Deep Dive 13/08/2024 – Heat, lightning, meteor showers & Northern Lights – Met Office weekly weather forecast UK
This is an in-depth Met Office UK Weather forecast for the next week and beyond. After a dramatic day on Monday with hot and thundery weather followed by a meteor shower and the northern lights overnight, we look at what’s to come. We also look at how heatwave forecasting is improving and the events at Boscastle 20 years ago. Bringing you this deep dive is Met Office meteorologist Alex Burkill.
Transcript
00:00Heatwaves, lightning, meteor showers, the northern lights, even some flooding.
00:04I have a lot to get through in this deep dive.
00:08And so let's get to it.
00:09Hello, welcome.
00:10I'm Alex Burkill, presenter and meteorologist here at the Met Office.
00:14And as always, this deep dive is coming to you exclusively on YouTube.
00:18And as always, if you like anything that I talk about, do hit the like button.
00:22If you have any questions, why not leave a comment?
00:25And if you want to share it with someone that you think might be interested in anything
00:29that I've been through today.
00:31But let's get to it.
00:32Like I said, a lot to get through.
00:34Last night, were you lucky enough to see the northern lights?
00:37There was a good, great display across much of the country.
00:41There were sightings even as far south as Devon and Cornwall, which is relatively rare.
00:47The reason for the northern lights being so dramatic last night, well, there was up to
00:51four coronal mass ejections which headed towards the earth, and that led to a strong or severe
00:57geomagnetic storm, which actually started to pick up during the daytime yesterday.
01:02But we still saw the effects of it as we went into the overnight period, which is why many
01:06places were lucky enough to see images such as these behind me.
01:12This wonderful picture from Rodri Viney in Aberaeron.
01:15Then there's another stunning picture from Atmet Jam on Twitter on X.
01:20And with this as well, not only the northern lights, but you're seeing the Perseid meteor
01:24shower, which was also in display last night.
01:27It peaked around Sunday, Monday night, and it's a really dramatic meteor shower.
01:32You get around 50 to 100 meteors an hour, and it's caused by the earth traveling through
01:37the debris of Comet Swift-Tuttle, and this is what gives this dramatic, the shooting
01:43star effect as we see the meteor shower occurring.
01:47As well as these images, I had many sent to me on Twitter or X, so please remember my
01:52handle is AtWeatherAlex if you do ever want to share any weather images, do reach out
01:56to me there.
01:57This lovely image again showed the northern lights and the Perseid meteor shower from
02:01Met Forecast UK.
02:03Lovely display of the northern lights from UK Weather Chase as well.
02:07And then this one from Warwickshire from Jack March as well, just shows that lots of places
02:12across the UK were lucky enough to see the northern lights last night.
02:16And so I know the question, are we going to see it again tonight?
02:20And there are a few things at play to answer this.
02:23Firstly, I mentioned the fact that we had that geomagnetic storm that started during
02:28the daytime yesterday.
02:29It is now easing.
02:30We've seen it at its strongest already.
02:33So with that, the signal becomes weaker.
02:35And so it's not out of the question, especially the further north you are, so northern parts
02:39of Scotland, a reasonable chance that we could see a bit more of the northern lights as we
02:44go through this evening and overnight into Wednesday.
02:47But we need to look at cloud cover.
02:49Last night, the clouds were pretty clear.
02:53And so we had lots of clear skies around, and that led to the fact that many places
02:57had a reasonable chance of seeing it.
02:59However, tonight, there's a bit more cloud around.
03:02We have a front that's making its way southeastwards across the UK.
03:06And with that front, there's rain.
03:07There's also quite a bit of cloud.
03:09So the chance of us seeing it, a little bit less.
03:11And the chance of you seeing the Perseid meteor shower, also a bit less because of the cloud
03:15as well.
03:16That being said, as that front clears away towards the southeast, there will be some
03:20clear skies developing.
03:21And it's across Scotland, maybe Northern Ireland, that we're going to see those clearer skies,
03:25particularly during the second half of the night.
03:28And like I said, it's across Scotland where we have the greatest chance, especially towards
03:31the north of Scotland, of seeing the northern lights again.
03:35And so there's a reasonable chance.
03:37It's definitely not out of the question.
