Numerical Forecasts of Explosive Winter Storms: Sensitivity Experiments with a Meso‐α scale Model

Mesoscale numerical forecasts of cases of explosive cyclogenesis during the Canadian Atlantic Storms Program are presented in order to examine the evolution and structure of the simulated storms, and to assess the model's skill in forecasting significant weather elements. The investigation focuses on a series of sensitivity experiments with various horizontal resolutions, sea surface temperatures (SST), surface energy fluxes and condensation schemes in order to understand the physical mechanisms responsible for explosive deepening. The results confirm the conclusions of several other investigators that realistic simulations of explosive storms and many of their subsynoptic and mesoscale features can be obtained using high resolution models with a complete set of physical processes, even when starting with synoptic-scale analyses only. In particular, the formation and maintenance of an intense southerly low-level jet (LLJ) ahead of the surface cold front appears to be instrumental throughout the r...