When you know a storm is about to begin (say that afternoon or at least within 24 hours) Draw into the Earth a picture or symbol of something you need or need to happen (not a "want", but a "need"!) And pour every ounce of sincerity that you can into this symbol or picture of "Need". Draw the pic/symbol with something natural (a stick, twig or better yet, your personal wand) Just don't be fussy if it gets a bit dirty. Draw this pic/symbol in a place in which it will NOT be disturbed until the storm passes. As the storm passes, it will take your pic/symbol into the Earth along with the water (a double effect!) and The Spell Is Done!
If you return and the pic/symbol is completely gone, be assured that your spell was heard!