Originally Posted by
PILOTGUY
No radar will paint a building thunderstorm unless there is some form of precip coming out somewhere in it. The precip is what gives the radar returns. This appears to have been part of the Air France issue. They flew in between to large cells among a line of severe weather. It looks as if there was no precip in that immediate area in front of them, but that is where the worst updrafts would have been.
I disagree precip held in the cloud by updrafts will still paint even if it is not falling.
Any storm that is worth going around will paint red at the FL250 level regardless if it is raining below it or not.