Improving Lead Time for Tropical Cyclone Forecasting : Review of Operational Practices and Implications for Bangladesh

Bangladesh is one of the most densely populated countries in the world. Owing to its low-lying topography, dense river network, location, and climate, it is exposed to a range of water and climate-related hazards. Tropical cyclones are among the most severe of these hazards. A key focus for improving disaster preparedness and early warning systems in Bangladesh is improved lead times for tropical cyclone forecasting including the quality and skill of the forecast. At present, the lead time for tropical cyclone forecast used by the Bangladesh Meteorological Department (BMD), the main government agency responsible for issuing forecasts for tropical cyclone and storm surges, is three days. If lead times of 10 to 15 days with relatively high accuracy are possible, as the European Centre for Medium-Range Forecasting (ECMWF) suggests, why is it not being done in Bangladesh and what can be done to improve the forecast lead time? This question motivated the writing of this paper. Critical to extending the lead times for forecasting is a better understanding of the factors that limit increasing the lead time of current forecasts. This book is arranged as follows: Chapter 1 gives description of the background and rationale for the report; Chapter 2 describes current global operational practices for forecasting tropical cyclones and storm surges, including practices at other national agencies; Chapter 3 assesses the extent to which Bangladesh uses international and regional operational practices and the technical and governance issues that limit their use; and Chapter 4 provides a summary and recommendations