Typhoon

Typhoon Nangka Recap: 29 Inches of Rain Reported

Typhoon Nangka made landfall in Japan late Thursday, lashing the country with heavy rainfall before petering out over the Sea of Japan early Saturday.

More than 2 feet of rain were reported in parts of Kōchi, Wakayama, Nara and Mie prefectures in the central part of the country. Many rivers went out of their banks as a result. Heavy rains came well in advance of landfall as well, bringing up to 10 inches of rain to northern parts of the Greater Tokyo area.

The center of Typhoon Nangka made its first Japanese landfall at 11:07 p.m. Thursday night local time near Muroto city, which is on the Pacific coast of Shikoku, one of Japan's four main islands.

Nangka was the equivalent of a Category 1 tropical cyclone on the Saffir-Simpson Hurricane Wind Scale at landfall with maximum sustained winds estimated at 75 mph, according to both the Japan Meteorological Agency and the U.S. Joint Typhoon Warning Center. (Japan is 13 hours ahead of U.S. Eastern Daylight Time.)

About seven hours later, Nangka made a second landfall after crossing the Seto Inland Sea separating Shikoku from Japan's largest island, Honshu. The second landfall, as a tropical storm, occurred in Kurashiki city, Okayama prefecture.

Nangka's center exited Tottori Prefecture and emerged over the Sea of Japan around 3 p.m. local time Friday. Later, JMA said Nangka had weakened to a tropical depression as of 3 a.m. local time Saturday, when it was centered over the Sea of Japan just west of the Noto Peninsula of central Japan's Ishikawa Prefecture.

(MORE: Nangka News/Impacts | Hurricane Central)

Nangka Rainfall Totals
(72-hour rainfall totals in Japan from Typhoon Nangka.)

Because of its slow movement and proximity to land, Nangka brought significant rainfall even to areas that don't normally feel the brunt of typhoon rains. Among the major cities in central Japan's Kansai region, Kobe was particularly hard hit with nearly a foot (300 mm) of rainfall.

What was not unusual is that the highest rainfall totals occurred in mountainous areas facing the Pacific Ocean. The highest reported rainfall total in Japan was 745.5 millimeters (29.35 inches) in Kamikitayama village, Nara prefecture, south of Osaka.

In a testament to Japan's soggy climate, that 72-hour total wasn't even a monthly record for that location, despite a recordkeeping period that only goes back 39 years. The same was true of most of the other locations that saw 20 or more inches of rain from Nangka.

Moist winds blew from south to north well before Nangka's arrival as a typhoon, sending a tropical air mass right into Japan's rugged mountains and a stationary front and forcing that moist air to rise and form rain-bearing clouds. That is a common setup for torrential rain far from the center of a tropical cyclone. In this case it brought a round of flooding rainfall to the Greater Tokyo area, hundreds of miles from what was then the eye of Typhoon Nangka.

One person died in Saitama prefecture after falling into a swollen canal during the flooding, according to Japan's Fire and Disaster Management Agency.

Nangka Peak Wind Gusts
(Peak wind gusts reported in Japan as Nangka passed through.)

The top reported wind gust from Nangka was 95 mph at Cape Muroto, a site whose elevation and position on the Pacific coast make it unusually wind-prone. That gust occurred shortly before midnight Thursday evening. Cape Muroto also reported the highest sustained wind from Nangka and was the only official site to report a sustained typhoon-force wind; that was 75.8 mph (33.9 meters per second) at 12:13 a.m. JST Friday.

High winds did affect more populated areas as well; for instance, Komatsushima Air Base in Tokushima Prefecture clocked a 77-mph wind gust at 3:24 a.m. JST Friday. In general, the highest winds in populated areas occurred on eastern parts of Shikoku close to the coast.

(FORECASTS: Nagasaki | Hiroshima | Osaka | Nagoya | Tokyo)

Storm History

Nangka briefly became a super typhoon -- maximum sustained winds reaching 150 mph -- late Thursday into early Friday, before northerly wind shear eroded convection on the north side of the circulation Friday, July 10.

According to hurricane specialist Michael Lowry, Wednesday, July 8 marked the first time in over 20 years that three typhoons were active in the western Pacific basin at the same time (Chan-hom, Linfa and Nangka).

As it approached Japan, Nangka fought off dry air to its north and northwest, which initially weakened its eyewall convection Wednesday.

Satellite imagery confirmed convection managed to wrap back around the center Thursday morning (local time) and the weakening trend leveled off prior to its first landfall Thursday night.