This study uses dynamical and statistical methods to understand end‐of‐century mean changes to Sierra Nevada snowpack. Dynamical results reveal mid‐elevation watersheds experience considerably more rain than snow during winter, leading to substantial snowpack declines by spring. Despite some high‐elevation watersheds receiving slightly more snow in January and February, the warming signal still dominates across the wet‐season and leads to notable declines by springtime. A statistical model is created to mimic dynamical results for April 1 snowpack, allowing for an efficient downscaling of all available General Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase 5. For all GCMs and emissions scenarios, dramatic April 1 snowpack loss occurs at elevations below 2500 meters, despite increased precipitation in many GCMs. Only 36% (±12%) of historical April 1 total snow water equivalent volume remains at the century's end under a “business‐as‐usual” emissions scenario, with 70% (±12%) remaining under a realistic “mitigation” scenario.