air in the north, warm air in the south.
05:55And this is really visualised very well by looking at a cross section of the atmosphere, a slice through the atmosphere.
06:03And again, Matthew Lennart provided another chart that shows this slice through the atmosphere.
06:08Imagine taking a slice of the atmosphere along two and a half degrees west.
06:13So that's roughly the Wales-England border up to Dumfries and out towards the north of Scotland.
06:19And you're taking this slice of atmosphere all the way from the Arctic Circle down to the south of France.
06:24So it's about there. Imagine taking two points and having a cross section through the atmosphere.
06:31And that is indeed what we're able to look at here.
06:35And at first, I know this is going to look thoroughly confusing.
06:39It took me a while to get my head around it as well. There's lots going on in this chart.
06:43It's highly technical. But if I just explain as we go along some of the key details, it really is quite interesting.
06:49On the left here, that's where we've got the Arctic Circle. It's about 70 degrees north.
06:54So two and a half degrees west, 70 degrees north.
06:57At the bottom of the chart, that's sea level.
06:59So we're running along here into Scotland, northern Scotland's about here up towards 57 to 60 degrees north.
07:08In fact, I might be able to draw here.
07:11Yeah, I think I did earlier.
07:13There we go.
07:13So that's about northern Scotland there and then running further south again.
07:17Here we've got north Wales and here we've got south Wales.
07:21So Wales represented by this horizontal black line.
07:24And then the south of England about there, the south of France there.
07:27So this is a slice from north to south of the atmosphere, sea level at the bottom.
07:32And then we go higher in the sky and get up to about 12 or 13 kilometres at the top there, 40,000, 45,000 feet, something like that.
07:40So the jet stream height is at about the top of that chart, around 200 hectopascals, 250 hectopascals.
07:48In fact, I'm going to talk about this in a moment.
07:51But the jet stream is actually here.
07:52It's highlighted by these black lines.
07:54So we're looking at slice of the atmosphere.
07:56There's lots of meteorological parameters.
08:00Bit of a tongue twister.
08:02Met parameters shown on this chart.
08:05Now, the colours represent something called potential temperature.
08:08Not quite temperature.
08:10If it was temperature, it would show pretty much getting colder from the surface up to the top.
08:15But that's not what we're necessarily interested in when we're looking at the clash of two air masses.
08:21Because that, well, when it always gets colder as you go higher up, hides a lot of the more interesting characteristics of these air masses.
08:32Potential temperature removes altitude from the equation.
08:38So basically, when you go higher in the sky, pressure lowers and air parcels get bigger.
08:45They expand and the temperature drops.
08:47So you typically see a temperature drop as you go higher in the sky.
08:50If you were to take the air from up here, so up at 40,000 feet, and you were to take it and bring it all the way down to the surface without adding or removing any heat to that parcel,
09:06then you would, what's called, you would adiabatically warm it.
09:11That's the technical term.
09:12But essentially, it would come down, there's more atmosphere pressing down on it, it compresses, and it warms up.
09:19So you take air from up here, take it down to the surface without adding or removing any extra heat.
09:24It warms up, and its temperature goes from, typically, it might be minus 35, minus 40 up here.
09:31But it warms up to a different temperature when it gets brought down to the surface.
09:35That's what these colours represent, the temperature that air would be if it was brought down to the surface.
09:40It's saying 22 degrees up there.
09:43So we know that if you take air from up there and compress it down to the surface, it's going to warm up to 22 degrees.
09:51The temperatures up here don't really matter.
09:52We're looking closer to the surface.
09:54This is where all the action's taking place.
09:56And what's happening is we've got these blues here.
10:00That's the Arctic air.
10:01The arrow here shows that's moving south into Scotland, into Northern Ireland.
10:06But at the same time, we've got the air from the north of Africa moving north.
10:12That's moving this way.
10:14These brighter colours indicate warmer air moving north.
10:18And along the boundary, we've got a very tight gradient of potential temperature.
