How Snow and Streamflow Observations Reveal Mountain Precipitation Patterns Missed by Conventional Means: Case Study of the Southern Sierra Nevada, California

Precipitation in mountain watersheds is difficult to measure accurately over large areas due to its spatial variability, which is not captured well by the sparse network of gauges located at high altitudes. Most hydrologic predictions rely on statistical techniques to map high-altitude precipitation based on lower-altitude gauges, leading to high uncertainty in flood and water supply volume forecasts. These methods miss precipitation patterns that shift with changing weather patterns and stormtracks. This has led to difficulty with hydroclimate modeling and predictions in mountain watersheds. However, other point observations are made more reliably in these areas, including snow and streamflow measurements. Here we examine patterns and causes of interannual variability and long-term trends in snow and streamflow in the Sierra Nevada, California, demonstrating how conventional precipitation gage-based methodologies have missed some of the patterns and dynamics most critical society, and how high-resolution numerical weather modeling, combined with snow and streamflow observations provides a more promising alternative.