Autumn weather preview: Why it's not time to farewell warmer days just yet - podcast episode cover

Autumn weather preview: Why it's not time to farewell warmer days just yet

Mar 09, 202520 min
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Episode description

It may not have felt like we had much of a summer this year – but a cold snap in Auckland has signalled that the seasons are changing.

Temperatures dropped in our biggest city, as a cold front passed over much of New Zealand last week.

It comes as cyclone season continues in the Pacific, with Cyclone Alfred last week on Australia’s east coast.

With those hot summer nights fading into memory, today on The Front Page we’re looking ahead to what autumn and the rest of the year could bring, with NIWA meteorologist - Chris Brandolino.

Follow The Front Page on iHeartRadio, Apple Podcasts, Spotify or wherever you get your podcasts.

You can read more about this and other stories in the New Zealand Herald, online at nzherald.co.nz, or tune in to news bulletins across the NZME network.

Host: Chelsea Daniels
Sound Engineer/Producer: Richard Martin
Producer: Ethan Sills

See omnystudio.com/listener for privacy information.

Transcript

Speaker 1

Yoda.

Speaker 2

I'm Chelsea Daniels and this is the Front Page, a daily podcast presented by The New Zealand Herald. It may not have felt like we had much of a summer this year, but a cold snap in Auckland has signaled that the seasons are changing. Temperatures dropped in our biggest city as a cold front passed over much of the country last week. It comes as cyclone season continues in the Pacific, with Cyclone Alfred last week on Australia's East coast.

With those hot summer nights fading into memory, today on the Front Page, we're looking ahead to what autumn and the rest of the year could bring us with NIWA meteorologist Chris Brandolino.

Speaker 1

Chris, if we're just cling.

Speaker 2

On to summer for just a few more minutes. Back in December, we were told to expect hotter, drier nights over the summer. So did the weather perform as expected?

Speaker 1

I would say mixed results certainly, I think areas in the North Island. So if I look back at our summer outlook, well we call for equal chances for normal or above normal rain for the North Island full stop. So there's three regions at the east, the north and the west of the North Island, and that didn't happen. So we had dryness for the Upper North Island, dryness from the western part of the North Island, so that

didn't work out great there. We had certainly some cooler temperatures in January, but when you look at it as a whole, I think February made up for that, and in some ways December was exceptionally warm. I think it was the fifth warmest December on record, or top five warmest December on record from a national perspective, so I would yeah, I would describe it as mixed. Look, the airflows didn't go as expected. So when we sit down and we assembled these long range outlooks for three months,

we're trying to identify basically themes. You know, what is the theme going to be. Just like if you go to someone's house for dinner and I don't know, it's a dinner party and the theme is Italian, Well, you don't know exactly what's on the mail, but you have an idea. I'd probably be some pasta, there'd be some sauce, maybe some pizza, this, that and the other thing. So that's what we're We're not giving you the menu. We're giving you these themes. And sometimes those themes look they

just don't they don't eventuate as expected. We look at guidance, and that guidance helps us give insight as to what the themes may be. But look, if you go to the doctor and you tell the doctor, hey, doc, my right arm is killing me. You know, it's just it hurts like heck, And okay, let's run some tests through some exercises or exams, i should say, and tests and scans, and they come back and oh, your right arms fine, Oh I'm sorry. Actually is my left leg that's bothering me.

So if you get bad intel, you're probably gonna have bad results or undesirable results. So we had winds coming from the east and southeast. We were expecting more east to northeast, and the change in airflow had a consequence not only on rainfall patterns, but also temperature pattern So, yeah, I would in summery, I would describe the summer outlook as mixed in terms of how it panned out. Yeah.

Speaker 2

I saw one story last month about Hamilton experiencing an unprecedented eleven day streak of hot days.

