This is the Met Office UK Weather forecast for the next 10 days 14/08/2024.
The jet stream is doing interesting things above the Atlantic how will this impact the weather?
Bringing you this weekend’s weather forecast is Alex Deakin.
The jet stream is doing interesting things above the Atlantic how will this impact the weather?
Bringing you this weekend’s weather forecast is Alex Deakin.
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NewsTranscript
00:00Welcome to the 10-day trend.
00:02It's the time of year where the tropics can influence
00:06our weather and certainly add some difficulties
00:09to the longer range forecast.
00:11We'll see more about that in a moment, because first of all,
00:14the weather looks fairly straightforward,
00:16a standard but fairly angry looking jet stream plowing
00:20across the Atlantic, certainly pretty
00:22lively for the time of year.
00:24That is going to bring most of us
00:26some rain during Thursday and Thursday night
00:28from these weather systems that it's pushing along.
00:31But notice how it does kind of weaken quite a bit
00:35as it moves in towards the UK.
00:37And then interestingly, it kind of splits.
00:40We have two jet streams almost as we go into the weekend.
00:45But before we talk about that and tropical system Ernesto,
00:49which is lurking behind me,
00:51we'll focus in on the shorter term
00:54because as these weather systems come in,
00:55they will bring some rain and also introduce
00:59a change in temperature.
01:00As this one comes in, bringing wet conditions
01:02across the north on Thursday, it will introduce quite warm
01:05and humid air for a time before this cold front
01:08moves southwards.
01:10And that will introduce something a little bit fresher.
01:12We can put the temperatures on and show that quite nicely.
01:14There's the warmer air returning to the south temporarily
01:18through Thursday and Thursday night.
01:20But then the cold front moves through and cooler,
01:23fresher air arrives for most of us on Friday
01:25and into the weekend.
01:27Although there is a bit of a question mark
01:28about how quickly that warmer air clears away
01:32from East Anglia and the southeast.
01:34But here's how the weather front manifests itself
01:37in terms of our weather.
01:38Quite a wet day across the north on Thursday
01:41and that rain trickling southwards.
01:42Much of East Anglia and Southern England dry
01:45until the overnight period.
01:47And then that rain should be moving through
01:49on that weather front.
01:50I say should, because as I said,
01:51there is a bit of a question mark about the timing
01:54of that weather front clearing through
01:56and taking away the warm and humid air,
01:59because it could just be that it's a little further back.
02:02The warmth and humidity could still spark
02:05one or two showers on Friday
02:07across East Anglia and the southeast.
02:09And that's showing up here quite nicely
02:11on what we call the postage stamps.
02:13These are the ensemble forecasts
02:15when you run the computer model,
02:17not just once, but many times.
02:19And each one of these different members,
02:21as they're known, or different stamps,
02:24showing a potential scenario for Friday
02:28and where the rainfall is.
02:29Most of them, I know you can't really see the detail here,
02:32most of them are showing it's going to be dry on Friday,
02:33but a few highlighted in the red boxes here
02:36are showing just the potential for some heavy showers
02:39across East Anglia and the southeast during Friday.
02:43And then there's a bit of a question mark
02:44about Saturday as well.
02:45Again, this is the ensemble,
02:46the postage stamps for Saturday now showing the rainfall.
02:52And again, most of them are showing that it's dry,
02:54but there are just a small number
02:57that actually have that weather front
02:58just pushing back from the near continent
03:01across the southeast,
03:02potentially bringing a little more rain here.
03:04But that's just a small chance at this stage
03:07because there's only a few of the ensemble members
03:11showing it.
03:11The most likely scenario
03:13is that actually most places have a fine weekend.
03:16There are these weather fronts
03:17close to the far north of Scotland,
03:19bringing at times some gusty winds and a little bit of rain.
03:22But for most of us, we've got a weak ridge of high pressure
03:25bringing for many a fine couple of days
03:27on Saturday and Sunday.
03:28And the fresher air means temperatures
03:30will feel pleasant in the sunshine,
03:33generally high teens across the north,
03:35low twenties across the south.
03:37And then we have these next weather systems
03:40coming in for Monday,
03:42and they're being pushed along by what we saw earlier.
03:46That split in the jet stream,
03:48one coming down from the Arctic,
03:49another one coming up from the south.
