In an earlier paper (Nishina, 1989), the author pointed out that a six-hour precipitation distribu-tion in Central Japan during the winter monsoon can be divided into three types: the TT type, the EF type, and the WA type. The TT type is associated with the high-precipitation areas of which there are two: one around Tsuruga, the other around Takada. The EF type is associated with the high-precipitation area ranging continuously eastwards from around Fukui through Kanazawa and Toyama to around Takada. The WA type has the characteristics of both the above types; in this last type, high precipitation occurs around Tsuruga and around Takada, and also in the area ranging from near Fukui to around Takada; consequently, a high rate of precipitation is obtained in almost the whole of the Japan Sea side of Central Japan.
In thiss paper, the synoptic features of these three types of daily precipitation distribution are discussed. It is pointed out that the location of cyclones and troughs under a large-scale situation and the upper wind directions at about the 850 mb level over Central Japan differ for the three types. Judging from the general locations of cyclones and troughs, the following can be stated:
1. In the TT type, cyclones are located to the east of the Kamchatka Peninsula from the sur- face to the 500 mb isobaric level. Troughs are located to the east of or in the Japan Islands. A northwesterly upper wind at about the 850 mb level blows over Central Japan.
2. In the EF type, cyclones are located in the central part of the Chishima (Kurile) Islands, to the east of Sakhalin, or in Primorskij. Troughs are located over the Japan Sea. A westerly upper wind at about the 850 mb level blows over Central Japan. A steeper thermal gradient is found than in the TT type at the 850 mb level.
3. The WA type has synoptic features of both the TT and the EF types; it can be found when the synoptic features in the EF type gradually replace those of the TT type, and this is par-ticularly clear below the 700 mb level.
This paper emphasizes that the difference in the dynamic conditions is more important than the thermal conditions. However, it is also mentioned that the thermal conditions may cause the dif-ference between yamayubi (the snowfall obtained high along the mountainous range on the Japan Sea side of Central Japan) and
satoyuki (the snowfall obtained high along the plain range of the same area).
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