NZ: Wintry blast coming this weekend, everyone will feel the temperature drop

[00:00:04][music] >> Hello, Kyoto. It's Monday the 20th of July. I'm Philip Duncan. Thank you for joining me. Well, this week we've got a wintry blast on the way. It really kicks in this weekend. But before that arrives, we've got a fair bit of high pressure still around the country and building out around Australia. So high pressure over the South Island today, light winds, mostly clear skies.

[00:00:28]Although there are some cloudy areas towards the South and the North. Dry or mainly dry right across the South Island. Then we've got a few showers around Cook Strait. And as you move further northwards, all this cloud around the North Island producing areas of patchy rain and showers, which will move through across today and then start to clear away from the western side as we go on towards tonight. And cloudy periods around the Chatham Islands with that colder southerly change, which is noticeable now around the eastern side of the North Island. You can see it a bit clearer on this map, the southerly change moving through eastern areas of the North Island, the Chatham Islands as well. So there is a temperature drop for some of you following the weekend. But there is a lot of high pressure on this map, as you can see, coming out of Australia and the Indian Ocean heading towards us and ballooning out even here near Tonga. But there is also a line of low pressure or lower pressure. The main low itself way up here around the Solomon Islands near the equator. But you can see this area all the way down to the upper North Island, sort of pockets of lower pressure in the mix helping to produce some of that wet weather that we're seeing around the North Island across today.

[00:01:33]So let's have a look at 3:00 this afternoon. This is just the snapshot showing the colder change moving into the North Island. It'll be felt as far north as around about Bay of Plenty, Waikato and Auckland. And that's where you've got a little bit of lower pressure, this trough producing some wet weather.

[00:01:49]Whether that's rain or showers tracking on the rain radar today. We've got a few showers also around the lower North Island. And just a little bit around the northwest corner of the South Island, mostly on the west coast over there.

[00:02:01]Otherwise, it's dry, but that colder wind also coming out and around the Chatham Islands.

[00:02:06]As we go into tomorrow, so the colder weather sticks around the eastern half of the North Island. It comes up to Coromandel Peninsula, so you'll feel that in the upper North Island as well, but it's not as cold as for some of you over here more towards the east. In the South Island though, the placement of this Tasman Sea high-pressure zone encouraging a westerly wind into the South Island. So, that pushes the polar boundary away from you, brushing Stewart Island, but if you're on the South Island, you're not going to be under the polar boundary whereas the eastern side of the North Island and the Chatham Islands still will be. So, there's high pressure dominating New Zealand and that slightly more northern placement encouraging the westerly winds that you see around the South Island. The low pressure to the north not coming down towards us.

[00:02:52]So, as we go into the middle of the week, now you can see the cold change that is coming our way. So, it kicks in for Tasmania, Victoria by the middle of the week. The polar boundary returns a little bit around the South Island so the temperatures dip a little bit.

[00:03:04]That's just courtesy of the high-pressure zone moving northwards and low pressure starting to dominate our weather maps again more so down around the Southern Ocean. 969 hPa maybe lower than that. I've seen a number of lows around the 940s, 950s circling Antarctica at the moment. So, the cold front comes in for Australia.

[00:03:23]We've got northwest winds around the South Island or at least light westerly quarter winds and in the North Island also bit of a light southwesterly around the Auckland area and western parts, but for the most part the winds aren't very strong as we go into Wednesday. They do pick up on Thursday though, so now we're starting to feel the change arriving and it starts with a cold front moving into the South Island. So, rain comes out of the Tasman, pushes some heavy falls into the lower half of the South Island.

