The Applying of Temporal Climatology Method in the Analysis of both Environmental Background and Model Forecasting for a Typhonic Tornado in Foshan

Basing on the ERA5 reanalysis data and S2D model output of European Centre for Medium-Range Weather (ECMWF), this paper extracts the tornado-related anomalous systems, occurring in Foshan in September 17, 2018 induced by the typhoon ‘mangkhut’, by using temporal climatology method and evaluates the operational forecasting model. The conclusions are listed below. Firstly, this tornado was more likely located at the overlap between axis of negative anomalous height and zero line of anomalous temperature. Secondly, this tornado occurred during the decay stage of both the positive anomalous temperature in the higher and negative anomalous height in the lower, accompanying with a development of negative anomalous temperature.Thirdly, The inf luence of prevailing wind in Foshan, before this tornado arised, shifted to the convergence between the anomalous southeaster and southerly wind near the ground and the mid-level atmosphere above was affected by negative anomalous advection, resulting in a unstable atmospheric stratif ication. Fourthly, negative anomalous height and positive anomalous moist vorticity were in favor of strengthening of tornadic parent storm and suppressing the downdraft, while positive anomalous moist divergence can enhance the downdraft. Lastly, the capacity of forecast of operational forecasting model, for all fields generally, is the best when the initial forecast time is latest, which can predict this tornado in advance of 12 hours.