10 Day Trend – Thundery breakdown, then what? 24/06/20
A thundery breakdown brings an end to this week’s brief burst of heat. But what happens after that? Met Office meteorologist Aidan McGivern has this week’s 10 Day Trend.
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00:00Hello, and welcome to the Met Office 10 day trend.
00:04George II apparently said that the British summer consists of three fine days and then
00:09a thunderstorm.
00:10And that's certainly the case this week.
00:12A brief hot spell, then it all goes bang.
00:14Thursday night into Friday, the thunderstorms clearing the air and allowing more typical
00:20British summer weather to arrive from the west.
00:23And that means it will turn cool, changeable, without breaks of rain or showers this weekend
00:28and throughout next week.
00:31Actually, not everywhere has seen three fine days.
00:34Western Scotland and Northern Ireland has seen a wet week so far.
00:38But on Thursday, the hot sunshine extends right across the UK and temperatures will
00:43soar as a result.
00:45Thirty Celsius possible, Glasgow, perhaps the Murray coast as well, widely mid to high
00:49twenties elsewhere and across the heart of England as well as parts of Wales, 30 plus.
00:56I think the hotspots will be West Midlands, West Wales, 33 Celsius possible here or even
01:0234.
01:03If you don't like the heat, head to the coast.
01:05There'll be some cooler sea breezes here, but wherever you are, the sun will be really
01:09strong.
01:10We've just had the solar, the summer solstice.
01:13And that means with Thursday's sunshine, well, the sun is about as strong as it gets at this
01:18time of year with high or very high UV levels across the country.
01:24So make sure you cover up if you're spending time outdoors and hay fever sufferers take
01:28note.
01:29We're looking at high or very high levels of grass pollen as well.
01:33Another risk comes along later Thursday, and that's because we've got the heat in place
01:37across Western Europe, but looking at the Atlantic, the jet stream is beginning to make
01:43inroads.
01:44In fact, that's dipping just to the west of the UK, it's dipping to the south and it's
01:47scooping up areas of low pressure and much cooler air.
01:50And as that cooler air collides with the heat across Western Europe, well, it's all going
01:54to go bang.
01:56And on Thursday evening, well, it's across Western parts of the UK where we'll see those
02:00thunderstorms start to move in.
02:02Severe thunderstorms, hit and miss, as is always the case with thunderstorms.
02:06Not everywhere we'll see one, but where they do occur, they could cause issues.
02:10Now into Friday, it's across Central and Eastern Britain that those thunderstorms move.
02:15And again, the risk of severe thunderstorms in places.
02:18That's why the Met Office have issued yellow warnings for Western Britain on Thursday night
02:22and for Central and Eastern areas for Friday and into the start of the weekend.
02:27A thundery breakdown is expected with the risk of some very heavy rainfall in a short
02:32space of time, 50, 60 millimetres in a few hours, and additional hazards of frequent
02:37lightning, large hail, as well as gusty winds.
02:40Like I say, not everyone will catch one of these severe thunderstorms, but where they
02:44do occur, well, they could cause a few issues.
02:48Once they're out of the way, well, it soon starts to cool off.
02:50Another hot day in the east on Friday, but by the weekend, westerlies across the country
02:56and much cooler air.
02:58Now on Saturdays, there'll still be some heavy showers and thunderstorms about.
03:02They'll be moved along fairly briskly by the wind, so I don't think they'll cause so many
03:05issues as Friday's thunderstorms, but some sharp showers around, certainly, mixed with
03:10some sunshine and a keen breeze.
03:13On Sunday, I think there'll be some drier weather across southern parts of Britain,
03:15particularly later in the day, some sunshine even, but it will certainly feel much cooler
03:20with a breeze coming in from the west and some increasingly persistent wet weather for
03:25western Scotland, I think, developing through the day and continuing into Monday.
03:31For the start of next week, well, taking a look at the bigger picture, we've got the
03:34jet stream in a straight line, more or less, across the Atlantic and heading towards the
03:38UK, and that means that it will pick up further areas of low pressure and send them our way.
03:44Now, the jet stream has often been in a weak and fairly flabby setup through spring and
03:48early summer, but it's not unusual for this time of year, late June, to see that jet stream
03:52pick up some oomph and for the westerlies to return.
03:56In fact, climatologist Hubert Lamb called this return of the westerlies back in 1959
04:02a return of the westerlies because westerlies are the default weather for the UK, not this
04:08hot sunshine that we've got at the moment.
04:11What does that mean?
04:12Here's a map for the middle of next week.
04:15In fact, this is taken from the Met Office medium range computer model and there's a
04:1975% chance, according to that model, that this weather pattern will prevail next Thursday.
04:26That's quite a high percentage chance, looking that far ahead.
04:29In fact, it's the same weather pattern, more or less, throughout next week with low pressure
04:32to the west or to the north of the UK, these westerlies bringing breezy, cool and changeable
04:38weather.
04:39The weather models are in agreement that that's the kind of setup we can expect through
04:43to the end of this 10-day period.
04:46What they all vary on is, of course, where we'll see the showers and rain from day to
04:50day, but that's always the case looking ahead more than five days or so.
04:54But the general theme for next week is that it will be much cooler than we are experiencing
05:00at the moment.
05:01It will often be breezy and we'll have a mixture of rain or showers.
05:04Good news for gardeners and farmers, of course.
05:07Good news for people who don't like the heat.
05:09But if you do like the heat, make the most of the next day or two because it's not going
05:13to last.
05:14Back to normal next week.
05:16Find much more detail, of course, on the Met Office social media channels.