The Australian climate varies from tropical in the north to oceanic in the south, so it is necessary to express the rainfall in a way that reflects the impact of the rainfall rather than the intensity.
We have adopted the design standard for minor hydraulic works in most Australian cities, which is for storms with an annual exceedance probability (AEP) of 10% (once in 10 years). This means that, if the rainfall is expected to exceed the 10% AEP depth, this will have approximately the same impact on a city, independent of the climate.
The Australian Bureau of Meteorology weather radar network provides good quality radar reflectivity observations in the major cities which, together with dense networks of real-time rain gauges, can be used to support a heavy rainfall warning service that is based on radar rainfall estimates and nowcasts.
The paper first describes the main attributes of the quantitative precipitation estimation System (Rainfields, Seed et al. 2007) and the Short Term Ensemble Prediction System (STEPS, Bowler et al. 2006) that is used to generate the nowcasts.
This paper describes the iterative process of design and implementation of the heavy rainfall warning service, involving researchers, forecasters, trainers and services experts. The resulting service is robust and user-focused and includes systematic competency-based training of forecasters.
References: Bowler, N. E., Pierce, C. E. and Seed, A. W. (2006), STEPS: A probabilistic Precipitation forecasting scheme which merges an extrapolated nowcast with downscaled NWP, Q. J. R. Meteorol. Soc., 132, 21272155.
Seed, A., Duthie, E., and Chumchean, S. (2007), Rainfields: The Australian Bureau of Meteorology system for quantitative precipitation estimation. Proceedings of the33rd AMS Conference on Radar Meteorology.
- Indicates paper has been withdrawn from meeting
- Indicates an Award Winner