The Relation of North Pacific Anticyclone and Rainy Front
If North Pacific anticyclone expands, the rainy front with heavy precipitation is expected to rise north of the Korean Peninsula than the average front. Thus, the impact of the front on the Seonbong could be expanded, and the damage from the precipitation would be increased.
Unexpanded North Pacific Anticyclone
The following is the case in which the North Pacific anticyclone has not extended northward due to the influence of the upper level trough formed between the upper level pressure located on East Siberia and Alaska, resulting the rainy front has remained south of Jeju Island. So, we can predict that the rainy front will rise north of the Korean Peninsula if the North Pacific anticyclone expands.
Expanded North Pacific Anticyclone
So then, let's look at the case where the North Pacific anticyclone is extended to the South. In this case, the rainy front will be located in North Korea and the central South Korea. Strong rain fell frequently in the central part of the country at this time, as air instability has been strengthened due to the influence of the upper-level trough that often pass north of Korea..
If the North Pacific anticyclone expands, the rainy front will rise north of the Korean peninsula from the average. This increases the impact of the front, resulting in more damage to Seonbong by the precipitation. However, the rain front does not unconditionally move northward, but it also vibrates north and south. In other words, it moves south and north repeatedly. This can be found through the following example.
