From September 21, rainfall information for the Melbourne, Albury-Wodonga and Mildura forecasts will be presented as chance of any rain and rainfall amount for day one of the forecast.
Chance of rain describes the likelihood of receiving a measurable amount of rain (>0.2mm) during the day at that location. For example, if the chance of rain for Melbourne is 30%, it means that on 3 out of 10 days with similar weather conditions rainfall will be measured in the Melbourne rain gauge.
The graphic illustrates that whilst there may be a 30% chance of rainfall, there is also a 70% chance of not receiving any rainfall at all.
Rainfall amount indicates the likely amount of rain in millimetres for the forecast period. Sometimes rain falls in a patchy pattern across an area with some locations receiving a heavy shower while an area nearby might miss out completely. On these days the rainfall range may be quite large, e.g. 5 to 30 mm. When steady rainfall is expected over a wide area, the range may be smaller, e.g. 10 to 15mm.
At this stage, only Melbourne, Mildura and Albury-Wodonga receive the chance of rain information. In the future, with improved forecasting techniques, the Bureau plans to extend this rainfall information to the rest of Victoria.
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