Deep Dive 12/12/2023 – Warming this week, what about Xmas? – Met Office weekly weather forecast UK
This is an in-depth Met Office UK Weather forecast for the next week and beyond.
A big shift in the jet stream brings a big change to our weather patterns this week and a calmer drier spell of weather is on the way but how long will it last and what about the weather for Christmas? Any whiff of snow?. Bringing you this deep dive is Met Office meteorologist Alex Deakin
A big shift in the jet stream brings a big change to our weather patterns this week and a calmer drier spell of weather is on the way but how long will it last and what about the weather for Christmas? Any whiff of snow?. Bringing you this deep dive is Met Office meteorologist Alex Deakin
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NewsTranscript
00:00 After what seems like months of wet and windy weather, is everything finally settling down?
00:06 How warm could it get this weekend?
00:09 And the biggie, is there any hint of a whiff of anything white for the festive season?
00:15 We'll try and answer all of those questions in this week's Met Office Deep Dive.
00:20 Welcome along.
00:21 My name's Alex Deakin.
00:22 I'm a meteorologist here at the Met Office.
00:25 This is coming to you from Met Office headquarters in Exeter in Devon.
00:30 And the Deep Dive is exclusive to YouTube.
00:33 So do hit subscribe and then you'll never miss a forecast, but you'll also never miss
00:38 a deep dive.
00:40 This is where we look at some of the more interesting facets of our weather over the
00:45 next few days or even weeks.
00:48 It'll be 20, 25 minutes, something like that.
00:51 Welcome along if you've not seen it before.
00:53 If you've seen it before, then you know the drill.
00:55 I thank you very much for your comments at this point.
00:58 But honestly, we really do love all of your comments.
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01:32 because as I say, we do read them.
01:34 Okay, let's get into it because as always, there's plenty to talk about.
01:40 We'll start with the bigger picture, the view from space.
01:42 You can see swirls have been barreling their way across the UK.
01:46 Low pressure systems, a couple of them were actually storms named by Met Air.
01:51 The Weather Service in the Republic of Ireland, we had Storm Ellen and Storm Fergus over the
01:55 course of the weekend.
01:56 They have since drifted away, but we do have another area of low pressure still dominating
02:01 our weather at time of recording on Tuesday.
02:04 You can see these swirls just moving in quite nicely.
02:07 But what I really want to draw your attention to is line on the satellite image.
02:12 As we go back even to the weekend, that was in place across Iberia, northern Spain, northern
02:18 Portugal into southern parts of France.
02:20 This line is actually telling us almost exactly where the jet stream is.
02:24 This is Cirrus generated high up in the sky by the jet stream.
02:28 It's Cirrus generated by the jet stream.
02:30 That's basically showing us where the jet stream is and as a result, it's been pushing
02:34 those low pressure systems that we've seen our way.
02:38 Let's take a closer look at what's going on at the moment because as I said, we've got
02:42 low pressure sitting over us.
02:44 We've seen a band of rain moving in overnight, the bright colors there, some pretty heavy
02:48 rain.
02:49 We've seen some yellow warnings that have been pivoting around.
02:52 That weather front's been moving through but down to the south, we've seen some very lively
02:55 showers, some very pokey showers indeed over the past 12 hours through the course of Tuesday
03:01 morning.
03:02 These showers behind this weather front have been moving in and we've seen some lively
03:07 downpours across Wales but also across southern parts of England and quite a few thunderstorms
03:11 as well.
03:12 Let's put the lightning on and we can just zoom into those for Tuesday morning.
03:18 We have to fast forward because we've got five days worth.
03:20 There weren't many thunderstorms over the course of the weekend but over the past 12
03:26 hours or so, just across the south there, notice how the lightning flashes start across
03:31 the sea but then we saw a batch of them just there towards the end across the southeast
03:36 of England, across, where is that, Kent-Sussex border, is it?
03:40 Yeah, just in there, blinking, you miss it.
03:42 But some lively thunderstorms, you probably noticed those if you were under them earlier
03:46 on today.
03:47 So we've seen some heavy showers, we've seen a lot of wet weather through recent weeks
03:52 actually all because of low pressure.
03:55 But let's just again come back to the here and now on the bigger picture.
04:02 Just pause it there however.
04:03 So we've got the jet stream in here and you can see that swirl there, that's low pressure.
04:07 If we just flip it straight away, you can see that, that's the pressure and there's
04:11 the jet stream.
