This is an in-depth Met Office UK Weather forecast for the next week and beyond.
Another low pressure will bring wet and windy conditions to the south on Thursday but how wet and how windy is still a little uncertain and it all depends on the jet stream. Bringing you this deep dive is Met Office meteorologist Alex Deakin.
Another low pressure will bring wet and windy conditions to the south on Thursday but how wet and how windy is still a little uncertain and it all depends on the jet stream. Bringing you this deep dive is Met Office meteorologist Alex Deakin.
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NewsTranscript
00:00 Debbie is done.
00:01 But what next for the UK?
00:04 Any more stormy conditions on the way?
00:07 And just how low will we go this Thursday?
00:11 I'll try and answer all of those questions
00:13 in this week's Met Office Deep Dive.
00:16 Welcome along.
00:17 My name's Alex Deakin.
00:18 I'm a meteorologist and weather presenter
00:20 here at the Met Office.
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00:49 We also love, love reading your comments
00:51 and your questions and your queries.
00:54 Please do keep them coming as well.
00:56 'Cause the first thing I'm gonna do this week
00:58 is answer the crucial question
01:01 that came up from last week's Deep Dive.
01:03 Lots of comments, including from the following.
01:06 J.T. Ruhm, Sue Wright, 12.99,
01:10 Francesca, 1963, CD, USA,
01:13 Nay, Baileys, 9.510.
01:16 Apologies if I got your name wrong.
01:18 Paul Markman, 5247, Claymore5,
01:22 AJB, 16.99, want a name but a few.
01:27 I can confirm that Alex Burkhill's baby
01:32 has still not arrived.
01:34 So that is the breaking news.
01:35 But thank you for all your congratulations.
01:37 There were lots of other comments
01:38 in the comments section last week about that as well.
01:41 I know that Alex read them all and is very appreciative.
01:45 So please keep your comments coming in
01:46 and make sure you tune in next week
01:48 for the latest update on Alex Burkhill's baby.
01:50 But yeah, not here yet.
01:53 Okay, we'll move on from maternity
01:55 and get onto the meteorology.
01:57 But we're gonna start with a birth in some ways,
02:00 the birth of Storm Debbie,
02:02 because this is the satellite sequence over recent times.
02:05 And just keep your eye on this stream of cloud
02:07 heading up from the south.
02:08 And just look at this little feature here.
02:10 That's springing out of that massive cloud is Storm Debbie,
02:15 turning into a big swirl as it crossed the UK
02:18 and headed out into the North Sea, what, 24 hours ago.
02:21 Really intense storm across the Republic of Ireland
02:24 in particular.
02:25 Let's look at that again.
02:26 Big swirl, old mature area of low pressure
02:29 out in the Atlantic here.
02:30 But just look at this.
02:32 This was Sunday evening, this area of cloud.
02:35 You can just see coming out of here.
02:37 Let's zoom in a little bit, 'cause this is really,
02:39 you can just see coming out of here,
02:41 this little swirl, this little hook.
02:43 That is Debbie as it really intensified.
02:46 You can see the slight difference in color there
02:48 of those two clouds.
02:50 This little area coming out, that's a swirl.
02:53 That's a different conveyor belt of the corduroy
02:55 swirling and tucking around.
02:57 That is the formation of a storm,
02:58 a classic formation of a storm out in the Atlantic.
03:02 Fast forward it a little bit further.
03:04 Try and pause it there.
03:05 As it came into the Republic of Ireland,
03:08 that little hook in there,
03:09 that's where the strongest winds are
03:11 as the low pressure dug down.
03:13 The strongest winds, there's this little hook feature there.
03:15 And if we just, let's just take it forward
03:17 a couple of hours to there and zoom right in,
03:21 because now you can really see that hook
03:23 as the corduroy is digging down,
03:25 behind that, that's where the strongest gusty winds were.
03:27 And that's why Galway bore the brunt of this storm system,
03:31 flooding 80,000 without power for a time
03:34 across the Republic of Ireland.
03:37 That storm system moved in,
03:39 knocked down all kinds of trees,
03:40 caused some structural damage
03:42 as well as those power outages as well.
