Estimated winter (October-May) accumulation at 2100 m and the difference between it and accumulation at 1500 m, both in mm water equivalent.
Precipitation was derived by scaling daily measurements at Forks, a nearby low-elevation station. Estimates for 1915-1947 come from a rain-fraction model (Rasmussen and others, 2000 ). Estimates for 1948 to present come from a radiosonde model in which precipitation at altitude z is assumed to be snow when T_z>2^oC. T_z comes from interpolating within the temperature profile measured by the radiosonde at Quillayute (Rasmussen and others, 2000 ). Horizontal lines are best-fitting piecewise-constant function.