Posted by BE on January 21st, 2013
Over the years, both in print and on this site, I’ve taken several swipes at the New Zealand Metservice. The thrust of these critiques has been that their weather forecasting results are little better than tossing a coin or looking out the window. To make the point I’ve invited readers to take note on a Monday of the forecast for the following Monday, then watch how that original forecast gradually changed during the week to conform to reality.
On several occasions I’ve received replies from the Metservice’s ‘Weather Ambassador’, the lovely and hugely entertaining Bob McDavitt. Bob usually points out that the closer you are to a weather event the more likely you are to get the forecast right. That is undoubtedly beyond question. But you might have thought that with all the electronic wizardry that’s available to today’s forecasters and with our planet circled by weather satellites, they might be able to get it pretty well right a week ahead and absolutely right for tomorrow. But they can’t and they often don’t.
I’m in a better position to pontificate on this now than I was a decade ago. A decade ago I took almost no exercise. Today Judy and I walk for at least an hour every day. So I’m interested in and familiar with the weather. I am, if you like, a weather-watcher.
This has led me to the conclusion that Metservice getting the forecast exactly right is the exception rather than the rule; getting it more or less right is closer to the norm; and getting it wrong far too frequent to justify the term ‘science’.
The Metservice has unwittingly assisted me in making these judgements by providing an excellent little app, which allows me to check the 10-day forecast for Auckland as I lie in bed each morning going through my emails and Stuff on my iPad.
In particular, the on-line ten-day forecast is graphically presented with golden suns, fluffy clouds and rainy teardrops, either alone or in combination.
As I write this, today’s Auckland forecast is shown as a golden sun with a fluffy cloud, which I take to mean ‘dry but some cloud’. Looking out the window I see that it is indeed cloudy but not raining. I could just look out the window anyway, but I don’t want to carp. At the moment the forecast for today is correct. (Based on our walking experience, I’m going to predict that the cloud will disappear later in the day, but I’m not putting money on it. The only satellite I have access to is the Sky dish on our roof.)
But today’s 10-day Metservice forecast for Auckland also gives me (and those of you who live here) a rare chance to check on my claim that they often get it wrong. You see, today’s graphic consists solely of nine golden suns, indicating nine fine, cloudless days starting tomorrow.
Here’s my prediction: there won’t be nine consecutive fine, cloudless days starting tomorrow in the City of Sails; There’ll be cloud and/or showers on one or more of those days. If you live in Auckland and you’ve nothing better to do, check out the Metservice’s prediction and mine for the next nine days and see who was right(er). (You can do the same thing for yourself in your area – their prediction versus yours.)
Now I want to finish on a conciliatory note. It isn’t my view that the Metservice regularly gets it horribly wrong. They don’t. But nor do they get it acceptably right. ‘Sunny’ days turn out to be cloudy days; ‘cloudy’ days turn out to be showery days; ‘rainy’ days turn out to be cloudy days etc. The trouble with forecasting that, our walking tells me, is more often partially right than totally right, is that it makes planning for the weather – from the layman’s point of view surely the most significant reason for checking the forecast – almost impossible. Which is why I’m so often chilled on ‘sunny’ days and char-grilled on ‘cloudy’ days, not to mention occasionally drenched on ‘dry’ days. Take it from me, there’s nothing more certain to turn you into a weather sceptic.
Got to go now – the sun’s coming out.
Monday (today) Metservice predicted sun and cloud; I predicted cloud would clear later in the day. It did. We were both right.
I’ve a huge problem with both weather forecasts and traffic reports – neither matter to me – I look out the window and dress accordingly. Traffic reports are a particularly long standing bug-bear for me – I doubt anyone takes notice of traffic flows, you leave when you leave and arrive at your destination when flows allow. I’ve never met someone who’s left for work at half past nine because the 8am traffic report said that traffic was heavy or backed up!
Cool story, bro.
This is the best local weather service available in your neck of the woods I reckon… http://greylynnweather.net/
It’s been a great service over the years. I miss Jennifer Weather Centre’s early days at bfm – weather reports have been relatively humourless ever since!
When it comes to traffic I rely on traffic cams rather than radio reports. There’s nothing more bizarre than sitting in a traffic jam listening to the radio report telling you that there are no issues and the motorway is free-flowing.
It’s easy to take the mickey out of Metservice…the coin toss comparison is apt. There’s more to it, though. I’m a self-confessed amateur weather geek. I grew up and lived in the US southwest, a place of climatic extremes, and developed a lifelong fascination with all things atmospheric. I was continually puzzled by several regional phenomena that the print and broadcast weather forecasters never really went into much depth on — especially what mechanics actually drove the Mexican monsoon and gave us such spectacular displays of lightning and much-needed downpours (when they actually came, instead of teasing us from the surrounding mountains).
