- 8 months ago
This is an in-depth Met Office UK Weather forecast for the next week and beyond. How hot will it get this week? Where could we see thunderstorms? Are we seeing a classic Spanish plume this week? We try and answer all these questions plus a look at Download and Glastonbury festivals. Bringing you this deep dive is Met Office meteorologist Alex Deakin.
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00:00Have we got a fruity deep dive for you this week?
00:03We've got heat, we've got humidity, and yes,
00:06they're going to mix together to create some big thunderstorms.
00:09Where are we going to see them?
00:11How hot is it going to get?
00:13Is it a classic Spanish plume?
00:16We'll be answering all of those questions,
00:17or at least trying to in this week's Met Office Deep Dive.
00:20Thank you for being there.
00:21If you could hit the thumbs up, that would be fantastic.
00:24Please, please also leave a comment.
00:27Let us know if you like this kind of stuff.
00:28Let us know if you've got any other questions about weather and climate.
00:32We may answer them in a deep dive.
00:34We may answer them in our Friday Weather Studio Live as well.
00:38We do try and read all of the comments, so thank you.
00:40Please do keep them coming.
00:42And share the love.
00:43Let other Met heads know that we do this deep dive every Tuesday,
00:47because some people don't know that we do it,
00:49even though we've been doing it for a few years now.
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00:56As I said, quite an interesting one this week.
00:59A classic summer set-up, if you like.
01:01We've got the heat rising.
01:02We've got the humidity rising.
01:04And, yes, that may well lead to some big thunderstorms.
01:08Let's take a look at the big picture first of all.
01:11For the past few days, well, since summer started, really,
01:14if not the week before,
01:15we've had weather systems coming in from the Atlantic.
01:17And, yes, they've been bringing often spells of cloud and rain
01:21and not a huge amount of warmth.
01:23You can see the systems coming in here one after the other
01:25through the weekend.
01:26That was Saturday's rainfall, about a bit of brightness on Sunday,
01:29then another system moving in at the moment.
01:31But things are starting to change.
01:33This area of cloud, this area of low pressure,
01:36isn't whizzing across the country,
01:38and that's because of a shift in the jet stream.
01:40You can see from the flow where the jet has been for the past week
01:44or so generally coming in from the west or the southwest.
01:47But that is starting to shift.
01:48Let's take a look now.
01:50So this is where we're at.
01:51So that swirl of cloud onto the Atlantic,
01:53that is this area of low pressure.
01:55And the jet stream has been kind of in this position,
01:58but a little further west,
02:00taking low pressure systems with it.
02:02But now we're seeing more of a wiggle developing in the jet stream,
02:05starting off that ripple down over the Americas.
02:10And a bit like, you know, giving a rope, a little flick like that,
02:14that is then pulsing downstream.
02:17And what's happening now is instead of the jet stream
02:20pushing low pressure systems this way,
02:22we're getting more of an amplified jet stream.
02:24If we fast forward to tomorrow,
02:26that jet is now going down and up here.
02:28And so that low is kind of trapped.
02:31It's not being pushed along by the jet.
02:32It's trapped in this trough.
02:33And it's just going to slowly meander towards the UK
02:37over the next few days.
02:38Ahead of it, it's allowing high pressure to build.
02:41That's why we're seeing fine weather on Wednesday
02:43for most places and temperatures rising as well.
02:46Notice this little arm of the jet stream, though.
02:50That is going to be crucial to developments
02:53over the next 24 to 48 hours,
02:56as we shall see shortly.
02:58But basically for Wednesday,
03:01as the jet drives south and then to the north again,
03:04this is a similar setup to what we've had for much of spring,
03:06allowing high pressure to build in this upper ridge.
03:09At the surface, we get high pressure
03:11and that's going to bring most places a fine day tomorrow.
03:14And if you put the surface winds on,
03:16take off the jet stream.
03:17These are not actually the surface winds.
03:19These are the low-level winds.
03:20I've changed them slightly,
03:21so they're a bit above the surface,
03:23but they're the low-level winds.
03:24And you can see where they're coming from.
03:27And they're drawing up our air from the south,
03:30from Spain,
03:31where the air is pretty warm at the moment.
03:32And that is why our temperatures are going to be rising.
03:36So let's take a look at the temperatures,
03:39first of all,
03:39for the next few days.
03:40Go through that.
03:42We can see that today,
03:43nothing too remarkable,
03:44getting into the low 20s across the southeast.
03:47Close to the average, really,
03:48for the time of year.
03:48But look at that.
03:49Those temperatures rising over the next few days.
03:53It's going to be warm and humid tomorrow.
03:54Probably the highest temperature,
03:56maybe northern England,
03:57away from that northeast coast in Lance.
03:59Mid-20s, 26, maybe 27 Celsius.
04:03Then on Thursday,
04:04a bit of an uncertainty,
04:05because there's going to be more cloud around,
04:07and the first batch of thunderstorms moving through.
