Catching alphas

Sorry if this has been asked before. I'm currently rank W and my strongest Pokemon is level 26. I'm in zone 6 right now trying to catch this level 33 alpha Houndoom.

My tactic is get rid of the small houndoors around, then wait for Houndoom to sleep. Once he does, I sneak up, use hypnosis and immediately throw a rapid ball. His catch rate is consistently showing 1 arrow, even when he's sleeping. I realize I might be a bit early to catch him but I just wanted to know if there was still a chance of me catching him, or am I out of luck for now? When the catch fails, he wakes up and gets angry, I hide until he goes back to sleep and try again.