WeatherWatch: Sometimes forecasters need to take a punt

BBC weatherman Michael Fish. Photo / Supplied

When does alerting the public to a potential weather risk spill over into alarming people unnecessarily? That's the question I've been battling with over the past two weeks as we went from first predicting a tropical storm to then having a slow, sluggish and very large tropical low hover over the upper North Island for several days.

We wait before making predictions on a big scale but we see no harm in discussing potential future weather risks. In the internet age the public can already see what online weather models are predicting up to two weeks in advance, and they then come to us wanting our take on it.

So we write news stories about it. people read the headline only - "Tropical cyclone may take aim at NZ". Then five days later they email us and say "so much for that cyclone".

So we asked our readers: "Do you like how we discuss future weather risks, or would you rather we only commented on weather events we have high confidence in?"

Overwhelmingly, the public said they wanted to know about systems well in advance, regardless of our confidence levels, so long as we explained the risks, potential and the full picture.

"As a dairy farmer, your advanced weather is fantastic," wrote Taranaki's Jackie Whitehead.

"It gives us plenty of time to work out what paddocks will be suitable when bad weather is predicted. As for this past week, the cows are now in paddocks sheltered from the wind."

David Harris of Tauranga agreed: "Forecasting is more an art than a science, although I appreciate that there is also a lot of science involved.

"I have lived and studied the weather in the Western Bay of Plenty for 50-plus years and generally you are getting it bang on. The law of probability says that we will all get it wrong occasionally."

I believe we shouldn't be scared to talk about potential severe weather, even if we're saying there could be a cyclone next week but we won't have a concrete prediction for five days.

Some of you may know of the famous stuff-up from the 1980s, when BBC forecaster Michael Fish told evening TV viewers: "Earlier on today, a woman rang the BBC and said she heard there was a hurricane on the way. Well, if you're watching, don't worry, there isn't."

That night, the Great Storm of 1987 arrived, claiming 18 lives.

The more advanced information we give the public, the more the public can make up their minds on weather risks.

It's a tricky area - one in which we're always trying to be better. So, do you think forecasters should stick to just talking about the next few days or is general discussion about future potential storms also a valuable service for New Zealanders?