10 Day trend - Any sign of the weather patterns changing? 13/11/19
The main themes of the UK forecast remain cold with spells of further rain. The weather patterns stay that way well into next week, with perhaps a subtle change later next week, Alex Deakin explains.
Category
🗞
NewsTranscript
00:00Thanks for joining me for this 10-day
00:02trend, where we look at the weather
00:04patterns and trends for the medium
00:05to long range.
00:07Now, in the short range, there's some
00:08more severe weather on the way.
00:10Plenty of heavy rain to come and
00:12there are weather warnings in force.
00:13I'm not going to go through those in
00:15detail here.
00:16If you want to know the latest on the
00:17severe weather, download the Met
00:19Office app or visit our website.
00:21Now, I'm looking at the longer range
00:23trends, which are for more of
00:25the same. It does look as if
00:26generally well into next week, it
00:28stays unsettled.
00:29Further spells of rain and often
00:31blustery conditions and always
00:32staying on the chilly side as well.
00:34There are hints that perhaps things
00:36could turn a little bit milder
00:38as we go through it next week.
00:39But the weather patterns kind of
00:41been stuck in a rut now for a
00:43number of weeks.
00:44Let's take a look at the big
00:45picture. This is the jet stream
00:46notice it driving down to the
00:48southwest of the UK, up across
00:50Greenland and then driving south.
00:52And in this position, it generally
00:53allows low pressure systems just to
00:55sit in here and mill around
00:58across the UK.
00:58That is why we keep seeing those
01:00spells of rain.
01:02Now, why are we seeing this
01:03repeating weather pattern?
01:04Well, one of the reasons is
01:06over in the United States, we're
01:07seeing a repeated pattern here.
01:09Cold plunges, areas
01:11of cold air drifting south from the
01:12Arctic over eastern parts of
01:14Canada and eastern parts of the
01:16United States. And we get another
01:17one of those pushes of cold air
01:19driving south this weekend.
01:21Why is that important?
01:22Well, the cold air derives south,
01:24clashes with the warmer air over
01:25the tropics, and that gives the jet
01:27stream a bit of oomph, a bit
01:29of extra energy.
01:30It pushes it to the north, up
01:31across Greenland, and then that
01:33drives down to the south
01:35to the west of the UK.
01:37Now, this is the chart for Sunday,
01:38but it does look remarkably like
01:40that one I showed you a minute ago
01:42for the one on Wednesday.
01:43So again, that weather pattern is
01:45set to repeat for the next few days
01:47and we stay on the cold side of the
01:49jet with low pressure nearby.
01:51Now, those low pressures will bring
01:53further spells of rain, one
01:54particularly across eastern areas
01:56into Friday night and Saturday
01:58could cause some further problems.
01:59And then this one just flirting
02:01with the southwest on Sunday.
02:03But notice it's not going to rain
02:04everywhere all weekend.
02:06Some places will be between those
02:07two weather systems.
02:08So there will be dry spells around
02:10this weekend, but just don't
02:12expect it to be warm.
02:13We stay on the cold side of the jet,
02:15so it's going to be chilly.
02:16Morning frosts are very
02:17possible and also some fog
02:19patches as well.
02:20But as I said, it won't rain
02:21everywhere all weekend.
02:22There will be some dry periods.
02:24We do need to flag that rain
02:25potentially across eastern England,
02:27certainly on Saturday morning.
02:30What about beyond the weekend?
02:31Will we continue with this
02:33repeating weather pattern?
02:34Well, chances are, yes,
02:36I'm going to show you a Hofmuller
02:37plot now. Now, it's quite a
02:39complicated graph, but it
02:40does show the repeated cycle
02:43quite clearly.
02:44Now, this is longitude along
02:46the x-axis to the bottom.
02:47There's the UK at zero, the Greenwich
02:49meridian. This dotted line
02:50represents where we are now.
02:52Things above that are going
02:54back in time and things below
02:56it are going forward in time.
02:58So this is the projection.
02:59It's basically a slice through
03:01mid-latitudes, medium
03:03or upper levels of the atmosphere
03:05where red represents
03:07higher pressure and blue
03:09represents lower pressure.
03:10Now, don't worry too much about
03:11deciphering the detail.
03:12I just really wanted to show you
03:14the repeated pattern as we go back
03:15in time here over the past several
03:17weeks. You can see that we've had
03:19this repeating pattern with high
03:21pressure, low pressure, high
03:22pressure. That's across the
03:23Mid-Atlantic and there's the UK
03:25stuck in that slightly blue zone.
03:27That's why we've kept on seeing
03:29low pressure systems across the UK.
03:31And it's also important because I
03:32want to show you going forward,
03:34that pattern is likely to stick
03:36around well into next
03:38week. So we're likely to stay with
03:40low pressure close to the UK.
03:42One subtle difference, though,
03:43that I want to highlight, just that
03:45red blob there, areas
03:47to the east of the UK
03:49just showing signs that the high
03:50pressure here may intensify,
03:53may get a little bit stronger next
03:54week. And if we see slightly higher
03:56pressure over the near continent,
03:58it means the lows may
04:00not be sitting as close to the UK.
04:01They're more likely to be a little
04:03bit further west.
04:04And if that's the set up, this is
04:05the most likely set up through next
04:07week. It means that the winds
04:09perhaps could start coming more in
04:10from the southwest.
04:11Now, that's important for a couple
04:13of reasons.
04:14It suggests that through next week,
04:15perhaps it won't be quite as
04:17cold. I'm not suggesting it's going
04:18to get warmer. We generally stay on
04:20the cold side of the jet, but
04:22it won't be quite so cold.
04:23Temperatures back closer to average.
04:25And it also means with the winds
04:26coming more in from the west, that
04:28it's western areas that are
04:30more likely to see the
04:31outbreaks of rain, which is good
04:33news with the flooding across parts
04:35of the east, of course, but not
04:37great news because it is very
04:38wet already across the west.
04:40So that's the themes into next week.
04:41Yet it remains unsettled.
04:43Low pressure will be the dominant
04:45feature, but we are more likely to
04:47see a subtle shift with more wet
04:48weather in the west compared to the
04:50eastern temperatures, perhaps just
04:52rising closer to average.
04:54As always, there's a lot of
04:55uncertainty. These are just the
04:57general trends.
04:57And as I said at the start, for the
04:59details of the very latest
05:01weather warnings, make sure you
05:02stay weather aware by visiting the
05:04Met Office website or following
05:06us on social media.