04:12 So they're in almost exactly the same spot, that low pressure system being pushed along
04:16 by the jet stream.
04:18 But a big, big change.
04:19 So this is the setup for time of recording for Tuesday, low pressure sitting slap bang
04:23 over us, the jet stream to the south of us.
04:26 Fast forward 24 hours, the jet stream's getting messy, that low pressure system is exiting
04:31 away.
04:32 Fast forward another 24 hours, notice a trend here, where's the jet going?
04:36 It's shifting northwards and that continues through Friday and by the time we get to Saturday,
04:42 the transition is complete, a complete switch around.
04:45 We've now got high pressure sitting just to the south of the UK and the jet has moved
04:50 way up to the north.
04:51 So we've gone from a south shifted jet to a north shifted jet through the second half
04:56 of this week and that is going to bring a dramatic change.
04:58 We say goodbye to the low pressure systems, we say goodbye to the spells of wet weather
05:02 and we say hello high pressure and hello dry weather.
05:07 And for most of us, it is going to be a lot drier really from Thursday onwards because
05:11 of that switch around.
05:13 Now not completely, in the next 24 hours we do still have low pressure system just steadily
05:18 clearing away so I haven't quite said goodbye to all of the heavy rain.
05:23 Let's zoom in a little bit on that actually.
05:28 Because the low is only slowly pulling away as we go through, let's take the jet off,
05:32 don't need that anymore.
05:33 So the low is gradually edging away as we go through the next 24 hours but it's still
05:38 going to be around, let's take a closer look actually, put the pressure on that and fast
05:43 forward to tomorrow.
05:45 Rewind a little bit.
05:46 So there's the low, this is tomorrow.
05:50 So you can see with the low pressure system in here it is heading that way but with the
05:52 winds going around the low pressure anti-clockwise it's still drawing in quite a brisk breeze
05:58 down this eastern side and that is also going to generate a lot of cloud and quite a few
06:02 showers so many places still waking up tomorrow to cloud and some outbreaks of rain.
06:06 Down this eastern side it's going to take most of the day before that low finally pulls
06:11 away and these winds start to ease.
06:13 So eastern England especially, so East Yorkshire, Lincolnshire, East Anglia and the South East
06:18 still having a pretty drab day tomorrow with outbreaks of rain but elsewhere we'll see
06:22 the brighter skies and some sunshine.
06:24 Now there is a weather front just toppling into the North West you'll have noticed as
06:27 well so that is also moving in Wednesday night and into Thursday.
06:32 Zoom out a little bit on that.
06:34 But that's starting now to bump up against the high pressure so it will bring some rain
06:38 in but it will also kind of fizzle out as it bumps up against the area of high pressure
06:43 and then from then onwards really it's really from Friday onwards that we're under the influence
06:50 of the high pressure to the South of the UK and that is going to bring many places a lot
06:55 of dry weather.
06:56 But notice it's still quite windy, notice there are still some brisk winds.
07:00 The isobars even though it's high pressure down here it is to the South of the UK still
07:03 a lot of isobars in the chart.
07:05 So still quite windy in here, still some brisk winds, let's put those winds on.
07:10 That will have an impact to make it feel cooler but with this area of high pressure actually
07:15 drawing the winds up from the South West it is drawing up warmer air.
07:20 And we can put the air mass on now and show you that so again if we rewind back to where
07:25 we are it's a bit of a mishmash with low pressure in at the moment.
07:28 But fast forward the next few days those weather fronts trying to do something a bit cooler
07:32 but as the high builds in Thursday and Friday it is bringing with it that warmer air from
07:38 the South West.
07:39 Almost up from the tropics, let's play through that again, that warmer air, there it goes
07:44 right across the UK as we go into the weekend.
07:47 So it is going to get quite a bit milder as we go through the weekend.
07:51 By day you may not notice it particularly if you've been in the South where it hasn't
07:54 actually been that cold over recent days but we will notice it at night in particular.
07:59 Now two things happening here we are seeing that warmer air come up from the South West
08:03 but notice as I said it is still quite windy across the North and that is going to have
08:08 an impact, quite a brisk wind coming in here across North Western areas and that is key
08:13 for generating even higher temperatures across parts of Scotland in particular.
08:19 Let's have a look, see how high we are going to get with these temperatures.