04:10So that opens up a bit more of a question mark.
04:12And then the hottest day of this spell,
04:14likely to be Friday,
04:16across the central and eastern parts,
04:18where temperatures certainly in and around London,
04:20up towards Cambridge,
04:21across East Anglia,
04:22in the high 20s,
04:23with 29 probably the top temperature.
04:26Notice it's not hot everywhere.
04:27However, it does get warmer in Scotland and in Northern Ireland,
04:31but we're not seeing the heat there, really.
04:32Temperatures just ticking up to a little bit above average.
04:35But even though the temperatures aren't rising that much,
04:38pretty much everywhere will notice, I think,
04:39the humidity rising.
04:41And it's going to get warmer by night,
04:43as we can see here.
04:45If we look at the next few nights,
04:47those temperatures getting into the mid-teens across the south,
04:51and staying in the teens further north as well,
04:54Thursday night, Friday night.
04:56And then it turns a little cooler.
04:58It does turn a little fresher as we go through the weekend.
05:00It'll take a while for your house to cool down,
05:02but certainly the next few nights,
05:04you will notice that,
05:05because we haven't really experienced that too much.
05:07When it was warm through the spring,
05:09often the nights were still chilly.
05:10This will be the first time we're getting quite warm nights
05:14over the rest of this week.
05:16So the nights are going to be warm.
05:18That's probably when you notice it most.
05:20But by day, it'll be warm and humid as well.
05:23Some sunny skies, but not all sunny skies.
05:27Let's take a look at the temperatures
05:29when you compare them to average.
05:31And we can see, as I said,
05:32pretty close to average at the moment.
05:34These are Wednesday's temperatures.
05:36And you can see they're kind of peak there,
05:39either side of the Pennines, really.
05:40Low levels across east Wales, northwest England,
05:42so northeast England away from that eastern coast.
05:45Then on Thursday,
05:46really will depend on the cloud cover,
05:48the highest temperatures when compared to average
05:50across eastern parts of England.
05:52And then a warmer day for eastern Scotland on Friday.
05:56And the highest temperatures across the central and eastern parts.
05:59So again, eastern Midlands,
06:01down towards the western home counties,
06:03up towards East Anglia.
06:04That's where we're likely to see the top temperatures on Friday.
06:07And then if we fast forward,
06:08you can see that Saturday,
06:10we're starting to see that fresher air coming into western areas.
06:12But still, temperatures above average across the east.
06:16So that's the detail for the temperatures.
06:18As I said, they will be rising pretty much everywhere.
06:20Certainly the humidity is what most of us will notice most.
06:23It's going to be close.
06:24It's going to be muggy.
06:26Is it going to be sunny?
06:28Well, that will depend on the rainfall that we see.
06:32This is the bigger picture.
06:34As we go through today,
06:35we're seeing that ridge starting to build,
06:37the high pressure building in at the surface.
06:39By the time we get to Wednesday,
06:41the middle of Wednesday,
06:43the jet stream is here.
06:44The high pressure is well and truly in.
06:46The winds at the surface are pretty light,
06:48gently wafting up some warmer air.
06:51And you can see that many areas,
06:53not expecting much clouds tomorrow.
06:54It's been quite grey across the south today,
06:56but tomorrow is a much sunnier day in the south.
06:58Again, fine weather for southern Scotland and northern England.
07:02But down here,
07:04the first clutch of from the storms starting to brew up.
07:09And we could well start to see some heavy downpours
07:11coming into the southeastern corner
07:13by the time we get to Wednesday evening.
07:16So that's the first watch point this week.
07:19The zone of thundery showers coming up from the south.
07:23That pushes north as we go through.
07:25Let's take that off actually and do it on a UK scale.
07:27So that comes up during Thursday into the southwest.
07:31Some heavy bursts of rain for Republic of Ireland
07:34as well as then Northern Ireland.
07:36Loses some intensity as we go into Thursday
07:38and it works further north.
07:40It becomes less kind of a thunderstorm risk
07:43and more just frontal rain pushing northwards
07:45into western Scotland, Northern Ireland.
07:47So yeah, it'll be a bit soggy.
07:49It'll be a bit breezy.
07:50It'll be a big change from Wednesday.
07:52But it shouldn't be anything too heavy at this stage.
07:55And it kind of fizzles out as it works its way then
07:58across parts of central and eastern England.
08:01And then into Friday,
08:04well, we keep the legacy of a weather front out west
08:08with some cloud and rain,
08:09some uncertainty about the position of that.
08:10It could be further west.
08:11It could be further east.
08:12But again, a good chunk of central and eastern Britain
08:15looking fine and sunny on Friday,
08:18which is why we'll see the highest temperatures in this zone
08:22because we'll have, should generally have the sunniest skies
08:24and eastern Scotland as well.
08:26But look at this.
08:28This is that next batch.
08:29We're going to get two rounds of heavy,
08:33potentially thundery downpours coming north this week.
