From Glossary of Meteorology


Precipitation from a convective cloud.

Showers are characterized by the suddenness with which they start and stop, by the rapid changes of intensity, and usually by rapid changes in the appearance of the sky. In weather observing practice, showers are always reported in terms of the basic type of precipitation that is falling, that is, rain showers, snow showers, sleet showers. In aviation weather observations, these are encoded RW, SW, and EW, respectively.
See airmass shower.