To tighten one type of energetic activity, like rain, on one level, would involve stretching it or taking rain away from another area or level. Regardless of good intentions, a domino effect would take place whenever manipulating magick. To manage such a system, a world network of magick workers would have to organize and work weather magick for a unified series of events. The possibilities of such an event happening would definitely give statistics for any parapsychology journal,but the possible backlash from the event would worry me. Manipulating the weather without harming anyone seems, to me, unmanageable.
Weather is one of the Earth's ways of managing itself.
By pulling and stretching on that system ourselves, we may well pull a muscle and create what for us might be a long term problem. Also, for other magickal folk, manipulating weather might not feel like a problem. As a Wiccan, I feel that causing weather knocks me out of sync with the cycles that my religion requires me to master.