03:45 So that's why Metairran named this storm.
03:48 They were, and I think they had some red warnings
03:50 in place for a time as well,
03:51 some damaging gusts from this storm system.
03:54 It then spread its way across into parts of the UK.
03:57 So still a swirl in there,
03:59 but it's just lost that peak intensity,
04:01 but it still brought some very strong
04:03 in places damaging gusts of wind across Northern Ireland,
04:07 into Wales and into Northwest England,
04:09 bearing the brunt, what, yesterday morning
04:11 into the afternoon period,
04:13 and then crossing its way out into the North Sea.
04:16 But it still brought some strong and gusty winds
04:18 as they bounced down the other side of the Penn Islands also.
04:21 So Storm Debbie moved through.
04:23 It didn't affect all parts of the UK.
04:25 Much of the South had fine and sunny conditions
04:27 through most of Monday and across Northern Scotland.
04:30 Yeah, it was fairly cloudy, but the winds weren't strong.
04:32 So Debbie was a more focused storm,
04:34 but it still brought some problems.
04:36 These were the gusts that we saw from Storm Debbie
04:39 across the UK that we recorded from Gwynedd in Wales,
04:44 county down, Republic of Ireland,
04:46 to the coast of Lancashire, Cumbria,
04:48 and also parts of West Yorkshire.
04:50 Gusts of 70 miles an hour or more.
04:53 So it was a pretty intense storm.
04:55 As I said, it didn't affect all parts of the country,
04:57 but the areas it did affect,
04:59 it brought some pretty gusty conditions.
05:01 But MetErin named this storm,
05:03 and you can see why when you look at that satellite picture
05:05 with that hook and those damaging gusts
05:08 and the problems that we've seen across Galway
05:10 and even further east across Republic of Ireland,
05:13 there were some pretty significant problems.
05:15 Let's just stay on Storm Debbie for a while.
05:17 Just a couple of interesting stats.
05:19 D, fourth letter of the alphabet.
05:21 First time we've got to, or the earliest we've got to,
05:25 D in our storm naming system.
05:27 Obviously, we start a new storm list from A in September,
05:31 and we're already up to D.
05:32 Been in the previous record,
05:34 which was from Storm Desmond back in 2015,
05:37 and that was, I've got it in my notes here,
05:39 the 4th of, no, the 5th and 6th of December, 2015,
05:44 Storm Desmond.
05:45 So that had been the earliest time we'd got to D,
05:48 but now we've broken that
05:49 because D arriving in November for the first time.
05:52 We've now had six storms since the start of August,
05:55 so an unusually stormy spell across the UK
05:59 for this time of year in particular.
06:01 As for the Es, the earliest we've got to an E
06:05 was, again, 2015.
06:07 That was the season, that was our first season,
06:09 our first full season where we named the storms,
06:12 and that was our busiest,
06:13 'cause we got to K, we got to Katie in 2015,
06:16 and that was also the earliest we got to E,
06:18 which was Storm Eva back on Christmas Eve in 2015.
06:22 So we've got until Christmas Eve to get to E
06:24 to beat the E record if we're going to do that.
06:27 But let's just focus on what we've seen so far.
06:30 Say Storm Debbie was a pretty powerful storm.
06:33 It's now heading its way across Northern Europe,
06:35 less intense now, but still bringing some heavy rainfall.
06:38 That's likely to be the big problem with this storm system
06:40 as it moves its way across into Europe,
06:44 bringing a lot of wet weather.
06:45 It's not as intense now, it's lost its intensity,
06:48 and the reason for that is actually the jet stream.
06:51 You can see it quite clearly here.
06:52 So the storm system now heading its way
06:54 across Denmark into Germany,
06:56 but bringing a lot of rain into parts of Germany as well.
06:59 The jet stream is really quite active and south shifted.
07:03 But notice it's kind of in a straight line,
07:05 and it's actually reasonably consistent.
07:07 It's quite powerful, the dark pinks in there.
07:09 But actually, when you have a jet stream like this,
07:12 it's not really ripe for developmental,
07:15 for developing low pressure systems.
