Forecast or Fiction? Making Sense of Weather Models on the Eyre Peninsula
The third Friday Climate Forum webinar for the EP Sustainable Agriculture Program was held on 12 June, and focused on understanding weather forecasts and tools. Guest presenter Dale Grey, Seasonal Risk Agronomist with Agriculture Victoria, explained that weather and climate models are built on grid squares, meaning forecasts are limited by model resolution. A forecast may appear location-specific, but in reality it may represent conditions across a grid cell ranging from a few kilometres to tens of kilometres, depending on the model and data source. This means small differences between nearby locations should not always be interpreted as precise or meaningful.
Dale explained that model resolution varies considerably. The Bureau of Meteorology’s ACCESS model is run at finer resolution over some parts of Australia, including South Australia, Victoria, Tasmania and major cities, while many global models operate at coarser scales. However, users may not always be seeing the highest-resolution version of a forecast, depending on which app, website or media outlet they are using.
A major theme was knowing where your forecast comes from. While Bureau of Meteorology observations underpin much of Australia’s weather data, many apps, media outlets and websites use private models, overseas models or modified model outputs, often with extra processing or improved visual presentation. Dale’s practical message was not that these sources are necessarily bad, but that people should understand whether they are looking at information from the BOM, ECMWF, Weather Zone, Apple, Google, The Weather Company or another provider before judging forecast accuracy.
Dale also stressed that forecast accuracy declines with time. The first few days are generally the most useful, while forecasts beyond about eight days become highly uncertain, especially for rainfall. Local accuracy can also be affected by the distance from actual weather stations. BOM weather stations provide real observations, but there are relatively few across Eyre Peninsula, so data away from those stations is often modelled or interpolated.
Radar was discussed as a valuable tool for seeing what is happening now and making short-term decisions, such as spraying or spreading urea. However, Dale clarified that radar is not generally what drives numerical forecasts; rather, models use atmospheric observations, satellite information and physics-based calculations to estimate what is likely to happen next.
The session also demonstrated practical tools, particularly the Bureau’s MetEye and interactive weather and wave forecast maps. Dale encouraged participants to use these tools to view current observations, rainfall, wind, radar, cloud cover, waves and short-term forecasts, and to compare multiple models rather than relying on a single forecast. The discussion finished with questions about radar on EP (or lack of), private weather stations and mesonets, highlighting that private weather networks can improve local observations, but only if they are well maintained, regularly checked and sustainably funded.
