In southern Ontario, heavy precipitation during the warm season frequently results in significant social hardships and economic impacts through flooding. The ability to estimate and predict streamflow in such cases is highly dependent on the ability to accurately predict rainfall events. This presentation will focus on our abilities to accurately forecast precipitation through atmospheric modeling and to accurately predict streamflow through the coupled atmospheric-hydrological simulations.

The objectives of this study are comprised of three components. The first is directed at ascertaining the accuracy of Quantitative Precipitation Forecasts (QPFs) based on meso-scale model simulations. Accuracy is established through comparison of model derived fields with observations (e.g., raingauge and Doppler Radar data). The second objective is geared to ascertaining our ability to estimate surface streamflows by coupling high-resolution nested numerical weather prediction models (such as MC2 and GEM HIMAP) with hydrological process models (e.g., Watflood). This ability is assessed by the comparison of model estimated streamflow with observed streamflow. The results will be presented for a number of extreme rainfall events that occurred in 2000 over southern Ontario.

The third objective is to identify key physical processes that were characteristic of some of the heavy rainfall events that have occurred in 2000 over southern Ontario. Diagnoses were performed and some of which will be presented, as these help to increase our understanding of the physical elements that are responsible for formation and maintenance of intensive precipitation.