Mist would also need to change the field, becoming misty terrain. Blizzard and Heat Wave (Lava Plume too?) should get increased power due to convection. Maybe tailwind again to stop the field, too?
I don't think Bomb-moves should get a power-up, only a decrease in accuracy. Also, I think pokemon with Sniper shouldn't experience decrease in accuracy (perhaps for every field?).
Also, you could make an additional Storm Weather-field by using Rain Dance on it, giving additional power to Thunder, water-moves and Hurricane, while decreasing fire-type moves, make Fly (and Bounce, maybe Sky Attack too, but maybe the latter should gain a boost from this weather) fail, just like all move that require throwing things at the opponent (like Rock Blast and Seed Bomb). Terminate it by other weather-moves, Tailwind petering out, or Heat Wave.