Abstract
On the 21 st. September 1934, the severe typhoon has attacked the city of Oosaka giving there and its neighbouring places many damages. This typhoon travelled to the Japan proper from the southwestern sea as is shown in Fig. 1 (p. 508). From the studies of thunderstorms the present author has noticed the fact that the thunderstorms have been observed at several places before the typhoon centre arrived. (Fig. 1) The thunderstorms of this nature are to be caused by the upward currents at the mountainous parts of the Japan proper, hence there the line of discontinuity, too, is likely to be observed before the arrival of typhoon. From our experiences we see that the line of discontinuity at the head of the typhoon in the middle latitude is apt to lead the typhoon. The present author investigated the thunderstorms occurred at the head of the various typhoons which attacked the Japan proper during these 12 years with the result showing that the thunderstorm is also apt to lead the typhoon. This fact may contribute to the forecasting of the path of typhoon at the Japan proper and its vicinities, because the line of discontinuity is not always perceived markedly on the synoptic chart, while the thunderstorm is very easily reported so far as the observing stations are comparatively numerous and the observations are communicated rather quickly to the weather bureau and the like.
