Weather Analysts In Australia Have Changed The Way Forecasters Describe How Much Rain Is Going To Fall

Australian rainfall chart. Image: BoM

Tired of hearing about scattered or isolated showers and trying to decipher what exactly constitutes patchy rain?

Then prepare for a change in weather. The Bureau of Meteorology (BoM) has revolutionised its rainfall forecasting language, making it easier for people to understand.

The new format will provide forecasts based on a percentage scale, using the terms slight, medium, high or very high to describe the chance of rainfall.

The terminology is based on BoMs MetEye system, an online mapping tool or Geographic Information System (GIS), used to visualise weather data for Australia.

BoM acting head of public, marine & agricultural weather services Vernon Carr told Business Insider that while the technology has been developed over time, the terminology is new.

“We’ve conducted research in the past about the terminology we were using and we found a lot of people couldn’t understand the differences between the terms we were using,” Carr said.

“Rainfall is one of the hardest things to forecast… it can literally rain a few kilometres down the road and you might be in an area where it’s bone dry.

“This new format is more accurate and helps people to make better decisions about their plans. It’s much more simplistic with a percentage number next to it.”

Here’s a breakdown:

0-10 per cent – no mention of rain in forecast
20-30 per cent – slight chance of rain
40-60 per cent – medium chance of rain
70-80 per cent – high change of rain
90-100 per cent – very high chance of rain

The forecast will also predict how many millimetres of rain will fall, giving weather presenters an opportunity to choose which information is best to relay to audiences.

All states and territories across the country have implemented the new format this week.

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