Why bother with these stupid half steps? Just speed up the pace of fixing the climate change and end tornadoes and hurricanes forever.
This is possible by inducing cloud formation in the right places at the right times to manage energy entering or leaving a weather system. Since clouds are light and heat reflective they are powerful tools for active weather management. It won't be the UN that develops this technology though, it will be the US military, and it will be used first for tornado creation to cleanse a battlefield before attack then to drop a fog down for cover.