Map of the Snake Watershed in Idaho (large red outline) and existing ground generator and observational facility sites on a map of terrain height (m; color shading). The Payette River Basin, Boise Basin, and Woods Basin target areas are located (north to southeast) in the western Snake watershed, north of Boise and each is also outlined in red. The Upper Snake River Basin target area is located in Eastern Idaho, also outlined in red. Ground generator locations are identified as circle and triangle symbols, and color-coded as red-filled circles (Payette, Boise, Woods), blue (north Eastern Idaho), and green (south Eastern Idaho). The circles are Idaho Power owned generators, and the triangles are generators operated by Let it Snow. Grey lines indicate flight tracks used by the cloud seeding aircraft. Black squares indicate the location of microwave radiometers, black x’s for atmospheric sounding sites, open blue and red circles are high-resolution snow gauge sites (located in the western Snake Basin).
The Idaho Power Company (IPC) conducts a winter cloud seeding program to augment snowfall along the Snake River Basin and its tributaries for hydroelectric generation. The program has been focused in the Payette River basin in western Idaho and the upper Snake River system in eastern Idaho, and has recently expanded into the Boise and Wood basins in western Idaho.
RAL has collaborated with IPC since 2010, conducting research to provide real-time and retrospective model-based guidance on the effectiveness of cloud seeding using ground generators and aircraft tracks. A key component of this effort has been the development of a real-time cloud seeding forecast guidance system using the Weather Research and Forecasting (WRF) model. This system includes real-time (“control”) forecasts, a case-calling algorithm that automatically identifies when seeding conditions are predicted based upon the conditions in the control forecast, and then a subsequent seeding forecast where the forecast model simulates seeding at times and places where the case-calling algorithm identified seeding potential. In addition, a real-time web-based display was developed as part of this system to provide IPC forecasters with graphical output from the real-time forecast system.
Web-based display showing the forecasted 3-hourly change in precipitation from simulated airborne seeding on 8 January 2017 at 06:00 UTC.
In order to evaluate and improve the cloud seeding model developed for IPC, RAL and IPC worked jointly to organize a field program aimed at studying cloud seeding in Idaho. The new field program, Seeded and Natural Orographic Wintertime clouds—the Idaho Experiment (SNOWIE), was funded by the National Science Foundation (NSF) in the spring of 2016. The NSF project is led by Dr. Jeff French (Univ. Wyoming), with collaboration from Drs. Bart Geerts (Univ. Wyoming), Bob Rauber (Univ. Illinois), and Katja Friedrich (Univ. Colorado), as well as Roy Rasmussen, Sarah Tesendorf and Lulin Xue of RAL. The project took place in January–March 2017 and aims to evaluate ground and airborne cloud seeding using physical and numerical modeling approaches, as well as to validate the cloud seeding model.
