The deadliest scenario of “killer mega-typhoons” hitting the Japanese archipelago one after another… They will become huge in size and unpredictable in their “sluggish” movements

Residents are helpless in the face of an unprecedented natural disaster.

Tiles flew off the roof, leaving holes and leaks. The power went out and we couldn’t even take inquiries from customers…I’ve been running a barbershop here for over 30 years, but I’ve never experienced anything like this before. One of our regular customers told us that the strong winds blew the roof off his house.

Sei Yamazaki, manager of BarBer NikoNiko, a barbershop in Miyazaki City, Miyazaki Prefecture, recalled the threat of the “strongest typhoon in history.

On August 29, typhoon “No. 10,” with a central pressure of 960 hectopascals and maximum wind speed of 55 m/s, made landfall in Kagoshima Prefecture. It snapped utility poles and destroyed many houses. The storm caused power outages in up to 280,000 homes. Torrential rains totaling more than 900 mm of rainfall caused landslides, flooded roads, and overflowed rivers in many parts of Japan.

A typhoon “different” from anything Japan has ever experienced

Typhoon No. 10, which caused 8 deaths, 129 injuries, and 30,000 evacuees, was “different” from anything Japan has ever experienced. The first characteristic that can be mentioned is its slow speed, which is said to be “as fast as a jogging machine. It remained stagnant in Kyushu and Shikoku for three long days after making landfall, resulting in torrential rains and strong winds that caused widespread damage. Weather forecaster Koshi Murayama explains the mechanism of the “slow-moving” typhoon.

Normally, typhoons that form over the southern ocean move northward in a parabolic pattern. Typhoon No. 10 made landfall in Kyushu and passed out of the Kinki region into the Sea of Japan, but after making landfall in Kyushu, it moved southward on its way to the northeast and made landfall on Shikoku Island. The typhoon was blocked by a strong Pacific high-pressure system that had been overhanging the area from the east, preventing it from moving northeastward. Typhoons are pushed eastward by the prevailing westerly winds, but this summer the prevailing westerly winds were weak and the typhoon could not move eastward. The combination of these factors made it a slow-moving typhoon whose path was difficult to predict, even for experts.

In addition to the prolonged duration of typhoon No. 10 and its “straying,” the common denominator among this year’s typhoons is their “large size. Mr. Murayama warns, “It would not be surprising if we see a succession of typhoons in the future that are even larger than No. 10, and whose paths are extremely difficult to predict.

The cause is high sea water temperatures. Rain clouds are created by water vapor that evaporates from the ocean surface, but in recent years, global warming has caused sea water temperatures to rise, releasing large amounts of water vapor and making it easier for huge rain clouds to form. When a typhoon passes over these rain clouds, its energy increases, and winds and rainfall become more intense.

A series of typhoons surpassing No. 10

In fact, the monthly average sea surface temperature in the seas around Japan in 2011 was the highest in recorded history for five consecutive months from August to December. In July of this year, the highest figure ever recorded for the same month was also recorded, and the rise in sea surface temperature is expected to continue in the future. According to data released by the Japan Weather Association, a maximum of 11 typhoons are expected to occur in September and October, and the situation remains unpredictable. Mr. Murayama continues.

This year, the temperature of the sea water is generally high from Japan’s southern seas to the equator, making it easy for powerful typhoons to form. Even if it starts out as a small low-pressure system, there is a high possibility that it will take in a large amount of water vapor and grow into a large typhoon. In fact, four typhoons formed one after another between August 8 and 13 this year, and we will need to be most careful during September and October. The temperatures of the sea and ocean are not aligned with each other, and the sea temperature is at its highest in September,” said Mr. Kurokawa.

Generally speaking, the tendency for typhoons to hit the Kinki and Kanto regions increases after September as westerly winds move southward. A series of “killer mega-typhoons” exceeding Typhoon No. 10 will hit the Japanese archipelago one after another. Such a nightmare is beginning to become a reality. Minoru Watanabe, a disaster prevention and crisis management journalist, warns, “We must not prepare for typhoons based on the image of what we have seen so far.

The size of Typhoon No. 10 was troubling, of course, but the fact that the damage was prolonged was also troublesome. The government has taken measures such as building river revetments and spraying mortar to prevent the soil on slopes from collapsing, but they are meaningless because the wind and rain exceeded the government’s expectations.
As evidenced by the frequent flooding damage in the Kanto region this time, it is not safe to stay away from the typhoon. It is important to evacuate as soon as possible.”

The sense of crisis is also evident in the JMA’s changing response to typhoons in recent years.

The JMA frequently holds press conferences and urges people to evacuate because their lives are in danger. In the past, this would not have happened. They would only issue warnings and advisories, not warnings as they do now. Nowadays, however, they are actively communicating the danger of typhoons, using weather charts to explain the situation. I think this is wonderful in the sense that people have become more aware of disaster prevention, but at the same time, it is a sign that disasters in Japan have become that serious,” said Murayama.

The arrival of Typhoon No. 10 is only the beginning. The worst season, in which the worst possible scenario of a “killer mega-typhoon wave attack” could occur, is just around the corner.

From the September 20, 2024 issue of FRIDAY