92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012
Snow-to-Liquid Ratio From the Microphysics Scheme Used in the High-Resolution Numerical Weather Prediction System for the 2010 Winter Olympics
Hall E (New Orleans Convention Center )
Anna Glazer, EC, Montreal, QC, Canada; and J. A. Milbrandt

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, Environment Canada designed 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 high-resolution model uses a detailed two-moment bulk microphysics scheme to parameterize cloud microphysical processes and to predict precipitation rates and types at the surface. In addition to the standard precipitation fields, this scheme produces several experimental forecast fields, including the instantaneous and cumulative snow-to-liquid ratio of solid precipitation, used to convert the standard liquid-equivalent quantitative precipitation forecast directly into the forecast quantity of unmelted snow. The properties of the microphysics scheme and of the field of snow-to-liquid ratio from a year of model output will be presented. The comparison with a few available data will be also presented.

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