In the Path of the Storm: Japan and Typhoons

Typhoon Season

Typhoons are tropical depressions developing in the western part of the North Pacific Ocean with sustained winds over 17.2 meters per second (62 kilometers an hour). According to the Japan Meteorological Agency (JMA), the 30 years from 1981 to 2010 saw an average of 26 typhoons form annually, with three coming ashore along the Japanese archipelago in a typical year. Typhoons forming in lower latitudes in early spring typically follow a westerly path toward the Philippines; however, with the onset of summer, storms begin to make their way north along the edge of the taiheiyō kōkiatsu, or the North Pacific High, a seasonal subtropical ridge of warm air that, in a normal year, moves in from the Pacific and sits over Japan from mid-July to mid-September. Typhoon season, or when the largest numbers of storms approach the archipelago, is July–October, with most landfalls occurring in August and September. Flooding and other disasters sparked by torrential rains are common in September due to the formation of a seasonal frontal depression, known as the akisame zensen, which acts as a catalyst to intensify precipitation when typhoons move ashore.

Major Storms

Storms can wreak havoc with winds, torrential rain, storm surges, and waves; and the worst disasters are triggered when several or all of these combine. An average of two destructive storms have come ashore each year during the last 10 years, and on two occasions typhoons inflicted casualties of nearly 100 dead or missing. The chart below shows the extent of damage from major storms over the last decade. 

Major Typhoons and Damage Since 2004

Notes: The JMA each year numbers typhoons sequentially; flooding figures include partially flooded homes.
Created by Nippon.com based on NAOJ’s Chronological Scientific Tables.

From June to November 2004, a record of 10 typhoons blew ashore, taking a massive toll on life and property as well as wreaking havoc on the agricultural, fishery, and forestry industries. Usually the Pacific High acts to deflect typhoons to the west, but that year the ridge moved higher north than usual, resulting in a typhoon “road” leading directly to the archipelago. The economic impact from this string of storms was enormous, with the three largest storms inflicting the greatest damage: Chaba causing ¥105.4 billion in damage, Songda ¥126.2billion, and Tokage ¥93.4billion.

The Three Great Shōwa Typhoons

From 1930 to 1950, Japan repeatedly suffered damage and loss of life from major storms. Three storms in particular, Muroto, Makurazaki, and Isewan typhoons—collectively known as the three great typhoons of Shōwa era (1926–1989)—were among the most violent and destructive.

Motivated by the catastrophic damage of the three great Shōwa typhoons and other storms, the Japanese government has implemented nationwide measures over the years to mitigate damage from such phenomena as storm surges and flooding. Although no storms comparable in scale have struck Japan in the past five decades—outside of Okinawa, whose lower latitude places it squarely in the path of stronger typhoons—these measures have enabled the country to keep the level of destruction and loss of life far below what was suffered from earlier typhoons. This is illustrated by casualty figures from the deadliest storms for each decade since 1970: in 1976 typhoon Fran killed 169, typhoon Bess in 1982 claimed 95, and 62 died when typhoon Mireille struck in 1991. Into the 2000s, figures have stayed below 100 dead or missing for even the strongest storms.

The debate over the effects of global warming has intensified in the wake of destructive super storms, such as hurricane Katrina, which devastated the southeastern United States in 2005, and typhoon Haiyan, which pounded the Philippines in 2013. And some are saying that these stronger storms are the result of climate change. The JMA has disputed any possible correlation, saying there is no clear evidence that global warming is having an effect on the number or size of storms. The agency, however, participated in a research group that tested the potential effects of global warming by simulating temperature rises to the end of this century. The results of the experiment showed a trend toward fewer tropical storms, but also predicted an increased occurrence of bigger and stronger storms.

(Title photo: A NASA satellite image of typhoon Neoguri taken July 6, 2014. Photo courtesy of NASA/Reuters/Aflo.)