Payette River Basin, Idaho: High-Resolution Modeling and Gauging

Idaho Power Company (IPC) is a hydroelectric based utility serving eastern Oregon and most of southern Idaho. Snowpack is critical to IPC operations and the company has invested in a winter orographic cloud seeding program for the Payette, Boise, and Upper Snake River basins to augment the snowpack. IPC and the National Center for Atmospheric Research (NCAR) are in the middle of a multi-year study to determine precipitation enhancement due to winter orographic cloud seeding in the Payette River basin.As part of this study, a target/control network has been established in the Payette River basin of Idaho using 15 SNOTEL gauges in or near the Payette River basin along with 14 IPC installed high-resolution precipitation gauges. The IPC precipitation gauges record to a hundredth of an inch (verses a tenth of an inch for SNOTEL) and can be used to determine precipitation enhancement from both individual storm systems as well as seasonal precipitation. Forecasts from a high resolution (1.8 km) WRF model, generated at the University of Arizona, for precipitation in the seeded and non-seeded areas will be compared against observed precipitation and used to determine the precipitation enhancement due to cloud seeding.Model to model and model to precipitation gauge comparisons will be compared in both seeded and unseeded areas in an effort to develop temporally and spatially explicit quantitative precipitation maps for the accumulation and variability in the basin.