One also has to keep mind crew might also be timed out with weather delays like this as they tend to operate multiple sectors in one day so a bit of storm activity in one city can cause massive flow on effects for the rest of the network for the whole day.There was a storm yes. Lasted one hour. All done by about 1pm. Then clear skies for rest of the day (but still windy). But that was enough to blow the whole system up for the rest of the day.
I’m no expert and will leave that to the experienced people, but that they couldn’t get MEL-SYD turn arounds up and going again did look very frustrating for a lot of people.
Granted QF might be better than VA in that they supposed to have spare aircraft and crew on hand but I am not sure how it works in practice.