The June 2013 Alberta Catastrophic Flooding: Water vapor transport analysis by WRF simulation

The Weather Research and Forecasting (WRF) Model was used to simulate 2013 Alberta flooding event. In the simulation, there were 2 nested domains; the resolutions for the inner/outer domain were 3 km/27 km respectively. The boundary condition was forced by NCEP reanalysis with 1 degree resolution every 6 hours. WRF simulated precipitation was then compared to CaPA and CMOPH data for calibration. The simulated timing and location of the precipitation, and the generated precipitation rates closely fit the observation data, indicating that WRF model is capable to reproduce this type of severe event. Water vapor budget analysis were applied to find out the moisture sources that caused the flood to occur, including the large scale moisture convergence by advection, orographic blocking and lifting, local recycling of the water through evaporation, etc. Sensitivity test of local topography was done with reduced-mountain height, less roughness, to see how much precipitation was contributed by the blocking effect, and how the correct timing and location of the precipitation relies on the micro-meteorology process within the Rocky mountain. This work is a preparation for future WRF simulations under global warming scenario to see whether this type of extreme events may happen more frequently in future.