Congratulations on entering the elite corps of Storm/Rad defenders. I haven't remade it on HC, but played one on live from i3 to sunset.
I'm not sure what you're trying to do with Gale. The damage isn't worth enhancing, but you've only slotted 1 %dmg proc. In any case, it needs more accuracy (turn off Aim in Mid's).
O2 Boost isn't a great power and not worth the 6 slot investment. The +reg/+rec unique needs to be in an active power and will only work for 120s after using O2.
There's no reason to take both Gale and O2 Boost, so just pick one.
Steamy Mist should have 6 slots. Both the defense and the resistance are worth enhancing.
Freezing Rain isn't worth slotting for damage and procs have a low chance to fire. Slot 2 recharge IOs or 3 pieces of a Defense Debuff set.
Hurricane should be slotted with a Tohit Debuff set (which will also cover end reduction). It doesn't require more than 3-4 slots. Note, the kb>kd doesn't affect the repel.
Sting of the Manticore is a better choice in Proton Volley.
Slot the Gaussian's %bu proc in Aim
In Cosmic Burst, swap the dmg/rech for the %dmg proc
Don't skip Irradiate. It's a massive defense debuff with a huge radius and accepts a lot of %dmg procs.