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