10 Day trend – Turning colder, but will there be any snow? 15/01/20
A big change is on the way with drier, calmer and colder weather arriving for the weekend. It may well last for much of next week too, but will this colder spell bring any snow to the UK? Alex Deakin explains why it’s turning colder.
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00:00Welcome to the Met Office 10-day trend.
00:02It's been a very wet first half of winter
00:06and a very wet and very windy first half of this week.
00:09So it is going to be quite a change that we see over the next 10 days,
00:14particularly through the weekend and beyond as the weather calms down.
00:18The winds will be lighter.
00:19It is going to turn colder and crucially a lot drier.
00:23For how long?
00:24And with it turning colder, any sign of any snow?
00:26Well, we'll deal with that in just a moment
00:29because let's deal with the transition first of all,
00:31because we're talking calmer weather, but that's to come from the weekend.
00:34The next couple of days still see low pressure, lots of isobars around.
00:38So another spell of wet and windy weather to come,
00:40particularly so on Thursday afternoon and evening.
00:43But here comes the area of high pressure,
00:45settling things down and arriving into the weekend.
00:48And it is set to stick around well into next week.
00:52Why are we seeing this shift?
00:54Well, for the reasons behind that,
00:55we need to take a look at the broader picture and rewind the clock
01:00and head across the pond.
01:01Across North America at the moment, a couple of really cold plunges of air,
01:05one in the west of Canada and this one in the east,
01:07setting up through Thursday and Friday is crucial to our weather.
01:11Cold air driving south across the eastern seaboard of the US,
01:15hitting the warmer air further south.
01:18And it's that contrast between the cold and the warm that drives
01:22and peps up the jet stream,
01:24that fast moving ribbon of air high up in the atmosphere.
01:27So the jet stream is getting supercharged later this week
01:31and that in turn then will spin up this area of low pressure.
01:34But so much energy going into this low that actually the low itself
01:39will then start to influence the jet stream.
01:41Instead of driving straight across the Atlantic,
01:43this intense low gives a bit of a kink to the jet stream.
01:47The jet stream pushes to the north and arches over the UK.
01:50So whereas for most of winter,
01:52the jet's been coming in across or to the south of the UK,
01:55come the weekend into Monday, the jet stream is to the north,
01:59allowing high pressure to establish itself across the United Kingdom.
02:04So, yes, we are going to see a big change next couple of days.
02:07Yes, there is more strong winds, heavy rain to come, but staying fairly mild.
02:11All change for the weekend.
02:13It turns calmer.
02:14The winds will be lighter.
02:15It'll be a lot drier.
02:17It will be colder with those frosty mornings, particularly noticeable.
02:20Haven't seen much of those so far this year.
02:24How long will it last?
02:25Well, the high pressure still in control, as we saw through Monday,
02:28probably Tuesday as well.
02:30There is this weather front to the north, which will bring maybe some cloud
02:33and rain across northern Scotland on Monday.
02:35We'll try and push further south, squeezing against that area of high pressure.
02:39But remember, now the jet stream is to the north.
02:43So there's not a lot of what we call forcing.
02:45There's not a lot of oomph to this weather front as it sinks south.
02:48It'll probably just bring a bit more cloud and the rain will tend to fizzle out
02:52as it drifts southwards and it'll just tend to shift the area of high pressure
02:56and maybe morph it around.
02:57But the general trend through next week is that high pressure is set to stick around.
03:02And that is shown on this chart here.
03:04It's a projection from the European model of the pressure anomaly for next week.
03:08Anomaly. So how far removed from the average is it?
03:12And the red colours are when the pressure is higher than average.
03:15Those dark reds, that dark red smudge sitting across the UK,
03:19suggesting that the pressure will be 10 to 20 millibars or hectopascals
03:24above average throughout next week.
03:27So yes, we are expecting high pressure to stick around next week,
03:30which means dry weather generally.
03:33But of course, the position of the high will be crucial to the feel of the weather.
03:37Now, the most likely scenario for much of next week is that the high pressure
03:41will rebuild in from the west, meaning that at times we could see the breeze
03:47picking up down the east coast, maybe a few showers here.
03:49But for much of the UK, it will be dry with more of an Atlantic influence
03:53after frosty conditions through the weekend and quite a drop in temperatures.
03:57Slowly in this scenario, temperatures could start to pick up.
04:01Certainly it won't be perhaps quite as cold at night.
04:04We could see some mist and fog and perhaps a lot of cloud around with that increased moisture.
04:09Another scenario is that the high pressure is a little bit further south.
04:13And at times if this happens, well, we'll start to see the Atlantic
04:18influencing the weather across Scotland and Northern Ireland.
04:20So there could be some weather fronts here, a bit of cloud and a bit of rain,
04:22whereas the bulk of England and Wales will stay dry in this scenario.
04:26That's a possible scenario.
04:27And we may switch between those first two.
04:30Now, if you're a big snow fan and you remember the beast from the east
04:34a couple of years ago and you're thinking, well, high pressure could allow that to happen.
04:38For that, we need the high pressure to be sitting further north
04:41and the winds would then start to come in from the east.
04:44But this doesn't look like happening at this stage.
04:47There's no signal from the computer models for the high to be shifted further north.
04:52Of course, it's something we'll be keeping a very close eye on.
04:54But for much of next week, it looks like large chunks of the UK will be dry,
04:59certainly a lot drier than the current week.
05:01It will be a bit colder and crucially, after some very strong gusts,
05:05the winds will be a little bit lighter as well.
05:08Make sure you stay up to date with the very latest day on day variations
05:11by following the Met Office on social media.