For example, the Texas Panhandle. It's anvil was at the ground to about 50,000 ft. It produced a tremendous amount of rain and hail. A lot of rainfall occurred in a short amount of time. If there is a greater dew point there is more water vapor.
Water vapor plays a great role in instability.
If there is more water vapor there are more thunderstorms. Evaporation occurs when water changes, for every gram there is a tremendous amount of cooling. It is associated with latent heat. Condensation does the opposite. Moisture condenses, heat lets out in the atmosphere.