Meteorologist Chester Lampkin explains what Cyclone Vaianu's category downgrade really means for New Zealand
A New Zealand Herald podcast episode in which meteorologist Chester Lampkin discusses the approaching Cyclone Vaianu and what New Zealanders should do to prepare.
Summary
Host Richard Martin speaks with Chester Lampkin, meteorologist for Earth Sciences New Zealand (ESNZ), about Cyclone Vaianu, which is tracking toward the top of the North Island and expected to make landfall near the Coromandel over the weekend. Lampkin's central argument is that the storm's category number is misleading and potentially dangerous as a public communication tool — a Category 1 or even an uncategorised storm can be just as devastating as a Category 4 or 5 depending on where and how it strikes. He warns that already-saturated ground, unusual easterly wind directions, and the high population density of the affected area make this one of the more serious storms of the season. MetService's decision to issue a wind watch covering the entire North Island several days in advance is described as highly unusual and a signal of forecast confidence in the storm's severity.
Key Takeaways
FULL TRANSCRIPT
Introduction and What Cyclone Categories Actually Measure
Richard Martin: Kia ora, I'm Richard Martin, sitting in for Chelsea Daniels, and this is The Front Page, a daily podcast presented by the New Zealand Herald. Cyclone Vaianu is currently tracking toward the top of the North Island, with forecasters warning it could make landfall between Auckland and the Coromandel this weekend. Heavy rain, high winds, and coastal surges are all in play, with officials stating it could be a potentially life-threatening weather event. Meanwhile, Prime Minister Christopher Luxon has recommended people stock up and get their supplies in order. So how bad could this get? Today on The Front Page, meteorologist for Earth Sciences New Zealand Chester Lampkin is with us to let us know what these cyclone categories really mean and how prepared we should be.
All right, so Chester, at the time of recording, Cyclone Vaianu is a Category 2 cyclone. What exactly does that mean?
Chester Lampkin: I want to start off by saying thanks for having me on the show — first time on the show. But I do want to say I don't want to spend too much time discussing categories, because I think sometimes we can get lost in the fact that Category 1, Category 5 — tropical cyclone, doesn't matter. They can be quite impactful. With that said, sure, Category 2 doesn't mean it's severe. It's a strong storm, certainly has strong winds. You can always get the latest from MetService — they've got all the latest details, and there will be a new update after we've recorded this podcast around midday. So they'll have the latest data. But essentially what people need to know is that this is going to be a strong, generally impactful storm. It's not likely to be a tropical cyclone when it arrives here in New Zealand on the weekend — late Saturday night, Sunday. But either way, the impacts are going to be the most important thing: that heavy rain, the wind, and the beach and coastal erosion that we're going to be watching.
Richard Martin: We won't spend too much time on it, but it was initially regarded as a Category 3 cyclone when it came through. So what is the category measuring, if not the impact?
Chester Lampkin: Generally it's just a measurement of how strong the winds are. I don't have the category numbers off the top of my head, but the idea is that the stronger the wind gusts, the higher the category of the storm. There's a direct correlation between the strength of the wind and the energy that the storm is producing and the damage that it could cause. So the most severe categories — three, four, five — those types of storms, when they make landfall in the tropics or have impacts on the tropics, they tend to be the most devastating.
The good thing is we have seen that weakening. You mentioned that it was a Category 3. It's down to Category 2 as of this recording. By the time we get to this time tomorrow, it's not even likely to have a category at that point anymore. It's just probably going to be a cyclone, because it's going to transition from a tropical cyclone. It's driving its energy from the warm ocean water — well, it's moving out of that now. It's moving towards the mid-latitudes where we are here in New Zealand. And so it's no longer going to be classified as tropical. However, again, it'll have impacts that'll be akin to a tropical cyclone. You could say the energy will be akin to a Category 1 or Category 2 tropical cyclone, but it will not be a tropical cyclone.
So the category is sort of — there's this misconception within the public, like "Category this, Category that." Essentially, they don't have much meaning when it comes to the amount of damage that can be done. You can have a weak or a Category 1 cyclone — if it hits in the right place, if it hits a highly populated area, or an area with a lot of mountains, or a place that's already had a lot of rain and then you put additional rain on top — that Category 1 can be just as devastating as a Category 4 or Category 5.
Richard Martin: Yeah, I'm interested to know more about these misconceptions around how the category relates, because as you're saying, it can still be quite devastating even if there's not actually a category to it.
Chester Lampkin: Yeah, and I'm not a social scientist — I've just read through some of the literature. We do have social scientists that work here at ESNZ who study these types of things around the meteorological world. Everywhere this is being studied, there's science around the psychology of how information is digested and how that's communicated to the public.