Speaker 1

Yeah, how unusual is that it is pretty unusual what happens oftentimes, particularly later in the season. When I say season, I'm talking summer season, when when the soils become unusually dry, and especially the second half of summer. Let's say that does tend to favor hotter temperatures because the sun is still obviously strong. But that energy, if the soil is unusually dry, the energy is not really going to say dry the soil or make it dryer. You know, it's

going to heat the ground. So there's energy coming from the sun. And if there's moist during the ground, particularly of any sensible amount of moisture, a meaningful amount, the energy or the heat from the sun is going to go toward drying the soils. But the soils are already dry, you're gonna do a much better job in actually heating the soils. So as a consequence, I think that probably

was a factor. So, yeah, it is unusual, but I think, you know, given the dryness that they have experienced in the Waikato, particularly in parts of well the western and central portion of the North Island, it does kind of add up in terms of, you know, expectations of temperature when you have really dry conditions, you tend to elevate the odds for really warm temperatures, and that's what we had in February. Certainly in the Waikata was unusually warm.

Many days. There were many days where temperatures were in the upper twenties, even lower thirties in places like Hamilton. So yeah, that was certainly a standout for sure.

Speaker 3

Uh. You know, it's interesting timing to go to be damned though, on a day where the temperatures are rocketing up and a heat wave is actually five days in a row above five degrees above the normal temperatures. So this is not a heat wave, it's just a burst of heat and above normal temperatures. And so whether that breaks records or not, you know, we've sometimes gone up to thirty degrees in September in this country, So we can get a hot northwest thro out of Australia heat off.

That hot continent comes straight on and goes over the mountains and as it does that, as it drops down the mountains, that lowering of air pressure means that it starts to heat up.

Speaker 2

Well, let's get into autumn. I think a lot of the country can say that they have experienced some chilly days, especially last week.

Speaker 1

What's behind that'll buy airflow? Basically, you know weather and weather forecast and in climate forecast and climbate outlooks. It's a challenging business. You've got to have thick skin because, look, your predictions aren't always going to come as expected or as predicted. But in a lot of ways, these things

can be simple. And that is airflow. Where is the air coming from, And over the past couple of days and probably for the next several days, we're going to see a propensity for airflows to come from the south. That is a cool wind direction. So that is driving not only the cool lean where we have experienced the past few days and are going to experience until about the middle part of the month, but it's also going to drive the dry condition autumn. The days are getting shorter,

so naturally we're going to get cooler with time. But certainly early mid March is closer to summer than it is winter. I mean, technically it is still as summer from an astronomical perspective until I think the twenty eighth or twenty first of March when we have the equinox. So some people would still say it's summer, but we are still expected to have summer like weather, I would think,

especially in March. So and answer to your question, it's southerly airflows we've had and that is likely to be a theme probably for the next I would say weakish. But as who work away into say the middle part of the month, as we get toward the fifteenth, the fourteenth, the sixteenth, somewhere in there, we're probably going to see more northerly quarter winds, so that could be northeast to northwest somewhere in between, and that is a warmer wind direction.

So I think we'll see a decidedly turn where a decided turn to warmer than usual temperature. So if you're a fan of summer, you want summer like weather, you like going to the beach, you don't want to give up summer yet. Hand in there, I think as we get to the middle part of the month, into the second half of March, quite frankly, that is when we'll find those really much warmer temperatures than what we're experiencing now.

Speaker 2

I read in Niewa's weather outlook that overall a mix of anti cyclonic flows and easterly quarter flows are expected over New Zealand over the autumn season. First off, what is an anti cyclonic flow. That's the first time I've ever read that in a sentence. So can you break that down to us in Layman's steams.

Speaker 1

So, look, when there's cyclonic flows, so cyclonic, think of a cyclone. Look, oftentimes when they hear the word cyclone in this part of the world, people think of like tropical cyclone, like Gabrielle or so the thing tropical cyclone, Well, tropical cyclone is just a type of cyclone. There's actually various types of cyclone. It just means low pressure. So think of cyclone low pressure and low pressure that brings, generally speaking, unsettled weather, so cloud cover, rain, snow, that

sort of thing. The opposite of low pressure is high pressure. And so instead of calling that a cyclone, we call it an anti cyclone. So basically the opposite, so high pressure usually brings settled weather. And when I speak to younger people, the kind of the trick I give people to remember these things is low pressure means lousy weather. High pressure means happy weather. They both began with a

respective letters, So a nice weather. Remember that high pressure is an anti cyclone, anti cyclone, it's just its formal name. It's kind of technical name. So when we say anti cyclonic flows, those are flows that would be associated with high pressure or happy weather. Airflow around low pressure is

like a clock in the southern Hemisphere, it goes clockwise. Okay, So think of a clock, so that airflows around that low pressure or cyclone like a clockwise Around high pressure or an anti cyclone, it flows counterclockwise or anti clockwise,

so the other way. So when we say anti cyclonic flows, that's basically saying, look, high pressure is going to be around New Zealand, and the flows that we're expecting are going to be flows around or associated with an anti cyclone or what's that once again, high pressure happy weather.

