The phrase "above all when" is correct and usable in written English.
It can be used to emphasize the importance of a particular situation or condition in relation to others.
Example: "I enjoy outdoor activities, above all when the weather is perfect for hiking."
Alternatives: "especially when" or "particularly in cases when".
Above all, when you score two goals we dropped our intensity and when you do that they can score.
He understands the political system and knows which levers to pull, how hard and — above all — when to pull them.
Above all, when Hume talked about God, one felt he was talking from the experience of prayer.
Above all, when the day comes that Ted steps down, it will be because his health is failing.
But above all, when many Japanese feel their nation is drifting and leaderless, Ms. Tanaka enjoys a rare reputation for decisiveness.
What constitutes "the best" of anything in racing is always subjective, above all when the old is set against the new.
We hung up, both in search of further information — above all, when Hood would be free to depart from the prison grounds, and under what, if any, restrictions.
And Zwirner says that, above all, when it comes to completing the editions, the more, the merrier, for the sake of art history.
A day, above all, when Davenport, one of the two women who have dominated the game in 2000, was beaten by the unseeded but hardly unmotivated Van Roost, 6-7 (5), 6-3, 6-3.
Above all, when I look over my list (which I put together rapidly and spontaneously), what leaps out, in regard to my primordial cinematic enthusiasms (mainly, for B-movie science fiction), is a lasting love for playfulness.
Above all, when Sexton got wind of the fact that Sargent's wife directed a program at Stanford to assist faculty members in buying housing in high-cost Palo Alto, he created a similar position for her at N.Y.U.
