Meteorological aspects of an extraordinary flash flood event near Dapto, New South Wales

Extraordinary short-duration heavy rainfall on 18 February 1980 was found to be caused by several meso and synoptic-scale focusing mechanisms. Of particular importance was the formation of a mesoscale low pressure centre which strengthened surface winds to storm force over a very localised area and enhanced convergence mainly in its southeast quadrant. Methods of providing estimates of probable maxi-mum precipitation had to be revised, because maximised rainfalls during the event exceeded available estimates for short durations and small areas by up to twenty-nine per cent. Because of the scale of the event, successful forecasts of similar occurrences. by synoptic or numerical methods, are unlikely in the near future. Utilisation of digital radar data, telemetered rain-gauge networks, and nowcasting techniques would appear to be the most promising means by which a warning service could be provided.