03:52Still at this stage, Ernesto churning away
03:55out in the Western Atlantic,
03:57not talking about that yet,
03:58but the split jet stream is quite interesting,
04:01likely to generate an area of low pressure
04:05in the mid Atlantic.
04:06Now, when we talk about jet streams,
04:08particularly the pinky colors here,
04:10the jet streaks where it gets really quite strong,
04:13we talk about entrances and exits to jet streams.
04:17We talk about left and right entrances,
04:19this being the right entrance here,
04:21and this being the left entrance.
04:24And then over here,
04:25where the winds are actually slightly decelerating
04:29and we lose some strength in the jet stream.
04:31Again, here you've got an exit
04:33and you've got a left and a right side.
04:35And the areas where low pressures generate
04:38generally down the right entrance or the left exit,
04:42as is happening here with this northernmost jet stream.
04:45And in the right entrance to the southernmost jet stream,
04:47just look at what happens here.
04:49The pressure pattern pretty slack initially,
04:51but we actually start to see a low pressure spinning up
04:55as we go through the weekend out in the Atlantic.
04:57And it's that one,
04:59but also combined with this tangle of weather fronts
05:02associated with the northern jet stream
05:04that combine to bring us cloud and outbreaks of rain
05:08as we head into Monday.
05:09Now, with such a lot going on in the Atlantic,
05:12quite a complex situation with that split jet stream
05:15and the developing low,
05:16there's actually quite a bit of agreement
05:18from the computer models
05:20that we will see cloud and rain
05:22spilling in across the country from the West during Monday.
05:25It might not look exactly like this,
05:27but pretty good agreement
05:29that we will see a spell of cloud and rain
05:31returning across the UK on Monday
05:33after, for most of us, what will be a fine weekend
05:37with some decent spells of sunshine
05:39and bar the odd shower, most places dry.
05:43What happens after that?
05:45Well, now we can finally start talking about Ernesto.
05:49At time of recording, still a tropical storm,
05:52but expected to become a hurricane
05:55later on Wednesday afternoon and into the evening.
05:58Currently clearing away from Puerto Rico
06:01and heading its way northwards
06:02out into open waters for Thursday and Friday,
06:05but potentially affecting Bermuda on Friday night
06:08and into the weekend,
06:10then tracking its way northwards.
06:13Still, there's a reasonably active system at this stage
06:17just off the coast of Canada.
06:19This is the forecast for Monday.
06:21Notice how it's been a long way from the jet stream,
06:23but as it then tracks further northwards,
06:26well, it may well start to interact with the jet stream
06:29as we head into next week,
06:31and that's what often happens with these tropical systems.
06:36And that's where things can get complicated.
06:39This map shows it quite nicely, actually.
06:41So this is the ECMWF Dalmatian plot
06:45showing where Ernesto is likely to be.
06:49The blue outline is the outline of Canada there,
06:53the Canadian coastline,
06:55and the lines are showing the pressure pattern
06:58from the main computer model run
07:00or the deterministic model run,
07:02but each black dot is an ensemble member,
07:06a different run of the computer model,
07:08but you can see they're all pretty much agreeing
07:11that the position of Ernesto
07:13is gonna be just somewhere off the coast of Canada,
07:16and that's quite good agreement, quite good clustering.
07:19All those black dots are pretty close together
07:21considering this is still five days ahead.
07:24So quite good agreement that by this stage,
07:27Ernesto or what's left of Ernesto
07:29will be just off the west coast of Canada.
07:33But if we fast forward,
07:35you can see that that's clustering does disappear.
07:38This is the same map, but I've just broadened it out.
07:41Now you can see the UK over here
07:43and the clustering of the low pressure system
07:44that's gonna bring us some rain on Monday.
07:46And again, quite closely clustered here.
07:49But there's that system we've just seen
07:51off the coast of Canada.
07:53Fast forward to Wednesday and well,
07:56the dots kind of just become splayed out all over the place.
08:01The deterministic, the main model run
08:03still has a system here.
08:04It won't be a hurricane by this stage,
08:06but it'll have gone extra tropical,
08:08but still as an area of low pressure in here.
08:10But all the dots are way more spaced out now.
08:13And that's because it's been interacting
08:15with the jet stream.
08:16So the uncertainty,
08:17there's a lot of energy within this system.
