In Hokuriku district, the distinct local fronts are observed often in the whole year. Especially, at Hukui, the regular wind variations by land and sea breezes are observed even in winter season and weather changes occur with them. In this paper, the author studied the relation with thunderstorms in winter and obtained the following results: (I) In winter, there are two air masses in this district; the one is NW monsoon on the sea, the coldest wet air mass, and the other is the inland warm dry air mass. Their difference is large in the inland and 3°C in temperature and 25% in relative humidity. (2) The thunderstorms in winter occur along the frontal zone between the two air masses.
In this paper, we studied the method of prediction of the maximum snowfall amount at Hokuriku district and obtained the following results: (1) Using the mean isobar in October and November, two types of the extreme amount of snowfall, the largest amount type and the smallest amount type, are classified. The largest one has a sharp front in Japan sea and the number of isobars along front are many, while the smallest one has a few isobars along the front and the front is not so sharp. (See Fig 1-2) So that, the prediction formula becomes as follows: The maximum amount of snowfall _??_ (Sharpness of front, the number of isobars along the front and the position of front). But the numerical values are not obtained at present.
In Niigata and its vicinity, when cloudy weather is expected based upon weather charts, it often rains or snows. The phenomenon is named “Shigure” provisionally. The nature of the phenomenon and the common points on weather charts are deseribed.
The local heavy snowfall in the maritime district of Northern Echigo Province and the mechanism of the above snowfall were investigated, and it was ascertained that the collision of the monsoon which has relatively high temperature and humidity by crossing the Japan sea with the wind from the local cold anticyclone nourished on the snow-lying inland is the principal cause of the above heavy snowfall.
The result of the inves_??_igation on the suspension of sailing between Echigo and Sado during 1939-1942 shows that when the wind waves are over 5 at Aikawa, the wind velocity more than 15m/sec, or the difference of atmospheric pressure is over 1.5mm per 100km in horizontal distance, the sailing of a regular liner is suspended.