This is an in-depth Met Office UK Weather forecast for the next week and beyond. A major hurricane is heading towards Florida whilst an ex-hurricane affects Europe. Bringing you this deep dive is Met Office meteorologist Aidan McGivern.
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00:00Hurricane Milton transformed from a tropical storm on Saturday to a Category 5 hurricane on Monday.
00:08It was the second fastest intensifying Atlantic hurricane on record and is now expected to hit Florida as a major hurricane.
00:17The second major hurricane to hit Florida in less than a month.
00:22Meanwhile, ex-hurricane Kirk slams into Europe, avoids the UK, but leads to colder weather as it clears away across much of the country.
00:33And how's it looking into the weekend and next week?
00:38Plenty to cover in this week's Met Office Deep Dive, exclusive to the Met Office YouTube channel.
00:42If you haven't already done so, please do hit subscribe so you never miss one of these updates.
00:47They come out every Tuesday and they are our regular in-depth look at meteorology in the UK and around the world.
00:54There's plenty to talk about around the world at the moment.
00:58And eagle-eyed viewers will have noticed that I've swapped sides.
01:03We used to present these on that side. That's where the buttons were.
01:07We've switched the buttons to put them on this side.
01:10And there's a slightly new interface, a slightly new design, which will, currently, very much work in progress,
01:17but which will hopefully in the next few weeks and months allow us to do even more, show you more things and be even more interactive.
01:25And, well, let's just say it's the first time I've been using it in this kind of presentation.
01:31So anything could happen. It's worth staying tuned just to see if anything does indeed go wrong.
01:37Now, first of all, Hurricane Milton. This shows the satellite imagery from Saturday to Tuesday morning.
01:45And it shows the speed of intensification.
01:49Truly powerful system by the time it reached the Yucatan Peninsula on Monday evening.
01:57At that point, sustained winds were 180 miles an hour and the central pressure was 897 millibars.
02:06And that central pressure made it the fifth strongest Atlantic hurricane on record by pressure.
02:12It was also the joint sixth hurricane in the Atlantic on record for wind speed and is now expected to move northeastwards
02:24and weaken slightly, but still hit Florida as a very powerful major hurricane.
02:31This is the official track from the National Hurricane Center.
02:34And worryingly, it does take Milton into Florida as a Category 3 hurricane.
02:42Sustained winds on landfall of 125 miles an hour.
02:47It then crosses the Florida Peninsula as a hurricane and leaves the other side, clears the east as a Category 1 hurricane
02:55before weakening quickly as it moves into the Atlantic and moves towards Bermuda.
03:01But, yeah, it's at the moment oscillating between a Category 4, high-end Category 4, low-end Category 5.
03:09So it's a very, very powerful hurricane.
03:12And it was the above-average sea surface temperatures in the Gulf that led to this very rapid intensification that we saw throughout Monday.
03:2024 hours it went from Category 1 to Category 5, and that's what made it the fastest intensifying,
03:26or the second fastest intensifying hurricane on record in the Atlantic area since, second fastest intensifying,
03:36got to get my facts right here, second fastest intensifying hurricane on record, the fastest being Hurricane Wilma in 2005.
03:45So truly a very, very powerful storm.
03:49And not only will the winds be destructive, but there's going to be the risk of widespread flash flooding as a result of the rainfall.
03:58This is the expected rainfall from the National Hurricane Center.
04:02And it shows areas of 300 to 400 millimeters of rain.
04:07They're showing it in inches.
04:09That's the scale there if you can see it.
04:12Obviously the really heavy rain out in the sea there, but still over Florida, 300 to 400 millimeters of rain in just a day or so,
04:20leading to widespread flash flooding, river flooding, and so on.
04:25And although the winds will weaken slightly, so it will go down from Cat 4, Cat 5 to Cat 3, it's expected to grow in size.
04:36And when these hurricanes get larger, the risk of storm surge is greater.
04:42They churn up even more water.
04:44And we saw that with Hurricane Helene, of course.
04:47That hit the Big Bend area of Florida.