10:23So this is why we use potential temperature, because this gradient is most highlighted when we use these parameters.
10:31So what happens when the cold air bumps into the warm air?
10:35This is Weatherfront 101.
10:38The cold air is more dense.
10:39It tends to force the warm air upwards.
10:42So the warm air rises over the top.
10:44That's what it's doing.
10:45It's rising over the top of that cold air, which is coming in along the surface.
10:50What happens when you lift a lot of warm air, which is, by the way, very moist.
10:56That's what this white line here, you might be able to see.
10:59It indicates relative humidity above 95%.
11:02So it's not only warm, it's very moist.
11:05It's full of moisture.
11:06What happens when you lift this large amount of warm, moist air into the sky?
11:11It cools down and it condenses.
11:13And all that condensation leads to clouds and rain and so on, but also leads to warming of the atmosphere because of something called latent heat release.
11:23When you condense something, it releases heat.
11:27It's the opposite of evaporative cooling.
11:30We all know what evaporative cooling feels like.
11:33It feels like that chill when you get out of the shower, the droplets of water on you are evaporating.
11:39They're taking energy, heat energy from your skin, making you feel colder.
11:43So condensational heating, that is the opposite of evaporative cooling.
11:49And when you get this heating, as the air rises, as the warm air and moist air rises and it condenses, you've got here, it can just about make it out.
12:01There's like a grey dashed line.
12:04That's where you've got so much latent heat release that it's causing the air in this area.
12:10And remember, this is about the latitude of South Wales.
12:15The air close to the surface is expanding.
12:17That causes a lot more rising of the air.
12:22So the air is really rising quickly here because of the extra heat being pumped into the atmosphere.
12:27So that compounds the issue with the warm air rising ahead of the cold front.
12:32You've got this extra ascent, this extra rising air and this extra release of cloud and rain and moisture and so on to the atmosphere.
12:42So all the ingredients there for a lot of rain.
12:45And, of course, that frontal boundary doesn't move through the day.
12:49So we've got this constant rising of warm and moist air all the way from North Africa as it pushes over the cold Arctic air, all in the same place.
12:59Combine that with the condensational heating of the atmosphere and all this air being pushed, being pumped upwards from the surface over southeast Wales.
13:09And if we turn our attention to further south, so this is over the channel or thereabouts, northern France at the same time.
13:19We've got here, this dashed line indicates a dip in the jet stream, a dip in the tropopause, not the jet stream.
13:26That's the top of the troposphere, so the stratosphere is up here.
13:30What that basically means is we've got lower pressure way up high in the atmosphere, what we call an upper trough.
13:37That causes air here to rise, leading to those thundery downpours that I mentioned that were pushing into Plymouth and South Devon at about 1500.
13:47So we've got that aspect as well behind the frontal rain, so the thundery downpours, the heavy showers.
13:55And one final aspect that's going on here, the black lines, as I mentioned, they are what we call ice attacks, lines of equal wind speed in knots.
14:06And you can see the black lines here, 100 knots up at jet stream height.
14:12So this is where the jet stream is, but there's another part of the jet stream over here.
14:16The jet stream was a bit all over the place.
14:18And you've also got, so you've got this strong wind high up here, but you've also got, if you can just about make out here, just over North Wales and Cumbria, that kind of latitude, you've also got a peak in wind speeds, 50 knots or so, just above the surface.
14:39And that's called a low-level jet.
14:40So that's where, yes, you've got this big enhanced thermal gradient and a lot of isobars on the pressure chart, for example.
14:49But the winds get squeezed over the higher parts of North Wales and Cumbria.
14:54These easterly winds were getting squeezed and you get this peak in winds just above the surface.
14:59And we ended up seeing a wind speed of 63, I've got it written down here, 63 miles an hour at Aberdaran in Gwynedd, 68 miles an hour.
15:10A walk-up range in Cumbria, so that's where that is.
15:15And then to the south of that, over southeast Wales, some remarkable rain accumulations.
