This phenomenon occurs because of the fact that a front tends to become stationary along the southern shore of Honshu as expansion of continental anticyclone which was dominant during winter in the vicinity of Honshu or the path of the migratory anticyclone leans to the north, and on the other hand, cold and wet northeast airstream flows along southern edge of the expansion of anticyclone from the north.
冬の間、本州付近を支配していた大陸高気圧の張り出しや、移動性高気圧の通り道が北に偏り、一方で、その北方高気圧の張り出しの南縁辺に沿って、冷湿な北東気流が吹いたり、本州南岸沿いに前線が停滞し易くなるために生ずる。