10 Day trend – Milder at first but could we see a cold snap next week? 29/01/20 - video Dailymotion

Met Office

After a chilly start to the week temperatures are on the rise with changeable the best way to describe the weather into the weekend. Next week there’s a good chance that high pressure will dominate but could that bring a cold plunge from the Arctic?

Transcript

00:00Welcome to the Met Office 10-day trend.

00:02The next five or six days, fairly straightforward,

00:05changeable, kind of sums it up.

00:07Each day different, one day cloudy, one day dry.

00:10The next day could see a little bit of rain.

00:12The main themes, though, certainly

00:13as we go through the rest of this week,

00:15is a lot milder than the start of the week,

00:17and often it's going to be fairly blustery, particularly

00:20across Scotland.

00:21There becomes more uncertainty as we go through the weekend,

00:25and particularly into next week.

00:27Uncertainty on one hand, but actually

00:29one of the things we're pretty confident on

00:32is that generally next week, pressure will be fairly high.

00:35That means that spells of really wet and windy weather

00:37are very unlikely.

00:38But high pressures come in different shapes and sizes.

00:42And if the high is in just the right position,

00:44well, we could get something of a cold plunge,

00:47a cold northerly wind bringing down air from the Arctic.

00:50And we haven't seen that that often so far this winter.

00:54But as I said, there is uncertainty,

00:57and that cold plunge may not arrive at all

00:59and if it does come, it may not last too long.

01:03More on that in a moment.

01:04First of all, let's look at the pressure pattern

01:06into the early part of next week.

01:07I talked about high pressure.

01:08This is the chart for Monday, and it's this area of high

01:11that we're expecting to topple in through next week.

01:14But before we get there, let's rewind the clock.

01:16And you can see over the next few days,

01:18we're expecting lots of low pressure systems

01:20to be drifting, particularly close to northern Britain,

01:23all pushed in by a fairly active jet stream.

01:27How this one interacts exactly with the jet stream

01:30will impact Sunday's weather quite a bit,

01:32but this is expected to bring a spell of rain

01:34across the country.

01:36As I said at the start, it will be turning a bit milder,

01:39and that could be reflected by this chart here.

01:41Yes, a chilly start to the week,

01:43but gradually temperatures are now rising.

01:46And so you can see the yellower colours there,

01:48the milder air as these lows bring in that milder air

01:52from the southwest over the rest of this week.

01:56But as I said, the position and intensity

01:58of this low on Sunday is open to doubt.

02:00Saturday's weather looks reasonably straightforward,

02:03a gusty, blustery day with showers,

02:06particularly across the north.

02:07Sunday's weather uncertainty really begins,

02:09the timing of the wet weather.

02:11Could be a chilly start,

02:13and then we are expecting a spell of rain.

02:15But how much rain and where it is, the wettest conditions,

02:18is at this stage open to some uncertainty.

02:21And this next chart kind of reflects that.

02:22This is the amount of rainfall

02:24we're expecting to see in Edinburgh.

02:27This is a European model and the magenta lines there

02:29is the main computer model run.

02:31If you followed that,

02:32you'd think that it would be a fairly dry day in Edinburgh.

02:35But of course, we don't just run these computer models once,

02:38they're run lots and lots of times.

02:40And each of these blue dashed lines

02:42is a different example or a different run.

02:45We call this an ensemble forecast.

02:47And you can see that a lot of those blue dashed lines

02:50suggesting that we could see quite a bit of rain

02:52in Edinburgh on Sunday.

02:54So that is where the uncertainty begins.

02:57After that, we are, as I said,

02:59looking towards that area of high pressure,

03:01slowly trying to topple in from the Atlantic.

03:04But low pressure and isobars

03:06continue to dominate into Monday.

03:07So again, expect a showery day

03:10and still fairly blustery conditions.

03:12But here comes the high,

03:15toppling in at some point into next week.

03:18And the exact position of that will be crucial

03:21in determining the type of weather we get.

03:23But this chart does show that we are expecting

03:26that pressure to be higher than normal next week.

03:29Low pressure, the blue colours dominating

03:32as we go through towards the weekend.

03:33We've seen that on those pressure charts,

03:35but look at this,

03:36a strong signal of the pinks and the reds taking over,

03:39which means anti-cyclonic conditions or high pressure

03:43is the most likely scenario

03:45from the middle part of next week.

03:47But high pressures do take different shapes

03:50and different sizes.

03:51This again is the European model,

03:52the main model run,

03:53and it shows where it thinks the high pressure

03:55is likely to be through the middle part of next week,

03:58out to the West.

03:59Now, if this scenario is true,

04:01if you follow the isobars,

04:03then they point all the way up to the Arctic

04:04and that's really cold air

04:06then driving south across the UK.

04:08That will be a shock to the system

04:09because we haven't really seen

04:11these kind of northerly winds at all this winter.

04:14They would bring sleet and snow showers with them as well.

04:18But one of the other computer models,

04:20the American model, the GFS model,

04:23has high pressure still in control,

04:25but this time the high now is down to the south of the UK,

04:28a very different shape.

04:29And so that would be a very different day.

04:31Yes, it's high pressure, it's still largely dry,

04:34but the wind's now coming in around the top of that ridge,

04:37more in from the Atlantic.

04:38So it wouldn't be anything like as cold.

04:40The cold air you can see is still way to the north of the UK.

04:44So all to play for really

04:45with how the pressure pattern maps out next week.

04:49And again, I'm just going to show the uncertainty here

04:51with the projected temperature.

04:52Again, this is for Edinburgh and showing that uncertainty.

04:56The temperature, the date's going along the bottom,

04:58bottom and here's the Y axis showing the temperature trend.

05:02You can see here that we are expecting things

05:04to turn milder.

05:05The size of these nodules represents the uncertainty.

05:09So those small nodules representing that,

05:12we're pretty confident it's going to turn milder

05:14over the next few days.

05:15Temperature's slowly drifting back closer to average.

05:17This is the average line here around the weekend.

05:20But then look at how those blobs just get bigger and bigger

05:24as we go through next week.

05:25Again, just representing that uncertainty

05:28in the computer models through next week.

05:31We are pretty confident changeable conditions

05:33will persist into the weekend.

05:34Milder at first, there's just the potential

05:37for the cold snap into next week.

05:39Nothing unusual about that.

05:40And again, this 10-day trend forecast

05:42is just highlighting things that could happen,

05:44things that we're looking at.

05:46So we just wanted to flag that for now.

05:47Make sure you stay up to date with the day-to-day details.

05:50Best way to do that is to follow

05:52the Met Office on social media.

10 Day trend – Milder at first but could we see a cold snap next week? 29/01/20

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