15:20120 millimetres was recorded between 6pm Thursday and 6am Saturday at Taflog in Gwent.
15:28That was a Natural Resources Wales rain gauge, 81 millimetres Environment Agency rain gauge in Worcestershire.
15:35So, yes, a lot to get your head around there.
15:38But it's such a classic diagram of how weather fronts work, where you've got cold air at the surface and then warm, moist air being forced over it.
15:48But this was an extreme example of it because of such contrast between those two sources of air.
15:56But let's move on.
15:59Let's move on because now the UK is seeing the cold air become more widespread.
16:07It's not just across Scotland and Northern Ireland.
16:09That Arctic air is across the whole of the UK.
16:12Let's take a look at the setup for the next few days.
16:15Here we are at the moment.
16:16As I mentioned, we've got a dip in the jet stream just to the northeast of the UK.
16:24These weather fronts, this little feature coming south at the moment.
16:29And yes, cold air, but not as cold as it's going to get because this Atlantic low has moved in.
16:37So initially we had northerly winds to start the week.
16:39This low has moved in and it's brought a messy mixture of rain, seat and snow to many places.
16:46And the best way to visualize that is to look at freezing levels.
16:50Now we've talked about this before in the deep dive.
16:54And what the freezing levels represent is the height of zero degrees Celsius above sea level.
17:01And meteorologists find it a useful tool to look at freezing levels because as a rule of thumb,
17:06if the freezing level is around 200 metres or lower, then you typically get snow at the surface.
17:14But if it's higher, then you need a bit more intensity to the precipitation.
17:19So particularly heavy rain or precipitation can cause the freezing level to drop further
17:26because the heavier the rain or sleet or snow, the more the atmosphere cools through that evaporative cooling I was talking about.
17:33So this is a useful tool for showing where we're likely to see snow, what kind of level, how high up you need to be.
17:40And when you factor that in with how heavy the precipitation is as well, that can be a good guide for where we're going to see it.
17:46And it's so messy for the rest of Tuesday.
17:49Now you can see here that Ireland into southwest Scotland, western England and Wales, we're in the mild air.
17:56It's a thousand metres plus.
17:58So no snow on Tuesday afternoon in western and southwestern fringes of the UK, but much colder across Scotland, much of northern England.
18:07And if we go forward to Tuesday evening, you can see that cold air starting to dig south.
18:13Now, at the same time as the cold air digging south, we've got that precipitation moving south.
18:19And I realise that many people will be watching this whilst this is happening.
18:24We've got precipitation moving south and it's a mixture.
18:27You can see across the southern half of England and Wales, it's rain showers predominantly.
18:32But further north, it's mostly snow for Scotland.
18:35And then this mixture in between where we do have a gradient in the height of the zero degree isotherm.
18:44So no chance of snow as we go into the evening across the south, but an increased chance further north.
18:51And in fact, if we play this forwards, you can see the freezing level is dropping through the night.
18:56So that's coming down at the same time as various bands of rain, seat and snow are coming through.
19:02And that means that by the time we get to 1am, for example, here's our band of, a little bit of an occluded front, band of rain, sleet and hill snow.
19:15It's coming south.
19:16Now, predominantly, this is going to be snow falling at about 100 metres or so above sea level.
19:21Certainly inland, around the coast, mostly rain.
19:26But you wouldn't rule out, because it's night time, things are cooling off.
19:30The wet bulb freezing level, as you can see in this area, isn't far off 200 metres.
19:35We've got this gradient from 800 metres in the south to 200 metres across northwest England at this time.
19:41So in between, that's where the front is.
19:44That's where this occluded front is.
19:46And it's ending up quite messy.
19:49So a real mixture.
19:50I wouldn't rule out, you know, a bit of snow falling on grassy verges as this sinks south.
19:55It does move south fairly quickly.
19:58But you could get a centimetre or two, perhaps more over the highest ground, across north Wales, into the Peak District and northern England.