08:19When it interacts with the jet stream,
08:21it just could go a number of ways.
08:23It's likely to be heading across the Atlantic, yes,
08:27but it could be being pushed further North
08:28up towards Greenland,
08:29or it could just kind of dip down to the South
08:32and head down towards the mid Atlantic,
08:34maybe down to the Azores.
08:36Most likely scenario is for it to be heading up
08:41somewhere between the UK and Iceland.
08:44That is the most likely scenario.
08:45But as you can see from that,
08:47there's quite a big jump.
08:49I'll just zoom in and show you closer here.
08:51There's not a lot of agreement,
08:53not a lot of clustering of those dots around
08:56where the deterministic model is.
08:58So there's a fair bit of uncertainty.
09:00That's typical because you've got that energy.
09:03It's a tropical system interacting with a jet stream.
09:05And it's also a week away.
09:06So this is for next Wednesday.
09:08So there's always gonna be quite a bit of uncertainty,
09:11quite a bit of spread in the possibilities.
09:14But Dan Holley,
09:15who's our Deputy Chief Meteorologist today,
09:18has been looking at this in much more detail
09:20and looking at the ensemble forecasts
09:22and coming up with the potential different scenarios.
09:24There's three most likely scenarios
09:27with the most likely of all
09:29being that the low heads up somewhere
09:32between the UK and Iceland.
09:35Again, it won't be a hurricane at this stage.
09:37It will have transitioned in some way or another,
09:40but it could still contain some pretty warm air
09:42as it heads its way northwards.
09:43So it could bring some warmth to the UK.
09:45And the closer you are to the low,
09:47that's likely to bring some wet and windy weather.
09:49The further you are away from it,
09:51so further south and east,
09:52it's likely to be drier and warmer.
09:55But there are a couple of other scenarios,
09:57less likely scenarios,
09:58but they could happen
10:00that the low actually gets pushed way up
10:03much closer to Greenland,
10:05maybe between Greenland and Iceland.
10:07And that may allow us to tap into some warmer air
10:10further south.
10:12So that's a scenario where we could see temperatures rise
10:15a little bit as we go through next week,
10:17but that's an unlikely scenario.
10:19I'd say the more likely one is the one we saw earlier.
10:21Another possibility is that the low,
10:24the remnants of Ernesto don't really get pushed up too far,
10:30mainly stay to the south of the jet stream
10:32and just kind of fizzles out
10:33and dips out towards the mid-Atlantic.
10:35And that would leave us
10:36with a fairly typical weather pattern.
10:38We'd see some wet and windy weather coming in again
10:41from the Atlantic to the north and the west,
10:43drier and brighter further south and east,
10:45but that's not really involving the remnants of Ernesto.
10:49So interesting to see what happens
10:51as we go through next week.
10:54Either way, the most likely scenario
10:56is it stays wettest and windiest to the north and west
10:59and driest and brightest further south and east.
11:02And that's what this is showing.
11:05This is the ECMWF, again, the ensembles,
11:08but now we're looking at the probability
11:10of seeing 10 millimetres of rain or more.
11:13And right throughout next week,
11:14the maps are pretty similar for every day,
11:16showing the highest probability of 10 millimetres of rain
11:20across Western parts of Scotland
11:22and the probability of seeing that much rain in a day
11:24further south and east pretty low.
11:26Again, it's just suggesting that weather pattern
11:28is always coming in from the Atlantic
11:30with the wettest weather to the north and the west,
11:32the driest weather further south and east.
11:34And the most likely pressure set up
11:36the stacked probabilities also reflecting that.
11:40Going through the dates through next week
11:42with the darker blue colours here showing positive NAO,
11:46which basically means westerly winds
11:48and the wettest weather to the north and west,
11:50driest further south and east.
11:51And that's the most likely, this dark blue shading,
11:55even well into next week, around or above 50%.
11:58And the next most likely scenario,
12:01pressure set up with that paler blue
12:04also has the winds coming in from the west
12:06just a bit more from the southwest,
12:07so perhaps a little bit warmer,
12:09but generally a similar kind of weather pattern.
12:12So that's the most likely set up
12:13as we go through next week
12:15and even beyond and into the weekend,
12:17which is for many of us, a bank holiday weekend.
12:21So plenty going on next week.
12:23Do keep up to date with the forecast.
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