04:49This area came up from the south, so a slightly different track, but still hit this area with a storm surge of 10, 15 feet.
04:57And expecting similar storm surge there for the Tampa Bay area, 10 to 15 feet.
05:03That's where the hurricane is expected to move through on Wednesday night, early Thursday.
05:13So yeah, 10 to 15 feet, really worrying impacts for Florida, and just the second major hurricane to hit Florida in less than a month.
05:24So all the official updates, you can get those through the National Hurricane Center.
05:29They are the authority on hurricanes in this part of the world.
05:33And of course, we'll be monitoring it as well here at the Met.
05:36Obviously, we'll be keeping you updated.
05:38Now, later, I'll mention how ex-hurricane Milton next week could cause some uncertainty with our own weather.
05:47But for now, we've got another ex-hurricane to think about, and that is ex-hurricane Kirk.
05:54And what I did last week was I saved the model data from hurricane Kirk because I thought it showed a really interesting transition from a hurricane to an ex-hurricane.
06:04And this is what's playing on the screen at the moment.
06:07There are a number of differences from hurricanes to ex-hurricanes.
06:11And so I did a video that you can find on the Met Office YouTube channel explaining these differences between tropical cyclones and extra-tropical cyclones.
06:21Extra-tropical cyclones are those cyclones that occur outside of the tropics.
06:26Hurricanes are tropical cyclones.
06:29And there are a number of differences in terms of where they get their fuel from and how they are structured.
06:34So I went through those in this video that you'll be able to find on the Met Office YouTube channel.
06:39But this shows one of the differences really well, and that is the temperature gradient around the storm.
06:48Now, in hurricanes, as they form in the tropics, there's little horizontal temperature gradient.
06:53It's warm across the whole area.
06:57But as hurricanes move into the extra-tropics or the mid-latitudes, they increasingly develop a temperature gradient.
07:06Now, we are familiar with temperature gradient in areas of low pressure ourselves because we call them weather fronts.
07:13When you get this steep temperature gradient from one area to another area, two different air masses colliding, we mark the boundary with the weather front.
07:23So we are familiar, virtually all the low pressure systems that we come across in the UK have some kind of weather fronts.
07:30Cold fronts, warm fronts, occluded fronts.
07:32We're always banging on about weather fronts.
07:34Hurricanes don't have weather fronts.
07:36They don't have that horizontal temperature gradient.
07:38But as they move north, they encounter cooler seas.
07:41They weaken unless they move over areas where there is a sharp temperature gradient and or a powerful jet stream.
07:50And it's those things that can cause additional energy.
07:53Those things fuel mid-latitude areas of low pressure.
07:57So hurricanes fuelled by very warm seas in the tropics.
08:01As hurricanes move north, they cool.
08:03They move over cooler seas and they weaken significantly.
08:06But the kinds of lows that we get at our latitude, they're fuelled by the jet stream and they're fuelled by temperature differences.
08:13And what you're going to see is as Kirk moved over cooler seas, it increasingly developed this temperature gradient.
08:21And on Monday, it went from officially being a hurricane to an ex-hurricane as it developed a different kind of structure and weather fronts.
08:32And it's those weather fronts that are moving into Spain, Portugal and France over the next couple of days.
08:37Really, you've got cold air.
08:41You've got all this warmth pushed north.
08:43And then you've got cold air coming in from the north and west.
08:48And that develops a cold front.
08:50And you've got the warm front with the higher humidities that are from the tropics.
08:55And you get this enhanced temperature difference.
08:58So one of the key differences is the temperature gradient across the storm.
09:03That's what marks the difference between a hurricane and an ex-hurricane.
09:07Another key difference is the spread of the winds.
09:10Hurricanes, as you can see, this is the wind gust graphic.
09:13And the darkest colour, the strongest wind gusts in the hurricane are focused right next to the eye of the storm.
09:21So you get a very small area of very intense hurricane-force winds.
09:28Now, in Milton at the moment, I think it's around 30 miles, or at least it was on Monday night, 30 miles of hurricane-force winds surrounding the eye.