20:06And by the time we wake up on 6am Wednesday, that's moving through central southern England, mid Wales, east Anglia and the southeast.
20:14And as you can see, again, it is that real mixture of blues and whites.
20:20So it's going to be one of those where it will depend on intensity.
20:24It will depend on how much these areas have cooled ahead during the night time.
20:29It will depend on the wet bulb freezing level, which again shows that gradient with higher levels across the far southeast, but really digging down quite close to the surface across parts of Wales and central southern England.
20:44So just it is a very messy one, a classic example of why it's difficult to predict snow in this country.
20:51Some areas here will have rain to wake up to.
20:54Some areas will have snow where you have snow.
20:57Unlikely to be particularly exciting, but there could be some slippery surfaces here and there.
21:04Could be some sleet or even wet snow settling on grassy verges on car windscreens, that sort of thing.
21:10It's not going to last long.
21:11It does move through and by lunchtime that feature is out of the way and things become a lot more straightforward because by Wednesday afternoon we're back into this straight northerly wind across the whole of the UK.
21:29And I want to talk a bit more about Wednesday and Thursday's weather now because it could cause considerable impacts, as I mentioned at the start.
21:40Now, here's how things are on Tuesday afternoon.
21:45We've got this messy mixture of rain, sleet and hill snow moving south across the UK.
21:51But by Wednesday afternoon that's clearing and the winds, as you can see from the isobars, are coming straight from the Arctic.
22:01So the air that comes south across the UK on Wednesday and remains with us on Thursday is directly from the North Pole.
22:10In fact, it's not just from the North Pole.
22:14This shows the source of air from several days ago and it shows it coming originally from Siberia, passing through the North Pole or the Arctic Circle and then coming south through the Norwegian Sea into the North Sea and into the UK.
22:30And this is where it ends up across the UK on Thursday.
22:34So Thursday's air comes originally from Siberia via the North Pole.
22:40It doesn't get much colder than that, even at the start of winter when things haven't properly cooled off.
22:46It's cold enough for some significant snow.
22:50But the snow isn't going to affect everyone.
22:54It would be cold enough for snow fairly widely.
22:58And I'll show you that on this graphic.
23:01This again shows the wet bulb freezing levels, the height at which the temperature goes below zero, the height you have to go up in the atmosphere.
23:09And this is the start of Thursday.
23:11And as you can see, fairly widely, even if we go to Thursday afternoon after the sun's come out and done its warming of the land, you can see fairly widely across the UK that wet bulb freezing level is 200 metres or lower.
23:24So the kind of height that you'd expect snow if you had precipitation to be falling close to the surface.
23:32A little bit higher for Wales in the southwest, coastal parts of Northern Ireland, Western Scotland.
23:37So around coastal areas, not quite as low, but certainly quite a large part of the UK, the air, because of its source, is cold enough for snow.
23:48And that continues into Friday, for example, fairly widely.
23:51Again, it's cold air, particularly cold for the time of year.
23:57But at the same time, that northerly wind coming through, it's going to be picking up moisture from the sea.
24:05The sea temperatures are above average.
24:07So cold air coming over warm seas picks up a lot of moisture.
24:10You get a lot of instability, a lot of showers.
24:13However, if we skip, well, let's go to Wednesday and we'll turn off the cloud.
24:20Those showers are mostly going to be affecting coastal parts, particularly northern Scotland, the east of England, parts of Pembrokeshire, southwest England, Northern Ireland.
24:32This is known as a Pembrokeshire dangler.
24:34You might have heard of it.
24:35It's where the winds, when they come from the north, they funnel together across the Irish Sea and leave a line of showers into Pembrokeshire.
24:44And, you know, these line of showers continue into parts of Cornwall.
24:47So this basically summarises which areas are likely to see stuff falling out the sky.
24:53Precipitation on Wednesday and more of the same into Thursday.
24:57It's these exposed northern and eastern coasts and some of these Irish sea coasts as well as parts of Northern Ireland.