07:17 It's not what we call a developmental jet
07:19 because it's kind of straight.
07:20 It will push low pressure systems on,
07:22 and that's why Debbie moved through
07:24 and is still moving through pretty rapidly.
07:26 But when the jet's like this,
07:27 even though it is pretty intense,
07:29 it's not really spinning up areas of low pressure
07:32 because for that, what you really need
07:34 is the jet to be accelerating or decelerating.
07:37 And if we fast forward 24 hours,
07:39 that is kind of what we've got here now.
07:43 So we'll fast forward to Wednesday afternoon.
07:46 Now the jet doesn't look as scary.
07:47 It's not as intense.
07:48 The pinks aren't as dark.
07:49 So the cores of the jet is not as strong.
07:51 So the winds in the jet are not as strong,
07:54 but it's got more shape to it.
07:56 It's got more wiggle.
07:56 It's got more wave to it.
07:58 And it's also got these sections
07:59 where it's accelerating and decelerating.
08:02 And that is much more conducive
08:04 to developing areas of low pressure.
08:07 And that is what is happening here
08:09 with this little area of low pressure.
08:12 Let's just take the jet stream off
08:13 because this low is the one we're keeping an eye on
08:16 for Thursday in particular.
08:17 Ahead of that, there's Debbie,
08:21 saying goodbye to Debbie.
08:21 There are weather fronts bringing rain
08:23 across Scotland certainly,
08:24 and some wet weather certainly to come on Wednesday.
08:27 But for most of us, this little ridge of high pressure,
08:30 let's fast forward a couple of hours,
08:31 the ridge of high pressure will dominate through Wednesday
08:34 and bring certainly much of the South a fine day
08:37 under this ridge of high pressure.
08:40 So finally, something a bit drier.
08:42 There'll still be some wet weather
08:43 from that weather across Scotland,
08:44 but for many, Wednesday is a dry and a bright day.
08:47 However, we do have to then look at
08:51 this area of low pressure and how it's going to interact
08:55 and how it's going to develop.
08:56 And that's the big question mark for this week.
08:59 This will be the main focus for this week's deep dive
09:02 because even though it's only a couple of days away,
09:04 there is still quite a bit of uncertainty
09:05 about how intense and how much rainfall
09:08 this low is going to bring.
09:10 Why is that?
09:11 Well, it is in part linked to what we just saw.
09:13 Let's zoom out and put the jet stream on.
09:18 It's part to do with that undulating,
09:21 accelerating, decelerating jet stream.
09:23 And it's also in part to do with this other low pressure,
09:26 which is further away, way out in the Atlantic.
09:29 This is a more mature feature.
09:31 Certainly it will be by the time it reaches our shores,
09:33 but it's intensifying over the next couple of days
09:36 thanks to this dip in the jet stream.
09:37 So again, the jet stream has got that more,
09:41 it's got more about it.
09:42 It's got that dip, we call this a trough,
09:44 and it's that which is spinning up
09:45 this area of low pressure.
09:46 Now, as this low is spinning and developing,
09:49 what it's doing is it's drawing down
09:52 colder air from the north,
09:54 but it's also pushing north some warmer air.
09:57 And it's that warmth combined with the jet stream
09:59 moving northwards, which is buckling
10:01 the jet stream downstream.
10:02 So we're not having that straight jet stream
10:04 that we had earlier.
10:05 The development here is creating this buckled pattern
10:10 in the jet stream further downstream, closer to the UK.
10:15 And it's this little arm of it.
10:16 So as it goes up here around this low,
10:18 and as it dips down here,
10:20 how it interacts with this low pressure system
10:22 is absolutely key to what weather we see,
10:25 certainly in the south on Thursday.
10:29 So if we just take it back a little bit,
10:31 let's just bring it back to here.
10:34 So this is Wednesday morning.
10:36 Zoom in a little bit on this low pressure.
10:42 'Cause at this stage,
10:43 that's probably a bit too close.
10:46 Not ready for its closeup yet.
10:47 At this stage, that doesn't look like much, does it?
