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There has been lots in the headlines around the polar vortex and what it could mean for our Autumn weather. But is there any truth in it? Bringing you this deep dive is Met Office meteorologist Honor Criswick.
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00:00So far this autumn hasn't felt very autumnal at all. In fact today is the 117th day. We've reached temperatures
00:09of 20 degrees or above. Also last week temperatures were barely dropping below 20 degrees and we've had some very
00:16mild nights. However this week it may start to feel that little bit more autumnal. We've got some wet and
00:23windy weather on the cards and also temperatures are starting to come down.
00:26But what does the rest of autumn look like and does it have anything to do with El Nino or
00:33the polar vortex? Well let's find out. Firstly though let's take a look at some of the weather we can
00:38expect for the rest of the week. Now some of us already this morning if we take a look at
00:44the latest radar and satellite imagery. We've had some spots of rain this morning. Also some drizzly showers towards the
00:50south. Quite a few of us also woke up to quite a foggy start this morning.
00:54If we take a look at later this evening we can start to see that some of this rain will
01:00eventually push its way south and eastwards. So if I just play that through some rain will start to push
01:06its way south and eastwards. It will start to turn a little bit heavier overnight as well.
01:10We've also got this secondary band of rain pushing up towards the south too. So that does mean some of
01:16us are going to have quite a wet commute to work or to school.
01:20But notice to the north of this where the rain clears. Plenty of clear skies. Still a fair few showers
01:25towards the northwest and it could be a little bit breezy here especially if we see any heavier showers here.
01:31So this is going to have a knock-on effect in terms of the type of temperatures we could see
01:35overnight. Notice there's a fairly good north-south split in temperatures tomorrow.
01:40So where the sky is clear and we've got that cooler fresher air following the rain that's where it's going
01:44to be a slightly chillier start.
01:46But actually amongst the cloud and rain it's still going to be relatively mild for this point of the year.
01:52This rain is likely to linger for some particularly across parts of East Anglia, London, Sussex and Kent as well
02:00even towards the end of the day.
02:02So actually some of us are going to have quite a wet commute to and from work especially in the
02:06southeast.
02:06But a lot of that rain does clear from the west though there are still going to be some showers.
02:11We do eventually start to say goodbye to the rainfall as it moves across.
02:16So once again as skies start to clear that does mean we're going to see a difference in temperatures and
02:21things are going to turn a lot cooler.
02:24There will still be some showers but it looks like they mostly linger around some coastal areas.
02:28So many inland areas are going to see that drop in temperature.
02:32So actually Thursday morning you might notice it's going to be drier for one and it's also going to feel
02:37a lot fresher.
02:38There could be some frost in places particularly towards northern parts of England.
02:42It's a very different start to Thursday.
02:44It will be brighter but it's also going to be that little bit chillier.
02:48And then it largely remains quite showery in nature towards the rest of the week.
02:54We will start to see another band of rain move through later Thursday and through into Friday.
02:59Most of it looks like it moves through overnight.
03:02Still we could see some heavier bands of rain and turning a little bit blustery as well amongst the heavier
03:07downpours.
03:08That looks like it tends to clear through the morning.
03:10Still some longer spells of rain possible but mostly turning quite showery particularly by the afternoon on Friday.
03:18So once again under any clearer skies overnight that does mean it's going to turn a bit chillier.
03:22And that remains pretty much the picture into the weekend as well.
03:25A mix of sunshine and showers and where we see the clearer spells that's where it's going to remain fairly
03:31chilly overnight.
03:33If we take a look at temperatures as well for the coming days notice today still very mild temperatures still
03:40reaching into the low 20s.
03:42I know it feels very nice out there if you do catch those sorts of temperatures obviously not getting quite
03:47as high towards the north.
03:48But it is well above average for this point of year and as we slowly progress later into the week
03:54the temperatures do start to come down along with that wetter area of rain that starts to come through on
04:00Friday.
04:00It's actually a warm front coming through so temperatures will be on the up by the time we reach Friday
04:05before they eventually start to come back down again on the weekend.