25:02And that's why Wednesday and Thursday we're going to see such substantial differences in amounts of snow across the UK.
25:11What weather will you experience if you're not getting these snow showers?
25:15Simply sunny skies, crisp early winter days, frosty nights.
25:21But where we do get these showers, a lot of places are going to see snow accumulating away from coasts, away from right down at sea level where it could be a sleety mixture.
25:30Some places are going to see significant snow building up.
25:34And we can show that by the snow depth forecast here.
25:41So this shows Thursday.
25:43Let's go to Thursday evening.
25:46And it shows how significant those snow amounts may end up being across the UK.
25:53But you can see large parts of the UK, no snow at all.
25:57No snow.
25:58Piddly amount in some places tonight.
26:00Then sunny skies for many because we've got the shelter from the showers.
26:04But if I zoom in here, then you can see a lot of snow building up inland across northern Scotland.
26:1220 to 30 centimetres in some places.
26:15So the Grampians, North West Highlands, zooming in a bit more, you can see North West Highlands, the Grampians.
26:23And then you come further south, not much at all through the central belts, perhaps a little bit of the southern uplands, Pentland Hills.
26:30Northern Ireland, Sperrins, 10 centimetres possible, but not much elsewhere.
26:35And then coming into northern England, certainly a little bit over the Pennines.
26:39But we've got this direct feed of showers across the North York moors and into the Yorkshire wolds.
26:45And so this is somewhere that we are particularly concerned about.
26:51Again, check the weather warnings on the Met Office web page and app.
26:54This area, the risk of 20 to 25 centimetres of snow above a few hundred metres.
26:59This area here, that could cause significant impacts on Thursday because of the sheer amount of snow building up over higher parts here.
27:07On the coast, barely anything.
27:09So real significant differences between what we're seeing around the coast and at low levels and over hills that are exposed to the northerly wind.
27:18And one prime example of that, I mentioned the Pembrokeshire dangler.
27:23Look at that, small part of Pembrokeshire, seeing snow shower after snow shower and 10 or more centimetres of snow building up there across parts of Pembrokeshire, higher parts of Pembrokeshire.
27:37And a little bit over Bodmin more, a little bit over Dart more, but not much at all.
27:42So significant impacts in some very specific parts of the UK by Thursday because of the sheer amount of snow building up 20, 25 centimetres in places, whilst many parts of the UK see no snow at all, just blue skies, sunshine and frosty nights.
28:00And it will feel cold.
28:02It will feel really quite cold.
28:05Here are the maximum temperatures over the next few days.
28:07You can see high single figures at best on Tuesday, even lower on Wednesday, Thursday, Friday.
28:14Add in the wind chill.
28:18And it makes a significant difference, particularly on Thursday.
28:22These are the feels like temperatures, 2pm Thursday, minus ones, minus twos fairly widely across the UK.
28:28These are the actual temperatures that a thermometer would record because it doesn't have that body heat to lose.
28:33So our bodies would feel more like this because we've got that layer of heat that can be blown away by a brisk wind on that coast.
28:42Minus two degrees there for Aberdeen, for example.
28:46And those temperatures are well below average.
28:50These are the temperatures and how they compare with average over the next few days.
28:53So several degrees.
28:54This is three to six degrees below average.
28:56That's what the darker blues indicate.
28:59Today, closer to average in the west, then we're below average fairly widely beyond that into Wednesday, into Thursday and so on.
29:10Likewise, minimum temperatures really quite low compared with average Thursday morning, Friday morning, Saturday morning, and then some recovery into Sunday morning.
29:21Why is that?
29:24Just to touch on the change into the weekend.
29:27We've got those northerly winds in place on Thursday, but the Atlantic is starting to get a bit more oomph.
29:35This low pressure is moving away.
29:39Here's Friday starting to see a transition.
29:42Friday, certainly a widespread frost to start things off.
29:46Temperatures down in rural spots where we've got some snow cover well below freezing.
