The problem I have in Australia after having flown overseas is that it is forecast much too conservatively. The result is that nobody has any idea when a flight REALLY should be cancelled.
Severe turbulence SHOULD mean that all flights in the relevant area should be cancelled.
At the moment, in the area I fly in OZ, I would guess about a fifth of all flights throughout the year would be cancelled if we didn't fly under the current 'severe'.
Not good enough.