04:09Slightly more towards average, slightly more towards what we would expect for this point of the year.
04:14But I just really want to emphasise the point that we have seen a very mild start to autumn so
04:20far.
04:20As I said at the beginning it's not really felt like autumn I went out on the weekend and it
04:25still felt like summer was with us with temperatures still in the low 20s down here in the southwest.
04:31But the question is, is autumn going to stay that way?
04:35Now of course here at the Met Office we do provide a seasonal forecast.
04:42The thing is with our seasonal forecast it's more for businesses and organisations to help them plan for the season
04:48ahead.
04:48But it does give us a bit of an insight as to the type of season we may expect.
04:54It looks at trends, it looks at patterns, so we don't have exact details in the forecast.
04:59But we can take a look at the kind of things we might be able to expect.
05:04So we're going to do that right now.
05:06So firstly we're going to talk about temperatures.
05:09So these are the kind of graphs I'm going to show you for temperature, also rainfall and wind.
05:15If we follow this dashed line, this is the normal likelihood based on how often each value has been recorded
05:22in past years.
05:24Whereas this more solid line, that's the current likelihood based on the outlook for this year.
05:30So notice already, taking a look at this graph, and we take a look at the kind of grey area
05:38with the solid line,
05:39there is that shift towards the slightly milder end of the scale, kind of towards the upper end of near
05:45average
05:46and just about pushing into that mild scale there.
05:49So the likelihood leans towards us having a slightly milder autumn, and potentially winter as well,
05:59slightly higher than normal, pushing into the mild side.
06:02However, it doesn't totally rule out that we could also have some cold weather,
06:07as is sometimes the case with El Nino.
06:10We tend to get milder, wetter, windier starts to the autumn,
06:14and then things could potentially turn a bit colder towards the end.
06:18Still remains to be seen, and there's still a lot of factors at play,
06:20some of which we're going to discuss in a moment.
06:23So colder spells certainly still can't be ruled out.
06:26But at the moment, the trend is looking like overall temperatures are going to be above the seasonal average.
06:33Overall, a general trend, yes, but don't forget there'll be local variations as well.
06:37So while some areas, yes, may see that milder end of the scale,
06:42there could also be some areas that will be more towards average, if not a touch below.
06:45For example, in a typical autumnal setup, the northwest tends to see wetter, windier conditions
06:52due to areas of low pressure moving through.
06:54And as any fronts move their way south and eastward, sometimes they tend to weaken,
06:59and we don't see as much rain towards the south and southeast.
07:02A bit more sunshine, temperatures start to increase a little bit more,
07:05so it could be a bit drier there and potentially a bit warmer.
07:08So there's always going to be those local variations as well.
07:11But overall, looking at the general trend, the general pattern,
07:16it does look like it may potentially be slightly milder autumn
07:22and potentially a slightly milder start to winter as well.
07:25So it might just delay winter a little bit more,
07:28and we'll see less of those cold, crisp mornings potentially into autumn.
07:34Let's take a look at the rainfall as well, how dry or wet could be.
07:40Once again, a similar kind of trend.
07:42We're just about pushing into that wetter-than-average box,
07:45so the likelihood leans strongly towards a slightly wetter autumn.
07:49There's actually double the normal chance of this period being wet overall.
07:54But once again, we could also see variations in rainfall.
07:57As I said before, the northwest may be a little bit wetter,
07:59whereas the southeast may be a little bit drier.
08:01But overall, that trend does look like it's moving more into that wetter category.
08:06And of course, this all links as well to the jet stream,
08:09you know, a slightly stronger jet.
08:10We're going to see more areas of low pressure move through.
08:13It's been a little bit quieter as of late,
08:15but we're starting to see some rainfall move through now,
08:18as we saw for the week ahead.
08:20You know, there's going to be some rainfall in the forecast.
08:23So areas of low pressure move through.
08:25They bring more rainfall as well.
08:27And not only this, but they can bring a little bit of windy weather as well.
08:32So potential for some wetter-than-average conditions increasing,
08:37so a bit more of an unsettled period, and windy weather as well.