09:37But it can be a very narrow area surrounding the eye of very intense winds.
09:42As hurricanes move north and they transition to the ex-hurricanes, what's more typical of mid-latitude lows is that
09:50those winds get more spread out.
09:52So you get stronger winds over a larger area.
09:55The low-pressure system itself expands, but the winds aren't as intense.
09:59And they're not necessarily focused around the central low pressure.
10:02And they're more asymmetrical.
10:05So in a hurricane, you've got much greater symmetry around the eye of the storm.
10:10Then as those winds spread out, they can be a lot more asymmetrical.
10:14Typically, with these mid-latitude lows, you get the strongest winds on the southern flank of the low.
10:20And, yeah, that's what we're seeing.
10:22So how is ex-hurricane going to affect?
10:28Let me just get the right graphic here.
10:30I told you it would be a learning experience for all of us.
10:33How is ex-hurricane going to affect Europe?
10:37Fortunately for the UK, at least, it is taking a southward-shifted track.
10:42The jet stream is very south-shifted at the moment.
10:45That is carrying Kirk away.
10:48Now what I'm going to show you here is the accumulated wind gusts.
10:52This is the maximum wind gust as you go through Tuesday into Wednesday and Thursday.
10:59So you can see basically the trail of strongest wind gusts as Kirk moves into Iberia and France.
11:08There's Kirk.
11:10And at the time of recording, just moving north of the Azores.
11:15And then if we just move this forward, and you can see the strongest winds moving through during Wednesday.
11:25And then weaken considerably as this low-pressure system moves into central parts of Europe.
11:32Still is a fairly deep low, still with some heavy rain in places.
11:36But here's the strongest sway of the wind.
11:38So these are the 50, 60, and in some places, so northern parts of Spain, parts of Portugal, 70 mph wind gusts during Wednesday.
11:47So that's the sway, the very strong winds.
11:51There was a risk looking at some of the different tracks from the model output this time last week.
11:57There was a risk that those winds would affect southern parts of the UK.
12:00But thankfully for the UK, it's France, Spain, Portugal that will bear the brunt of the strongest winds.
12:07And that's why Meteo France have named this.
12:11They've named it Storm Kirk.
12:14When these things come across as ex-hurricanes, they typically keep their name.
12:18So Meteo France have named it as Storm Kirk.
12:21No longer a hurricane, of course, but still has a very wet and windy system.
12:26And expected to bring some very heavy rainfall in places as well.
12:29Now this is a similar thing I'm going to show you.
12:32And it's accumulated rain.
12:36So how the rain builds up basically during the next few days.
12:40And as Kirk arrives during Wednesday, you can see this area, this swathe of heavy rainfall.
12:4850 to 100 mm across northern France.
12:51And more than that across the south of France, northern Italy as well, over the mountains of course, parts of Portugal and Spain.
12:58So more than 100 mm, up to 200 mm perhaps over the mountains as Kirk moves through.
13:04So the UK has been spared, because of that south shifted track of Kirk, the very worst of the wet and windy weather.
13:11However, the UK won't be completely unaffected by Kirk because there will be impacts on our own weather.
13:18So I'm going to take you through the jet stream at the moment.
13:20It's quite an interesting setup.
13:22There's two streaks of the jet stream there at the time of recording.
13:26There's one that's south shifted compared with normal.
13:29We've talked a lot about south shifted jet streams recently.
13:32And that's because a climatological position or a more typical position for the jet stream is somewhere just to the northwest of Scotland.
13:40But frequently we've seen the jet stream much further south than that.
13:43And that's what we're seeing at the moment.
13:45That's why at the time of recording we've got low pressure sitting across the southwest of England, south Wales as well.
13:52And some very lively, heavy showers moving in around that low.
13:57Slow moving, thundery downpours, hail in places during the rest of Tuesday.
14:02More details on that in our short term forecast.
14:05Of course, there's no point in me talking too much about that because by the time a lot of you watch it, it will be all over.