When I got my first internet connection back in the early 1990s, one of the first sites that became a routine visit for me was the National Weather Service’s forecast discussion and raw data, a set of products aimed at other meteorologists, aviators, and enthusiasts. I believe we got to it via telnet or Gopher back in those days. Within a few months, I gained a deep appreciation for how much the forecasters were able to glean from the daily soundings produced by weather balloons: the measurements of the upper layers of the troposphere which could be plugged into computer models to derive glimpses of the future.
Anyway, the main thing that I noticed was that in the season when the prevailing wind shifted and began importing tropical moisture from the south, the uncertainty in the forecasts went up. This was largely because there was scant upper air data available from Mexican observing sites, and both the frequency and resolution were lower than the world-class information coming from US facilities. Remote sensing onboard satellites has done a great job filling much of this gap in the last decade, and so have the models of the monsoon, but you still can’t say from day to day in July and August which parts of the desert will get a dash of water, and beyond three to five days everything can turn into a crapshoot.
NZ forecasters have it even harder. The only consistent sources of measurements for upper air parcels outside our borders are 1600 km to the west, and airmasses coming from Australia are often modified substantially in crossing the Tasman Sea. We rely on maritime reports and satellite data, but this coverage is spotty and often limited. A seemingly trivial wiggle in a jet stream can have profound implications days later and thousand of kms distant.
Given the paucity of “upstream” data they have to work with compared to their colleagues on large continents, I’ve been favourably impressed with the prediction of several events in over seven years of living in NZ: Cyclones Evan, Wilma and Funa, the bomb low of July 2008, and the cold blast of August 2011 were well signalled in advance. It’s the mundane, yet fickle nature of subtropical airmasses during our summers that tend to make a mockery of those pretty golden sun icons, and more so the further north you go.
I’d say that in the final analysis you’re best off remembering the advice of Robert Heinlein: “Climate is what you expect. Weather is what you get.”
BE: Helpful comment, Phil. Thanks. But really all the average Kiwi citizen wants is to know is what the weather’s going to do today and tomorrow. What seems, because of its imminence, to be the least problematic thing to accurately predict, appears in reality to be the most difficult.
I think Metservice forecasts are very good, they don’t always get it right but they are pretty close to the mark most of the time.
Taking into account that local variations can be significant. For example I’ve seen some months where part of Dunedin has had half the rainfall of another part just a few km distant. Cloud cover can vary a lot on the coast, especially in the afternoon and evening. You learn where sea fog comes from and usally gets too, and the afternoon sea breezes.
Small variations in weather systems can make a big difference. In Dunedin the angle cold fronts with southerly airflows hits the bottom of the South Island can make a big difference, land mass can accentuate or deflect.
Keep in mind that forecasts are informed guesses, not promises.
I suggest a simple rule of thumb – tomorrow’s forecast is 90% likely to be 90% accurate, 2 days out is 80/80 etc.
I use a combination of Metservice’s 5 day forecast, the weather chart and rain forecasts, the rain radar for same day timings, I look out the window and I add local knowledge.
Often weather changes and front arrivals are accurate to within an hour or less. Rain or not is much more variable.
And…mostly I love the sun, mostly I appreciate the rain, mostly I appreciate the seasonal changes, and I can’t do a damn thing about any of them anyway.
BE: Very philosophical Pete.
Remember how Auckland is on this little isthmus between a thousand mile sea, and a many-thousand mile ocean. That has a lot to do with this. It makes the weather more unstable both long-term and short-term.
There’s also a bit of attribution bias going on here, the days they get it wrong stand out to you more than the days they get it right.
BE: There’s a theme developing in the comments: “It’s just too hard to predict the weather in New Zealand and especially in Auckland.” OK, then can the forecasters on the telly, on the radio and in the press please include the following disclaimer with their reports: “Due to the difficulty of predicting the weather in New Zealand, this forecast should not be regarded as definitive. The Metservice takes no responsibility for any discomfort or harm caused to individuals who rely on this forecast to determine any particular course of action.”
Weather is a chaotic system and inherently unpredictable beyond a few days. There will never be reliable long term forecasts. However short term forecasts have become very much better in my lifetime.
However, on any average Auckland day it will rain, be windy and sunny – the only question is when. If you don’t like the weather, wait half an hour.
BE: Three seasons in one day? You must be thinking of Melbourne. Anyway, reliability for “a few days” would be entirely acceptable. I suspect you’re not a walker.
Move to Christchurch! Here, the weather is either hot and windy, cold and windy or (usually in winter) wet and windy. Metservice get the temperature correct most days- and they’re always right about the wind!
BE: I lived in Christchurch for 5 years when I first came to New Zealand. I remember the Nor’Westerlies which put everyone in a foul mood, but not that it was generally windy.
If it were not for the unpredictability of the weather what would there be to talk about?
In more predicatble climates even Ken ring would become ‘mainstream’.