08:40But that's all linked to the areas of low pressure,
08:42you know, slightly stormier conditions, potential for named storms moving through.
08:47It brings rainfall, but it also brings stronger winds.
08:50And so once again, the likelihood leans towards some slightly windier weather,
08:53and also the chance of some slightly higher wind speeds as well.
08:58As those areas of low pressure move through,
09:00we may see slightly higher max gusts move through as well.
09:04It doesn't necessarily mean it's going to be windy every day,
09:07but as those areas of low pressure move through,
09:10we could see some windy weather as well.
09:13So as we move through into, continue to move through into October, November,
09:17there is an increased risk of some period of stronger winds
09:21associated with areas of low pressure moving through.
09:24Now, it's quite a broad brush picture of autumn, as you've probably noticed,
09:29because of course, it's very difficult to forecast any detail
09:32once we start to get to 7 to 10 days ahead.
09:35As you've noticed, if you watch our 10-day trends towards the end of the period,
09:39we do just look at the trends and the patterns.
09:41It's very difficult to give a precise forecast for a location this far into the future.
09:46But nevertheless, it does give an indication of the kind of weather we could potentially see,
09:52especially considering the start of autumn has been slightly different
09:56to what we would perhaps normally expect.
09:58But it does look like as we move further into the season,
10:01things will start to get that bit milder, that bit wetter, and that bit windier.
10:06It sounds lovely, doesn't it? Can't wait.
10:10And what you might have noticed as well is that these trends are broadly consistent
10:15with what we may expect from a slightly stronger El Nino as well.
10:19We tend to see a slightly stronger jet stream,
10:22so more areas of low pressure moving through at the beginning of the season.
10:25But then there is the suggestion or some likelihood that things may start to turn a bit colder
10:29towards the end of the season as well.
10:31So one to bear in mind.
10:33But of course, there are several factors at play, all happening across the globe,
10:38which could potentially affect the weather in the UK.
10:41Two that are really hitting the headlines at the moment are, of course,
10:45the El Nino, a much stronger El Nino, perhaps one of the strongest in history.
10:50And also the polar vortex is very much hitting the headlines as well.
10:55So I thought we could take a look at that and dive a little bit deeper
10:57into the polar vortex and what it could potentially mean for the autumn to come.
11:06So firstly, I thought we'd take a look at what the polar vortex is.
11:10You might have seen already the Met Office has done a huge amount of content
11:13around the polar vortex, so I'll just go through it briefly.
11:16In fact, there's a great video of Alex Deacon a very long time ago
11:19talking about what the polar vortex is.
11:21So I would go have a look at that one if you want to see what Alex Deacon looked like
11:25a few years ago. But here it is, the polar vortex.
11:29It swirls around. It's a circulation that happens on top of the poles,
11:34way up in the atmosphere, between 30 to 50 kilometres,
11:38so well above the jet stream.
11:39It's a circulation. It happens every year.
11:43It's not anything to do with the El Nino, anything to do with the autumn that we've had.
11:47This setup happens every year. It usually starts around about now
11:51and it continues to move. It continues all the way through until spring
11:56and then it starts to fade away, usually around April time.
11:59But it's a big circular, almost donut shape over the poles
12:04and this holds in cold air well up into the atmosphere.
12:08Obviously, as we head towards winter, the Earth starts to tilt away from the sun
12:13and it holds that cold air within this circulation.
12:18Now, what we tend to find with our polar vortex circulation,
12:22which continues swirling around no matter what kind of,
12:26that's the general kind of circulation over kind of autumn and winter.
12:31And what we tend to find is that it's very much linked with a stronger jet stream.
12:35This is still high up in the atmosphere, still a circulation of winds slightly lower,
12:40more towards kind of 9 to 16 kilometres high.
12:43And what we find is that it very much kind of links with a strong jet stream,
12:48kind of like the one shown on this diagram here.
12:51And this kind of would bring in areas of low pressure,
12:54bring in that wet and windy weather.
12:57Now, what we do find is that the polar vortex can weaken.
13:03It can start to get a little bit out of shape.
13:06Happens to the best of us.
