The Guy Carpenter Asia-Pacific Climate Impact Centre (GCACIC) at the School of Energy and Environment, City University of Hong Kong, has released its 2020 predictions for tropical cyclone formations and landfalls using a regional climate model focusing on East Asia. This model uses information from a global climate prediction model made available in March 2020.
A 2014 study (1) by Huang and Chan shows it is possible to use a regional climate model to more accurately predict the number of tropical cyclone formations compared to predictions based solely on a global climate model. In this briefing, RegCM3 refers to the GCACIC’s Regional Climate Model, Version 3, while CFSv2 refers to the global Climate Forecast System, Version 2, from the U.S. National Centers for Environmental Prediction.
The global Climate Forecast System is used by the RegCM3 as initial and boundary conditions for a dynamic downscaling model to predict the number of tropical cyclone formations and the number of landfalls with a lead-time of one to six months.
The RegCM3 model is run eight times, each using slightly different initial conditions on March 1-2, 2020, so that the predicted numbers shown are the average of these eight runs. For the early season from May to June 2020, RegCM3 predicts the monthly number of tropical cyclone formations to be similar to the climatology, and CFSv2 predicts an above-normal number of formations for the early season. For the peak season of July to September, the number of tropical cyclone formations is predicted to be below-normal, compared with the climatology for both RegCM3 and CFSv2. This pattern is also seen in the spread of the eight RegCM3 runs. The majority of the eight runs for the early season of May and June are above the average number of tropical cyclone formations. For the peak season, there are a below-normal number of formations.
Footnotes: 1. Huang, W.R. and J. C. L. Chan, 2014: Dynamical downscaling forecasts of western North Pacific tropical cyclone genesis and landfall. Climate Dynamics, 42, 2227–2237. ONI