Gundog,
I still think the word 'provision' is not specific enough to imply that it must be replanned in flight.
Have you looked at the CAR from which the AIP quote has been taken?
The title of the rule is 'planning' of flight. The wording of the rule is such that part 2 quite clearly follows on from part 1.
Part 1 - Before the flight, check weather
Part 2 - If the weather that you have checked is below alt minima, provide an alt.
239 Planning of flight by pilot in command
(1) Before beginning a flight, the pilot in command shall study all available
information appropriate to the intended operation, and, in the cases of
flights away from the vicinity of an aerodrome and all I.F.R. flights,
shall make a careful study of:
(a) current weather reports and forecasts for the route to be followed
and at aerodromes to be used;
(b) the airways facilities available on the route to be followed and the
condition of those facilities;
(c) the condition of aerodromes to be used and their suitability for
the aircraft to be used; and
(d) the air traffic control rules and procedures appertaining to the
particular flight;
and the pilot shall plan the flight in relation to the information obtained.
(2) When meteorological conditions at the aerodromes of intended
landing are forecast to be less than the minima specified by CASA, the
pilot in command shall make provision for an alternative course of
action and shall arrange for the aircraft to carry the necessary
additional fuel.
Penalty: 25 penalty units.