When I was growing up, when I was young and living in the States — that's where I'm originally from — we'd be worried about a Category 5 or Category 4, which is a really strong hurricane. But we've seen hurricanes since then, and cyclones, tropical cyclones, that were weaker but had bigger impacts. So the idea of getting hung up on a label or a number — we're trying to move away from that in meteorology. It's great for science, it's great for geeking out, it's great for being able to put things into nice, tidy categories for scientific purposes. But when it comes to the human element, we know that we are impacted in different ways that can't always be put into a number or a category.
Category 5 means nothing if it makes no landfall anywhere. But a Category 1 — you'll remember that storm if it blew your house down, or if it destroys your neighbourhood, or if you know someone who unfortunately loses their life in that storm. And I think that's where the science is trying to move to when communicating how dangerous these storms can be.
Easily, this could be one of the worst storms we've seen in years. It could also be a storm that no one will remember in a year. It can be in that range. And the category number — it's one of those things where it's like, how important is it? It's not very important.
Richard Martin: Yeah, it makes for a good headline, I think, as part of the thing — just to give it a number.
Chester Lampkin: And there's nothing wrong with that. Totally.
How Serious Is Vaianu Compared to Other Recent Storms?
Richard Martin: We see a lot of these cyclone warnings come through — it feels like all the time, and increasingly so with climate change and the way these major weather events are getting more and more frequent. How seriously should we be taking this one, on a scale of light drizzle over the weekend to something like Cyclone Gabrielle?
Chester Lampkin: It certainly needs to be taken seriously. I would say — and it's hard to argue this just because it's almost like fatigue — we're getting hit by so many. This summer alone, we've been hit by multiple extratropical cyclones, or former tropical cyclones, or subtropical lows. Either way you put it, we've been hit by multiple storms. It seems like about one a month. We had one around the holidays — the December, New Year period. We had the January storm. We had the February storm around Valentine's Day. Just a few weeks ago in March, we had another storm that had significant impacts to the country.
But I would say, out of the storms we've seen so far this summer, this is certainly going to be one of the more serious ones. And that's primarily because of where it is going to impact the country. It is currently forecast to make landfall somewhere in the North Island. It could be as far west as eastern Northland, or as far east as perhaps even northern Gisborne, the East Cape region — somewhere in that range. But right now, the current forecast from our colleagues over at MetService is for it to make landfall somewhere near the Coromandel.
The idea is that this is a highly populated area, especially here in the North Island. But in addition to that, it is a place that has already seen rain. We've had some heavy rainfall over the last week, so the soil and the ground is a bit saturated, a bit primed. We've had a lot of rain over the last few weeks. As a result, the ground is not going to be able to hold as much water. So more than likely, flooding and slips will be a concern. Beach erosion will be a concern because of the strong winds with this system.
And the wind — I don't want to dismiss that either. Our friends over at MetService issued a wind watch that covers the entire North Island on Wednesday, days in advance. I think that points to how serious this situation could be as far as wind impacts. And I know they've put out some heavy rain watches as well. So yeah, I would certainly say this is a top-two serious situation of the summer — or summer-autumn, I should say, the tropical season.
The Significance of the Wind Watch Issued Days in Advance
Richard Martin: MetService has issued a strong wind watch for the entire North Island from 1am Sunday. If this cyclone continues to track the way it's indicating, we could see damaging, potentially life-threatening winds. This watch is a nod to the expected wide-ranging impacts we could see. Because we're still four days out from Vaianu's arrival, we still have uncertainty in the cyclone's exact track and the exact location set to receive the most severe winds. We will see other watches issued too — heavy rain and strong winds, large swells — and we will see regions upgraded to orange, even possibly red warnings.
The wind warning that came out so far in advance — how rare is that, to do it for not only a few days in advance, but also covering such a wide area?
Chester Lampkin: I'm not 100% sure how rare it is, just because I've only recently returned to New Zealand. I worked at MetService for a couple of years about ten years ago, left, came back, and now I'm working for ESNZ. But I do know that it is pretty rare. I'm not entirely sure if they've ever issued a wind watch this far in advance covering such a large part of the country. And I think that speaks to forecast confidence. It speaks to the seriousness of the potential impacts, and to the fact that weather forecasts are getting better — getting better at pinpointing where situations like this are going to arise days in advance. We're not always going to be able to tell you three or four days in advance that we're worried about widespread wind impacts, but we certainly had some good indications going back as far as a week with this system.
Richard Martin: What's making it easier? What's making these predictions possible now?
Chester Lampkin: I think it's a lot of things. One is certainly experience — especially this summer and autumn, we've experienced a lot of extratropical cyclones, unfortunately. And I like to take a side journey, if you will. I know Chris Brandolino, who's usually on the podcast with you guys, likes to go on these little side journeys with metaphors and sprinkle in some science, which I appreciate. I love that.