I find the sheer bloody mindedness of our weather one of the joys of living in NZ. Reminds me of Manchester during a test match where it is said if you can see the Pennines it is about to rain. If you cannnot see the Pennines it is already raining.
As for the poor old Met Service; they get it in the neck but in truth they are no more unreliable than the Treasury. The two organisations probably share the same piece of seaweed and crystal ball.
BE: Another philosopher. But inaccurate weather forecasting can lead to everything from a child’s disappointment that this or that looked-forward-to event has been cancelled to sheer devastation. Though I do agree that it would be a bit boring if they always got it right, expecially when the forecasts were for bad or unelpful weather.
Indeed I am a walker, Brian, but having a dog weather is irrelevant except for what to wear and where to go. Not going twice a day is not an option.
BE: Aha, two very good reasons for having cats. Though, to tell the truth, we have to discourage our two Burmese from coming with us.
I think you’re expecting too much BE, not unusual in the modern world where there’s a tendency to expect the Government to fix everything, the police to stop all crime, sports stars to all be perfect role models and weather forecasters to plan our day for us.
Weather is a great leveller, it’s socialist, where all people are treated with equal disdain. In Dunedin the cold of a southerly is felt up every kilt, no matter what the cut of the tartan.
All the rich can do is buy a flash umbrella – and even that is levelled in Wellington.
BE: I like the idea of weather being the great Socialist leveler. However, I don’t want Metservice to plan my day for me, I want them to help me plan it for myself.
If it’s not clear that anyone could do a better job than the metservice is doing, then it appears pointless to complain, and there’s no reason to think that they aren’t using best practice rather than throwing bones or peering at sheep guts.
Just while we’re on the subject of largely useless broadcast information I find the nightly statement on nightly television news of what the local and international stock markets are doing bizarre and irritating. At whom is this information directed? Only a small group of people (relatively speaking)are professionally interested in this data and they have far more accurate and regular sources of information about its movements. At the same time it tells you nothing about the state of the real economy. It would be far more interesting and useful for that purpose to have the daily data on the unemployment rate on the television. But that of course would be ‘political’
When we want to go tramping we look up the Met Service and Metvuw forecasts, pick the one that looks the best and go with that one! lol.
Actually Brian, it’s even more unpredictable when you live in, or near, mountains as we do in Golden Bay. Often we look out across the Bay and it’s doing the opposite of what we are getting across at Collingwood. And driving over Takaka Hill will often find clear skies on one side and rain on the other. So the forecasts are often irrelevant and even looking out the window not reliable.
“BE: Aha, two very good reasons for having cats.”
Gareth Morgan begs to differ: http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10860653
“we have to discourage our two Burmese from coming with us.”
Yes, our old Burmese died last year and when she was young she used to come on walks with the dog by the beach. But her walks consisted of short sprints and once we got about 500 metres from home she would abandon us. Though she did march into a ratepayers annual meeting once to find us, bold as brass.
As for Gareth Morgan, not sure if he has become an eco-fascist or just a fascist. At any event he needs to stick to herding his cats at the Phoenix by all accounts. His credibility will be on a par with Garth McVicar soon.
Faith isn’t something I generally have. Having said that, I do think they’ll do a good job.
I check the Ken Ring forecast and plan for the opposite. Usually works.
I’m not sure if it is happening already, but weather forecasters may be forced to hedge their bets so as not to be deemed liable for unpredicted loss of life and property in future. Look at how in Italy geological scientists have been found guilty of not accurately predicting an earthquake.
Tony Simpson at 08:07 asks who the stock market segment in the TV news is aimed at. I suspect its purpose is to give the illusion that the broadcaster is abreast of the day’s events, at the least possible cost.
Not sure how often you are using that handy iPad app Brian but you should have noticed that the erudite, articulate, easy on the eye ex BBC Brit, Dan Corbett, is the new Face of MetService. Bob has been gone for nearly a year now, still doing his yacht duties but no longer a daily part of MetService.
BE: I’m sorry to hear that, but am impressed by the charming and urbane Mr Corbett.
Many have commented – quite rightly – on the difficulty of making weather forecasts in New Zealand, where topography in particular adds all kinds of challenges. Here in Wellington I have found the standard short range forecasts to be pretty good, and by simply noting the minority situations where the forecast is least reliable and using my own knowledge to modify it, I’m getting about a 95% result – i.e there’s a clear surprise only about 5% of the time. Obviously in the most unsettled scenarios this drops a bit, but not very much. Locally one of the challenges is to notice whether a frontal passage has a SW signature or more southerly one – the outcomes are very markedly different.
I’ve met Dan Corbett and found him very pleasant to chat to. Some of the stuffier weather followers in the UK thought he was too “folksy”, but you can’t please them all.
Re Wendy Hay’s comments on wind – which is not confined to Wellington – spending time in the polluted air of Europe was enough to convince me of the benefits of windiness.
It would appear that forecasting when meteorologists are going to be wrong is even more difficult than forecasting the weather.