Here is the third clue:

    Cumulonimbus clouds are forming and it's getting dark outside.  Positive and negative electrical charges are now being equalized.  There are flashes of light and energy.

    What weather condition is the weather machine going to make?
                        A. Windy
                        B. Snowy
                        C. Thunder and Lightening

Please hurry, Dr. Zorber needs to know about this one!