10:49 It's a fairly what we call flabby
10:51 or weak area of low pressure.
10:53 It's on the warm side of the jet,
10:55 the south side of the jet.
10:58 But if we just fast forward 24 hours or so,
11:02 maybe a little bit longer,
11:05 look at how it's now shifted.
11:07 Now, crucially,
11:09 it's on the cold side of the jet.
11:12 It has transitioned across.
11:15 And as it moves across, that's how it intensifies.
11:18 I did a deep dive on the,
11:21 I just came to check my notes there,
11:22 11th of July, all about the dynamics of jet streams
11:25 and how they work.
11:26 And this is now in what we call a left exit area
11:29 of this jet stream.
11:30 And because it's crossed, because it's jumped across,
11:32 that is why it has intensified
11:35 as it's moved its way up towards the UK.
11:39 However, this is just one computer model,
11:43 and they're not all in complete agreement.
11:46 If this would happen,
11:46 then we'd certainly bring a spell
11:47 of very wet and windy weather across parts of the UK.
11:50 But there is a bit of uncertainty about the position,
11:53 and it's all tied in with all those complex dynamics.
11:55 That first low, exactly how it intensifies the jet,
11:58 how the jet moves in,
11:59 and then exactly the timing of that low crossing the jet
12:03 is absolutely crucial.
12:05 I'm gonna show you a graphic now,
12:07 which hopefully explains that a little bit.
12:09 Apologies for the color change here.
12:11 We've gone from the pinks to the yellows here
12:13 for the jet stream.
12:15 And you can just about hopefully make out the UK is here.
12:18 Now, this is what we've just seen,
12:20 'cause this is the Met Office model,
12:22 the projection for the jet stream for 6 o'clock on Wednesday
12:28 and then every six hours.
12:29 So midnight into Thursday, 6 o'clock Thursday morning,
12:32 midday on Thursday, 6 o'clock Thursday,
12:35 and then midnight Thursday into Friday.
12:37 And it's showing what we've just seen
12:38 with the jet fairly weak, fairly innocuous initially,
12:42 but picking up this arm of the jet stream
12:45 as it digs southwards,
12:46 and that interacts with this low pressure,
12:48 which is quite weak initially,
12:50 but as it crosses, it intensifies.
12:52 And particularly by this timeframe,
12:53 by the time we get to 6 o'clock on Thursday,
12:56 there's a really active jet digging down here,
12:58 and that's helped to pep up that area of low pressure,
13:01 and it's moving right across southern parts of the UK.
13:04 But compare that with the European model,
13:09 and broadly speaking, it's very similar.
13:12 It's got a similar setup, pretty weak jet,
13:13 area of low pressure here.
13:15 It's got an active part of the jet digging down here,
13:17 but that part of the jet is nowhere near as strong
13:20 by the time we get to Thursday.
13:22 And as a result, the low also hasn't crossed it faster.
13:25 So the low isn't as intense.
13:28 I'm gonna show that in a bit more detail now by comparing.
13:30 Direct comparison for 6 o'clock Thursday
13:33 from the UK model compared to the European model.
13:35 Again, broadly speaking, pretty similar.
13:38 The pattern is very similar if you just kind of look at it,
13:41 but the detail, the jet is much stronger here.
13:44 The low has crossed the jet earlier,
13:46 and so that low is much more intense
13:48 than the one here in the European model.
13:50 It's got a low, and it's just across northern France,
13:52 but the jet, 'cause the jet isn't strong,
13:54 because that low hasn't crossed it earlier,
13:56 it's not as intense.
13:57 It's those subtle differences that make a big difference,
14:00 'cause this is gonna bring a spell of wet
14:01 and windy weather to the UK.
14:03 This one will probably just bring a few showers
14:05 and not much in the way of wind at all on Thursday.
14:07 So it's not quite all or nothing,
14:09 but it's pretty similar to that.
14:11 There's a big disparity between these two main model runs
14:15 from the European model run and the Met Office model run.
14:18 Now, fortunately, we don't just have to pick
14:21 one of these two.
