The exceptional rainfall is calculated by comparing the forecasted weekly rainfall to the percentiles of the long term total observed weekly rainfall for the same week.

Exceptional Rainfall Forecast f90

This indicates a forecast where the predicted rainfall amount has a 10% chance of being exceeded in a given week, based on the long-term climate record. In other words, the forecasted rainfall total is expected to be greater than or equal to the amount that is historically seen

Exceptional Rainfall Forecast f95

This points to a more severe weather event. The f95 threshold signifies that the forecasted rainfall is expected to be of a magnitude that is historically met or exceeded only 5% of the time. Such rainfall can lead to significant flooding and disruption.

Exceptional Rainfall Forecast f99

This is a forecast for a very rare and potentially hazardous rainfall event. The f99 designation means the predicted rainfall accumulation is so high that it falls within the top 1% of historical rainfall events for that location.Rainfall at this level is often associated with widespread and severe flooding, landslides, and significant impacts on infrastructure and communities.