08:22 I'm going to put a graph, some graphs now of the minimum temperatures over the next
08:28 few days and this is looking at Eastern Scotland.
08:30 So if we come down to the South here, notice actually the minimum temperatures for the
08:35 next few days will get a little colder through the middle of the week before it gets a little
08:38 bit milder again, that's because we will start to see clearer skies, cloud cover is quite
08:43 important across the South.
08:44 So actually say that the South you will see a dip in temperatures mid-week before it gets
08:48 milder.
08:49 But if we just look at particularly Eastern Scotland here, North Eastern parts of Scotland,
08:54 the far North East of Scotland, Caithness, Southern, look at these, these are the minimum
08:58 temperatures.
08:59 So Wednesday morning 1.2 could well be a touch of frost across Scotland.
09:04 By the time we get into the weekend, these are the minimum temperatures, 9.6 Celsius,
09:09 well above the average maximum for Northern Scotland at this time of year.
09:13 So we could easily be seeing temperatures staying in double figures across parts of
09:17 Scotland into the weekend overnight.
09:21 That is pretty unusual, fairly exceptional, and that's because of something called the
09:24 Fern Effect, so that the strong winds are also impacting on these temperatures as we
09:29 will see shortly.
09:31 How unusual is that?
09:32 Well, I've got a chart to show you that.
09:35 In fact, as things get milder through, you'll notice the daytime temperatures getting higher
09:40 as well, so we're talking temperatures in the mid-teens in places, perhaps even a little
09:44 higher than that in one or two spots.
09:46 But I think it'd be the nighttime temperatures that we notice the most.
09:50 Now, this is something called the Extreme Temperature, or the Extreme Index from the
09:55 European model, ECMWF, from when we run the model many, many times.
10:00 And it compares the ensemble, when you run the model many times, to the average for that
10:08 particular place and that particular time of year.
10:11 Now, the orange colors in here are representing on the index, a darker orange color, anything
10:17 above 0.8.
10:18 Now, anything above 0.5, anything yellow, is basically unusual, but anything orange
10:23 will be classed as extreme.
10:26 These are the averages for this time of year.
10:28 These are averaged over the whole day, and we're looking there at between 5 and 15 degrees,
10:33 generally across the UK.
10:35 But this is indicating the extremes.
10:37 I'm going to zoom in on that because we've got a closer map here.
10:41 You can see, there you go, that's better.
10:43 Thanks, Steve.
10:44 So, in the UK, the southern half of the UK, not colored in there, so it's not unusual
10:48 for the southern half of the UK, the temperatures we're going to see.
10:50 But across from really what, Northern Ireland, Northern England, those orange colors and
10:54 even some reds in there, indicating extreme index, could be 0.8 or above.
10:59 So extreme temperatures are likely in this part of the world as we go through.
11:04 This is Friday into Sunday.
11:06 So that's how unusual.
11:07 It's almost plotting where the most unusual weather is.
11:11 And you can do that on the ECMWF, not just for temperature, but things like rainfall
11:15 as well.
11:16 So that's a really useful guide telling us how unusual it could be through the course
11:20 of this weekend.
11:21 The maximum, sorry, the record minimum temperature for Scotland in December is 12.5.
11:29 That's been recorded a couple of times.
11:31 Back in '94, there was a really warm spell, and that's when the UK record was set.
11:37 That was recorded in Wales, and that was 15 degrees as a minima.
11:41 That was in Wales in '94.
11:43 Unlikely to break that, but there is a reasonable chance we're going to get very close to that
11:47 Scotland record for December of 12.5 Celsius.
11:50 As I said, we picked out some that are likely to stay in double figures, but a few locations
11:55 could stay above that 12.5, which is a December record.
11:59 The other record for the UK or for the nations, 13.7 is the England record, 14.3 is the Northern
12:05 Ireland record, that was also set in '94.
12:08 They're unlikely to be broken, but that, as I say, that Scotland record is something to
12:12 watch as we go through the weekend, those nighttime minima.
12:15 The daytime records also possibly under threat, but that depends on a lot of things coming
12:20 together.
12:21 So it seems unlikely at the moment.
12:22 The more likely record we would break would be that nighttime temperature one.
12:26 So yes, some very mild weather heading our way through the weekend, a lot of dry weather
12:30 as well.
12:31 It's not necessarily going to be gloriously sunny, however.
