This year has been a little extraordinary, as there has been no typhoon so far. However, the 10th typhoon of the season seems to be closing in, but from an unorthodox direction.

The No. 10, named Lionrock, is currently located south of Japan main islands and slowly moving southwest. It seems to take a quite unusual course for a typhoon moving towards Okinawa. Typhoons usually approach Okinawa moving in from south as they make their way up north, but Lionrock seems taking a completely opposite path.

According to Hiroyuki Yamada, an associate professor of meteorology at the University of the Ryukyus, a low pressure, called “monsoon vortex” that occurred over the ocean from the south of Japan to the east of the Philippines, affects the course of typhoon.

Most of typhoons that approach Okinawa are formed over the ocean east of the Philippines, and take a course up north along the edge of the Pacific anticyclone. This year, the enhanced Pacific anticyclone weakened after July 20, and the monsoon vortex has occurred instead from around Aug. 5th. Accordingly, most of typhoons this year were formed south of Japan and have taken a course along the edge of the vortex anticlockwise.

The typhoon No.10 was also formed south of Japan, and is now approaching Okinawa. According to Yamada, when a vortex is formed, several small typhoons are formed at the same time. Typhoons No.9 and No.10 were formed on Friday, and No.11 on Saturday. Meteorologists expect the monsoon vortex to continue for about a week.

Although its yet far from clear whether Lionrock would hit Okinawa, it is likely to affect the weather this weekend.

• 
• NO DATA