03:39But I think most places, less likely to see it than last night because the signal's significantly
03:44weaker and there is quite a bit more cloud around as well.
03:48But if you do see any images, why not send them to us of either the northern lights or
03:52the Perseid meteor shower?
03:54Did you see them last night?
03:55Let me know in the comments.
03:57The other thing that happened yesterday, which most of you will no doubt be aware, it was
04:01the hottest day of the year so far.
04:04We had temperatures reaching 34.8 Celsius.
04:08The highest temperature was recorded in Cambridge.
04:10Now obviously this is a provisional figure at the moment.
04:13Our verification team will verify the data to make sure that the site's safe and the
04:19site is up to scratch and that it is a reliable data source.
04:25But we're going with 34.8 being the highest temperature recorded yesterday and therefore,
04:30yes, the hottest day of the year so far.
04:33But the thing that we've looked into and I wanted to draw your attention to is the fact
04:36that days as hot as yesterday are becoming more frequent.
04:40If we look back over the decades and in the 1970s, we only reached 34.8 or higher in one
04:48summer and that was in 1976.
04:51In the 80s, we never reached it.
04:53In the 1990s, we only had two summers getting that high, getting that hot.
04:58Again, in the noughties, only two summers.
05:00By 2010s, we had the three summers or three years with temperatures reaching 34.8 or getting
05:07higher.
05:08By the 2020s, we have already had three instances and obviously, we're only just about halfway
05:14through the 2020s and so we're seeing a real trend that the hotter spells are becoming
05:20more common, are becoming more frequent.
05:23With that hot weather, now I am aware that the hot weather wasn't across the whole of
05:27the UK.
05:28It was very hot towards the southeast, less so across Scotland.
05:32Across Scotland, you had something a bit different.
05:35Yesterday, there was a lot of thunder and lightning around.
05:38If I show you that now instead, and I don't think my lightning is actually working today.
05:44It wasn't when I tested it, but you never know, it might have started working.
05:47If I zoom into the UK and we had this feature that pushed its way across parts of Northern
05:52Ireland and more so across parts of Scotland as we went through yesterday, if I just try
05:57and pause it, I missed.
05:59If we try and pause it and you can really see the intense rain and with that, there
06:04was a lot of lightning around yesterday.
06:06There were around 16,000 lightning strikes recorded across the UK yesterday and about
06:1314,000 of them came across Scotland.
06:16So it was really frequent lightning and that did lead to some issues.
06:20We did have a warning out and that's because thunderstorms like these do cause some problems.
06:25There are reports of a building being struck by lightning and catching fire and that's
06:30the kind of thing that we're warning about when we issue our thunderstorm warnings because
06:34of the frequent lightning, the intense rain, the large hail, the gusty winds.
06:39All of these can cause some problems and we did see some problems as a result of this
06:43system that came through yesterday.
06:46Now, with the reason that we had so much thundery weather was because of the hot air and so
06:52that led to those high temperatures that we saw across parts of the southeast in particular
06:56Whilst we're on that topic, I wanted to share with you a study that's been carried out with
07:02our urban forecasting team here at the Met Office supported by the University of Reading
07:08and it's been looking at machine learning and how we can use machine learning to better
07:13forecast heatwaves in urban areas.
07:16The way they've done this is by using machine learning and looking back at heatwaves across
07:21London in 2019 and 2021 and fed that information into the machine and then come up with a forecast
07:29using a finer resolution.
07:31Now when I talk about resolution, I'll use this image behind me to try and explain what
07:36I mean.
07:37On the left-hand side, I have our current standard Met Office forecast resolution and
07:41with that model, we split the earth up into 1.5 by 1.5 kilometre grid squares and then
07:49within that grid square, we calculate what the weather is going to do.
07:52I say we, the supercomputer calculates what the weather is going to do in terms of temperature,
07:57in terms of rain and cloud, all those different variables.
08:02Now the greater the or the larger the grid square, the less detail we have because you're
08:10calculating what's happening within this grid square and you get one value per grid square.
08:15If you make the resolution finer, like they have done in this study that they've been
08:20doing for this urban heatwave, then you're able to be a bit more accurate with exactly
08:27what we can expect in terms of temperatures in individual areas.