12:35 Again, as we go through the forecast, Friday, again, we don't really need a jet stream again,
12:41 with this high pressure, it's not completely, it's down to the south, it's not sitting right
12:45 over the UK.
12:46 High pressure is where the air is descending.
12:48 So you're still going to get a feed of moisture in from here.
12:51 So it could still stay fairly cloudy.
12:53 So I'm not promising sunny skies and gorgeous winter sunshine through Friday and the weekend.
12:58 There'll be some bright weather around, but the key thing is certainly across a good part
13:02 of the UK, it's going to be a lot drier than it has been, but still quite breezy with those
13:07 strong winds up to the northwest.
13:10 What happens after that?
13:11 Well, every chance that this high may well actually stick around as we go through the
13:16 weekend, Sunday, and even into Monday.
13:23 It does show signs of weakening a little bit, but most of the models are signaling that
13:27 high pressure is going to be at or close to the south of the UK.
13:29 There's a weather front toppling in, which will actually reduce those temperatures by
13:33 night across northern Scotland as that weather front comes in at some point through the early
13:38 part of next week, maybe through Sunday night.
13:41 So those warmer nights in Scotland probably won't last all that long, but it is going
13:45 to stay dominated by high pressure.
13:48 And the most likely setup, certainly for the first half of next week, is something like
13:51 this.
13:52 Now, this is showing the pressure anomaly.
13:54 Those reds are not temperature, it's pressure anomaly, so how much higher or lower pressure
13:59 is compared to average.
14:01 But higher than usual pressure set to dominate across the south through well into the middle
14:06 part of next week, with lower than average pressure just to the north of the UK.
14:10 And with that setup, it basically means more of the same.
14:13 So westerly winds, northwestern Scotland will see showery rain at times, but a lot of the
14:17 UK will have a lot drier weather, likely to continue well into next week.
14:23 Probably Monday, Tuesday, then around the middle of next week, we could start to see
14:27 a shift.
14:29 Quite a bit of uncertainty.
14:30 I should expect this is over a week away.
14:32 But the general weather pattern is going to keep high pressure somewhere to the south
14:36 or southwest of the UK.
14:37 But if that high starts to shrink away, that does allow the potential for something a little
14:43 chillier to come in from the northwest.
14:46 And that is actually the most likely setup from midweek of next week as we go in.
14:51 And I've been working with Nick Silkstone, our deputy chief meteorologist, who is a remarkably
14:58 clever guy.
14:59 And he's been looking at the potential weather regimes as we go through next week and up
15:04 towards the Christmas weekend, of course.
15:07 And the most likely scenario is this one here, certainly for the early part of the middle
15:11 part of next week, rather, for the Wednesday, Thursday session of next week.
15:16 Wednesday, Thursday, Friday part of next week.
15:19 The high pressure may well start to topple.
15:21 We've still got the jet stream up here.
15:23 But the high pressure edges away to the southwest.
15:25 And that just opens the door for something of a colder spell, some cooler air coming
15:31 in from the northwest.
15:32 I'll just zoom in on that one a little bit as well.
15:34 So this is the most likely regime for the middle part of next week.
15:38 The high edges away.
15:39 And we see something colder coming in from the northwest.
15:41 Now that's not particularly cold.
15:43 It just means a northwesterly wind is more likely.
15:46 And as we say here in the text, it means that periods of northwesterly winds become more
15:50 likely through the second half of next week.
15:52 That does mean the temperatures will drop off and we'll see something a little bit colder,
15:56 which in December does open the door for something a bit wintry, but snow likely to be mostly
16:01 over hills.
16:02 But the potential for some snow and ice in this scenario, that's for the middle to latter
16:07 part of next week.
16:08 Then as we go into the Christmas weekend, these two scenarios become kind of equally
16:13 likely.
16:14 And this one is where the high builds back in.
16:17 That middle one is like we'll see for most of next week with the high pressure closer
16:21 to the southwest, the jet stream toppling back in and that cutting off, if you like,
16:25 cuts off the colder air and we see a return to milder weather.
16:29 As I say, these two scenarios both seen as equally likely as we go towards the Christmas
16:35 weekend.
16:36 Another potential possible scenario or regime is that it all shifts back further to the
16:41 west.
16:42 Again, I'll show you in the closer up one.
16:44 It all actually shifts to the west.
16:46 The high shifts west.
