On Sunday 18th march 1990, a savage hailstorm devastated regions of areas from southwest Sydney to near Dee Why. Hailstones the size of cricket balls and in some case larger pummeled vehicles and punctured holes in house roofs across many suburbs particularly Liverpool, Bankstown, Bass Hill, Auburn and Lidcombe. Hail sizes reported from this storm were up to 8cm in diameter. One reliable report from Liverpool used two hands to indicate the sizes of the hail that fell at his residence.
The supercell developed along a SE change boundary with a sharp upper trough and rapid destabilisation creating an environment for rapid intensification. The supercell tracked to and weakened near Dee Why but not before causing damage estimated into the hundreds of millions of dollars. Some suburbs looked like a tarpaulin corridor.
It was the most costly hailstorm up that time and it took the 1991 hail and windstorm as well as the devastating supercell in 1999 to match and top this event.
Dave Croan, you experienced this event if I recall.