Please view the main text area of the page by skipping the main menu.

Typhoons rapidly developing this year due to higher sea temperatures, irregular winds

In this photo dated July 30, 2018, a woman shovels earth out of her garden in Saka, Hiroshima Prefecture, after Typhoon Jongdari passed through the area. (Mainichi)

Typhoons are forming at an extraordinarily fast pace this year apparently due to higher temperatures on the surface of the sea where they are formed as well as irregular seasonal winds, say experts.

Typhoons are defined as tropical cyclones above the northwestern Pacific, including areas off the Philippines, as well as the South China Sea with maximum wind speeds of at least 34 knots, or about 17 meters per second.

According to the Japan Meteorological Agency (JMA), 12 typhoons were formed from the beginning of this year to the end of July, more than a normal year. This year's 15th to 19th typhoons developed for five consecutive days from Aug. 12 to 16. Typhoon Cimaron, the latest tropical storm and this year's 20th, was formed on Aug. 18 -- the second fastest pace since 1951 when statistics became available. The fastest pace was recorded in 1971 when the 20th typhoon appeared on Aug. 8.

The year 1967 saw the forming of a record 39 typhoons, and that year's 20th typhoon developed on Aug. 25.

This year, most of the necessary conditions for the development of numerous typhoons were met in August. The temperatures of the surface of the sea far east of the Philippines rose to about 30 degrees Celsius, 0.5 to 1 degrees Celsius higher than a normal year, making it easier for cumulonimbus clouds to be formed.

Moreover, the Asian monsoon that brings the rainy season to India and other areas has been blowing from the west more strongly than normal, joining easterly winds along the edge of high pressure systems along the Pacific Ocean. This makes it easier for atmospheric vortexes moving in a counterclockwise direction to be formed. Such vortexes develop into typhoons.

Moreover, westerly winds have also contributed to the formation of more typhoons than usual. Westerlies are meandering above the Pacific Ocean and generating atmospheric vortexes moving in a counterclockwise direction, which move south and lead to the formation of typhoons.

The current atmospheric conditions are expected to change by the end of August, but experts say they are unsure of whether the pace of the formation of typhoons will decline.

(Japanese original by Tomohiro Ikeda, Science & Environment News Department)

Also in The Mainichi

The Mainichi on social media