0:00:02 > 0:00:04We are going into a colder spell which could last a week or so.
0:00:04 > 0:00:06There will be some frost
0:00:06 > 0:00:08and there will be some snow for some of us, too.
0:00:08 > 0:00:10We start Thursday on a chilly note,
0:00:10 > 0:00:12that's for sure, with wintry showers
0:00:12 > 0:00:14pushing down across Scotland,
0:00:14 > 0:00:16some rain showers for parts of Wales
0:00:16 > 0:00:18and the West Country, particularly round the coast,
0:00:18 > 0:00:19pretty heavy ones, too.
0:00:19 > 0:00:21But most of us will actually have
0:00:21 > 0:00:23a lot of dry weather through Thursday,
0:00:23 > 0:00:24sunshine hopefully, where you are.
0:00:24 > 0:00:27The wind is not too strong, it shouldn't feel too bad.
0:00:27 > 0:00:29A bit of a nip in the air, but not desperately cold.
0:00:29 > 0:00:315 degrees in the north, 8 or 9 across
0:00:31 > 0:00:33some southern counties of England.
0:00:33 > 0:00:34As we go into the night-time,
0:00:34 > 0:00:36frost returns for a good few of us.
0:00:36 > 0:00:38There will be wintry showers knocking about
0:00:38 > 0:00:40across parts of northern England for a time
0:00:40 > 0:00:41then this area of low pressure
0:00:41 > 0:00:43glides across the far south-west,
0:00:43 > 0:00:44bringing more persistent rain
0:00:44 > 0:00:46and throwing some showers up across
0:00:46 > 0:00:48other southern counties through Friday.
0:00:48 > 0:00:49Another band of wintry showers
0:00:49 > 0:00:51then pushing down across Scotland,
0:00:51 > 0:00:52but again, many of us -
0:00:52 > 0:00:54the vast majority of us, actually -
0:00:54 > 0:00:56will have a lot of dry weather through Friday,
0:00:56 > 0:00:58light winds for the most part.
0:00:58 > 0:01:004 degrees in the north, 7-8 degrees in the south.
0:01:00 > 0:01:02Now, what about the weekend?
0:01:02 > 0:01:04It is causing us some problems here at the weather centre
0:01:04 > 0:01:06in terms of getting the detail right.
0:01:06 > 0:01:07Quite a challenge.
0:01:07 > 0:01:09We do think it'll be predominantly cold,
0:01:09 > 0:01:12some rain in the south and the chance, or the risk,
0:01:12 > 0:01:14depending on your point of view,
0:01:14 > 0:01:16of a bit of the white stuff.
0:01:16 > 0:01:17The first ingredient to the puzzle is
0:01:17 > 0:01:20this area of low pressure pushing in from the west.
0:01:20 > 0:01:22That will bring wet weather, we think,
0:01:22 > 0:01:25to southern and western parts of the UK on Saturday.
0:01:25 > 0:01:27Trying to push milder air in as well,
0:01:27 > 0:01:30but coming up against a block of cold air.
0:01:30 > 0:01:32Now, the dividing line between the cold and the mild
0:01:32 > 0:01:34is quite important,
0:01:34 > 0:01:36because as that rain tries to push northwards,
0:01:36 > 0:01:39encounters that cold air, there is a chance
0:01:39 > 0:01:41some of it will turn to snow.
0:01:41 > 0:01:43At the moment, we think that is most likely
0:01:43 > 0:01:45across parts of Wales and the Midlands,
0:01:45 > 0:01:47especially over the high ground,
0:01:47 > 0:01:48but this could change.
0:01:48 > 0:01:51It could be further north, it could be further south.
0:01:51 > 0:01:53What we are more confident about, actually,
0:01:53 > 0:01:55is what happens next.
0:01:55 > 0:01:57Later on through Sunday, and into early next week,
0:01:57 > 0:01:59cold air will flood southwards,
0:01:59 > 0:02:00quite a stiff northerly wind.
0:02:00 > 0:02:02It will feel distinctly chilly, we think,
0:02:02 > 0:02:04through the early part of next week.
0:02:04 > 0:02:06There will be some wintry showers,
0:02:06 > 0:02:08sleet and snow showers,
0:02:08 > 0:02:10particularly where you've got exposure to those winds,
0:02:10 > 0:02:13so northern and eastern coasts in particular.
0:02:13 > 0:02:15There could be a few centimetres of snow over the high ground.
0:02:15 > 0:02:18A lot of sunshine, though, further south and west.
0:02:18 > 0:02:20Feeling cold in that wind.
0:02:20 > 0:02:22So, yes, this could be a typical scene
0:02:22 > 0:02:24through the early part of next week -
0:02:24 > 0:02:27bright and crisp to cold, with overnight frost
0:02:27 > 0:02:30and a dusting of snow in some places.
0:02:30 > 0:02:33Now, how long does the cold spell last?
0:02:33 > 0:02:35Certainly through the early part of next week,
0:02:35 > 0:02:37those northerlies should prevail.
0:02:37 > 0:02:40There are weather fronts trying to come in off the Atlantic,
0:02:40 > 0:02:43but they are being held up by this ridge of high pressure.
0:02:43 > 0:02:45So through the early part of next week,
0:02:45 > 0:02:48we've got this block of cold air in place,
0:02:48 > 0:02:49mild air trying to push in.
0:02:49 > 0:02:50We think it will succeed -
0:02:50 > 0:02:52the motion of everything is west to east.
0:02:52 > 0:02:54But there is a catch.
0:02:54 > 0:02:56The catch is that the jet stream
0:02:56 > 0:02:59is getting all kind of...well, tangled up.
0:02:59 > 0:03:02Look at the huge great ripples in the jet stream.
0:03:02 > 0:03:04It's a bit like a crumpled carpet,
0:03:04 > 0:03:06and if you try to iron out a crumpled carpet,
0:03:06 > 0:03:07it's not easy, is it?
0:03:07 > 0:03:08It's trying to do that -
0:03:08 > 0:03:10it is coming up against this block.
0:03:10 > 0:03:13The question mark is how quickly
0:03:13 > 0:03:15that block will get shifted.
0:03:15 > 0:03:16The computer models often
0:03:16 > 0:03:18have difficulty in nailing down
0:03:18 > 0:03:21the detail and the timing of that change of type,
0:03:21 > 0:03:23so later next week, eventually,
0:03:23 > 0:03:26it might turn milder and potentially wetter,
0:03:26 > 0:03:27but watch this space.
0:03:27 > 0:03:29Sarah will update you again tomorrow.
0:03:41 > 0:03:43You're my psychiatrist, you want to know what's going on in my head
0:03:43 > 0:03:45and I want to know what's going on in your head.
0:03:45 > 0:03:47Nearly one in 500 new mothers
0:03:47 > 0:03:50can suffer from an extreme form of psychosis.