14:23 That's why we have ensemble forecasts.
14:25 That's, if you're a regular viewer to the Deep Dive
14:28 or our 10-Day Challenge,
14:29 you'll know what I'm talking about,
14:30 ensemble forecasts, where you run the model
14:32 many, many times, and that gives you a better idea.
14:35 Rather than just having to pick one or two,
14:37 you have a better idea.
14:39 It gives you a more probabilistic look
14:41 at weather forecasts, or the chance of something happening.
14:44 And that's more useful,
14:45 particularly in this kind of situation.
14:47 So that's what we've got here,
14:49 plotted as something called a Dalmatian plot
14:53 for obvious reasons.
14:55 Now, this is back to the Met Office model.
14:57 This is the previous run from 12 o'clock on Monday,
15:02 and this is the most recent one,
15:03 time of recording from midnight last night.
15:06 And each of these purpley-blue dots
15:08 represents a position of the low.
15:10 When you run the model many times,
15:11 you get a different position of that low.
15:13 Where is the center of the low?
15:16 This one from midday yesterday
15:18 has more of them south-shifty.
15:19 Just about make out the UK there, hopefully,
15:21 the blue background, the pale blue background,
15:23 has more of the lows actually running
15:25 through the English Channel.
15:27 The color of those dots is important
15:29 because that tells you how intense the low pressure,
15:32 what the central pressure of the low is.
15:35 That was the one at 12 o'clock,
15:36 but by the time we got to midnight,
15:38 actually, more of the computer models
15:40 have now got it shifted further north,
15:42 actually mostly into parts of South Wales.
15:45 Still some of them just moving it through the Channel,
15:47 and some of them are deeper as well.
15:48 The low pressure is lower,
15:50 but down to 990 in some of these as well.
15:52 So that's our computer model,
15:55 the Met Office computer model,
15:56 just suggesting it's likely it's moving
15:58 towards that more intense and slightly further north.
16:01 When we look at the European model,
16:03 remember their deterministic one
16:04 didn't have much of a low pressure.
16:07 And if we go back even further, one more run,
16:09 this is midnight Sunday into Monday,
16:11 it's all over the place.
16:12 It's got low pressure systems from the Humber, whoops,
16:16 from the Humber all the way down to the Bay of Biscay,
16:19 and quite a wide spread on its dalmatian plot.
16:22 By the time we got to midday yesterday,
16:24 it's got more of a collective, where's that low?
16:27 Well, probably most likely somewhere in the Bay of Biscay.
16:30 Some of them though are in South Wales,
16:32 like the Met Office one.
16:33 And it's not as strong, it's not as weak,
16:35 because in the European model's mind,
16:38 it's not crossing the jet stream early enough.
16:41 So it's not as intense.
16:41 So the central pressure isn't strong.
16:44 By the time we get to the most recent run,
16:47 midnight last night, it's, again,
16:49 it's just shifting a bit further north.
16:50 They are more clumped now.
16:52 So again, that just builds a bit more confidence.
16:54 There is gonna be a low pressure exactly where still,
16:57 it could be just across Northern France,
16:59 but it could also be across Southern parts of the UK.
17:01 So the European model is still further south
17:03 from the UK model, but it is getting closer with time.
17:07 So just different ways of comparing
17:09 the computer models there.
17:10 Another way that you can do that,
17:13 instead of running the model many, many times,
17:14 is actually just look back at what previous
17:17 model runs were doing.
17:18 We kind of did it there with that,
17:19 but this is looking at rainfall now.
17:22 And these ones across the top,
17:24 showing where the heavy rainfall is gonna be.
17:26 So this is the rainfall for the whole of Thursday.
17:28 So from midnight into Thursday, midnight into Friday.
17:31 And these are the three most recent Met Office model runs.
17:35 And they're all agreeing that the rain's gonna be
17:36 in kind of the same place from that low as it comes in.
17:39 So with South Wales, the Midlands,
17:41 seeing the heaviest rainfall.
17:42 But look at this one in the middle.
17:44 It hasn't got anything like the same intensity
17:47 of rainfall as the other two.