29:50But then we've got these weather fronts moving in for Saturday.
29:56They contain less cold air.
29:58They're mixing with the cold air, though, at the surface.
30:01And so there's always a chance of some additional snow.
30:04But this time on Saturday, well, let's take a look at that because it's not going to lead to such widespread snow.
30:14Mostly it's going to be rain.
30:16You can see a few flakes of snow over higher parts of Scotland.
30:21Another couple of centimetres for higher parts of Scotland.
30:24But the angle that this system is moving in, this is the start of Saturday.
30:28It's mostly bringing rain and temperatures will begin to recover.
30:33And that's highlighted here, really, from these temperature graphs.
30:36Let's take a look, for example, at Newcastle.
30:42Press that again.
30:43Hello.
30:44There we are.
30:45And you can see that little temperature rise into the weekend.
30:48Seven Celsius.
30:50Overnight temperatures back up to the low single figures or the mid single figures.
30:55There's London.
30:56Glasgow.
30:57So we're not seeing particularly mild air temperatures heading back towards average, although not quite as mild as last week.
31:07Not quite as cold as this week.
31:10And there's a reason for that.
31:15And that's because, firstly, there is some uncertainty about Sunday's weather.
31:21This is the European computer model.
31:27Skip forward to Sunday.
31:29This is midday on Sunday.
31:31So I talked about the weather front crossing the UK on Saturday, bringing a spell of rain.
31:35Perhaps there's some additional hill snow in the north before, eventually, something a little less cold moves in from the west.
31:42Then we've got another low coming along for Sunday.
31:45And this low, there's a lot of difference in the computer modelling.
31:49Now, the Met Office model looks something like this.
31:52It's got a relatively deep area of low pressure across the south of the UK, spell of rain and wind.
31:59Cold rare to the north.
32:01But whilst that's matched more or less in Member 5 of the 50-member European model ensemble,
32:11there are a number of other scenarios that are quite different.
32:14So, Member 1, for example, has low pressure over northern Scotland.
32:20And this one here has low pressure over Wales, for example.
32:25And this one has it over the central part of the UK.
32:27There are differences in the track of this low and also in its depth.
32:31And that will make a big difference in terms of what the weather's like on Sunday, how warm, how cold it will be,
32:37and also where we'll see any precipitation.
32:39But as a general rule on Sunday, it looks most likely that we're going to see some more unsettled,
32:46showery weather move in, most likely rain, before that clears through.
32:50And what happens after that is that that low moves away and we're likely to see this is, again,
33:02looking at lots of different computer models and summarising the most likely weather patterns going into the start of next week.
33:08And here's a good way to show it.
33:10This is the top three most likely weather patterns for the start of next week.
33:14That's Sunday the 22nd, Monday the 24th.
33:18And this shows the top three most likely weather patterns.
33:21So we've got low pressure moving across the UK at some latitude and at some depth.
33:27But either way, it's moving across the UK on Sunday.
33:29Second most likely weather pattern still has that low in charge.
33:32So showery, average temperatures, that's what the colours represent.
33:36But the most likely weather pattern here shows northerly winds returning after that low moves off to the east.
33:41Not likely to be wind straight from the Arctic like later this week,
33:46but certainly something a little colder coming in along the back of that low as it moves away.
33:52Then what looks most likely is that we'll have something a little quieter for a couple of days.
33:58That's what some of these projections indicate, most likely weather patterns.
34:03Nothing particularly unsettled or particularly settled.
34:05It looks like next week as a whole will be dominated by a subtle return of Atlantic weather,
34:13but not as wet and windy or as mild as we've seen through November so far.
34:18But equally, not as cold as it's been this week.
34:22So weather systems moving through, but with ridges of high pressure in between, basically.
34:27Frosty nights where we've got ridges of high pressure,
34:30but a little milder when we've got these weather systems moving through.
34:34That explains why, when we look at the chart that I've shown before,
34:38for the most likely weather patterns all coloured up for each day out to the next two weeks.