08:36First one Wednesday night and then into Thursday
08:38and the next one then really late Friday,
08:40Friday night and into Saturday
08:42and some angry looking downpours on there,
08:44some really bright colours.
08:47Again, don't take this as gospel.
08:49This is a few days away.
08:51And with these thundery downpours,
08:53there's always some uncertainty about the exact position.
08:55So don't take that as gospel,
08:57but just showing you that zone of potentially very heavy rain,
09:01thundery storms, thundery storms,
09:03thunderstorms, lightning, large hail, gusty winds,
09:06tracking their way northwards Friday night
09:08and then into Saturday.
09:10And by the time you get to Saturday,
09:11you've got actually a circulation.
09:13You've got low pressure swinging in across the country.
09:15Still some heavy rain there Saturday morning
09:18coming into the northwest.
09:20And then further south,
09:21we'll have some showers coming in,
09:22but these will be a different breed.
09:25They won't be the same intensity
09:26because we've changed to fresher air coming in.
09:29So there's not the same amount of energy
09:31with these showers
09:32and they'll be moving through on the breeze.
09:34These are kind of more like the showers
09:35that we've seen of late zipping in from the Atlantic.
09:37Could still have some thunder mixed in,
09:39but there'll be fresher showers
09:41if you see coming in from the west
09:43by the time we get into the weekend
09:44because as we saw earlier,
09:46those temperatures will be dipping off
09:47and we'll have lost some of the humidity
09:49by the time we get to Saturday and Sunday.
09:52And then Sunday, actually,
09:53a decent day again
09:54for a good chunk of England and Wales.
09:56And as we saw earlier,
09:57it won't be as warm.
09:59Those temperatures will have dipped off
10:00a little bit by the time we get to Sunday.
10:03We're looking at those highs
10:05getting closer to average.
10:08Could still see low 20s across the east
10:10with some sunshine.
10:11So yes, it is getting hot this week
10:13in places, but not everywhere.
10:15It is going to feel quite humid,
10:17but it's probably not going to last too long
10:19as we go through the weekend fresher air.
10:21But we do have to watch
10:23those two zones of thundery showers
10:26heading their way northwards.
10:28Wednesday night and Thursday
10:29and then again on Saturday.
10:31Let's take a little closer look
10:33at that rainfall coming in.
10:35If we do the accumulations,
10:39let's show the little spikes
10:41because they're quite funky.
10:43That's the rain coming in.
10:44So these are the three-hour rainfall accumulations.
10:48Anything orangey-red is 25 millimeters
10:51in that three-hour period.
10:54And if we just bend the map down,
10:56you can see actually northern France
10:57could get a real paggering
10:59from that first zone.
11:00So this is through the night.
11:03Look at that, those spikes there.
11:04And across the Republic of Ireland,
11:05some quite heavy downpours
11:06coming their way northwards
11:07through the early hours.
11:09Then into parts of Wales,
11:11southwest England,
11:12across northern Ireland as well.
11:14That then calms down a little bit.
11:17Maybe some individual spikes,
11:18but the intensity loses a bit
11:20as it tracks its way northwards.
11:22And we don't see as many thunderstorms
11:24further south and east.
11:25But, yeah, some big accumulations
11:27in places are possible.
11:29As always with these summer storms,
11:30it is going to be hit and miss.
11:32Don't take those spikes too literally,
11:34but it shows you that one place
11:36could get, you know,
11:3730, 40 millimeters of rain,
11:39whereas just a few miles away,
11:40you may not get much at all.
11:41That's the nature of summer storms.
11:43They're very much hit and miss.
11:46So that's Wednesday night
11:48and into Thursday morning.
11:50Calming down a little bit on Thursday.
11:52If we then look at the extended charts
11:55and show those angry clutches
11:59of storms coming north.
12:01Again, let's put the spikes on,
12:03tilt the map so you can see it
12:04a little bit better.
12:04Again, look at that.
12:05Northern France likely to see
12:06some of the heaviest downpours there
12:09as we go through Friday afternoon
12:11with the heat building
12:12across northern France.
12:13And then as we head through the night,
12:15whoa, look at that.
12:16Look at that.
12:17Ping.
12:19Jumping up, jumping out of there.
12:21Some heavy downpours.
12:22Again, don't take that too literally.
12:24This is even further ahead.
12:25This is into Saturday or Friday,
12:26Friday evening into Saturday.
12:28And there's quite a bit of uncertainty
12:30as I'll show you in a minute
12:31about exactly where we get the rising air,
12:34where we get the thunderstorms.
12:36But again, just showing you the potential
12:38for dropping quite a lot of rain
12:40in a short space of time.
12:41A lot of energy involved in this
12:43because of where the air is coming from.
12:45So, again, it all calms down a little bit
12:49as we go through Saturday.
12:50And the rainfall amounts not quite as intense.
12:54The peak's not quite as high
12:55as we head across into Scotland
12:57and Northern Ireland.