This is reflective, I think, partially of the La Niña that we are just coming out of, which tends to allow more tropical intrusions of air to come southward from the tropics. So we've had a lot of that this summer, and we've seen these heavy rain events and high wind events as a result of the tropics being so active. The tropics are very active right now. And so we've experienced it enough times this summer to know that this is likely to happen.
But in addition to that, forecasts are getting better because we are doing more research. We have local scientists researching how to make weather predictions better here in New Zealand, here in Aotearoa. We are also getting more and better weather data. We have high-resolution modelling. We have what we call ensemble models — basically, you take the model and you run it multiple times in different what we call perturbations. It's essentially the same model, but you can split it up into, say, 18 versions, and you can say, "Hey, in these 18 versions, half the models are putting down 200 millimetres in Tairāwhiti with this storm." So we're able to use that information to make better weather forecasts.
And we are striving to get better and better, using the latest technology — high-performance computing clusters, and now AI-driven models. All of this is feeding into the forecasting beast, as I like to call it. That allows us to make these improved forecasts. We're always going to get some elements wrong, but there will be improvements overall. We're starting to get better at looking farther into the future and being able to predict impacts more precisely.
What to Expect and When — A Timeline for the Weekend
Richard Martin: So are we able to know precisely — what's your best estimate for a time that we should really be on the lookout?
Chester Lampkin: We'll have to watch for impacts maybe starting as soon as Saturday. I know some of the watches have been posted from MetService beginning Saturday evening. So depending on your location, places like Northland, perhaps Auckland, the Coromandel, will start to see some impacts as soon as Saturday evening and Saturday night, with more widespread impacts across the rest of the North Island during the day on Sunday. The current forecast seems to be pointing at this cyclone moving into New Zealand sometime Sunday morning to midday, or perhaps as late as early afternoon.
So Sunday is the big day. You want to get your prep done now. Thursday, Friday, Saturday — those are the days you want to prepare. You want to run out to the local Warehouse and get the supplies you need, make sure your backup batteries are charged, and make sure that you have your plans for emergencies — phones charged, backup chargers, food supplies.
I don't think it's going to be extreme to the point where widespread areas will be losing power for days at a time, but there's that possibility. There could be power cuts. And there could be places that are cut off. We saw that in Gabrielle. We saw that with cyclones earlier this summer. There are places that may get cut off for hours, if not potentially days, because of slips and damage to roads and other types of flood issues, in addition to the power cuts and the wind knocking down trees, causing damage and just causing mayhem across parts of New Zealand.
Richard Martin: This is shaping up to be a very significant and damaging weather event. And obviously, with a big impact on the North Island, particularly around Sunday, it's a great opportunity to remind New Zealanders to do everything they can to stock up, get their supplies in order, get items that may be loose in their backyards tied down or in secure storage. The agencies are on full notice and are preparing for it. I know it'll be unwelcome news for many communities that have recently been affected by severe weather events and are still recovering. But it's important that we use the time we've got to make sure that people are prepared as much as possible at their homes and households.
How to Prepare — and What Not to Do
Chester Lampkin: Yes, I think you've done a good job of illustrating the sorts of things we should be doing to prepare. And Christopher Luxon has said it's time to stock up and get your supplies ready. But are there things you'd want to advise against people doing? Is this the time to rush the supermarkets and buy all the toilet paper?
Richard Martin: I would never encourage that, that's for sure.
Chester Lampkin: As someone who's lived through a variety of natural disasters in different parts of the world — I remember living in Wellington during the Kaikōura earthquake, and I remember COVID and how everyone rushed out and bought toilet paper — this is certainly not that. But it's good to take those measured approaches. Make sure that you do have something you can eat and have those supplies you need for at least a few days within the house. And make sure that you have something that people in your household will actually enjoy. Yeah, you can have canned this and canned that, stuff that you have to make on a fire or wood-burning stove. But it's also a good idea to have some extra snacks that'll make you feel comforted in case you do lose power for a couple of days.
As a parent, I think about that. I want to make sure that my kids have what they need to feel comforted in case there is an emergency. So make sure your iPads and tablets are charged up and you have a game for them to play. You have flashlights and things that you can do with the family and the kids and your loved ones so that if you do lose power for a couple of days, it's not the end of the world. She'll be all right, right? We'll get through this. It's just all about being prepared ahead of time.
Richard Martin: What would be your message to people in Auckland who woke up this morning and the sun was shining — after a few days of being overcast, coming to work this morning I was like, "Oh, I guess part of me thought the cyclone isn't happening."
Chester Lampkin: Right, exactly. Yeah, don't be fooled by this sunshine, that's for sure. Even I was taken aback by how beautiful it was this morning. I live in the Auckland region as well, and on my way into work I was just like, wow, this is a delightful day. I wish I could copy and paste it through the weekend and forget about this cyclone.
