Very shortly after the crash (closest in time I saw) the top of the tower was visible but not the very top of the remaining crane. Shortly after the crash, news reports on Sky and BBC showed the overcast gradually dropping so that the upper floors of the building were lost from sight, and at the lowest height of overcast the damage to the crane could not be seen. By 10:00 the news transmisions show the sky to be 999 NSW.
The weather-related low-level (below 1200ft) flying conditions changed by the minute that morning.