12:58But it could still be quite wet in that zone.
13:00It's more the persistent nature of the rain
13:01coming into western Scotland
13:03during the weekend.
13:04So, a few things to watch out for.
13:07These storms are going to be high energy.
13:09They will drop a lot of rain
13:11in a short space of time.
13:12One other thing I want to show you, actually,
13:14was the winds picking up on Thursday.
13:19In here, let's take that off.
13:23This zone, so ahead of this weather front
13:25in the east,
13:26you could see some quite lively gusts of winds
13:29because the air here is actually
13:30what we're going to call quite stable.
13:32It's not rising too much.
13:33And in this zone,
13:34we could get kind of a layer of trapped winds
13:36brushing along the east coast of England
13:38into eastern parts of Scotland.
13:40That's quite an unusual wind direction
13:42coming over there.
13:43So, the North York Moors
13:44creating some interesting gusty winds
13:47as we go through Thursday.
13:48So, that's an extra feature to watch out for.
13:50Not just the lightning,
13:51not just the temperatures,
13:52but actually some gusty winds
13:54coming in across these eastern areas
13:55as we go through Thursday also.
13:59So, plenty going on in the forecast.
14:02Plenty going on,
14:03as you might imagine,
14:05over the next few days.
14:06And one more thing I want to show you,
14:08just to highlight that uncertainty
14:10about Friday night and Saturday's rainfall
14:14when we run the model many times.
14:16So, what I showed you there
14:16was the Met Office computer model,
14:19the main deterministic run,
14:22as we call it,
14:23of where it thinks the rain
14:24is going to be on Saturday.
14:26But when we run the model many, many times,
14:28if you watch the deep dive,
14:29you'll know about this.
14:30This is called an Ensemble Forecast.
14:32So, you tweak the initial situation
14:34ever so slightly
14:35and generate lots of different potential outcomes.
14:39And this is showing the rainfall pattern
14:41from those different variations,
14:44those slight variations.
14:45They're called the postage stamps.
14:47If I just play it,
14:48it might zoom in.
14:49Yeah, zoom into a couple here
14:50and shows you that variation.
14:52They're kind of,
14:53I mean, they're all pretty similar.
14:54They've got those bright pink colours
14:56and the oranges and the whites,
14:58which show the heaviest rainfall.
14:59But they're in slightly different areas
15:01for each one.
15:02And that's typical in this kind of setup
15:04for four days ahead.
15:06We're not going to pin down
15:07the exact position of these storms coming in
15:11until we get much closer to the time.
15:13But some of them are showing
15:14that eastern England's dry.
15:16Other ones are showing,
15:16like this one, number 29,
15:18that actually eastern England gets the worst of it.
15:20And we get the heavier rain here.
15:21So they really do show
15:23lots and lots of different scenarios.
15:25I mean, they're all kind of telling the same story.
15:27Yes, we're going to get some heavy rain.
15:29Yes, we're going to get some thunderstorms
15:30moving northwards.
15:31But the exact location,
15:32too hard to pin down at this kind of range.
15:35As I said, that's fairly typical for the summer.
15:37So what we're doing now is just flagging
15:39that we are likely to see some thunderstorms.
15:41And then, you know,
15:42you really need to keep up to date
15:43with the forecast,
15:44especially if you've got plans for the weekend.
15:47So download this weekend.
15:48I'll talk more about that in a moment.
15:50And we'll have a look at Glastonbury prospects as well,
15:54if you are interested in the festivals.
15:56But I just thought I'd show you that
15:57to show you that it's not nailed on
15:59where we're going to see the heaviest rainfall.
16:02But we are pretty much nailed on
16:04to see some very lively downpours.
16:08While we're on the subject of the thundery showers,
16:11this projection is showing the probability
16:13or the chance of seeing certain things.
16:17This is quite interesting
16:17because they're highlighting the same area for rainfall.
16:20So this is the probability
16:21or the chance of seeing 10 millimetres of rainfall
16:24from Wednesday night and Thursday's thundery showers.
16:27It's really picking out South Wales
16:29and South West England there.
16:31That's where the highest probability
16:32of seeing 10 millimetres of rainhares.
16:34And that is the probability of lightning.
16:37So that's highlighting, again,
16:39that northern France lightning zone,
16:42but also the same kind of areas.
16:44So it's where I am, actually,
16:46where Met Office HQ is.
16:47Devon and parts of South Wales there for Thursdays.
16:51But if we look at Friday's one,
16:54it's quite interesting the difference we've got here
16:56because this is now the same thing.
16:57So it's the probability of 10 millimetres of rain.
16:59It's actually highlighting that western Scotland
17:02is the most likely area
17:04or the area with the highest chance,
17:06the yellow colours in there.
17:08That's where the highest probability is.
17:10But actually, the highest chance of lightning
17:12is from that clutch,
17:14that heavier clutch of thunderstorms coming up
17:16potentially across East Anglia and the southeast.
