A significant amount of precipitation was recorded in the middle part of the Korean peninsula on 12 July 2006, with a local maximum value of 399.0. Most of the rainfall was observed during the 24-h period, and the maximum rainfall intensity was 77.5 mmh-1. During the rainfall, deep clouds were covering the middle part of the Korean peninsula. At that time, the typhoon ‘Bilis' with the central pressure of 975 hPa was located at the southeast of Taiwan.

Firstly, a detailed analysis of various observational data including radar is performed to investigate the mechanism associated with such an excessive rainfall. Next, the Weather Research and Forecasting (WRF) model is used to simulate the heavy rainfall event. Further efforts including the bogussing of the typhoon landed in southern China, and the radar data assimilation with WRF 3D-VAR are given to improve the forecast of the heavy rainfall.