Where can I find historical snowfall data?
A basic conversion of precipitation to snow can be used to obtain an approximate snow reading. If snow precipitation is listed as e.g. 0.05 inches, this is water equivalent. Multiply by about 12 to get snow in inches. In the above example, 0.05 x 12 = 0.6 inches of snow. Dry, fluffy snow has much less water in it, and one should use a conversion factor of about 20 instead.
U.S. Snowfall data can be found at these sites:
http://www.nohrsc.nws.gov/
Western U.S. mountains:
http://www.wcc.nrcs.usda.gov/snow/
California:
http://cdec.water.ca.gov/snow/