Photo/Illutration The Asahi Shimbun

A Japanese researcher said Typhoon No. 10 did not turn out to be as strong as expected because it followed on the heels of Typhoon No. 9, which cooled the sea surface temperature near Japan.

Meteorology specialist Tetsuya Takemi, an associate professor at Kyoto University’s Disaster Prevention Research Institute, said the surface temperature in the southern sea area of Japan was, for the most part, higher than 30 degrees in August.

But then it dropped after Typhoon No. 9 passed through the area.

Typhoon No. 9 stirred up the sea water, which reduced the amount of water vapor in the air and the amount of heat needed for typhoons to grow larger.

Takemi thinks Typhoon No. 10 was weakened by the drop in surface temperature before it approached the Kyushu region.

While still powerful, it was not as destructive as expected. It did not cause the same kind of widespread river flooding that last year’s Typhoon No. 19 did, and the Japan Meteorological Agency did not issue a special alert over it.

Still, Typhoon No. 10 had a central atmospheric pressure of 945 hectopascals and was as powerful as other large typhoons that have caused tremendous damage in the past.

It had maximum sustained winds of 162 kph when it approached the main island of Kyushu. If it had veered off course enough for it to pass through an area closer to land, or if conditions like the tidal level had worsened, it could have dealt much more damage.

But Takemi said people heeding the alerts put out by the authorities was a major factor behind reducing the scale of damage.

“The Japan Meteorological Agency and other institutions were giving serious warnings to the public at an early stage, and people also tried to evacuate as early as possible,” Takemi said. “That’s why the damage was mitigated.”

The sea surface temperature remains high, so it is likely that other powerful typhoons will follow.

(This article was written by Yusuke Ogawa and Yu Fujinami.)

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