A BUREAU of Meteorology (BoM) forecast for greater Brisbane in the first week of March predicted up to 80 millimetres of rain, with only about 3mm subsequently recorded.
It was a similar story last week when a rain forecast predicted possible riverine and flash flooding, which cast doubt on weekend sports fixtures and events throughout south-east Queensland.
The annual Funfest at Faith Lutheran College at Thornlands was cancelled on the afternoon of Wednesday May 17, three days before the Saturday event.
According to meteorologist David Sercombe of Weatherwatch at Ipswich: “It is fairly rare for people to cancel an outdoor event three or four days in advance”.
“We’ve just had quite a high-end flood on the Logan River, and when there is a big event I think in the immediate time afterwards people are quite cautious and human instinct kicks in.”
“The event in March was what we would call convective rainfall, thunderstorms and heavy showers, where the reality can be quite patchy,” Mr Sercombe said.
“So you might get 50 millimetres in Jimboomba and 20 millimetres in Beenleigh, 15 in Beaudesert but 100 in Brisbane; but when the model puts out its summary in a graphical form, everywhere will have a similar value as if it’s an event where there’s nice big rain areas everywhere.
“Obviously I’m a private provider so I’m in business partly because the Bureau isn’t perfect, but the truth is the Bureau’s forecast is reasonably well considered and takes into account the different types of rainfall.
“There’s a whole bunch of meteorological organisations across the globe that run modelling of the atmosphere.
“Some of those charts are publicly available. I use them every day. If you get a week of convective rainfall it is going to be patchy,” he said.
The hard call
“It felt like it was the right decision, but certainly we were aware of the ramifications,” principal of Faith Lutheran College Shane Altmann said of the decision to postpone Funfest.
“It felt terrible because you’re postponing something everyone’s looking forward to.
“The reason we had the conversation midweek was because of all the doom and gloom that was coming though in the news. We were trying to weigh up the reality.”
According to Mr Altmann, the tension in the decision was due to the potential for financial penalties from various suppliers the school had engaged, such as rides and food providers.
“Thursday morning was the cut-off point for many,” he said.
“Given that we’re not just trying to create a community event, but also a fundraiser, those decisions that might cost a few thousand dollars in cancelling late can eat into potential profit, taking it away from goods and services that you can deliver to your students.
“Overwhelmingly all the people involved were very generous. They understood.
“It was the right call. We had very heavy rain all day Friday afternoon and evening. By Saturday morning the day cleared up and of course when the sun comes out you think ‘shivers we could have had it’, but it would have been a shambles setting it up.
“It would have been a disaster, particularly around safety,” he said.
MetEye in the sky
A spokesperson from BoM said that while the Bureau's daily rainfall forecasts are a useful tool for those planning outdoor activities, the decision to cancel an event or activity based on a forecast is always up to the community group itself.
“If your event or outdoor activity will be strongly dictated by the weather, we advise that you visit our MetEye weather map, where you can see how close you are to the area of significant rain.
“Sometimes a small change in the pattern can have a huge impact on how much rainfall you receive,” they said.
“The Bureau's rainfall forecasts are made up of separate pieces of information and it's important not to run these together. ‘Chance of any rain’ refers to the likelihood of a location receiving more than the minimum measurable amount of rainfall over the 24 hours from midnight to midnight. If rainfall is forecast, the ‘Possible rainfall’ field is represented as a range between two values (otherwise it will appear as '0 mm').”
For more information on interpreting the forecast go to the BoM website.
Faith Lutheran College Funfest is going ahead on Saturday, June 10, weather permitting.