BOAC,
Compressor Stall is correct. It's slightly different, but so long as you are carrying the appropriate holding fuel of 30 minutes. However, the weather must be forecast to be better than:-
From Australian AIP ENR 1.1 -87 see para 58.2.1
a. cloud - more than SCT below the alternate minimum (see paras 58.2.12 and 58.2.13 ); or
Note: In determining requirements for alternate aerodromes, fore- cast amounts of cloud below the alternate minima are cumulative. For determining requirements, the cumulative cloud amount is in- terpreted as follows:
FEW plus FEW is equivalent to SCT,
FEW plus SCT is equivalent to BKN,
SCT plus SCT is equivalent to BKN or OVC.
b. visibility - less than the alternate minimum; or
c. visibility-greaterthanthealternateminimum,buttheforecast
is endorsed with a percentage probability of fog, mist, dust or
any other phenomenon restricting visibility below the alternate
minimum; or
d. wind - a crosswind or downwind component more than the
maximum for the aircraft.
Note: Wind gusts must be considered.
ENR 1.1 -88
58.2.3 When weather conditions at the destination are forecast to be as
specified at para 58.2.1, but are expected to improve at a specific time,
provision for an alternate aerodrome need not be made if sufficient fuel is carried to allow the aircraft to hold until that specified time plus 30 minutes.
58.2.4 When weather conditions at the destination are forecast to be above the values specified at para 58.2.1, but, additionally, inter- mittent or temporary deteriorations in the weather below the va- lues are forecast, provision of an alternate need not be made if suf- ficient additional fuel is carried to allow the aircraft to hold for:
a. 30 minutes for intermittent deterioration (INTER); and
b. 60 minutes for temporary deterioration (TEMPO).
Phew. There you go.
