An NHC-led scientific team recently identified for the first time that the North Pacific High (NPH) sea-level pressure anomaly is a strong determinant and predictor of extreme precipitation as well as total winter precipitation in California. Building from this finding, NHC developed a forecasting system for April 1 snowpack at Mammoth Pass and other locations in the eastern Sierra Nevada. The system employs a statistical method that is novel in the water resources field to predict April 1 snow water equivalent based on late January conditions, as well as a range of probability relative to historic normals. As a result of this work, the Los Angeles Department of Water and Power (LADWP) is now able to obtain an early February forecast each year for the peak spring snowpack above its Owens Valley system. This forecast will allow LADWP to issue summer runoff forecasts, inform decisions regarding reservoir storage, and better plan water supply throughout the summer months for the Los Angeles metropolitan area.