17:49 So even the same computer model isn't necessarily agreeing
17:53 with just how intense or how heavy the rain
17:55 is gonna be with this storm.
17:56 And of course, that bottom chart here
17:57 is comparing the three main computer models
18:01 using the global model from the Met Office,
18:03 European model.
18:04 So again, the heavy rain is in a similar position
18:07 to the ones above across Wales and the Midlands.
18:10 But the European model,
18:10 because it's got that low pressure further south,
18:13 the heaviest rain is further south
18:14 across Northern France and into Belgium.
18:16 The American model there, much better agreement
18:19 with the UK model, with our model.
18:21 But just showing you, you can compare models
18:24 in lots of different ways.
18:26 And it's a bit of a minefield.
18:27 And they're all basically giving us signals
18:29 that there's not a lot of consistency.
18:32 We are pretty confident there's gonna be a spell
18:34 of wet and windy weather across southern parts of the UK.
18:37 But how much rainfall and how strong the winds
18:39 are gonna be, well, that is still open
18:41 to a little bit of doubt.
18:43 Right now, as I talk to you,
18:45 well, about 50 yards that way,
18:46 the supercomputer is churning away.
18:48 So hopefully, the midday run of the computer model
18:50 will actually gain some consistency
18:53 and we'll be a little bit more confident
18:54 about Thursday's forecast.
18:55 But basically, keep tuned to the forecast for Thursday,
18:58 'cause there is likely to be a spell
18:59 of wet and windy weather across southern parts
19:02 of the UK in particular.
19:04 But just how low that pressure goes
19:06 is still open to some doubt,
19:09 as we've seen from the Dalmatian plots.
19:11 Why is the low pressure, just how low we're gonna get,
19:16 how, why is that important?
19:17 So you can see here that trend
19:18 from the sort of browny purples here
19:20 to the darker blues in this one,
19:23 to the sort of mid purple ones in here.
19:25 And again, the color of that Dalmatian plot
19:28 determines the center of the low.
19:30 Why that's important is basically
19:33 because how low the central pressure gets
19:36 basically determines how strong,
19:37 how intense it's gonna be in terms of wind speed.
19:41 And the reason for that is we can just draw
19:43 a quick schematic diagram maybe here.
19:45 I'll jump back to my GCSE art skills here.
19:48 So if we imagine the background pressure,
19:51 the background pressure is around 1,000
19:56 hectopascals or millibars.
19:59 If you've got a low pressure,
20:03 center in here, that's 850.
20:07 Then you've got, if you draw isobars every five millibars,
20:16 that's your,
20:17 that's not right, is it?
20:20 So that central pressure is 980.
20:26 980, 1,000 millibars here.
20:30 This one, if you draw every five millibars,
20:33 so that's your 985.
20:34 That's your 990.
20:38 That's your 995.
20:40 But if the central pressure is lower,
20:44 basically if you've got a 970 millibar,
20:46 if the central pressure is 10 millibars,
20:48 hectopascals lower,
20:49 then you're gonna have more isobars
20:53 before you get to that background.
20:54 You're basically gonna have 975.
20:59 There's your 980.
21:00 There's your 985.
21:03 There's your 990.
21:05 And there's your 995.
21:07 So the distance between here and here is the same.
21:12 But this one, that's 970,
21:14 you've got more isobars packed in.
21:17 So you've got a much stronger gradient across here
21:20 than you have across here.
21:20 It's the closer the isobars, the stronger the wind.
21:23 So the deeper the low pressure,
21:25 the stronger the winds are gonna be
21:27 compared to that background.
21:28 Now this is obviously a bit of a schematic,
21:30 but hopefully that shows you why the depth of the low
21:34 is important in determining how strong
21:36 those winds are going to be.
21:37 Now, just as a point of reference,
21:40 well, let's look at, actually,
21:41 let's look at the Met Office ones.
21:43 The deepest ones we're seeing in here,
21:46 these dark blue colors are kind of 990 millibars in here.
21:50 When you compare that to the previous storm, Storm Keron,
21:53 that low pressure was 950 odd,
21:56 and it actually broke the record
21:57 for the lowest pressure recorded in England
21:59 and Wales for November.
