BOSTON, Oct. 16, 2013 – According to catastrophe modeling firm AIR Worldwide, although Typhoon Wipha did not make landfall on Japan’s main island of Honshu today,as had been expected, the storm brought soaking rain and gusty winds to much of both Honshu and Hokkaido, including the Tokyo region, which experienced a total of 150-300 mm (6-12 inches) of rain. Tokyo International Airport reported some of the highest sustained wind speeds in Japan from this storm: 79 km/h (49 mph) 10-min sustained and a 116 km/h (72 mph) gust. However, Tokyo escaped Wipha’s worst effects. The storm’s heaviest rains (over 100 mm/h [nearly 4 inches] at times; 400-800 mm [15.7) fell on the island of Oshima, south of Tokyo, causing mudslides and flooding. A little farther south of Oshima Island, at Hachijojima Airport, is where the strongest wind gust was reported at 155 km/h.
The most serious flooding and mudslides have been reported on the island of Oshima,south of Tokyo. Although Tokyo experienced drenching rains, it escaped serious damage.
“As Wipha progressed northeastward past the Kanto Region, it continued to move through an environment unfavorable for maintaining its tropical characteristics,” said Dr. Peter Sousounis, senior principal scientist, AIR Worldwide. “Wipha encountered cooler ocean waters, a colder baroclinic air mass, and increasing vertical wind shear and so continued its extratropical transitioning. A final report
on Wipha was issued by the Japan Meteorological Agency (as of 06:00 UTC, October 16, 2013), in which the agency downgraded Wipha to an extratropical low that will no longer affect Japan. A surface analysis valid at 12:00 UTC, October 16, shows the location of extratropical cyclone Wipha moving away from Japan just northeast of Hokkaido with a central pressure of 964 mb.”
Dr. Sousounis observed, “Izu Oshima, an island about 120 km south of Tokyo, was the worst hit by this storm, experiencing a record rainfall of 122.5 mm per hour (4.8 inches per hour). Wipha’s total rainfall of 824 mm (32.44 inches) on Izu Oshima saturated soils, causing mudslides along a 2-km stretch of mountains. Roads in the region are clogged with boulders and mud. Rain-swollen rivers remain a flood hazardfor people and property.”
The typhoon season in the Northwest Pacific remains active. The Japan Meteorological Agency has classified a recently developed system near the Mariana Islands as Tropical Storm Francisco. If TS Francisco follows a track similar to Wipha’s, as it is forecast to do over the next three days, this system has the potential to bring further high winds and heavy rains to the Japan region late next week.
AIR will continue to monitor this storm closely and will post additional information if necessary.