Current and potential use of ensemble forecasts in operational TC forecasting: results from a global forecaster survey

Abstract

In order to understand the current and potential use of ensemble forecasts in operational tropical cyclone (TC) forecasting, a questionnaire on the use of dynamic ensembles was conducted at operational TC forecast centers across the world, in association with the World Meteorological Organisation (WMO) High-Impact Weather Project (HIWeather). The results of the survey are presented, and show that ensemble forecasts are used by nearly all respondents, particularly in TC track and genesis forecasting, with several examples of where ensemble forecasts have been pulled through successfully into the operational TC forecasting process. There is still, however, a notable difference between the high proportion of operational TC forecasters who use and value ensemble forecast information, and the slower pull-through into operational forecast warnings and products of the probabilistic guidance and uncertainty information that ensembles can provide. Those areas of research and development that would help TC forecasters to make increased use of ensemble forecast information in the future include improved access to ensemble forecast data, verification and visualizations, the development of hazard and impact-based products, an improvement in the skill of the ensembles (particularly for intensity and structure), and improved guidance on how to use ensembles and optimally combine forecasts from all available models. A change in operational working practices towards using probabilistic information, and providing and communicating dynamic uncertainty information in operational forecasts and warnings, is also recommended. Keywords: tropical cyclones, operational forecaster survey, ensemble forecasts, probabilistic forecasts, uncertainty