Characteristic Features of the Heavy Rainfall at Shimabara and Its Vicinity in Nagasaki Prefecture on 3 May 1988

The heavy precipitaion occurred at Shimabara districts in Nagasaki Prefecture on May 3, 1988 was studied with a special interest in the evolution and fine structure of rain storms. The records of 52 rain-guages in this region were the main material of this study. The results are summarized as follows: (1) The heaviest rainfall took place at Shimabara City with a strong precipitation of 131 mm per hour, which is the new record in May in Japan. (2) The rain cloud system associated with the stationary front developed near the line from Isahaya to Shimabara, and new convective clouds appeared along this line. This feature suggests the successive evolution of new rain cells probably due to the orographic effect. (3) The rain storm attacked Shimabara City can be classified as three convective rain cells, each of which evolved very rapidly in its vicinity