00:00Welcome to a 10-day trend of two halves. High pressure will dominate for the next few days,
00:06bringing many of us a fine weekend. After that, well, we have to consider things in the tropics,
00:12and particularly with what is currently Hurricane Erin. More on that in a moment. First of all,
00:17the bigger picture shows a fairly bland weather signal. These winds are the winds high in the
00:23atmosphere, the jet stream, which isn't doing very much close to the UK. And that's meaning we're
00:30sitting in what's called a cull between two areas of high pressure and two areas of low pressure.
00:35But what we will see over the next day or so is the high pressure building in both from the north
00:41and from the west. And that high pressure will control our weather for the end of this week,
00:47and indeed into the weekend, gradually working its way from west to east. When high pressure
00:53is in control, the air is generally sinking, which means there'll be a lot of dry weather.
00:58But things are starting to stir out in the Atlantic by the time we get to this stage.
01:03The jet stream is becoming a little agitated, and the reason for that is tied into this area of low
01:10pressure, which, as I say, is currently, at time of recording, Hurricane Erin. It's going to track
01:15northwards and it will no longer be a hurricane by the time we get to the weekend. But it is still
01:19going to have big impacts on our weather one way or another eventually. We'll get to that in more
01:27detail shortly. But let's get back to the shorter term with the high pressure building in. There is
01:31going to be a lot of fine weather, but also cooler air is spreading its way across the country. So
01:36some cool, fresh mornings likely. Friday morning temperatures in the countryside down into single
01:43digits. Quite a bit cooler than it has been. You'll notice that fresher feel for the journeys to work.
01:49So, yes, it is turning a little bit cooler over the next couple of days, but temperatures will
01:53probably start to rise then as we go through the weekend because the high pressure is building its
01:58way in, gradually shifting out into the North Sea. Under that area of high pressure, old weather
02:04fronts trying to move in from the west will introduce a bit more cloud. So it's not a clean
02:09high. It's what we call a dirty high. We'll have quite a bit of cloud mixed in with it. But still,
02:15most of us will have a dry weekend. Most of us having a bank holiday. It's not a bank holiday
02:19in Scotland, I know, but elsewhere it is. So a three-day weekend, which promises a lot of dry
02:25weather. Not good news if you're after rain, of course, and it has been a very dry summer. It's
02:30also been a pretty warm summer and it is likely to turn a little warmer after that fresher feel
02:35through the end of this week. Temperatures will be rising for Saturday and Sunday. Let's take a look at
02:41the numbers then for the weekend. It'll vary depending on whether it's cloudy or sunny,
02:45but certainly on Saturday with a bit of sunshine across the south, we could see those temperatures
02:49getting up to 24, maybe 25 degrees Celsius. Temperatures probably rising with the help of
02:55insulation, with the help of a bit more sun by the time we get to Sunday. More widely over 20
03:00Celsius. Low 20s, of course, pretty much all parts of the UK, maybe high teens across northern
03:05Scotland. But in the south, 24, 25, perhaps even 26 degrees Celsius. So those temperatures
03:11ticking up again through the weekend, still close to or maybe a little bit above average.
03:15This map is comparing those temperatures on Sunday to the mid-month average. You can see
03:20Scotland in particular, parts of Northern Ireland, likely to be a little bit above average. It'll
03:25feel warm this weekend in the sunshine, albeit with slightly cool mornings still. What about
03:30Monday? As I said, a bank holiday for many of us. High pressure likely by then to have
03:35established itself across into the North Sea and bring many places a fine day. Throughout
03:40the weekend, there's always the possibility of some showers coming into the west and they
03:44can't be completely ruled out, particularly on Monday across the far southwest because
03:49we could see things getting a bit complicated by then because of this weather system, which
03:56is, of course, what's left of Erin. I say what's left of Erin because we track it back to
04:01the shorter term. This is where it's moving at the moment up the eastern side of the United
04:06States, staying out to sea generally. At the time of recording, it is a hurricane. But as
04:12we go through the weekend, it will go through what's called extra tropical transition. Now,
04:17if you watch Aidan's deep dive from yesterday, I highly recommend it. He talks in great detail
04:21about how this weather system, how Hurricane Erin pushing northwards takes warmer air with it
04:27right the way through the atmosphere. And it's that pushing northwards in contrast to the colder
04:32air further north that really sparks the jet stream into life. Pretty feeble at the moment. But
04:38by Erin moving northwards, it creates that temperature contrast, which really generates
04:43this first arm of the jet stream. So Erin really initially pushes the jet stream on. But then what
04:49happens as it changes, it goes from being a hurricane to being a more typical area of low pressure. We say it
04:55goes through extra tropical transition. So it's no longer a hurricane. It's no longer a tropical storm.
05:00It's no longer being fueled by the sea because it's moved northwards over cooler waters. It's now
05:07a classical weather system. And what happens now is it draws in that colder air behind it on its back
05:13edge. And now the temperature contrast is on its southern side, which is why the jet stream goes from
05:19being active ahead of it to potentially being more active to the south of it. And that crossing of the
05:25jet stream means that low pressure system no longer a hurricane, but could intensify because of its
05:31movements across the jet stream. But it's kind of a chicken and egg thing because it's generally also
05:36sparking that increase in jet stream because of the way it's drawing down the colder air from further north.
05:42And then the temperature contrast is more marked to the south of it rather than to the north of it.