16:47 There is a colder northwesterly, but that also shifts and we see we're on the other
16:52 side of it again and get something a little warmer coming back up across the UK as we
16:56 see on the other side of that of that trough.
16:59 So they're the most likely three regimes or scenarios as we head towards the Christmas
17:05 weekend.
17:07 This one does suggest something a little bit colder, but notice even in this scenario,
17:11 it's not a northerly, it's not a northeasterly set up.
17:16 It's just a kind of northwesterly with a few showers bringing some winterness over the
17:20 over the hills, potentially perhaps at lower levels.
17:23 But obviously, that's something we'll be keeping a very close eye on as we get towards the
17:27 Christmas period.
17:28 And we'll have more on all of that in the 10 day trend, which Annie will be doing tomorrow.
17:34 Annie Shuttleworth doing the 10 day trend tomorrow.
17:36 So another reason to hit subscribe.
17:38 And then you won't miss that when we put that out through Wednesday afternoon.
17:42 And obviously, as we run up towards Christmas and lots of travel plans, we'll be keeping
17:46 you posted on on all the potential weather.
17:50 And for those day to day details, and if you really are desperate for snow, then you need
17:54 to kind of tune in this time next week because it's just too early to say with any kind of
17:59 detail.
18:00 So these are just the potential scenarios that could happen.
18:03 But locating rain or specific weather on any day, it's just too early to say at this stage.
18:08 So make sure you again hit subscribe and then you'll see all of our forecasts in the run
18:12 up to Christmas.
18:14 But I thought I'd touch on, you know, it is that time of year people are getting very
18:17 excited about a white Christmas.
18:19 So what is even the definition of a white Christmas?
18:21 Because a lot of people don't really know.
18:24 Lots of people think a white Christmas is, you know, deep and crisp and even, a foot
18:29 of snow outside their front door.
18:31 But that's not the meteorological definition of a white Christmas.
18:35 The meteorological definition of a white Christmas is just one measly flake of snow.
18:39 If you see one flake of snow, it could be mixed in with some sleet between midnight,
18:46 Christmas Eve into Christmas Day, and the end of Christmas Day into Boxing Day, between
18:50 midnight and midnight.
18:51 If you see one flake of snow, you can say that you have had a white Christmas.
18:55 That is the Met Office definition.
18:57 And by that definition, actually, most Christmases somewhere in the UK are white.
19:04 Most in the UK, more than 50% of the time since 1960 is recorded a white Christmas by
19:09 that simple definition of one flake of snow.
19:13 Because, you know, seeing flakes of snow across the mountains of Scotland in late December
19:17 is not that unusual.
19:20 Typically, if you compare December to January, then December is a lot less snowy.
19:27 February, also quite a lot snowier than December.
19:30 March, even, you are more likely, across the whole month of March, to see snow than you
19:35 are in December.
19:36 But, of course, that's skewing it a little bit because Christmas comes towards the back
19:40 end of December.
19:41 So it's a bit of a myth about that, more likely to see snow at Easter than you are at Christmas.
19:47 But technically, you are more likely to see snow in March than you are in December.
19:53 But for a white Christmas, you just need one flake of snow.
19:55 And I say by that definition, I think since 1960, somewhere in the UK has recorded a white
20:01 Christmas more than 50% of the time.
20:04 So you are more likely to have a white Christmas somewhere in the UK.
20:08 But for that kind of general impression of a white Christmas, widespread lying snow,
20:13 now that is rare.
20:15 Only four times since 1960 have we recorded widespread lying snow.
20:20 By widespread, I mean by more than 40% of our observing network have recorded lying
20:26 snow since 1960.
20:28 So I say white Christmases where the snow is lying everywhere are pretty rare.
20:32 Last one of those was 2010.
20:34 Who remembers that?
20:35 Put it in the comments if you remember 2010 and the white Christmas.
20:38 But there have been white Christmases since, but only, I say, by that definition of just
20:42 seeing one flake of snow.
20:45 If you are a snowmantic, then as I say, please do keep up to date with all of the latest
20:50 forecasts from the Met Office.
20:53 Please do keep all your comments coming in as well.
20:55 There will be another deep dive next week.
20:58 So again, we'll have more on the chances of a white Christmas and the weather generally
21:04 in the run up to the Christmas period.
21:06 Hit subscribe, hit like.
21:07 And as I say, please do share this with people who are into weather.
21:12 Thanks for watching.
21:13 See you soon.
21:13 See you soon.