10 Day trend – Stuck in a rut? 19/02/20 - video Dailymotion

Met Office

Is our weather stuck in a rut? Or, more precisely, are we currently subject to a repeating 7-day cycle in our weather patterns? Are there any signs of a change? Met Office meteorologist Aidan McGivern looks at this week’s 10 Day Trend.

Transcript

00:00Hello, and welcome to the Met Office 10-day trend. It's not good news, I'm afraid. During

00:06the next 10 days, the strong signal is that we will continue to see low pressure after

00:11low pressure after low pressure, bringing yet more wind and more rain. Each individual

00:17event may not be as disruptive as the last two named storms, but we certainly don't want

00:23any more rainfall across parts of the country where we are particularly sensitive at the

00:28moment. What on earth is going on? Well, it's no coincidence that we had Storm Dennis last

00:34weekend and Storm Kira the weekend before. The jet stream at the moment circling the

00:39Northern Hemisphere has a certain wavelength, which means that we're stuck in a seven-day

00:45cycle. What does that mean? Well, if you look back to around this time last week and this

00:50time the week before, what we saw was a cold plunge. Arctic air coming south across Canada,

00:56bumping into mild air across the Gulf of Mexico, and helping to fuel a vigorous jet stream.

01:02And you can see the dark colours there, that powerful jet stream emanating out of North

01:06America, which then helps to fuel areas of low pressure arriving in time for the weekend.

01:14These lows are the low pressure systems that are arriving for Friday and this weekend to

01:19bring some unsettled conditions. But this low coming along later, well, it starts off

01:26on the warm side of the jet stream and then it switches to the cold side. And when that

01:31happens, well, we really start to pay attention because that can help to spin it up into a

01:36deep low and bring some disruptive weather, perhaps on Monday. More on that in a moment.

01:42But by this stage, Monday, well, the strongest part of the jet stream eventually clears through.

01:47Stays unsettled, yes, but at this time next week, well, what we're starting to see is

01:54the first stages of another cold outbreak across Arctic Canada, potentially renewing

02:01that seven-day cycle once again. In the immediate future though, well, our main concern is rainfall.

02:07The start of Thursday sees more wet weather across southern Scotland, northern England,

02:11parts of Wales and the south-west. Western Hills in particular are focused for the heaviest

02:16rainfall. Yellow warnings in force because these areas do not need more rainfall. The

02:21rain sweeps through after lunch and it's going to be particularly lively as it clears the

02:26south-east of England. Some strong gusty winds and then a sharp temperature drop. Colder

02:30air follows but with brighter skies and a few showers. Some lively downpours, hail and

02:35thunder, snow over hills or even down to lower levels for northern and western Scotland,

02:40certainly building up over the hills. And it will feel cold in the wind behind that

02:44weather front. Fast forward to Friday and a reversal of conditions. We're going to see

02:49milder air return, south-westerly winds strengthening through the day, wet weather pushing back

02:54into Scotland, northern England and northern Ireland through daylight hours and again that

02:58rainfall building up, each successive event building up across northern England. That's

03:03an area of concern during the next few days because of that. It will also be windy, some

03:07strong gusts particularly for south-east Scotland, north-east England, 65 mph perhaps as the

03:13wind bounces over the hills. Eventually turning milder through Friday and largely dry for

03:18southern half of the country until after dark. That's when this cold front does clear through,

03:25bringing some rain for the start of the weekend. But by Saturday afternoon this is how it's

03:31looking. Cold front's gone through and then we're back into bright spells and blustery

03:35showers and again these showers in cold weather that follows will be falling as snow, mainly

03:40over northern hills but perhaps again to lower levels for the north and the west of

03:43Scotland, certainly building up over the hills but there will be some sunshine in between.

03:48A strong gusty wind through Saturday for all areas but particularly in the far north. Feeling

03:54cold in that wind but we're at the point where the cold air is bumping into the mild air

04:01and if we trace that all the way back towards the Atlantic you can see, well first of all,

04:06Monday's low starting to form on the warm side of the jet stream at this stage and then

04:11just ahead of it just a small disturbance which starts to develop into an area of rainfall

04:17and there's some uncertainty at this stage in terms of the line of attack of this but

04:22it looks likely that the southern half of the country will see some wet and windy weather

04:25for the start of Sunday. Again, yet more rain over western hills and risk of gales around

04:31coastal areas. Further north likely to stay cold but in between there's the chance of

04:35some hill snow where that rain bumps into the cold air but the exact position of the

04:40rain at the moment opens doubt. Whatever happens it does clear and by Sunday afternoon most

04:46places back into that cold, bright but showery airflow. Again, a windy day on Sunday, particularly

04:53in southern parts of the country. Feeling cold in that wind as the front clears through

04:58and then back to the jet stream, that powerful core of the jet stream crossing the country

05:02and by this stage, this low is crossing to the other side of the jet stream, spinning

05:07up into a potentially deep and disruptive area of low pressure and that will bring some

05:12strong winds for virtually all places on Monday but the focus for the strongest winds most

05:18likely to be the northwest. And some wet weather sweeping through, hopefully relatively quickly

05:25but it's still a long way off so still a little uncertain. What happens after that, still

05:31like I say, it's a long way off as we get into next week so too early to give specific

05:35details on individual areas of low pressure but it looks likely that around the middle

05:39of next week, Tuesday night into Wednesday, another low will come along carried by the

05:43jet stream to bring yet more wind and rain. Fast forward to the end of next week and another

05:49low on that conveyor belt pushing in to bring an unsettled end to next week and potentially

05:55the following weekend. Too early to give specifics on these individual lows of course, suffice

06:01to say next week is going to stay unsettled with the particular focus for the time being

06:07on Monday staying very windy and potential for more rain. Mixed after that, no real sign

06:13of change over the next 10 days so pay attention to the forecast and the warnings during the

06:18next few days. Rain of course could cause problems and then wind for the start of next

06:24week and beyond. And you can stay up to date by following the Met Office on social media,

06:28heading to the website or downloading the app. Bye bye.

10 Day trend – Stuck in a rut? 19/02/20

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