Improvements in the Canadian Regional Ensemble Prediction System

The current Regional Ensemble Prediction System (REPS), running operationally at the Canadian Meteorological Centre (CMC), is composed of the limited-area version of Global Environmental Multi-scale model (GEM). A 72-hour ensemble forecast, with 21 members, is produced using a single model configuration with stochastic perturbations of physical tendencies (PTP). A new system will be compared to the operational one in parallel mode during the summer of 2013. This system is planned to become the operational one in the fall of 2013. The resolution of the new system has been improved significantly. The horizontal resolution increases from 33km to 15km grid spacing and the number of vertical levels from 28 to 48. Some modifications in the application of the stochastic perturbation have been made to correct occasional unrealistic precipitation amounts by some members in areas of convectively unstable air mass and strong topographic lift. The presentation will discuss the new 15 km system in relation to the 33 km one and will explain the new design of the PTP. Some information on the future development of the REPS will also be provided