17:18That more eastern one
17:19has the highest risk of lightning mixed in with it.
17:22So the different flavours
17:23of those two different types
17:26of fondery downpours
17:28that we're going to see
17:29over the course of the next four or five days.
17:32So lots to talk about,
17:34lots going on.
17:37Are we going to see a Spanish plume?
17:41That's a big question
17:43that's being talked about at the moment.
17:45What is a Spanish plume?
17:47Well, basically, a plume is an area of air
17:50and Spanish suggesting
17:52that it's coming up from Spain
17:54or that kind of part of the world.
17:56Now, the true definition of a Spanish plume
17:59is really quite specific.
18:01But in recent years,
18:03it's been diluted a little bit,
18:04partly by the media,
18:05partly by meteorologists.
18:08And, yeah, a lot of the time,
18:10this kind of setup
18:11that we have at the moment
18:12is described as a Spanish plume
18:14and it's not actually a true Spanish plume.
18:17Now, Spanish plumes are interesting
18:19and really useful to understand
18:21because they generate
18:22a lot of our summer rainfall.
18:25Most of our summer downpours
18:27come from a Spanish plume type setup
18:30where we've got warm air
18:32wafting up from Ibera,
18:34from Spain and Portugal
18:36and dropping thundery showers
18:38across the UK.
18:40This is where we get
18:41some of our biggest thunderstorms from,
18:43large hail, gusty winds
18:45and often a lot of lightning as well
18:47and potentially tornadoes too.
18:49But, as I say,
18:50not all Spanish plumes
18:51are absolute classic Spanish plumes.
18:54A Spanish plume is a kind of thought.
18:58It's a meteorological ideal, if you like.
19:01And, actually,
19:01the weather never really quite plays ball.
19:03Just like most weather fronts
19:04aren't your classic weather front,
19:06most Spanish plumes
19:07aren't your classic Spanish plume
19:09that you'd find in a textbook.
19:10But, what is a Spanish plume?
19:13Well, it's a zone of air
19:14coming up from Spain.
19:17But, its exact source region
19:19is really quite vital.
19:21First of all,
19:21let's take a look at
19:22what we're talking about
19:24because it's quite interesting
19:25when we look at
19:26the geography of Spain,
19:28why that plays a part.
19:30If we head to Spain,
19:31that's a good place to start
19:32if we're talking about Spanish plume.
19:34Zoom in a little bit
19:35and tilt the map.
19:38You can see, actually,
19:38across central and northern Spain
19:40in this area here,
19:42it's called the Maceta Central.
19:44My GCSE Spanish
19:46coming in a treat there.
19:47Miss Cochran will be proud of me.
19:49That's hills,
19:51high grounds,
19:52and quite high ground
19:54covering quite a broad area of Spain.
19:56Madrid, actually,
19:57I think I'm right in saying,
19:58is the highest capital in Europe,
20:00which is not necessarily
20:02what you'd expect.
20:03Most of us experience Iberia
20:04around the coast and by the sea.
20:06But, this part of Spain,
20:07not particularly well populated
20:08away from Madrid,
20:09is actually quite hot.
20:10Quite a lot of hills here.
20:12And, at the moment,
20:13as you can imagine,
20:15it's pretty hot
20:17and especially warm at the moment.
20:19Temperatures have really been rising
20:20over Iberia over recent times.
20:22Let's now put those low-level winds on.
20:25And, if we play through
20:26the next kind of 24 hours or so,
20:29we can watch as those winds
20:31start to switch direction.
20:32There's low pressure developing
20:33off the coast of Portugal
20:34and those winds start to push northwards.
20:38And, as you can imagine,
20:40those winds are going to push
20:41that plume of air
20:42that's sitting over the mountains.
20:44So, it's not at sea level.
20:45It's higher up in the atmosphere.
20:48Those mountains are about
20:49six, seven hundred metres up
20:51and the air above those mountains
20:53gets hot and dry
20:55and it doesn't just sit at six hundred metres.
20:59It goes up a few,
21:00up to about two, three thousand metres,
21:03two or three kilometres up in the atmosphere.
21:05So, you've got a wodge of hot, dry air
21:08and the winds, as you can see,
21:09are pushing that further north
21:11over the next day or so.
21:14If we zoom out a little bit more,
21:16you can see that hot, dry air
21:18getting up to the UK.
21:20That's why temperatures are rising
21:22because the warm air is moving in
21:24but the really warm air,
21:26which isn't sitting at the surface,
21:27remember, it's a little bit higher up,
21:30is drifting up towards northern France
21:32and then up towards the southwest of the UK
21:35by the time we get to Wednesday evening.
21:37Now, if we take a look at what's going on,
21:39this is where my other GCSE skill comes in,
21:44my artistry.
21:46Oh, there's me cheat code.
21:49A little bit of a...
21:51I was doing my homework
21:52just to prove I was doing my homework.
21:53So, what we have across the UK on Wednesday
21:56is a zone of warming air down to the south.