Speaker 2

Speaking of tropical cyclones, we're also in that peak zone, aren't We Look at Brisbane with Cyclone Alfred, it's the first cyclone to make land for there since nineteen seventy four. What are some of the factors that have contributed to that event?

Speaker 1

Well, obviously, so the reason this is the peak time of year. So when you look at weather history, basically late summer through about mid autumn, so think about February till about Easter, you know, early mid April somewhere in there. That is generally the peak tropical cyclone season, and there's a reason for that. The ocean temperatures in the tropics are typically after peak. Likewise here in New Zealand late February, generally speaking, other weather factors in the atmosphere are more

favorable for tropical cyclones. So all these things come together so that allows for tropical cyclones to form, and this is the peak of the tropical cyclone season, so that's kind of the background. So this is really not unusual. We're in early March, we're kind of smack dab in the heart of the kind of the apex of the tropical cyclone season when we expect them the form. What's happening in this particular case is that we've had a

tropical cyclone. It's been in the Coral Sea. It's been kind of losing intensity gain an intensity based on its environment. Tropical cyclones like certain things. They don't like dry air, they don't like ocean temperatures below about twenty six twenty seven degrees. They actually want warmer ocean temperatures, and they like the atmosphere to have a wind profile where there's

not much change in wind, we call that shear. So sheer basically describes the wind changing direction as you travel up, say like in a hot air balloon, or if you go up in a plane as you're taking off. Now it's approaching the coast and it's slowing down, and because it is slowing down, that could really enhance the rainfall

in that area. I've been looking at some of the latest computer models and look parts of Brisbane, maybe not Brisbane proper, like downtown Brisbane, but say the northern suburbs or you know, say the Brisbane metropolitan area, particularly northern suburbs. We're talking maybe a half meter to a meter of rain over a two or three day period.

Speaker 4

We would wish to outline to Queenslanders the latest on the four key challenges of this weather event, waves, wind, rainfall and flooding. What's critical for people to understand across the large scale that.

Speaker 1

We're dealing with.

Speaker 4

It's a large area and a large population and it's important that we update people on what is occurring. You will experience at least one of those key four challenges waves, wind, rainfall and or flooding, and it's important that Queenslanders prepare for that.

Speaker 2

What's the risk of a cyclone or an X cyclone as it normally is for us passing near New Zealand this year?

Speaker 1

So this year we've pegged it our normal to elevated. So when you look at again weather history, we average about er point eight of a tropical cyclone. Now obviously either it's kind of binary, you get it or you don't, but the average, the long term average is right around one because at that point we just rounded to one. So that tells us that in any given year we would expect at least one X tropical cyclone to come about five hundred and fifty k's of the North Island

of New Zealand. So this year we're describing that risk as normal to elevate it. And that's largely because of things like La Nina, which is what we call a climate driver. So people may be wondering what is a climate driver, Well, who's at the steering wheel Mother Nature's car? Who's actually driving Mother Nature's car? And if you understand who's driving the car, you have a much better idea

in which direction you're going to go. It's not a guarantee, but it certainly helps to paint a picture and help identify those themes we talked about when we're looking at a long range outlook the next couple of months, the next three months, et cetera. And so Linina we identified as a climate driver. And this goes back to your opening question about summer and how it panned out. We did have Linina, but it was a kind of an

odd ball la nina. La nina generally describes the trade winds and the tropical oceans of the Pacific Ocean up near the dateline and the equator, or those two meet going all the way to the Galopicus Islands in South America. If you can imagine that the trade ones actually blow much stronger, and that's what happens with Lininia. But when the trade winds blow really strong, it really affects where there's unusually warm ocean temperatures near the equator and unusually

cool ocean temperatures. And this year we had unusually cool ocean temperatures in areas that we typically don't find your quintessential classic Lininia, and as a consequence, that meant we had different airflows in New Zealand. What happens in the tropics actually has flowing effects here in New Zealand, and we call that a teleconnection. It's something that happens far

away but can still influence our local weather. And that happens with Linina and it happens with El Nino, and those are two opposite phases of what we call enso e Nso it just means El Nino Southern oscillation, and that's what it is. It's an oscillation between a warm face Elmino in a coal phase La Nina. Right.

