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Climate
The climate in east King County is generally categorized as temperate and wet. On average the City of North Bend Receives about 60 inches of rainfall a year, but the higher elevation portions of the watershed receives over 100 inches of rainfall. As such, the mean annual precipitation in the Snoqualmie River watershed above Snoqualmie Falls is about 104 inches per year.
There are several precipitation gages in the area including: Cedar Lake (1932-present), South Fork of the Tolt River (1962-present), Grouse Ridge (1994-present), and Snoqualmie Falls (1899-present).
Precipitation falls mostly as rain in the lower watershed, but the upper watershed is considered a “transient–snow” basin because precipitation falls as a mix of rain and snow. Snowfall in the upper watershed is very important because snowmelt in the spring helps sustain river levels in the summer and fall. In effect the snowpack acts as a storage reservoir that stores water in the winter and releases it when air temperatures increase in the summer. Snowpack levels this winter were minimal, meaning streamflows this summer could drop to precariously low levels, depending on the amount of summer rainfall.
Scientists at the University of Washington are concerned that the current global warming trends will cause more of the winter precipitation to fall as rain rather than snow. This shift could potentially cause lower streamflows in the summer because snowpack in the upper watershed will be reduced (UW CIG, 2004).
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©2003-2007 Golder Associates
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