13:08And what that can do is have a bit of a domino effect on the jet stream.
13:13It can create a bit of a weaker jet stream
13:15and create a bit of a bit of buckling of the jet stream as well.
13:20So that could look something a bit like this.
13:23So it will start to kind of look a little bit more bendy,
13:27is probably the word,
13:28and perhaps look something marginally like that.
13:32And as the jet stream weakens and it becomes a bit more meandery,
13:37that means those areas of low pressure won't move directly towards us in the UK.
13:42It might, for example, be pushed slightly further north or northeastwards
13:46and avoid us in the UK.
13:48Sometimes it can even set up blocking areas of high pressure as well.
13:51So it stops and blocks a lot of those areas of low pressure moving through.
13:55And then we start to see a bit of a drier season.
14:00Now, what it can do as well,
14:02if we're blocking those areas of low pressure moving through,
14:06we'll start and obviously stopping that kind of prevailing westerly that we used to,
14:10we might see a change of where our air comes from.
14:13And it may introduce a northerly airflow,
14:16or it may even produce a bit more of an east or northeasterly airflow,
14:20a colder a stream.
14:22And that's when it starts to pick up or we start to pick up
14:27perhaps a slightly colder end to the season
14:31because we've got that change in air stream.
14:33We're getting that colder air move through
14:35and we might see something colder.
14:37We might be a slightly higher likelihood of some colder conditions,
14:42some frosts, potentially some snow.
14:45And what's really interesting about this is that it's all linked together
14:49with our slightly stronger El Nino.
14:52That does slightly increase the chance of the polar vortex weakening.
14:57That does then also increase the chance of our jet stream weakening,
15:02buckling and potentially becoming a bit more meandering in shape.
15:07And then that also may potentially change where our air comes from.
15:13We might see a more north or northeasterly flow.
15:15And that also may increase the chance of some slightly colder conditions towards the end.
15:21Notice how I'm using words such as it may, it may increase the likelihood,
15:26it may do this, it may do that.
15:28That's because nothing is certain.
15:30We've got the polar vortex, we've got the jet stream, we've got El Nino.
15:33There are several other factors at play which could influence the weather here in the UK.
15:39None of it is certain, but certain things such as the slightly stronger El Nino
15:44may tilt the favour in favour of setups like this, but it still remains to be seen.
15:51And we'll still have to keep an eye on our weather patterns
15:53and how they change through the coming months to really understand
15:57what the impacts could be from a super El Nino.
16:00As it's, you know, like I said, it could potentially be quite historical
16:03and it's something we've not quite seen before.
16:05But as I've already mentioned, you know, there are some links with the El Nino
16:09and the autumn that we've had so far.
16:12You know, it has been milder, it's starting to turn wetter
16:15and potentially a little bit windier.
16:17And we may start to see that pattern increase as the autumn continues.
16:21And there is a chance that these things could all link together,
16:24we'll get the perfect ingredients, and that means we could see
16:26potentially a slightly colder end to the season.
16:28But like I say, nothing is certain and we'll still have to keep an eye
16:32on all the different links as we move forward.
16:36And that's the thing I really love about meteorology is that there's so many factors at play.
16:40There's so many different things that link together.
16:43And that's why it can make for a really interesting forecast.
16:47So I think that's pretty much it for today.
16:50So we've had a look at the autumn this week.
16:52We've had a look at how it could potentially pan out over the next few weeks
16:56and a few links with the polar vortex and El Nino as well.
17:00Now, if you do have any further questions, don't forget you can drop them in the comments box.
17:05I'll try and get some answered for you.
17:07But also they could move forward into our live, which is at 12.15 this Friday.
17:12It's not actually me this week.
17:14I'm not sure who it is, one of the Alexes and one of the Aedans.
17:18So they'll be also able to answer some of your questions.
17:22And of course, we're here every week giving you these deep dives.
17:25I'm once again covering for Annie for another year,
17:28so I'll be available to answer some of your questions.
17:31And of course, if you did like this video, make sure to give it a like
17:34and also subscribe if you're new here.
17:36Otherwise, I'll catch you again very soon.