0:00:03 > 0:00:06Hello. It's already turned cold, but this cold snap has another gear.
0:00:06 > 0:00:09It is going to get even colder as we go into the weekend.
0:00:09 > 0:00:12Potentially, turner milder at some point next week,
0:00:12 > 0:00:16but there is a lot of uncertainty about that, as we'll see in a moment.
0:00:16 > 0:00:19For the time being, it is cold and we have low pressure sitting over us,
0:00:19 > 0:00:24bringing moisture. That combination providing some wintry weather.
0:00:24 > 0:00:27Yes, some snow falling at the moment and it will continue, as that low
0:00:27 > 0:00:31slowly heads out into the North Sea. A mixture of rain, sleet
0:00:31 > 0:00:35and hill snow across parts of England and Wales, becoming confined through
0:00:35 > 0:00:39the afternoon across the east. But still some sleet and snow likely,
0:00:39 > 0:00:42chiefly over the hills, but potentially, even down to low levels.
0:00:42 > 0:00:44Some wintry showers across northern Scotland, Northern Ireland.
0:00:44 > 0:00:48For many, turning sunny, but it will be a cold, cold Thursday.
0:00:48 > 0:00:51There is further potential for problems from this wintry weather.
0:00:51 > 0:00:55A combination of ice, sleet and snow during Thursday and, indeed,
0:00:55 > 0:00:59into Friday. Because that low slowly pulling away, still on Thursday
0:00:59 > 0:01:02evening proving a mixture of rain, sleet and some hill snow
0:01:02 > 0:01:06across eastern England. Then, further snow flurries coming in on this
0:01:06 > 0:01:09weather front during the course of the early hours of Friday morning
0:01:09 > 0:01:12could provide a covering on Friday morning's rush hour
0:01:12 > 0:01:16and, again, potentially, quite icy. Friday, for many, is a sunny day,
0:01:16 > 0:01:19but it will feel bitter in the winds and there is still a sprinkling
0:01:19 > 0:01:23of snow showers to come. So, don't be surprised if you see the odd flake
0:01:23 > 0:01:27over the next 48 hours or so. Then, for the next 48 hours, as I said
0:01:27 > 0:01:31at the start, we see a change in gear. The isobars spread out,
0:01:31 > 0:01:35as high pressure builds in. That means the winds fall lighter.
0:01:35 > 0:01:40With light winds and high pressure and cold air, cold air is dense,
0:01:40 > 0:01:45so it just sinks. With no winds to stir it up,
0:01:45 > 0:01:48things just get colder at the surface and the nights, in particular,
0:01:48 > 0:01:51this weekend will be bitter. Severe frosts likely.
0:01:51 > 0:01:55This is not just going to be cold compared to this current,
0:01:55 > 0:01:58pretty mild winter. This is going to be cold compared to ANY winter.
0:01:58 > 0:02:02Now, there is a pay-off, in that most of us this weekend will see some
0:02:02 > 0:02:06sparkling sunshine, but the mornings are going to be very cold.
0:02:06 > 0:02:08Exceptionally cold. How low will we go?
0:02:08 > 0:02:14Well, negative double figures is likely. -15C is possible,
0:02:14 > 0:02:17where there is snow lying on the ground.
0:02:17 > 0:02:20The coldest spell since, at least, March, 2013.
0:02:20 > 0:02:23Into the new working week, high pressure still nearby.
0:02:23 > 0:02:27Low pressure systems trying to come in but, as you can see, on Monday,
0:02:27 > 0:02:30sort of, failing, really. The high is still dominant
0:02:30 > 0:02:34as we go into next week. Yesterday, we were talking about just when
0:02:34 > 0:02:37the milder air would arrive, pushing that high pressure system
0:02:37 > 0:02:40out of the way. There is still a lot of doubt, but for the first half
0:02:40 > 0:02:43of the week, it looks like the cold air, with the high pressure,
0:02:43 > 0:02:48still in control. Now, this graph shows how we expect things to pan out
0:02:48 > 0:02:51through the week ahead. Take this line.
0:02:51 > 0:02:55This line is the computer models. Pretty much all of them suggesting
0:02:55 > 0:02:57it is going to stay cold until at least Wednesday.
0:02:57 > 0:03:01The problem comes after the middle of the week. Some computer models
0:03:01 > 0:03:04will keep it cold. Others turn it much milder quicker.
0:03:04 > 0:03:10And this spread, if you like, this change in the graph, this area
0:03:11 > 0:03:14means there is a greater uncertainty, more uncertainty than usual,
0:03:14 > 0:03:18about just how things will change. We do know it is going to be messy.
0:03:18 > 0:03:21The start of the week looks cold. There is the risk of some snow.
0:03:21 > 0:03:25It will eventually turn milder and wetter, but there is still a lot
0:03:25 > 0:03:28of uncertainty, because those computers
0:03:28 > 0:03:30are just not agreeing about exactly when that will happen.