But this is the time. This is the time where you need to prepare. So yeah, enjoy the weather. Enjoy getting outside. I know a lot of New Zealand is seeing generally fine weather today — not as nice out towards the Bay of Plenty and places east where it's a little rainy still. But up here in the far north — as I like to joke with my friends who live in Wellington, the tropical north — we're definitely having a beautiful stretch of weather ahead of the cyclone.
So still, just be prepared. This is the time to make your grocery run. Don't rush. Don't panic. Get there, get the supplies you need. It's not going to be a situation where you're going to be out of sorts for days and days, but it's certainly good to be stocked up and have your backup plans ready to go. Check on your loved ones. I have a friend who lives over in the Bay of Plenty — I checked in with them to make sure they were prepared. Things like that. It's a good idea to do those things now so that you're not caught out later this weekend.
Richard Martin: Should people just be staying at home on Sunday?
Chester Lampkin: I think it depends on where you are. For anyone who may be listening from the South Island, not likely to see impacts. And even the lower North Island isn't going to see a lot of impacts. So for a lot of the country, you can go about your business.
But if you live in the places where the warnings are likely to be issued — and some of these warnings could end up being red warnings, according to MetService — places like Auckland, Coromandel, certainly Northland, Bay of Plenty, and northern Gisborne and the East Cape region — those areas really need to be mindful and watchful. Those are the places where you may want to alter your plans. If you have a trip planned, maybe you cut it a day or two early. If you plan on flying out of Auckland on Sunday, maybe try to swing that Saturday flight or push it back to Monday. Little things you can do now to save yourself headaches later.
The Combination of Threats — Wind, Rain, and Coastal Erosion
Richard Martin: And I guess what's the biggest threat we're looking at here? Is it the wind? Is it the rain? The coastal erosion?
Chester Lampkin: I think it's a combo threat — a combination of the wind and rain. This is going to be quite a windy system. I believe MetService had some mention of potential gusts exceeding 110 kilometres per hour. That's severe for most regions in New Zealand.
I think a combination of that and the fact that we're going to have an unusual wind direction makes this particularly concerning. The winds are going to be coming out of the east and southeast to start, especially for Bay of Plenty, Gisborne, and perhaps the Coromandel as well. These areas will see east to northeasterly or southeasterly winds — that's an unusual wind direction for New Zealand. The trees are more used to westerlies. So with soggy ground and trees getting hit with a strong gust from an unfamiliar direction, that could lead to a lot more tree damage, a lot more trees falling. These east-facing slopes are probably going to get battered — the east-facing slopes in the areas of mountains, ranges, and foothills. So again, heavy rain and gusty winds — it's a combination for slips and widespread power cuts.
Some of those power cuts may just last hours. Some of them may last days. But these are the types of impacts that we're concerned about across the North Island, especially the upper North Island.
Beach erosion is certainly going to be a concern. There's still some question as to how high the wave action is going to be, but I've seen some forecast data pointing to seven to eight metre waves, and that certainly is going to lead to some coastal inundation, storm surge, and the potential for beach erosion — especially where you're getting that onshore flow. East-facing beaches in particular are going to be quite a concern across the upper North Island Saturday night and Sunday.
What It's Like Inside a Weather Forecasting Office Before a Major Storm
Richard Martin: You've done a great job of informing us and letting us all know what to expect. But one thing I just want to ask before you go — what's the vibe like in the Earth Sciences office right now when something like this comes along? Is this go time for you guys?
Chester Lampkin: Oh, for sure. This is probably when we reach our busiest — when we have big storms impacting the country. We're a small team over here at ESNZ. We have a lot more researchers than we do operational forecasters, which is what I am, and what Chris Brandolino is, and the other members of my team. We're the ones who are actually making weather forecasts, while our researchers do amazing work. But on a day like this, when we're preparing for the big storm, they just do their jobs as usual — it's a usual day for them. They're getting on with their projects and their work.
But for us forecasters, this is go time. We're working long days. We're talking to you all in the media. We're talking to FENZ, or DOC, or other organisations throughout New Zealand, getting them prepared so that when the big storm does hit, they're ready to respond — prepared for the potential damage and the potential impacts.
It's exciting, but at the same time it's also a stressful time. It's not a positive excitement, if you will. It's a time where it's like, "Hey, we've got to get this done." We want to keep people safe. And I think that's true of anybody who works in the forecast realm. I worked at MetService before, so I know that those ladies and gentlemen are doing the same thing. They are in go mode right now.
Richard Martin: Well, it sounds like I better let you go then. Thanks so much for joining us.
Chester Lampkin: I appreciate it. Thank you.