22:00 So we're a notch higher than that.
22:03 So that goes to show, again,
22:04 and we're not expecting the same kind of levels of wind
22:06 from that, but still a pretty powerful storm.
22:09 And of course it does depend
22:10 on that background pressure as well.
22:11 So just for comparison, not as deep as the previous storm,
22:16 but with all that uncertainty about its exact position
22:19 and exactly how much rain,
22:20 exactly how much wind we are going to see.
22:22 So that is the big question mark
22:23 that is challenging our meteorologists
22:27 and the great minds that are working upstairs.
22:30 As I say, hopefully we'll have a bit more clarity
22:32 and a bit more confidence in the forecast
22:35 by the time we get to the end of play on Tuesday.
22:38 So do keep up to date with the latest forecast.
22:41 So that's what's, as I say, occupying minds at the moment.
22:45 What's going to happen on Thursday
22:47 and this area of low pressure?
22:49 Let's just put the rain and the winds on,
22:51 because if the Met Office model is correct,
22:55 you can see why we are keeping a close eye on it,
22:59 'cause that is going to bring a spell of wet weather
23:00 across some parts of England and Wales on Thursday,
23:05 and particularly as those isobars pinch together in there,
23:07 some pretty gusty winds along the southern flank
23:10 and through there.
23:11 Now, of course it could be a little further south,
23:13 it could be a little further north,
23:14 but the intensity and track of that low will determine
23:16 where we're going to see the worst of the conditions.
23:18 So that is why we do need to keep a very close eye on it.
23:22 And that's why you need to keep up to date with the forecast.
23:24 But whichever way you slice it,
23:27 by the time we get to Friday,
23:31 that low pressure system is clearing out of the way.
23:33 So what does that mean after that?
23:35 Well, actually, we've got another one of these little bumps,
23:38 these little ridges of high pressure,
23:40 and although there'll be a few showers around,
23:41 let's take the winds off,
23:43 for many, as we head into Friday,
23:45 the weather looks like calming down again,
23:47 and for many, it will be dry and fine.
23:49 But what's this out in the Atlantic?
23:53 Well, if it isn't our old friend, low pressure from earlier,
23:55 you know, the one that helped to push the jet stream north
23:58 and intensify the previous area of low pressure.
24:02 Well, it's still there,
24:03 it's still wiggling around out in the Atlantic,
24:06 and it's this one that will bring us the wet weather
24:10 as we head into the weekend.
24:11 So if we just play through the sequence,
24:14 these weather fronts marching in,
24:16 so Friday's generally a dry and a fine day,
24:18 but here comes low pressure,
24:19 we'll see a spell of rain coming in,
24:22 and then we'll see more showers coming in behind it as well.
24:25 Let's move right the way through to,
24:27 there's Saturday, Saturday night, rain coming in,
24:29 Sunday, plenty of showers coming in
24:31 as that low pressure continues to dominate.
24:33 So yes, no sign, certainly for the rest of this week
24:37 and into the weekend with the weather settling down,
24:39 there'll be some fine days, Wednesday and Friday,
24:42 looking pretty good for most parts,
24:43 but that spell of wet and windy weather
24:44 across the south on Thursday,
24:45 and then most areas seeing rain as a band moves through,
24:48 followed by heavy showers coming in for the weekend.
24:52 Interesting, we had a question from Steven Crosskey41,
24:57 who commented on our week ahead forecast
24:59 that Alex Burkill made yesterday,
25:02 'cause he was talking about the system coming on Thursday
25:05 and how we're so unsure about it,
25:06 not sure where the low is gonna be
25:08 and how strong the winds are and how heavy the rain is.
25:10 And it's a really good question from Steven Crosskey,
25:12 who said, "How can you have confidence
25:17 "in after that low pressure system
25:20 "if you don't know where that low itself is going to be?"
25:22 And that's a really good question, really good point,
25:25 'cause normally, if you think about
25:27 how much confidence you have in a forecast,
25:28 the further ahead in time you go,
25:30 the less confidence you have.
