Precipitation event means a quantity of water resulting from drizzle, rain, snow, sleet, or hail in a limited period of time. It may be expressed in terms of recurrence interval. As used in these regulations, precipitation event also includes that quantity of water emanating from snow cover as snowmelt in a limited period of time.
30 CFR § 701.5
As used in this chapter, the following terms have the specified meanings, except where otherwise indicated: