as with most builds it's all down to style of play, chi made a pretty good storm/dark guide HERE which you may find useful
EDIT: one thig i will say is take hurricane and slott it with -acc imo it is THE reason storm is a defender set it prevents anything short of AV's/GMs from getting into melee range of you or anyone near you, great for protecting team squishies, i just say this because i didn't take it til the second respec and still can't believe how idiotic that was of me 
I agree completely with dark siren. Slot hurricane and dont get hurt! (as much as normal anyway...)
Oh, and get tornado 
Needs
1) Snow Storm, Freezing Rain, Hurricane, preferably all three as soon as they are available.
2) Two fitness powers of your choice and then Stamina at level 20.
Wants
3) Most of the storm powers. They are all good, although thunderclap is situational and requires heavy slotting to be functional.
4) Teleport if you can fit it in, even if it's not your primary travel power, for relocating your accuracy debuff anchor efficiently 
Hello, I have a friend, who's pretty new to the game and has just made a storm defender and has asked for advice. While I'm not a noob, I have 0 experience with Storm powers, in fact I don't think I've ever seen one, what powers are good, what kind of order should they be picked in and how's best to slot what. I'm pretty sure it's a Storm dark build, familiar with dark but are any powers that work in tangent well?
Cheers guys and gals.