Question: Can you clarify what is meant by “Snowmelt Date” [Eric & Ray M.]

Answer: Runoff is water from any source (rainfall, snow melt, and even excess irrigation) which is not absorbed into the ground but flows on the earth’s surface (sheet flow) eventually reaching creeks, streams, rivers and could go as far as the ocean.

Snow melt is one source of runoff. Generally, it happens anytime the temperature is above freezing and increases as the temperature rises. It can also be increased by warm rainfall as in 1997.

‘Snowmelt Date’ (USGS)

The date of surface runoff produced from melting snow as measured by the stream flow transition from wintertime low flow to spring time high flow. It is also called the ‘spring pulse date’ and is associated with cold weather climes.