22:04So, it's warm here
22:04and reasonably moist.
22:11You've got some humidity in there as well.
22:13But what then happens
22:14is that air,
22:16that wodge of air from Spain
22:19comes in across
22:21and sits above
22:23that warm air.
22:26And this air is hotter
22:27than the air at the surface
22:29because it's been heated up
22:31over those mountains of Spain
22:32and it's very dry.
22:34We call that an elevated,
22:37mixed layer of air.
22:38It's hot and it's dry
22:39and it comes in,
22:40it sits over that warm air at the south.
22:42And what it does,
22:43it acts like a lid.
22:44It kind of traps the warm,
22:45moist air at the surface.
22:47Now, in a true Spanish plume,
22:49what you then find higher up in the sky
22:52is you introduce cold air,
22:55zone of colder air aloft,
22:57either from a cold front
22:59or some other mechanism
23:01that generates lift
23:03and eventually
23:04you get rid of this lid
23:06of hot air
23:07and the air will rise
23:09all the way through the atmosphere
23:09and when you get air rising
23:11from the surface
23:12all the way to the top
23:13of the mesosphere,
23:14you get thunderstorms.
23:16The only cloud that goes
23:18from the surface
23:18all the way up to 30,000 feet
23:20is a cumulonimbus.
23:22And that's how you generate
23:24thunderstorms
23:25and it's this hot, dry zone.
23:27That is the Spanish plume.
23:28That has come up
23:29from those mountains
23:30over Spain
23:31and pushed its way northwards
23:33and when you get
23:33that classic setup
23:34that we have at the moment,
23:35that's kind of what we've got here.
23:38If we fast forward to tomorrow
23:39and look on that bigger picture,
23:41what's happening
23:41is those winds
23:42coming up from the south,
23:43the hot air
23:44coming in
23:45at those higher levels
23:46and what happens
23:47is this little dig
23:48in the jet stream,
23:50remember I talked about that earlier,
23:52that is what breaks the lid.
23:53It creates forcing,
23:54it creates lift
23:55and it breaks that lid
23:56and everything goes bang.
23:59Another way of looking at it
24:00is through a slice
24:01of the atmosphere
24:01using teffigrams.
24:04So this is kind of
24:05another cross section.
24:07This is from northern France
24:09from our friends
24:10at windy.com
24:11sampling the Spanish plume
24:14if you like
24:14coming northwards.
24:16Now this is temperatures
24:17along the bottom here.
24:20Called a teffigram,
24:21in America
24:21they call it a teffigram
24:22but instead of temperatures
24:24going up like that,
24:25the line of constant temperatures
24:27goes off at an angle
24:28like that.
24:28So if it was 20 degrees
24:29all the way,
24:30it would go up at this angle.
24:30That's the zero degree isotherm.
24:32So that's where it's zero degrees.
24:34That is effectively height.
24:36It's actually measured in pressure.
24:37It's effectively height.
24:38So you cross-section,
24:39broadly speaking,
24:40through the atmosphere.
24:41This red line
24:42is the temperature
24:43of the atmosphere
24:44as sampled at this point
24:45in northern France
24:46and you can see
24:48that the temperature
24:48goes like that
24:49and the blue line
24:51is here.
24:51In fact,
24:51if I play fast forward
24:52we can have a closer look
24:55at it.
24:55The blue line
24:56is the wet bulb temperature
24:58and effectively
24:59the closer those two lines are
25:01the more saturated the air.
25:03So you can see up here
25:04the air is pretty saturated.
25:05That's where we've got cloud.
25:06Now the warm air
25:07wants to rise
25:09from the surface
25:10from down here
25:11but it's just not hot enough
25:13because of this.
25:14See that?
25:15We call that a nose
25:16and you can see why.
25:18It looks a bit like a nose.
25:19You've got to get past that nose
25:21in order for the air to rise
25:22to create the thunderstorms.
25:24But notice in here
25:25you've got that separation.
25:28That is the Spanish plume.
25:29That is the dry zone
25:31not at the surface
25:32higher up.
25:33There is the Spanish plume.
25:35There's the dry air
25:36and the air can't get
25:37that low air
25:39the air right at the surface
25:41can't get past that nose
25:42to rise and create
25:43the thunderstorms.
25:45So there is an example
25:46cross-section
25:47through the atmosphere.
25:47That's the Spanish plume
25:48before it actually rises
25:49and goes up.
25:51But just a few hours later
25:52we have realised
25:54those temperatures.
25:56The jet stream
25:57that forcing high
25:58in the sky
25:58has done its job
25:59and now it's leaning
26:00much more back.
26:01The temperature of the surface
26:02has risen above that nose
26:04and the air is going up
26:05and we've got whoosh
26:06moisture going all the way
26:07up through the atmosphere.
26:09And this isn't
26:09the most moist
26:11that it could be.
26:12This example
26:13they could be closer
26:14those lines
26:14and when they are
26:15then you've got
26:15thunderstorms going
26:16all the way up
26:17and that's what
26:17generates those
26:18thundery showers
26:19that we see.
26:20So that is
26:21in essence
26:22what we're looking at.
26:23Are we seeing
26:24a true Spanish plume
26:26this time round
26:27either on Wednesday night
26:28or on Thursday
26:29or on Friday rather?
26:30Well if we look at
26:31the source region
26:33of our air
26:33these are the trajectories
26:35of our air parcels
26:37at 700, 600 and 500
26:41hectopascals
26:42basically 3,000 to 5,000 metres
26:47and you can see
26:48that the air
26:49well yeah
26:49it is coming from Spain
26:51but it originates
26:51a little further south
26:53it actually originates
26:54across northern Africa
26:55so you could argue
26:56it's not a true
26:57Spanish plume
26:58but it is being affected
26:59by the mountains
27:01of central and northern Spain
27:03it's going across
27:04that area
27:05so well
27:05is it a true
27:07Spanish plume
27:08or not?
27:09I'll leave you
27:10to decide for that one
27:11but the air is actually
27:12being sourced
27:12from northern Africa
27:13and that actually
27:14gives us
27:16an extra element
27:16to these thundery showers
27:18because they're likely
27:18to have picked up
27:19some Saharan dust
27:20so when it does rain
27:23over the next few days
27:24don't be surprised
27:24if your car
27:25is a little dirtier
27:26in the mornings
27:27after that rain
27:28has come through
27:28because it could be
27:29quite dusty
27:30the air
27:31there's quite a bit
27:32of Saharan dust
27:33in the air
27:33source region
27:34at the moment
27:35so it may well be
27:36that you wake up
27:37when there's
27:38little brown splodges
27:39all over your car
27:40from the overnight
27:41thunderstorms
27:42and another thing
27:43that this does
27:43when there's more
27:44dust particles
27:45in the atmosphere
27:47it increases the likelihood
27:48of lightning
27:49there's more condensation nuclei
27:51and you've got
27:51a greater chance
27:52of getting more lightning
27:53because there's more dust
27:54in the atmosphere
27:55as well
27:56so yeah
27:57really interesting
27:58to see where that air
27:59has come from
27:59that's from the system
28:01through Wednesday night
28:02and into Thursday
28:04plenty going on then
28:07with our weather system
28:08oh just one more thing
28:08I want to talk about
28:09with the Spanish plume
28:10the one on Friday
28:11actually
28:13we put the rainfall on
28:15is more generated
28:17by this cold front
28:18coming northwards
28:19rather than thunderstorms
28:20coming in
28:21so again
28:22probably not
28:24a classic Spanish plume
28:26in that sense
28:26with these fronts
28:27coming northwards
28:28and generating
28:28their own rainfall
28:29rather than just
28:30that destabilisation
28:31of the hot air
28:32from the south
28:33so again
28:34they're never quite
28:36the textbook classics
28:37but two examples
28:38of almost Spanish plumes
28:41coming through
28:42the rest of this week
28:43what about looking
28:45beyond that
28:45well actually not
28:46too far beyond that
28:47let's get back
28:47to the weekend
28:48because I promised
28:48festival goers
28:50a glimpse
28:50at what could happen
28:52this weekend
28:53Donington Park
28:56place I've been to
28:57to watch the motorbikes
28:58many many years ago
29:00is where download festival
29:01I've never been to
29:02download festival
29:02but let's zoom in a little bit
29:04we should be able to get
29:05Leicester on the map
29:06yeah
29:06so in here
29:08showers likely
29:10on Thursday
29:11from that first pulse
29:12of heavy down
29:13not the same intensity
29:14by the time they get
29:15this far north
29:15so if you're going
29:17on Thursday
29:18getting set up
29:18that kind of thing
29:19well there might be
29:20a few showers
29:20around on Thursday
29:21Friday for the first day
29:23of the festival
29:24looks pretty good actually
29:25I mean it's going to be
29:26hot it's going to be
29:27humid not particularly
29:28great for camping
29:29in a tent
29:29but by the time
29:30you get to
29:31late Friday afternoon
29:34increasing chance
29:35of seeing some of those
29:35thundery showers
29:36now
29:37it's impossible to say
29:39exactly as we've already
29:40discussed when and where
29:41but certainly
29:42I would say
29:43Leicestershire
29:43in the fiery line
29:44for some of those
29:45thunderstorms
29:46most likely Friday
29:47night and into Saturday
29:48so that is something
29:49to take into account
29:50if you are going
29:51to download this weekend
29:52it's going to be warm
29:53it's going to be humid
29:54Friday looks like a nice day
29:56risk of thunderstorms
29:57Friday evening
29:58Saturday
29:59possibly showery
30:01but not too many showers
30:03and Sunday looks like
30:04a decent day as well
30:05and it will be turning
30:06fresher through the weekend
30:07also
