One of the tricks in recording a good storm is to have your levels set high enough so that your recorder picks up the rain clearly but not so high that a sudden crack of thunder will result in a distorted signal. In addition, each raindrop smacking a sensitive mic creates an annoying thud that must be removed later. Best to shield your mic in some way from the constant drops without muffling the sound. Using a windsock for this can work if you can leave air between the mic capsule and the sock. Any mic covering will also tend to cause an attenuation of higher frequencies.