I don't know if that's the standard rotation but the rotation I like to use and seems to work the best for me is Blizzard 3--> Thunder 2--> Fire 3--> fire 1 until out of mana (with fire 3 procs). Use Thunder 2 prox to cast Thunder 3. I don't like to use Thunder 3 to start the rotation because the cast time is just too long for the little extra damage you get.