This new project began in July 2017. It will investigate the development of a pilot capability to make useful predictions of community impacts of extreme weather, improving timely mitigation actions. This pilot project will focus on hydro-meteorological events impacting eastern Australia – events in areas where most of our population is concentrated, particularly the coastal regions of southern Queensland, New South Wales and eastern Victoria. These events, which include East Coast Lows, can occur at any time during the year, with gale or storm force winds damaging coastal areas, widespread rain often causing flooding, and very rough seas and prolonged heavy swells damaging the coastline.

Currently, hazard forecasts in Australia are based on meteorological analysis of many data sources (numerical weather prediction models, satellite and radar observations), which is combined with local knowledge, and informed by years of experience issuing and verifying forecasts. Up until recently, forecasts have been general in nature, due in part to uncertainty of forecast accuracy and the short lead time. But there has been substantial improvements in forecast accuracy over the last couple of decades, and the availability of higher and higher resolution models means that the potential for more specific forecasts is ever increasing.

Impact may be qualified and/or quantified by integrating hazard forecasts with data about community vulnerability, exposure to the hazard and localised damage models. The issue of variable quality data will be explored with the nature of the impact-based forecasts to be determined according to available data and end-user needs.

Impact-based warnings could be developed by integrating specific (both spatial and temporal) hazard forecasts with exposure and vulnerability data at the community level. The capability to develop impact assessments has been applied generally within the natural hazard risk modelling community, however the ability to develop such assessments within a forecasting and warning process currently does not exist in Australia. The recent advances in weather forecasting as described above suggest that useful impact-based warnings are now a real possibility.

End-users, especially the operational emergency management stakeholders, may want to understand many things from an impact-based forecast, such as:

• When and where the impacts will occur?
• Who and what might be affected?
• How badly will they be affected?
• Who most urgently needs assistance (and who can help themselves)?
• What are the possible cascading effects (e.g., landslides)?

While it may be some time before an impact prediction capability can specify all this information with sufficient precision, accuracy and reliability to be included as a stand-alone forecast element in addition to current practice, there is an existing capability that could be integrated into an operational forecast that has the potential to greatly improve the quality and local relevance of hazard forecasts.