The microphysics scheme in the high-resolution numerical weather prediction system for the 2010 Vancouver Olympics

The 2010 Winter Olympic and Paralympic Games were held in the Vancouver-Whistler region of western Canada in February and March, 2010. The close proximity to the Pacific Ocean and the complex orography make the forecasting of precipitation and other fields at specific locations in the region particularly challenging. In order to provide the best possible weather prediction guidance using state-of-the-art science and technology, Environment Canada ran an experimental prediction system for these special events. The system included high-resolution (2.5-km and 1-km) limited-area numerical weather prediction model grids, run operationally twice daily by the Canadian Meteorological Centre. The system also included a special suite of meteorological instruments used to measure standard and special meteorological fields at various venue sites in order to provide short-term forecasting guidance and to evaluate the performance of the model.

The high-resolution model used a detailed two-moment bulk microphysics scheme to parameterize cloud microphysical processes and to predict precipitation rates and types at the surface. While these schemes have become more common in research models in the last few years due to increasing computer resources, this is the first time (to our knowledge) that such a detailed microphysics scheme has been used in an operational setting. In addition to the standard precipitation fields, the scheme also produces several experimental forecast fields, including the instantaneous solid-to-liquid ratio of frozen precipitation, used to convert the standard liquid-equivalent quantitative precipitation forecast directly into the forecast quantity of unmelted snow.