Seasonal forecasting of tropical cyclone activity in the coastal region of Vietnam using RegCM4.2

This study presents an experimental seasonal forecast of tropical cyclone (TC) activity for Vietnam's coastal region during the 2012−2013 typhoon seasons, using the Regional Climate Model (RegCM, version 4.2) to downscale the global Climate Forecasting System (CFS) forecast. Using an improved vortex tracking algorithm that detects vortex centers efficiently, RegCM reasonably forecasts the general distribution of TC counts in time as well as the TC track pattern during the entire experimental period from February to July 2012 and 2013, despite significant underestimation of the TC counts in the global CFS forecasts that are used as initial and lateral boundary conditions for the RegCM model. Further examination of the storm activity in the Vietnam East Sea that directly influences Vietnam's coastal region shows, however, that RegCM tends to overestimate the TC frequency in this sub-region compared to observation. This suggests that direct applications of the RegCM model for seasonal forecasts of TC activity in Vietnam's coastal region has a significant bias that will need to be corrected before the model can provide useful information.