08:32And now this study splits the grid up into 100 by 100 metre squares, so a much finer
08:41resolution than the one that we currently use with the Met Office.
08:45Now a few things to bear in mind.
08:47This is just a study.
08:48It's not something that we're able to implement operationally just yet because it took a lot
08:52of work and this was just looking at London and it used machine learning, which is something
08:57that we're trying to use more and more of here at the Met Office, but it made huge developments
09:02and it discovered that the forecast for an event that's already happened, but they then
09:08used the data from those previous heatwaves that they'd fed into the machine to forecast
09:14what would happen and they came up with the temperature error was around 11% improved
09:21using this data with the machine learning forecast resolution.
09:26And so it really did make quite an improvement in terms of the forecasting.
09:30One way that you could think about it when you look at the grid squares is you're going
09:35from not really being able to pinpoint the temperature individually in an area within
09:421.5 kilometers going down to you could come up with different temperatures within just
09:46a street because by this point you're looking at just 100 meters difference between places
09:51and so the accuracy in our forecast really can improve.
09:55So interesting study.
09:57If you want to know more about this, then do head to our website.
09:59It's on our homepage with more information about what was carried out and the findings
10:03from it.
10:04But let's go further ahead.
10:05I already started looking about what we can expect through the next few days and let's
10:11start off by showing you the jet stream because as you can see, actually, let's come back
10:15to the jet stream later.
10:17Let's start off by looking at our rain.
10:18And I mentioned that we have a front going through overnight tonight into Wednesday.
10:24And if I zoom in a bit more across parts of the southeast, that rain is probably not going
10:30to be too much.
10:31It will probably break up.
10:32As we go into the afternoon tomorrow across parts of the southeast, we could see some
10:36heavy showers developing.
10:38And so do watch out for those elsewhere.
10:40Once that front clears through during the early hours, it's actually looking like a
10:43pretty decent day.
10:44But now I'll put the jet stream back on because as we go through later Wednesday and into
10:49Thursday, the jet stream is going to be piling into the UK, particularly across northwestern
10:54parts of the UK.
10:55And this is then going to be driving some very wet weather across parts of Northern
10:59Ireland, Scotland, even into northwest England.
11:01Cumbria could have quite a high amount of rain as we go through Thursday.
11:05So a pretty wet picture across the northwest of the UK on Thursday.
11:09A little bit or quite a bit drier towards the southeast, but that front will gradually
11:13then make its way southeast as we go through later Thursday and into Friday.
11:18And with that, then it clears away towards the southeast.
11:21It might take a little bit of time to clear away from the southeast on Friday.
11:24So do be aware across southeastern parts could be a bit wet for a time, but it should clear
11:29away eventually into the afternoon before then more wet weather comes in from the northwest.
11:33That feature doesn't look as heavy as the one that's coming through on Thursday.
11:38And then that comes through.
11:39And then thereafter, actually, as we go into the weekend, yes, there may be a bit of rain
11:43around, but really for much of Saturday and also Sunday, a lot of dry weather to be had.
11:48It's actually looking fairly decent, not as hot as it was previously.
11:53Temperatures are just around average for the time of year.
11:55But at this time of year, if you get any decent sunshine, that's still pretty warm.
12:00However, it may not last.
12:02The largely settled picture for this weekend probably won't last particularly long.
12:07There's another system waiting to come in from the west.
12:09If I just scroll this to the end, you see that's coming towards the UK and we are going
12:13to see some wet weather arriving as we go through next week.
12:17And that's kind of the theme that we're going to take through much of next week as well.
12:21It really does look like we're going to have a mobile westerly pattern.
12:24So various features coming in from the west, bringing some wet and windy weather at times.
12:29And it's kind of what we've seen a fair amount of so far this summer.
12:33And that's what we're going to see through much of next week.
12:35A few things to bear in mind with that pattern, the heaviest rain, the strongest winds will
12:39be generally towards northwestern parts, but there will be some rain pushing through as
12:43well.
12:44So in the southeast, it's likely to be drier, but not totally dry.
12:47That being said, there will be some fine weather around in between any systems that come in
12:52from the west.
12:53It's just generally going to be that mobile westerly pattern with various features coming
12:56through.
12:57So not always raining, but there will be some rain for most of us, especially towards northwestern
13:02parts.
