The four large hail assessment techniques in severe thunderstorm warning operations in Australia

Every severe thunderstorm warning issued by an Australian Regional Forecasting Centre (RFC) requires the specification of a least one of the four expected severe convective phenomena: large hail, damaging winds, tornadoes or flash flooding. Equipped with a knowledge of the storm environment, four primarily radar-based techniques (base reflectivity and base velocity) for large hail assessment will be presented: (1) the “hail nomogram”, (2) the three-body scatter spike (TBSS), (3) storm structure analysis and (4) the WDSS hail detection algorithm. This paper will illustrate the “balance of evidence” warning approach for large hail that is currently in use as best operational practice in Australia.