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This is the year of the typhoon

by Minoru Matsutani

Staff Writer

We have never had more taifū (台風, typhoon)-related news than we have had this year. Japan has had at least 28 typhoons so far in 2013 and the number is likely to surpass 30 — the first time this will have happened in 19 years.

A remarkable point is that this year there have been many aki-taifū (秋台風, fall typhoon), which has something to do with September and October being unusually hot. According to kishōchō (気象庁, the Japan Meteorological Agency), the number of typhoons up till August was 15, which is heinen nami (平年並み, close to the level in an average year). But September saw eight typhoons, well above the 4.8 average.

There needs to be only two typhoons in the remaining two months of the year to reach 30, and with the average for November and December being 3.5, that seems sure to happen.

The reason Japan has had lots of fall typhoons this year is that the kaimen suion (海面水温, water-surface temperature) off the east of the Philippines was 0.5 to 1 degree celsius higher in September than in an average year, according to an article in the Yomiuri Shimbun citing the Meteorological Agency. Typhoons are created near the water off the east of the Philippines when water-surface temperature is 26 C or higher. Under such conditions, large sekiran’un (積乱雲, cumulonimbus clouds) form, creating a typhoon. Also, the henseifū (偏西風, jet stream) is stronger this year, another factor favorable to cumulonimbus clouds.

The third factor for the increase in fall typhoons is izentoshite tsuyoi seiryoku wo tamotteiru (依然として強い勢力を保っている, still holding strong power) taiheiyō kōkiatsu (太平洋高気圧, high-pressure system in the Pacific Ocean), according to the article. The high-pressure system sits at Nihon no nantō kaijō (日本の南東海上, on the water in Japan’s Southeast), and thus typhoons move northward along the edge of the high pressure, riding on the jet stream.

Citing a meteorologist, J-Cast online news website says the active emergence of fall typhoons stems from the fact that the jet stream is further north this fall than an average year, when the jet stream is pushed south by high pressure systems in the north. Typhoons move along the jet stream, and therefore typhoons have hit Japan more often this fall, instead of veering away eastward further down the south of Japan, as is the case in an average year.

This means Japan will keep suffering typhoons unless it becomes reasonably cold in fall. But the recent trend shows Japan is becoming hotter and hotter.

This year’s summer was particularly hot. Japan had four spots where the daily high exceeded 40 C. Such hotspots were nonexistent for at least the previous three years, and the Meteorological Agency even had trouble giving a special name to a day as hot as that.

Days with a temperature exceeding 35 C are mōshobi (猛暑日, super-hot day), 30-C days are manatsubi (真夏日, mid-summer day) and days of 25 C are natsubi (夏日, summer day).

Also, zansho (残暑, lit: “leftover summer” but actually meaning summer-like heat in fall) has become longer in recent years. On Oct. 9, Itoigawa, Niigata Prefecture, marked 35.1 C, making it a 猛暑日. Japan has never recorded a “super hot day” in October.

The combination of these climate conditions can make deadly typhoons. Taifū 26 gō (台風26号, Typhoon 26) was the largest typhoon in a decade and Nihon jūdanshita (日本縦断した, moved vertically, or south to north in this case, in Japan) from Oct. 15 to 16.

In Japanese, the name of a typhoon consists of the number showing the chronological order in the year, following the word taifū. Elsewhere, Typhoon 26 this year was called Typhoon Wipha.

Typhoon 26 killed 34, injured 106 and left 15 missing as of Oct. 23, according to shōbōchō (消防庁, the Fire and Disaster Management Agency). Of those killed, 30 were in Izu Oshima (伊豆大島, Izu-Oshima Island).

Typical typhoon-related news reads as follows: The typhoon hasseishita (発生した, was born) near the Mariana Islands around 3 a.m. Oct. 11, hattatsu shinagara Nihon no minami kaijō wo hokujō (発達しながら日本の南海上を北上, heading north on the water in the south of Japan while growing bigger). It landed on Kanto chihō engan (関東地方沿岸, the coast of Kanto region) at predawn Oct. 16. Then the typhoon headed north at Kanto no higashi kaijō (関東の東海上, the water off the east coast of the Kanto region) and changed to an ontai teikiatsu (温帯低気圧, temperate-zone low-pressure system) at Sanriku oki (三陸沖, water off the coast of Sanriku, or Miyagi and Iwaki prefecture) around 3 p.m. on Oct. 16. By this typhoon, on Oct. 15 and 16, nishi Nihon kara kita Nihon no hiroi han’i de bōfū, ōame to natta (西日本から北日本の広い範囲で暴風、大雨となった, wide areas ranging from western Japan to northern Japan had violent wind and heavy rain).

The 27th and 28th typhoons hit Japan almost simultaneously on Oct. 26 and 27, which also left much damage to Nihon rettō (日本列島, the Japanese archipelago.)

The largest typhoon in a decade and the combination of two typhoons certainly made this year taifū no atari doshi (台風の当たり年, the year when we hit the jackpot of typhoons).