13:04The other thing that I wanted to show you, and if I just start back to the here and now,
13:07when it comes to next week's weather, it's actually quite important to look at what's
13:12happening across the other side of the Atlantic.
13:15I'm going to zoom out because it was taking me a bit long to get there.
13:18And there is currently Tropical Storm Ernesto, which is affecting eastern parts of the Caribbean,
13:24the Leeward Islands in particular.
13:26And it is forecast to become a hurricane as it makes its way northwards.
13:31It clears away from the Caribbean, but then is likely to head towards Bermuda.
13:35And this could be quite a feature, and it could intensify, it could become a major hurricane,
13:40and that could cause some problems for Bermuda.
13:42A similar storm was Hurricane Fabian back in 2003, which did cause a lot of damage to
13:49Bermuda.
13:50And so they do need to be aware that there is some intense weather heading their way.
13:56There is some uncertainty, and this plays a part in what we can expect in the UK.
14:01So let's look at that now.
14:03Here is the current forecast track from NHC showing the feature.
14:08And you can see it's a tropical storm, but likely to become a hurricane as we go through
14:12Thursday before heading further north towards Bermuda, still in hurricane status, as you
14:17would expect as it travels over the warm seas.
14:20And as it then hits Bermuda, it could be a major hurricane, likely to cause some problems.
14:25But what happens thereafter, and that's when things get a little bit more interesting perhaps
14:29from the UK's point of view.
14:32And we can look at that in a couple of ways.
14:33So this is ECMWF data on the left-hand side.
14:36I have various forecast tracks, and you can see they all take it westwards across the
14:40parts of the Caribbean, then northwards up towards Bermuda, and then most of them spin
14:45it then a bit eastwards.
14:46And it's likely that we're going to see the – it won't be a hurricane by this point.
14:53It will have weakened, but it's likely to interact with the mid-latitude flow and then
14:59come eastwards towards the UK as we go through next week.
15:02Now, there is a fair amount of spread in exactly the track that it's going to take.
15:06And if – on the right-hand side, if you look at the probability, yes, I mean, quite
15:10likely that the low that was ex-Ernesto would come towards the UK.
15:16But it will be heavily modified, as always happens as you get across the – as it goes
15:21across the Atlantic Ocean.
15:23With that then, what does that mean for the UK?
15:26Well, because there's so much uncertainty as exactly what it's going to do, as always
15:30happens when it comes to hurricanes and how they progress, how they then move across the
15:34Atlantic, there's a lot of uncertainty as to how it's going to impact the UK's weather.
15:40But this is one possible outcome for next Friday, again from ECMWF, and it shows a pretty
15:47deep area of low pressure because of what was Ernesto coming across the Atlantic, a
15:52deep area of low pressure heading close to the UK.
15:54And if this came off, we'd have some very strong winds, some very wet weather across
15:59parts of the UK.
16:01But it's worth throwing in the caveat that another model run had a very different picture
16:05from the UK's point of view.
16:07It takes that low, not as deep and a bit further north, and as a result, allows for high pressure
16:12to push in from the south.
16:13And so, if this came off, we'd have a very different Friday, and it would actually be
16:17largely dry and a fine picture.
16:20And so, whilst I'm fairly confident that the general trend through next week will be
16:24that westerly pattern, various systems coming in from the west, exactly how the feature
16:29that is currently tropical storm Ernesto will become a hurricane, then weaken, is going
16:33to interact with the UK, that's still all to play for.
16:36It could bring something unsettled.
16:38It could bring something a bit drier and a bit warmer, or it could bring pretty much
16:42everything in between.
16:45So I think that's everything that I wanted to cover about Ernesto.
16:47And before I go, there are a couple of other things I did want to mention.
16:51This Friday is the 20th anniversary of the severe flooding event that happened at Boss
16:56Castle in Cornwall.
16:58I don't know if you remember it, but I do.
17:00It was a real severe event, and it was caused by an area of low pressure just to the southwest
17:05of the UK.
17:06Now, this area of low pressure then led to some heavy rain, some showers aligning parallel
17:12to the North Cornwall coast, and then they sort of stalled.
17:17And so you ended up with these showers just sticking around over the hills just to the
17:21east of Boss Castle.