Speaker 2

So, finally, Chris, if we get out your crystal bowl, what about the rest of the year. Do we know anything yet about what twenty twenty five may hold for us.

Speaker 1

Here's what I'll say. Let's start with autumn and we'll kind of encapsul ate autumn. You have to think of weather as Mother Nature's mood, and you think of climate as Mother Nature's personality. When we give you these long range outlooks, we're attempting to describe Mother Nature's personality over the next three months. And there will be days when Mother Nature's mood is incongruent with her personality. That is expected, But generally speaking, we think you know the flavor will

be they generally will be aligned. So that said, for those that need the rain, and that is areas like Tetanaki, areas like the Manawatu, areas like the Waikato, Unfortunately, it's going to be very dry for the next few weeks. I do think for areas like Tetanaki and Manawatu it may be a dry through the autumn season. So if there's going to be dryness for the next three months, it's likely to be in the western part of both island.

If there's going to be any wetness this autumn season, again as a whole, it'll be likely the eastern part of Both island. Now, in terms of temperature, we think there's going to be a warm, lean pretty much everywhere. We feel most confident in areas not named the Eastern North Island and not named the Eastern South Island, So those two parts of the country, Eastern North and Eastern South Island, because the area is likely to come off the ocean more times than not. That's an easterly wind.

We think about normal, average or above average, so somewhere in that kind of spectrum of average to above average. So what does this mean for you? You're listening to this and like, that's great, Chris, you just talked a lot. I don't know what the hell you're talking about. Well, here's what it means. It means that there are days where we're likely to be more summer like than usual, especially in March, so perhaps days, more days at the beach.

Who can maybe extend summer a bit longer. It means if you're on tank water those dry areas that we talked about, or the risk for dry areas, you could be calling someone to fill up your tank because mother nature is not doing it. If you're farmer, if you just or have a large garden, that may be a big impact for you for getting irregular or unreliable rainfall. So it basically means we could have a little bit of an extension of summer as you progress through March

and April. I think as we get toward April and May, we are looking at increasing the odds for getting more rain, especially Western South Island. Right now, it's been very dry in the Western South Island. That's bad news because their hydro catchments are down there. Those hydro catchments, keep in mind, they generate a lot of our electricity, so when they get really low that can affect electricity prices and the

overall electricity market. It does look like it's going to be quite dry for the next week to ten days, but we shouldn't get some meaningful rain in that area over the next, say, middle part of the month. But as we get toward winter, going even the route, I'll say this not a colder than usual winter. The odds would probably favor warmer than usual conditions. We're getting quite early. This is not our official outlook quite yet, but it looks like those airflows, remember I talked about its all

about airflows. It looks like those airflows may favor the east and northeast for the winter season. And if if that happens, well, look at east and northeast wind. That doesn't get you to Antarctica, does it. You need a southerly So if you don't have a lot of southerly winds, you just ain't gonna get that cold. Of course, it gets cooler because our days get shorter. But in terms of what is usual, it looks like it may be

a warmer than usual winter. We'll see if that happens, and it looks like we may start to get better chances of raying for the Upper North Island as we work away to the end of autumn May and into winter June, July, and August. We'll hope so because it's been very dry for the Upper North Island. And then after that, boy, you want to talk about spring and maybe next summer. We're watching for a potential second Linina. So Lininia right now is waning, and which is typical.

We expect Lonina to come to lose it giddy up as you work away into the autumn season down in the Southern Hemisphere. No La Nina or for that matter, El Nino's average. They all have their own personality and their own footprint.

Speaker 2

Thanks for joining us, Chris. That's it for this episode of The Front Page. You can read more about today's stories and extensive news coverage at enzdherld dot co dot nz. The Front Page is produced by Ethan Sills and Richard Martin, who is also a sound engineer. I'm Chelsea Daniels. Subscribe to The Front Page on iHeartRadio or wherever you get your podcasts, and tune in tomorrow for another look behind the headlines.

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