14:11But there is a weather warning in force.
14:13And so, yeah, full details on our YouTube channel for all of that.
14:17But that's all caused by this south shifted jet stream.
14:22Then looking at the Atlantic near the Azores, which are there, an even further south shifted jet stream.
14:28And that's what's picking up Kirk and taking it during Tuesday into Wednesday.
14:36On that track that mostly avoids the UK.
14:42But here's the important thing.
14:47Because the jet stream is quite far to the south, as Kirk moves away, it opens the door to Arctic winds.
14:55And you can see that temperature plunge through Thursday.
14:59So let's turn on the maximum temperatures for Thursday.
15:01Thursday is the coldest day widely across the UK.
15:05There will be some sunshine out there, just a few showers across the north and east of the UK.
15:09But you can see how high those temperatures are, 9 to 12 Celsius widely.
15:13And feeling even colder when you add in the effect of the wind chill.
15:16So let's take a look at the wind chill.
15:18Let's go forward to Thursday there.
15:21And Thursday afternoon, you can see, what, 6, 7 Celsius or so.
15:28That's what it's going to feel like.
15:30Not only that, but overnight temperatures are going to drop as well.
15:34So this shows the minimum temperatures for Edinburgh.
15:38Edinburgh, that's the minimum temperature trend through the next few days.
15:42Down to the low single figures.
15:44Glasgow, for example.
15:46Stormwake.
15:47Temperatures are a bit up and down as we head into the weekend.
15:51And that's because there's a little bit of a complicating factor emerging.
15:57Now, we start off Thursday with those northerly winds.
16:01So sunny spells, showers.
16:03Those showers pushing into the north and the east as well as northwestern parts of the UK.
16:09The showers will be turning wintry over the Scottish mountains.
16:12So we can expect some sleet and snow, even down to 300 or 400 metres.
16:16But mostly any lying snow will be 500 or 600 metres and above.
16:20Still, though, some significant snow expected during Thursday into the start of Friday.
16:26Over, for example, the Cairngorms.
16:28So above 500 or 600 metres, you can expect 5 to 10 centimetres of snow.
16:33Really significant for the start of October.
16:36At lower levels, of course, it will be rain, perhaps some hail showers.
16:40But by Friday, some mild air is on the way.
16:44Because what happens is this slice of jet stream emerges in the Atlantic and starts to move towards northern parts of the UK.
16:54Now, in the south, it stays relatively chilly on Friday.
16:59But further north, we've got this slice of less cold air arriving.
17:04And by Saturday, that's also going to lead to some showery rain across parts of Scotland, for example,
17:12perhaps fringing later on into northern parts of England and Northern Ireland.
17:17This slice of jet stream, though, is causing a few issues in the computer modelling, some uncertainty.
17:23Now, in the Met Office output, it just leads to some showery rain.
17:27But there are some computer model simulations that cause this slice of jet stream to spin up a relatively deep area of low pressure
17:37and cause more widespread wet and windy weather across northern parts of the UK on Saturday.
17:41So that's something that we'll keep a close eye on.
17:44Further south, we keep a ridge of higher pressure, although, again, a fly in the ointment is this low pressure,
17:50which some computer model simulations push a warm front up into southwestern parts to give some cloud and patchy rain.
17:58So, yeah, a few details to iron out for Saturday.
18:02There's the chance of showery rain in northern parts of the UK, especially Scotland,
18:07and the smaller chance, the lower likelihood of more widespread wind and rain in the north and northwest.
18:15Meanwhile, in the south, it's most likely going to be a fine day on Saturday,
18:19but there is that chance of a warm front emerging to bring some cloud and patchy rain.
18:23By Sunday, no matter what happens with those systems, there's good confidence that a ridge of higher pressure will build across the UK, settling things down.
18:33Meanwhile, out in the Atlantic, these areas of low pressure, it gets messy, basically.
18:42And this is an increasingly strong jet stream.
18:47So we've got 130 to 140 mile per hour wind speeds on that jet stream.
