The largest hailstorm in our history

The combat agencys perspective on command and control. Howard, B.W. (2000) National Emergency Response, 15 (1)

Late in the afternoon of 14 April 1999, an intense supercell thunderstorm formed south of Wollongong. It dumped hail in and around Kiama, Albion Park and Shellharbour around 5pm, but did little damage there. It then moved out to sea and travelled slowly north, but just before 7:30pm it suddenly turned inland near Bundeena and moved through the Sutherland Shire, Botany Bay, the airport and the suburbs in and around the CBD depositing very large hail as it did so. It then tracked north along the northern beaches and finally collapsed near Broken Bay at around 10 pm.

The most serious damage was caused by giant hail between Lilli Pilli on Port Hacking and Darling Point on Sydney Harbour in a band 25km long by 3km wide. Most of the damage was to residential property and vehicles. The total cost is likely to be in the vicinity of $2.2billion making this event almost four times more costly than the giant storm of 1991 over Sydney's northern suburbs. It also damaged more than four times the number of properties than that storm.

The April storm was the most costly thunderstorm ever to strike Sydney. Ironically the State Emergency Service (SES), which is the combat agency for severe storms (and floods) was in the process of preparing a state level Sub-Plan to the State Disaster Plan covering severe storms when the hailstorm struck.

The SES was preparing the Plan because all major storms require multi-agency responses. While the cooperation between the emergency services and functional areas has always been excellent, SES had experienced the occasional problem with coordination between the services, particularly following the larger storms. It is also appropriate to keep in mind that storms cause regular major responses from all the Emergency Services. Indeed over the last decade they have been our most costly natural hazard.

The decision to prepare a Storm Plan was therefore reasonable in the circumstances. The pity of it was perhaps that it was not in operation when the storm struck the most densely populated part of Sydney on the evening of 14 April 1999.

Download the research paper for more information.