34:42There are so many colours here.
34:43It's not that we don't know what's happening at all next week.
34:47It's just that we've got various systems moving through at different times.
34:50Different computer models give different timings for those systems.
34:53So we've got a mixture of high and low at times through next week.
34:57Basically, a bit of a ridge moving in, a gap between systems, a day or two of dry, fine weather,
35:03before another band of rain moves through, and so on.
35:05And that seems to be the trend through next week.
35:09Westerlies, occasional spells of rain, not as mild as last week, not as cold as this week.
35:16Temperatures closer to average.
35:18What happens after that?
35:20Well, then we're into December.
35:24And, just to finish off, there is something else that's happening next week
35:29that may be of interest to those of you who've been paying attention.
35:35And it's something called a sudden stratospheric warming.
35:38No time to explain all the ins and outs of sudden stratospheric warmings.
35:42Right now, some of you know what they are and what they mean.
35:45Some of you might not, but there is a helpful explainer on the Met Office YouTube channel
35:51all about sudden stratospheric warmings.
35:53And we can provide a link in the description of this video.
35:57But a sudden stratospheric warming is looking likely next week.
36:01And this chart shows why.
36:02This is from the European model.
36:04And it shows the average wind speed up in the stratosphere surrounding the North Pole.
36:10Now, when the North Pole stratosphere cools through the autumn and into the winter,
36:15you get a stronger circulation going from west to east surrounding that North Pole.
36:19It keeps the cold air bottled up in the stratosphere.
36:22But sometimes you can get disturbances in that flow.
36:25And if those disturbances knock the wind surrounding the stratospheric,
36:31what we call the stratospheric polar vortex, off course,
36:34well, that wind surrounding the stratospheric polar vortex can either slow down or it can reverse.
36:42And if it's reversed, rather than going west to east, it's going east to west,
36:47well, that can rub up against our very own jet stream.
36:50And so the two are linked.
36:51There's a time lag, but the two are linked.
36:53And what we look out for is that, you know, if the stratospheric winds reverse,
36:59then the temperature goes up in the stratosphere above the North Pole.
37:03It goes from very cold to significantly warmer.
37:06Really quite sudden warming.
37:08That's why it's called sudden stratospheric warming.
37:10And this shows the potential for those winds to reverse.
37:13So here we've got westerly winds going up in speed as you go higher in the graph.
37:19And then we've got easterly winds going up in speed as you go lower in the graph.
37:23Here's the line where the wind speed is zero.
37:27And you can see it's dropping through the rest of this month.
37:29And by the last week of November, by next week, start of December,
37:34most of the computer models from the European model show that wind reversing,
37:39a sudden stratospheric warming taking place.
37:42Why is this significant?
37:43Well, firstly, it's unusually early for it to be happening if it happens.
37:47It doesn't often take place at this time of year.
37:52So that's interesting in of itself.
37:55Secondly, it can impact the UK's weather.
37:59Not all the time, but on roughly 70% of occasions,
38:03when this happens, it increases the likelihood of cold weather in the UK.
38:09I should say on 70% of occasions, cold weather happens in the UK.
38:13So 70% chance of a colder than average start to winter.
38:18It all depends on how the jet stream behaves and where we see high pressure building as a result of a weaker jet stream
38:26and the direction of winds and there are lots of other factors involved.
38:28So it's not a guarantee.
38:29But when this happens, and it looks likely to happen next week,
38:33it can, 10 to 14 days later, impact the UK's weather and it can increase the chance,
38:39for example, in this case, of a colder than average start to winter.
38:44So yes, winter's arrived early right now.
38:46Lots going on this week to focus on, particularly that snowfall,
38:50particularly North York Moors, Yorkshire Wolves, for example, on Thursday.
38:53But then could be further interesting things as we go through the next few weeks to watch out for as well.
38:59And we'll keep you updated right here at the Met Office, as always.
39:02Bye-bye.
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