[00:03:50]There'll be a little bit of spillover into western Otago, western parts of Southland. Otherwise, dry or mainly dry for you. And those northwesterly winds will start to lift temperatures up. Not a huge amount, but just noticeable after some of the colder weather or lighter winds we've been having. Still light winds around the upper North Island, there could be some fog patches around here and there, but once you're around the central plateau southwards, that western northwesterly wind will start to pick up. And around the Chatham Islands, still colder for you, but you will get those northwesterly winds eventually arriving. Probably by Thursday night, the polar boundary should be east of you. Cuz it is by noon Friday, so it moves away. Northwesterly winds coming for the Chatham Islands. High pressure is north of New Zealand or northeast of us, and now we're getting that northwest flow right across New Zealand. So, the cold front moves into the North Island.

[00:04:40]It falls apart to some degree, but there are some heavy falls around Taranaki, Horowhenua, maybe even uh some other lower parts of the western North Island.

[00:04:49]Right along the west coast, you've got rain and showers pushing through, and then that will start to turn as snow as that colder change arrives. Now, the snow levels over the weekend do chop and change a fair bit. They could go as low as 200 m in the South Island, and maybe 600 m for the North Island. It won't be uh that way for Friday, but that colder weather starting to arrive in the lower half of the South Island.

[00:05:13]So, the weekend looks colder pretty much right across New Zealand. It certainly will be by the end of the day. Uh low pressure moving out around the Chatham Islands. That's the front there moving in towards you.

[00:05:24]Kind of broken up with some heavy falls in the mix. For the rest of New Zealand, showers are the main theme, and some of those could be heavy and squally. There might be some hail showers in the mix, burst of wind with some of those downpours as the colder weather sweeps right up into Northland. So, all of New Zealand will be colder on Saturday and Saturday night. Now, the uh mentioned the snow level uh at the early estimates are getting down to 200 m, but if you look here, there's a lot of dry weather around. So, while the snow level may lower to 200 m, there still needs to be moisture and actual rain showers or snow showers, I should say, moving through.

[00:05:59]And there are some large dry areas around. So, we'll it will be cold, but not necessarily snowing all along the mountains as you might expect. But, I do expect snow flurries through the North Island, possibly even uh getting up to the Kaweka Ranges or the highest points, Mount Taranaki, for example, may get a a very light dusting on the top of the mountain there as we go through Saturday night. And on Sunday, another cold day, although some of the forecasts for Sunday show the polar boundary retreating. This one here does not, uh but it does still show a very cold south to southwesterly flow right over New Zealand. Most of the wet weather, southern half of the South Island, where there will be snow flurries down to a couple of 100 m by the looks of it here.

[00:06:41]And in the North Island, snow levels, like I say, probably several 100 m, if not 1,000 m. But again, we'll update you as we go through the week and keep up to date with the Met Service warnings and watches, and of course, their mountain forecasts to get more details on the snowfall. But yeah, that's a cold change, all of New Zealand affected by it as we go through the weekend, and it starts as early as Friday. So, before I go, let's have a look at the expected 7-day rainfall, starting with just today's rainfall. So, you can see we've got that wet weather uh basically roughly from the central part of the North Island northwards up to southern parts of Northland. Some of those areas in there are getting between 20 and 30 mm. There might be a few spots that go a little bit higher than that. And while there is the risk of a shower in a couple of parts of the South Island, it's probably going to stay drier, at least mostly dry, for most of you. Let's now animate this through to the uh Sunday period, and you'll see that cold front arriving here, moving up. And as we go into the weekend, a lot of showers.

[00:07:39]It's It's that westerly lean to it. So, eastern areas, Hawke's Bay, up towards Gisborne, Tairawhiti, also around Marlborough, Canterbury, especially on the coastal areas, not really seeing very much in the way of wet weather.

[00:07:52]There will be some that spills over and some of those southerly changes might bring in a few showers, but most of the rain, heavy rain, over in Fiordland and right across the West Coast with a bit of spillover into both Otago and Southland getting rainfall up to 40, maybe 50 mm or more, especially the further west you are with that heavy rain. So, a number of moving parts to our weather as we go through this week, but it's a fairly quiet start to the week for most areas. Thanks for joining me. Don't forget to download our new lightning alerting app. We may have some thunderstorms as we come in this weekend. See you again tomorrow, Tuesday.