I should also have mentioned: on the face of it weather, human factors (bad design, negligence, human error etc) an 'unforeseen circumstances' (which could be a combination of the above) always seem to factor highly in any accident, aviation or not.
Now, if weather alone was a primary cause in the case of AF447, then has avaiation been incredibly lucky, or did we see unknown weather in the area? If not, then surely logic will say that such events should be more common: how many windshear events have caused incidents at airports, even when known about? If similar weather events could cause total loss of conrtol then surely statistically there would be more cases even if the particular area sees less traffic? I don't know.
I also do not think crew incompetence or absence or whatever has much if anything to do with AF447 - but as we are told it did not break up in mid air, it really leaves only the options previously mentioned - which may or may not have much in common with the prevailing weather.