Watchgod
Why on earth SYD ATC go to RWY 25 only with 20 knots X/W on the parallels?.
Sometimes the decision is made on the basis of the forecast, reported upper winds, typically 500ft or 1000ft and input from Sydney Airport Met Unit (SAMU). Many a time the wind out on the bay is the determine factor (and the winds along 25 are not as strong).
Of course, this was all less of an issue when MAX 25 knots was the runway selection criteria. Now its 20 knots and this change from 25 knots to 20 knots was driven partly by an industrial campaign.
A "managed change" is preferable to an "immediate change". An immediate change to 25 only when a large number of RWY 34R departures are "caught" south of RWY 25 is not a pretty sight.