30:08but be prepared for some
30:08quite high temperatures
30:09on Friday
30:10and watch out for those
30:12thunderstorms too
30:13what about the other
30:15big festival on the horizon
30:17Glastonbury
30:18I mentioned this in our
30:19TikTok yesterday
30:20you can go and check that
30:21out on our TikTok channel
30:22just wanted to show you this
30:25because I thought it was fun
30:25these are the different
30:28flavours of weather
30:32that we could see
30:33Aidan's done lots of
30:35deep dives on this before
30:39and we've talked about
30:41them before
30:41the different types
30:42of weather flavour
30:43that you can get
30:43when you break down
30:44the weather
30:45into different kind
30:45of pigeon holes
30:46rather than saying
30:47it's definitely going
30:47to be hot and sunny
30:48different kind of
30:49influences of our weather
30:50these are the main
30:51eight types
30:52and that then breaks
30:53down into a further
30:5430 categories
30:56as I say
30:56Aidan's done a deep dive
30:57on this before
30:58you can check that out
31:00for more details
31:01but I wanted to show you
31:02this
31:02I've pinpointed
31:03Glastonbury there
31:05pretty much
31:05or close to Glastonbury
31:07near enough
31:11and if we look
31:13at the flavour
31:14at the moment
31:14Scandinavian high
31:15is dominating
31:16at the moment
31:16week two
31:18next week
31:19let's take the
31:20rainfall off
31:21because I just
31:22wanted to show you
31:22this
31:23oh that's gone
31:25need to keep that on
31:26so
31:26there we go
31:28week three
31:30is actually
31:30when Glastonbury
31:31starts
31:31this is Tuesday
31:32the 24th
31:33I think people
31:34can get in
31:34from the Wednesday
31:35is it
31:36the Wednesday
31:36the 25th
31:37around that time
31:38but if we go
31:38through those
31:39three days
31:40four days
31:42or five days
31:43even up to Sunday
31:44those
31:44that period there
31:45just want to draw
31:46your attention
31:46to these dots
31:47because they're
31:48the different types
31:49of weather
31:50that are possible
31:51of those 30
31:51different ones
31:52and if we just
31:52run through them
31:53there
31:54the size of the blob
31:56is how likely
31:57they are
31:58don't worry too much
31:58about that
31:58but I just want to
31:59highlight the distribution
32:00because at this stage
32:01it's really too hard
32:02too early to say
32:03anything with any
32:04definition about
32:05exactly what the
32:05weather is going
32:06to be like
32:06but I just wanted
32:06to highlight
32:07there are more
32:08drier scenarios
32:10than there are
32:11wetter scenarios
32:11go through those
32:12few days again
32:13that scatter plot
32:14there suggesting
32:15that there's a
32:16higher chance
32:17of it being drier
32:17than it being wetter
32:18and probably cooler
32:20but that just means
32:21cooler than the
32:22long term average
32:22if it's dry
32:23and it's sunny
32:24it'll still feel
32:24pretty warm
32:25but generally speaking
32:26there are more
32:27drier solutions
32:28than wetter solutions
32:29that was all I wanted
32:30to draw your attention
32:31to there
32:31that's all we can say
32:33at this stage
32:33it's over two weeks
32:34away to Glastonbury
32:35so keep up to date
32:36with Met Office
32:37Forecast
32:37follow us on TikTok
32:38we're posting about it
32:39pretty regularly
32:40on there
32:41in the coming weeks
32:42but at the moment
32:43there is a higher chance
32:45of it being drier
32:46than average
32:47than being wetter
32:48than average
32:48and that's pretty much
32:49about all we can say
32:50about Glastonbury
32:51at this stage
32:52right
32:54I think that's about it
32:55from me
32:55for today
32:56it's been an intense one
32:57I hope you've enjoyed it
32:58if you have
32:59do hit that like button
33:00do give us a thumbs up
33:01that would be fantastic
33:02do keep your comments
33:03coming as well
33:04make sure you're
33:05checking out
33:05everything that we're
33:07doing across social media
33:08I've mentioned our
33:08TikTok channel
33:09you can follow us
33:10on WhatsApp
33:11as well
33:11we post regularly
33:12on there
33:13if you've not subscribed
33:13to this YouTube channel
33:15then make sure you do
33:16that as well
33:17because that's
33:18pretty much the only place
33:19that you can watch
33:20the deep dive
33:21and you can get it
33:22on your TV as well
33:23on your YouTube channel
33:24also
33:24so yeah
33:25make sure you've hit subscribe
33:26do give us that like button
33:28do keep the comments
33:29watch out for us
33:30on Friday
33:31it'll be the weather studio live
33:33I think it's me and Aidan
33:34and Aidan will have
33:35the 10 day trend
33:36tomorrow as well
33:37so he'll have more details
33:37about the thunderstorms
33:39at the weekend
33:40and what could happen
33:41as we go into next week
33:42but that's it from me
33:43for now
33:44thanks for watching
33:45I'll see you again soon
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