17:22And so we saw a lot of rain falling in just this relatively small area.
17:27We had around 200 millimeters of rain in just a few hours, which is more than twice the
17:33month's worth of rain that you'd normally expect through August for this area.
17:38And as a result of that intense rain from those showers just stalling and sticking around,
17:43we then saw around 2 billion liters of water going into the rivers that lead towards Boss
17:50Castle.
17:51And then we had that heavy, intense flow of rainwater coming towards Boss Castle.
17:56It led to such damage and such destruction.
18:00Buildings were damaged, livelihoods ruined, and homes destroyed as well in places here.
18:07You can see the rescue elephant, elephant, rescue event, rescue effort, that's the word,
18:15going on with a helicopter trying to help people and rescue people that are trapped
18:21on top of and in their buildings.
18:23Cars were just pushed to death in the fast-flowing water, down and destroyed, and here's more
18:29damage of those same cars, all caused by this intense rainfall that started over the hills,
18:35and then that water came down to the valley that then led towards Boss Castle.
18:40And this image really just shows how much damage and destruction was caused in just
18:45such a short period of time.
18:47It really was very problematic.
18:50But the question then is, could this still happen today?
18:54And to some extent, in as much as the weather event could definitely happen again if we
18:58had exactly the same setup.
19:00But we would be much better at forecasting it and letting people know that it's going
19:04to happen for a number of reasons.
19:07In the middle here, I have the actual radar from that day on the 16th of August, and you
19:12can see that intense line of showers that just lingered parallel, like I said, to the
19:17North Cornwall coast and just continues to give some really heavy rain to those hills
19:23near Boss Castle, which is why we saw those rainfall totals building up.
19:27Then on the left-hand side, I have the model data that we had available to us at the time
19:3220 years ago.
19:33And you can see those grid squares that I mentioned earlier when I was talking about
19:37the urban heat paper study that we've been doing.
19:42And you can see those grid squares.
19:43They were 12 by 12 kilometers, so quite big, really big in comparison to the 1.5 by 1.5
19:50we have currently.
19:51And as a result, those grid squares, they were able to point out that there were going
19:55to be some showers around, but it didn't capture just how intense they were and where those
20:00intense showers were most likely, because it spread the intensity of the rain over relatively
20:06large grid squares, and that's why it didn't capture just how impactful this event was
20:11going to be.
20:13But if we compare it to the same output that we would get in that same event if we used
20:19our current 1.5 by 1.5 kilometer forecast, then you can really see it much better captures
20:25that intense rain that we saw in association with those showers that just lined up and
20:32really brought that devastating heavy rain, heavy flooding across parts of Boscastle.
20:38As well as the improvements in our forecast accuracy because of improvements in our supercomputer,
20:44our model capability, we've also become better at warning people.
20:47So we have our warning system.
20:50We work with the Environment Agency, with our Flood Forecasting Center, to better understand
20:56how places are going to be impacted by wet weather, by the rain, and where we're most
21:02likely to see the flooding.
21:03So this event could happen again, but if it did, we would be in a much better position
21:08to see it coming and let people know that this is going to occur.
21:13Now the last thing that I did want to leave you with before I go is something globally.
21:16And if I put the temperatures on, I just wanted to highlight, actually, I'll start off back
21:19at home.
21:20And I just wanted to highlight that over parts of Greece at the moment, we have had some
21:25very hot weather.
21:27And we've had really hot, dry weather through much of the summer, really.
21:31And it's this that has contributed to the severe wildfires that have been happening
21:36around the outskirts of Athens and have caused lots of problems.
21:39So lots of devastation in association with the wildfires there.
21:43That's everything that I wanted to talk about.
21:45I think I've talked for long enough.
21:47Do join us again next time.
21:49Alex Deacon will be here tomorrow with the 10-day trend.
21:52I'll be updating the 14-day outlook, which appears in the long-range section of our app.
21:57So if you're interested in what happens as we go through next week and beyond, then do
22:01check that out.
22:02Otherwise, have a lovely rest of your day.
22:03And as always, I will be replying to some of the comments this afternoon.
22:07So if you do have any questions, do check me out there.
22:10I'll see you again soon.
22:11Bye-bye.