Digital Typhoon: Typhoon 200423 (TOKAGE)

Typhoon TOKAGE looks as if it shattered into pieces over Chubu mountainous area, but the number of death and missing is still increasing, and the human damage reached a level next to that of Typhoon 197920, which killed 115 including missing (Detail in Japanese). This may be because resistance to disasters has already been reduced due to the repeated attack of typhoons in this season. In addition, this typhoon was really unusual. Exceptionally wide areas of strong winds, strong winds and heavy rains in the north of the typhoon (usually this area is called a navigable semicircle and has weaker winds), strong winds at distant places from the center... These features may lead to extensive damage. The following is no more than a guess, but these features may be related to seasonal factors. The typhoon with warm air moved through cold air which is dominant on Japan at this time of year, October, so compared to warm summer, the difference of temperature between warm air and cold air is greater especially in the north, leading to more severe meteorological phenomena in the north. In any case, this is a unusual typhoon including the season of making landfall and the scale of disasters, so I think scientific explanation about what really happened will be useful knowledge for taking measures against the typhoon.

Typhoon TOKAGE made landfall around Tosa-Shimizu City, Kochi Prefecture. Strong winds are observed in distant places from the center (such as the maximum gust of 63.7m/s at Unzen, Nagasaki) due to the large size of the typhoon. The amount of rainfall is increasing in the areas of Shikoku and Kii Peninsula because of the presence of very active rainy clouds in the eastern part of the typhoon just ahead in the direction of movement. From now on, the areas of heavy rains and strong winds will move to Kinki, Chubu and Kanto districts. Repeated disasters are concerned in areas where extensive damage was already given by as many as ten typhoons that made landfall on Japan during this season. Typhoon season records related to this typhoon (since 1951 / since 1955 for Okinawa) :

The number of typhoons making landfall on Japan : 10 (Previous record = 6 in 1990 and 1993)
The number of typhoons approaching near Okinawa : 13 (Previous record = 12 in 1966)
The lateness of making landfall : 3rd (1st = Typhoon 199028 on November 30, 2nd = Typhoon 196734 on October 28)

Typhoon TOKAGE is likely to move along a traveling-through-the-nation-of-Japan course, which starts from Okinawa Island to Amami Islands, Oosumi Islands, Kyushu, Shikoku, Honshu and Hokkaido. This means that everywhere in Japan, except for Ogasawara, will be affected by strong winds and rains. It is also likely that this typhoon will stubbornly keep its intensity rather than instantly lose its intensity after landfall because of the large size of the typhoon.

Typhoon TOKAGE is approaching Okinawa keeping its size as an extremely large typhoon. The forecast says it may make landfall at either Kyushu, Shikoku or Honshu, but we had only about ten typhoons that made landfall in October in these fifty years or so since 1951.

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