18:53Within it, we've got these areas of low pressure.
18:56But meanwhile, this is by this stage ex-Hurricane Milton, weakening considerably as it moves over the cooler waters of the Atlantic.
19:07And down here, we've got ex-Hurricane Leslie.
19:11So Leslie also weakening as it moves north.
19:15And those two ex-tropical systems are likely to bump into the jet stream, this powerful jet stream,
19:22and just add to the uncertainty for next week's weather, because how they interact with the jet stream and how the jet stream interacts with those
19:30will determine how the jet stream affects the UK's weather through next week.
19:36Now, there are a lot of model simulations that have low pressure sitting just to the northwest of the UK, to the south of Iceland.
19:46And this is the most likely weather pattern for Tuesday, next week, so a week's time.
19:52The second most likely weather pattern for the same day has that low pressure sitting slightly further south.
19:59And rather than southwesterlies, we've got more southerlies for the UK.
20:05Still the wettest and windiest weather to the west of the UK and the northwest, drier to the east.
20:12And you can see these plus 0.7, plus 0.8 numbers on the map, indicating that it's going to be warmer than average.
20:20But those subtle differences in the two most likely weather patterns.
20:24Remember, these weather patterns are the result of all the different computer model simulations from the European model, the American model, the Met Office model.
20:34And those simulations are summarised in those two most likely weather patterns.
20:40But when we look at the detail, this is from the operational run of the European model, and it shows something a little bit differently.
20:48So this is from the higher res run rather than all the different lower resolution simulations that we see.
20:55This shows lower pressure further to the west, much more of a direct southerly wind and the rain in the west staying away from the UK.
21:03So this is the UK here, if you can't see it that clearly in the camera.
21:06And this plume of wet weather moving into the southeast because you've got this southerly flow.
21:14And in this simulation, we've got higher pressure exerting itself over Scandinavia.
21:20Meanwhile, the main run of the American model shows something similar.
21:25The rain largely kept to the west of the UK. Again, this is Tuesday of next week.
21:29And these continental plumes are more of a southeasterly airflow rather than a southwesterly.
21:34So many parts of the UK dry, higher pressure over Scandinavia again.
21:39But the chance of some rain moving up from the continent to affect southeastern areas.
21:43So these are the kinds of uncertainties we're dealing with.
21:45And the reason the weather is uncertain for next week is because of the interaction between those ex-tropical systems and the jet stream.
21:55It's a week away. So we'll have to see how Milton moves through flora, comes out the other side, moves into the Atlantic, moves over colder waters, interacts with the jet stream.
22:05Leslie then joining in as well and how those very powerful but very small systems interact with the jet stream will determine how amplified the jet stream is.
22:14Now, if the jet stream is very amplified by that, I mean, it's wriggly, then we end up with this kind of pattern where the rain largely stays out to the west and we get a direct southerly or southeasterly.
22:25If the jet stream is a bit flatter, then you get more progression from the Atlantic.
22:29So these systems sweep through. So lots of uncertainty for next week.
22:34And we'll be covering that, I'm sure, in much more detail in the 10-day trend tomorrow.
22:39That will be done by Alex Deacon. So stay tuned for that.
22:43Hope you have more insight and we'll have a clearer idea of how these systems will affect the UK through next week.
22:50I suspect, given that the tropical systems are the key in determining the amplitude of the jet stream, it might be some days before we have a much more confident idea of what's going to take place through next week.
23:04But most likely unsettled towards the west, higher pressure over Scandinavia and some sort of slow moving pattern in the vicinity of the UK.
23:17Like I say, we'll be covering that in much more detail in the 10-day trend tomorrow.
23:21I've talked for long enough today. I hope you've enjoyed it.
23:25Thank you for sticking with the new touchscreen interface. It will take us some time to get to grips with it, I'm sure.
23:33But let me know if you've got any comments or feedback about that or anything else you'd like to see in these deep dives.
23:40We'll be here once again doing the same thing next Tuesday.
23:43Thank you for watching. Bye bye.