0:00:02 > 0:00:05Hello, it's cold and getting even colder this weekend.
0:00:05 > 0:00:08When will the mild air return? That is such a big question.
0:00:08 > 0:00:11If anything, the forecast for next week has become even more
0:00:11 > 0:00:14uncertain than it was this time yesterday.
0:00:14 > 0:00:15More than that in just a moment.
0:00:15 > 0:00:18First of all, let's focus on this cold spell.
0:00:18 > 0:00:20Follow the isobars, they point up to the Arctic.
0:00:20 > 0:00:22That is where our air is coming from.
0:00:22 > 0:00:24Low pressure clearing away from the east.
0:00:24 > 0:00:26Still a few showers across East Anglia,
0:00:26 > 0:00:28but the winds will be a little less vicious on Friday.
0:00:28 > 0:00:31Some snow showers across parts of the west and the north-east
0:00:31 > 0:00:34of Scotland through the day, but for many it's a dry, bright
0:00:34 > 0:00:36very cold day.
0:00:36 > 0:00:393 to 6 Celsius. And feeling even colder.
0:00:39 > 0:00:41And getting colder still on Friday night,
0:00:41 > 0:00:45it could well turn icy, particularly where we've got any showers.
0:00:45 > 0:00:47The showers fading in the west but will continue to feed sleet
0:00:47 > 0:00:51and snow showers across eastern parts during the course of the night.
0:00:51 > 0:00:54And those temperatures tumbling, towns and cities a couple of degrees
0:00:54 > 0:00:57below freezing, in rural areas well below, negative double figures
0:00:57 > 0:01:00where there's snow lying on the ground across Scotland.
0:01:00 > 0:01:03It's a really cold start, then, to the weekend.
0:01:03 > 0:01:04Could be some mist and fog around,
0:01:04 > 0:01:07and we'll continue to see some showers in the east,
0:01:07 > 0:01:10rain on the coast, but inland they will be of sleet and snow.
0:01:10 > 0:01:13But for the majority it's another cracking, sunny, sparkling,
0:01:13 > 0:01:15very cold day.
0:01:15 > 0:01:17We could see thickening cloud bring a bit of wet
0:01:17 > 0:01:20weather across parts of Northern Ireland later on.
0:01:20 > 0:01:22And we may see this weather front bringing a bit more wet
0:01:22 > 0:01:24weather across the far north-west,
0:01:24 > 0:01:27but for most, high pressure dominates into Sunday.
0:01:27 > 0:01:29It's going to be another day of sparkling sunshine
0:01:29 > 0:01:31although it could be foggy first thing.
0:01:31 > 0:01:35And it will be certainly very cold first thing,
0:01:35 > 0:01:40Temperatures on Sunday morning -8, -9, -10, maybe even lower, again,
0:01:40 > 0:01:42where there's the snow lying on the ground.
0:01:42 > 0:01:46High pressure means it's probably going to be a frosty start to Monday,
0:01:46 > 0:01:49but after that the forecast gets complicated. Low-pressure systems
0:01:49 > 0:01:54trying to arrive, trying to reintroduce the milder air.
0:01:54 > 0:01:57What we know about next week, it will start cold and frosty,
0:01:57 > 0:02:00it will probably be milder by the end of the week, but the timing
0:02:00 > 0:02:05of that change back to milder weather is very, very uncertain. Why?
0:02:05 > 0:02:07Well, a couple of reasons...
0:02:07 > 0:02:09The first one - we need to look not just at the cold air
0:02:09 > 0:02:11across the UK
0:02:11 > 0:02:14but the intense cold across the north-east of the United States
0:02:14 > 0:02:18and eastern Canada, which has in recent days led to scenes like this.
0:02:18 > 0:02:20That cold air digging south,
0:02:20 > 0:02:23hitting against the warm air, providing a contrast,
0:02:23 > 0:02:27and it's that contrast which intensifies the jet stream,
0:02:27 > 0:02:31that fast-moving ribbon of air high up in the atmosphere, it's driving
0:02:31 > 0:02:34southwards and that contrast then forcing the jet stream further north.
0:02:34 > 0:02:37Allowing this pool of warm air to be sitting in the middle
0:02:37 > 0:02:39of the Atlantic.
0:02:39 > 0:02:40The jet stream then comes back south
0:02:40 > 0:02:43and we are on the cold side of the jet.
0:02:43 > 0:02:46But with the warm air sitting there, it's got energy,
0:02:46 > 0:02:48it wants to shift
0:02:48 > 0:02:51but it's surrounded, it's flanked by pools of dense cold air
0:02:51 > 0:02:54and with the jet stream not moving across it, there's very
0:02:54 > 0:02:56little to shift it.
0:02:56 > 0:02:58When we've got those blocked patterns,
0:02:58 > 0:03:00the computer models always struggle.
0:03:00 > 0:03:02Add into the mix a hurricane, yes,
0:03:02 > 0:03:05a hurricane in January in the Atlantic.
0:03:05 > 0:03:07And things are only going to get more complicated.
0:03:07 > 0:03:11It's very unusual to see a hurricane and this time of year,
0:03:11 > 0:03:13only four have been recorded in history,
0:03:13 > 0:03:15records going back 150 years.
0:03:15 > 0:03:18The storm system moves northwards, interacts
0:03:18 > 0:03:22and adds energy to that warm air in the middle of the Atlantic,
0:03:22 > 0:03:25adding confusion to the computer models
0:03:25 > 0:03:27and therefore the forecast as we go into next week.
0:03:27 > 0:03:30Hopefully we'll know more in the next day or two.