25:32 And most of the time that is true,
25:34 but sometimes it's not necessarily true.
25:36 And we're pretty confident
25:37 that this will happen at the weekend
25:39 because all the models are in agreement
25:42 that there's a area of low pressure coming in
25:44 and it will bring a band of rain
25:45 and it will bring some showers.
25:47 So all the models are in agreement,
25:48 plus this is not a developing system.
25:52 That low pressure is kind of just, put the jet on,
25:55 it's kind of just being pushed along by the jet.
25:57 It's not really interacting with the jet stream.
25:59 Whereas that other one, it's that key differential,
26:02 is that how is it gonna interact with the jet?
26:05 What time will it cross as to how intense it's gonna get?
26:08 This one isn't really having anything to do with the jet.
26:10 Once it's formed out in the Atlantic back on Tuesday,
26:17 out here, once it's formed,
26:20 it then kind of departs itself from the jet stream
26:23 and it just gets pushed along.
26:27 And so most of the models are in agreement
26:31 with how it's gonna interact.
26:32 And so that is the reason.
26:33 So yeah, it's a good point 'cause most of the time
26:36 you would be less sure about the weekend
26:38 than you are about Thursday at this point in time.
26:41 But this is one of those occasions
26:43 where we're very confident that on the weekend
26:46 we'll see a band of rain moving through
26:47 and we'll see showers dominated
26:49 by that area of low pressure.
26:50 So a really good question from Steven Crosskey.
26:52 So do keep your questions coming in.
26:53 As I say, we do read them all.
26:55 We do love all your comments and all your questions
26:58 around the Met Office Deep Dive.
27:01 One last thing, just talk about consistency
27:04 with where the rain is gonna be on Saturday.
27:08 So that's Saturday.
27:09 Let's just take it back a little bit.
27:10 Where are we?
27:14 Let's go into, yeah.
27:15 So we're going to Friday night and Saturday.
27:16 There's the low.
27:17 There's the weather front approaching the UK.
27:20 And let's just have a look at this
27:23 'cause I love a spaghetti chart.
27:26 This is European computer model.
27:28 Again, we're comparing model runs going through time.
27:32 It's an ensemble forecast.
27:34 So each one of these red lines is a position
27:36 of that warm front approaching the UK.
27:39 You can see the blue outline of the UK there.
27:42 And these are for a snapshot
27:43 for Friday night into Saturday.
27:45 And you can see there from the previous model run,
27:48 from the model run, two model runs ago, lots of lines.
27:51 It could be that that front is still 300 miles away
27:54 from Portugal, or it could be that weather front
27:56 is already across Devon and Cornwall.
27:58 When you get to yesterday's midday run,
27:59 there's a more consistent signal.
28:01 As you would expect, the spaghetti is getting together
28:05 and it's way more bunched by the time we get
28:06 to the midnight run from last night.
28:08 That is a pretty consistent signal
28:09 that that weather front is gonna be moving in
28:12 and is in this kind of position.
28:13 So what, two, 300 miles away from Cornwall at midnight.
28:16 So reasonable consistency there.
28:18 So again, that just backs up why we're more confident
28:20 about Saturday's forecast than we are for Thursday's forecast.
28:25 Okay, I think that is pretty much it for this week.
28:29 So again, thank you so much for watching.
28:31 Thank you for all your comments.
28:33 Please make sure you subscribe
28:35 and then you won't miss a forecast.
28:36 Tomorrow, it'll be the 10-day trend.
28:38 So we'll be looking at how things could develop next week.
28:40 There are signs of some higher pressure
28:43 down to the southwest and perhaps things
28:44 turning a little cooler and showery next week.
28:48 So far from settled, but perhaps less low pressure systems
28:53 barreling in from the Atlantic.
28:54 But, ooh, I don't know.
28:56 I think it's gonna be Alex tomorrow,
28:58 obviously depending on the birth of his child.
29:01 But it may be Aidan.
29:02 I'm pretty sure it's not gonna be me.
29:03 But hit subscribe and then you won't miss a 10-day trend.
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