00:00Another 10-day trend in the middle of a heat wave. So the big question is, is the heat going
00:06to disappear in the next 10 days?
00:08Well, we will see changes, but they're going to be pretty subtle changes.
00:11The big picture shows why we've got the heat with the jet stream.
00:15It's arching way up over Iceland, allowing higher pressure to build right across the UK.
00:21We've got an upper ridge, high pressure sitting across the UK, allowing the sun to beat down.
00:25And that's lifting temperatures steadily through this week, probably peaking on Friday.
00:32Gradually, the jets, albeit fairly weak affair, nudges a little closer to the UK.
00:37This weather front may introduce a bit more cloud and one or two showers on Friday across the far northwest.
00:42But behind that, the high pressure rebuilds, but now in a different position.
00:47High pressure sitting to the north of the UK, and this low just nudging closer to the south,
00:52which means the isobars squidge together.
00:54So the first subtle shift will be the strength of the wind picking up across the south
00:59as we go through Friday and into the course of the weekend.
01:03That'll be noticeable because it will be obviously bringing fresher conditions with the wind itself,
01:08but also introducing slightly cooler air into eastern areas.
01:13So temperatures probably peaking on Thursday from the Midlands down to the southeast into the low 30s.
01:19But then that heat subtly shifting more westwards over the course of Friday and into the weekend.
01:25Probably we'll see a peak on Friday, 35, perhaps even the 36 somewhere in the Gloucestershire down towards Bristol area.
01:33Further north, we're looking at temperatures in the mid to high 20s, maybe low 20s further north across Scotland,
01:38where that weather front could bring a bit more cloud and a bit of showery rain.
01:42By the time we get to Saturday, notice how that heat is drifting away.
01:46It's still hot in London at 30 degrees, but the peak of the heat more down to South Wales and
01:51southwest England.
01:52That continues into Sunday as that breeze starts to pick up, bringing cooler conditions along those North Sea coasts.
01:58Another way to look at that is to show the temperatures compared to average widely on Friday.
02:03There's a big red blob there for temperatures 10 degrees in places above the average for the time of year.
02:09But as we go through the course of the weekend, the cooler conditions certainly spreading into eastern areas.
02:15The temperature is back closer to average.
02:17And if it is misty on the east coast, well, temperatures could be below average,
02:20whereas we keep those temperatures well above average through the weekend for Wales and southwest England.
02:25And so all the while pretty warm this weekend in western Scotland and northern Ireland too.
02:30That weather front, as I said, draped through the high pressure will bring more clouds on Friday and for a
02:36time on Saturday.
02:37Of course, Scotland, a little bit of showery rain is possible.
02:40But the high pressure then builds in, wringing that weather front out, if you like,
02:44and should reintroduce plenty of clear skies and sunshine across the north by the second half of the weekend.
02:50At the same time, just about make out a weak push there of the jet stream.
02:57It's kind of fragmenting and weakening, but breaking down to the south.
03:00And I'm just pushing up this area of low pressure, threatening to bring a bit more cloud
03:06and just bringing the possibility of one or two showers during the latter part of the weekend.
03:12So through the course of the weekend, across northern areas, that high pressure building in.
03:17Yes, that weather front could bring some cloud and patchy rain for a time, but largely dry, some warm, strong
03:23sunshine and the winds fairly light.
03:25There will be some sea breezes, of course.
03:28In the south, though, the winds will be quite noticeable through the weekend.
03:31Still largely dry and sunny.
03:32But the heat, as we've seen, is going to really shift its way from east to west,
03:38with the focus for Friday, Saturday and Sunday being more across south Wales and south-west England.
03:43Certainly Saturday and Sunday being across the south-west rather than further east.
03:48And that brisk wind will be pretty noticeable as well.
03:51So what happens after that?
03:53Well, eyes down to the south-west.
03:55High still dominating to the north of the UK.
03:57But how this low interacts with the jet stream and threatens to push up showery rain.
04:02That's the big question for the early part of next week.
04:05Increasing chance of seeing some thundery showers across parts of France drift their way northward.
04:11Don't take this chart too literally.
04:13It's just giving an idea of where we could see that low, introducing more moisture and the threat of thunderstorms.
04:19Still, the isobar is quite close together as well.
04:20So it's still quite breezy across the south into the early part of next week.
04:24And then beyond that, well, it looks like, generally speaking, high pressure will dominate.
04:29But the position of the high will be key.
04:32Likely to sit to the north-west of the UK.
04:35And that will continue to introduce the breeze coming in from the North Sea.
04:39So notice in this second most likely scenario, actually cooler than average on the east coast.
04:44And this one suggesting temperatures closer to average across central and eastern parts with the warmth in the west.
04:50And it's a similar pattern for Wednesday.
04:52Again, high pressure likely to be the dominant feature.
04:55And even this third most likely scenario, high sitting further north, a stronger easterly breeze.
05:01Again, introducing cooler conditions across parts of the east.
05:04So we will see those temperatures trending down as we go through the weekend in the east.
05:09And then for many places into next week.
05:12But it's just how the low pressure will influence things.
05:16That's a bit of a big question mark.
05:17This is what we call the Dalmatian plot from the ECMWF model.
05:23And it's plotting, when we run the model many times, an ensemble forecast, where that low could be.
05:28Each of these dots is the centre of that low, effectively.
05:31The colours represent how deep the low is.
05:35Now, this isn't a particularly intense area of low pressure.
05:37So the colour is fairly irrelevant.
05:38It's just a question of where the position of that low is.
05:42The closer it is to the UK, the greater chance of seeing some showery rain from it.
05:46And you can see that, well, it kind of could be all over the place.
05:50But there is a focus across southern parts of England to northern France, whereas further north, not many spots here
05:55at all.
05:56So we are expecting that low to be creeping its way up somewhere situated to the south or southwest of
06:02the UK, increasing the chances of some more cloud, certainly.
06:06But also some thundery showers are increasingly possible as that low gets closer to the UK and things tend to
06:12destabilise.
06:14Wednesday, again, a very similar picture.
06:16Hard to pick out a particular area where that low is, but a strong signal that's going to be much
06:21closer to the south than it is to the north.
06:23If we take a look at the pressure signal through next week, the multi-model outlook, when we look at
06:30lots of all the different models and then put all their ensembles together, we've seen this pressure chart before.
06:36Dates along here going back in time, showing the previous model runs, dates going forward in time here.
06:42Red is high pressure and strong signals.
06:45Even through the middle part of next week, the high pressure will still be dominant.
06:48So even if that low gets close, it's quite a weak feature, we've still basically got high pressure in charge,
06:53but that doesn't mean to say we won't see showers coming up across the south.
06:57And then we start to see that signal weakening as we get towards the end of the week, suggesting perhaps
07:03the low pressure may start to have more of an influence, or at least the high starts to weaken away,
07:09which could again destabilise things, allowing a greater chance of some cloud and showers coming in across parts of the
07:16south.
07:16So all in all, the heat continues through this week, gradually shifting into the weekend.
07:22Then for next week, still very warm, certainly across western areas initially, but the temperatures for everyone I think will
07:28be gradually trending down.
07:30Perhaps the exception will be across Scotland, where the sunshine could lift the temperatures a little further.
07:36But basically, we are looking at the intense heat this week starting to ease through next week, but it's only
07:42going to be a slow old process.
07:44And the big question mark is how much cloud, how many outbreaks of showery rain, the potential for thunderstorms will
07:50we see coming up across the south.
07:53So definitely could be an interesting week of weather.
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