Thanks, about that I was not informed. This should help highlighting the importance of critical forecast reading. As luck would have it, we have a Tranining Needs Analysis coming up at my academy in the next months, and the Met syllabus received some criticism for being too demanding (I quote: "...appears to be written for forecasters, not pilots&quot. What I have learned here will certainly help me in the discusssion! Also thanks for sharing your TS criteria. The anvil, sharp edges and dark bases I already mention in my textbook (dark base means loads of precipitable water, and the blurry / cotton wool look indicates ice). In addition, a tree-cake like structure also indicates strong updraught. The distance hints (orange hue / individual bulges and shadows) were new to me, and I will try to incorporate them in any way into my lessons. As to the "hat", I do indeed mean that lenticularish cloud (a Cb with that accompanying cloud is incidentally called "pileus&quot, and I say exactly the same thing: pileus means quite violent updraught. So thanks again for your help, it is good to know that I am doing the right-ish thing in the classroom. Best regards // Grille