05:48So quite a complex interaction going on with what will be ex-hurricane
05:53Erin by this stage. And when we've got that complex interaction with a highly energetic system,
05:59well, it does bring some uncertainty to the forecast. Most of the computer models are in agreement now
06:05that the jets will dip down and the low pressure will head up out into the mid-Atlantics.
06:11So this is by Monday, still way, well, quite a bit away from the United Kingdom. And as the jet digs in
06:17like this, well, it's not really pushing this system along. It kind of sits still. So it could become
06:22quite slow moving out in the Atlantic. Now, I said most of the models are in agreement now, more so than they
06:29were 24 hours ago. And I can show you that on this chart. These are the three models that we use most
06:35frequently here in the Met Office. The one behind me here, that's the one I've just shown you, the UK
06:41Met Office model. That's the weather system out here. These are all for Monday. There's the UK
06:46sitting there. This is the European model. So not in exactly the same position, but pretty similar
06:51for five days ahead. There's that weather system and there's the UK. And the American model, GFS,
06:57has it also in a pretty similar position as well. Now, these are the deterministic, the main computer
07:02model runs. Obviously, if you watch the 10-day trend or our deep dive, often enough, you'll know that
07:06we don't just look at one computer model run. We run the model many times. And that's what's
07:12called an ensemble forecast. And then we generate things like these, the postage stamps for the same
07:18timeframe for Monday. These are the ones from our model looking at where the low pressure could
07:24be. Now, I don't expect you to read too much into the detail for this, but just giving a few examples.
07:29This one, member 25, that's not airing, but it does have a little area of low pressure close to the
07:34southwest of the UK, which is why I said we can't completely rule out showers through the weekend.
07:38There will still be the threat of one or two, possibly in the southwest on Monday. Whereas other
07:44model runs, members 28 there, has airing a bit closer to the UK. And other low pressure systems say
07:52on member number 32 there. So there is still quite a bit to play for. As I said, we've got to go through
07:57that transition of this weather system as we go through the weekend. Let's track it back a little bit
08:04and look at the ensemble model runs as they go through the next few days. So there's a pretty
08:10good agreement that the storm system will track its way away from the coast of northeastern United
08:18States and eastern Canada. So thankfully, it's not making landfall. It could still bring quite a bit
08:22of swell, particularly to the east coast of the US, then bending its way away. And these are the
08:29ensemble model runs. So you can see pretty good agreement there that that is the track of it by the
08:34time we get to Saturday. And it's during Friday and Saturday in particular, that it undergoes
08:39extra tropical transition. That's when we start to see the change from a tropical system to an extra
08:45tropical system. And that's when the uncertainty starts to grow and the spread grows. Now,
08:54that interaction with the jet stream is going to be critical. But notice not all of those tracks
09:00take it up to the west of the UK. Still quite a few of them actually take that system down
09:05further south, down towards the Azores. Not as many as there were yesterday. So in yesterday's
09:13model runs, when we're tracking that system, far more of them kept that system down to the south and
09:18close to the Azores. And only a few of them moved them up towards the west of the UK. So there is a bit
09:24of a trend in the past 24 hours to have more of them of that more northerly track of the system,
09:30as it were. But then it becomes slow moving, as we saw, because of the position of the jet stream.
09:35So just going through the details, things that we're keeping an eye on for next week, because there is
09:40increased uncertainty because of that tropical system. The probability plot of the different
09:46flavours of weather certainly show a trend. An increased likelihood of the blue colours. The more
09:52unsettled weather generally dictated by low pressures getting closer to the UK. So bright red
09:58to start with, a dark red to start with. High pressure in control as we go into the weekend.
10:03Increased chance through next week of either a southwesterly or with low pressure sitting right
10:09over the UK. So what does that mean for our weather? Well, I've already been through the long
10:14bank holiday weekend. Most places will be dry, but then we are likely to see a change. But how quickly
10:20that happens will depend on the position and the track of that low pressure and just how it interacts
10:27with the jet stream. But the most likely weather set up for Tuesday is low pressure sitting some way
10:32to the west or potentially having edged in a little closer to the UK. And Wednesday and indeed Thursday
10:40and Friday's most likely weather set up are for low pressure to be either sitting just to the west
10:46or across southern parts of the UK. And of course, low pressure, the air is rising, generating more cloud
10:52and generating some outbreaks of rain. Good news, as I said, if you're after some wet weather, it has been
10:58a very dry summer so far, but perhaps not the greatest news for the last week of what will be the school
11:03holidays for certainly much of England and Wales. So what can we say about the weather next week? Well, there is
11:09an increased likelihood of rain, probably still warm because that low pressure is going to like to bring
11:14some tropical air or some some winds up from the southwest, whether it's actually the remnants of
11:20Erin or another area of low pressure that brings in the cloud and the rain. It is still likely to be
11:26bringing in the winds from a relatively warm sea. But there is that increased uncertainty due to the
11:32position of Erin. So it's something we'll be keeping a very close eye. We're not going to get hit by a hurricane.
11:38It won't be a hurricane as it changes over by the time we go through the course of the weekends.
11:44But the remnants of Erin may well impact our weather one way or another as we go through next week.
11:51Do keep up to date because it should be quite an interesting story following this over the next few
11:55days. Best way to do that, of course, is to follow us on social media. If you're watching this on YouTube,
12:00do hit subscribe.
