"there is a notam indicating "down currents" near approach end runway 17...could this have helped bring the plane down as it went over that end while taking off again?"
Actually, the air is turbulent around the airport because it is surrounded by buildings...it is a very central airport, right in the middle of Sao Paulo. Nickname is "airplane carrier" and the usual briefing between the pilots is "touch down maximum at 1000ft runway marks or go-around". Very marginal operation for this airplane in this weather.