Abstract
Environment Canada ran an experimental numerical weather prediction (NWP) system during the Vancouver 2010 Winter Olympic and Paralympic Games, consisting of nested high-resolution (down to 1-km horizontal grid-spacing) configurations of the GEM–LAM model, with improved geophysical fields, cloud microphysics and radiative transfer schemes, and several new diagnostic products such as density of falling snow, visibility, and peak wind gust strength. The performance of this experimental NWP system has been evaluated in these winter conditions over complex terrain using the enhanced mesoscale observing network in place during the Olympics. As compared to the forecasts from the operational regional 15-km GEM model, objective verification generally indicated significant added value of the higher-resolution models for near-surface meteorological variables (wind speed, air temperature, and dewpoint temperature) with the 1-km model providing the best forecast accuracy. Appreciable errors were noted in all models for the forecasts of wind direction and humidity near the surface. Subjective assessment of several cases also indicated that the experimental Olympic system was skillful at forecasting meteorological phenomena at high-resolution, both spatially and temporally, and provided enhanced guidance to the Olympic forecasters in terms of better timing of precipitation phase change, squall line passage, wind flow channeling, and visibility reduction due to fog and snow.
Highlights
The 2010 Winter Olympic and Paralympic Games took place 12–28 February 2010 and 12–21 March 2010, respectively, in the Vancouver and Whistler areas of British Columbia, Canada
An overview of the atmospheric systems is given in MAILHOT et al (2010), JOE et al (2010) and ISAAC et al (2012), while the land surface forecast system is described in detail by BERNIER et al (2011, 2012)
The present paper focuses on the description of the high-resolution deterministic numerical weather prediction (NWP) system, which consisted of three nested grids
Summary
The 2010 Winter Olympic and Paralympic Games took place 12–28 February 2010 and 12–21 March 2010, respectively, in the Vancouver and Whistler. Real-time mesoscale numerical modeling was done using the Penn State/National Center for Atmospheric Research Mesoscale Model (MM5) with three nested grids of 36-, 12-, and 4-km horizontal grid-spacings, incorporating observations from the MesoWest network into the near-surface initial conditions. This Olympic system was found often to outperform operational models over complex terrain, due mainly to its improved resolution of orographic features. The comprehensive study of MO et al (2012) documented the impacts of mid-mountain clouds on the Whistler alpine skiing competitions These conditions generally represented major challenges to the forecasters throughout the Olympic and Paralympic Games.
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