Typhoon Nangka

Post Landfall 1 | Summary
Posting Date: July 17, 2015, 12:30:00 PM

Meteorological Summary and Forecast

Nangka made landfall July 16, 2015, at 23:07 Japan Standard Time (JST) (14:07 UTC) with a central pressure of 965 mb near Muroto City, on the eastern coast of Shikoku Island, Japan. It was the 11^th typhoon of the season. Maximum sustained wind speeds were estimated at just over 120 km/h (75 mph) at landfall, the equivalent of a Category 1 tropical cyclone on the Saffir-Simpson scale. The storm moved slowly northward across Shikoku and made a second landfall at Kurashiki in the Okayama Prefecture just past 6:00 a.m. JST on July 17, 2015, (21:00 UTC, July 16, 2015) with maximum sustained winds of 80 km/h (50 mph). As of 12:50 UTC Nangka had a forward speed of 25 km/h (16 mph), and had moved off Tottori Prefecture. Nangka continues to impact Japan with tropical storm–force winds and torrential rain. Sustained winds were estimated at 65 km/h (40 mph) with gusts of 90 km/h (56 mph).

The highest wind gust reported was 153 km/h (95 mph), at Muroto just before midnight on July 17, JST, about an hour after the storm made landfall. Sustained winds in the area reached 122 km/h (76 mph). A wind gust of 124 km/h (77 mph) was recorded at Komatsushima Air Base in Tokushima Prefecture, at 3:24 a.m. JST on July 17. In Nagoya, winds reached 74 km/h (46 mph), while Tokyo reported winds up to 58 km/h (36 mph). Winds reaching 63 km/h (39 mph) affected several other cities including Osaka.

As the storm interacted with the mountainous regions of Japan and a stationary front, it produced extremely heavy rainfall. Rainfall rates reached 77.5 mm/h in Kawauchi, Fukushima Prefecture. In Kamikitayama, south of Osaka, 740 mm of rain had already fallen by 12:00 UTC on July 17, while 690 mm had fallen in Odie, Mie Prefecture. Umaji, Kochi Prefecture, had reported rainfall totals of 660 mm. Sediment disaster alerts (landslides) have been issued for south-central coastal areas, including Tokyo.

Tropical Storm Nangka is expected to continue moving northeastward through the Sea of Japan and weaken due to increasing vertical wind shear and continued interaction with land. Strong winds and torrential rain are expected to impact both coasts of Japan during the next few days, with warnings issued for central and south-central areas of Honshu, including the cities of Osaka, Kyoto, Nagoya, Kobe, and Tokyo. The affected region includes several other cities such as Kochi, Oita, and Okayama. Rough winds have created dangerous surf along much of both the eastern and western coastlines of Japan.

Figure1. Track forecast for Tropical Storm Nangka as of 5:00 UTC, July 17, 2015
(Source: Japan Meteorological Agency)

Figure 2. Risk of damage due to winds, flooding from rainfall, and storm surge from Nangka
as of 12:33 UTC, July 17, 2015 (Source: Japan Meteorological Agency)

Damage and Disruption

The storm is impacting all of Japan’s main islands, with warnings issued for the south-central areas of Honshu, including Osaka, Kobe, Nagoya, and other major cities. The warnings are also in effect in Tokyo, which has been impacted with heavy rains and flooding. Prior to the storm 4,000 people were evacuated from Kochi Prefecture due to the potential of mudslides. On Thursday, approximately 500,000 were advised to evacuate; currently evacuation is advised for nearly 100,000 people located in western Japan. In Kobe, more than 30,000 households have been advised to evacuate. At least two lives have been lost and government officials are warning that some areas could see up to 1 meter of rainfall. Up to 25 mm per hour was still falling in some areas as of July 17.

Reported building damage has been mostly due to flooding, although several homes have also reported some wind damage. About 130 homes have flood damage, mostly in the prefectures of Tokushima, Wakayama, and Tochigi, although some have been reported in Tokyo. Nearly 60 homes, mostly in Tokushima Prefecture, have reported flood damage above the first floor level,

In western Japan, traffic disruptions were widespread, and Shikoku Railway canceled all train service Thursday evening. West Japan Railway canceled more than 100 limited express routes, affecting approximately 200,000 people. High tides and flooding caused parts of the expressways west of Tokyo to close. Flight cancellations were widespread, with about 48 flights canceled at Kansai International Airport. At Itami Airport, Nippon Airways and Japan Airlines canceled more than 30 flights.  

Forecast

As of 18:00 JST (11:00 UTC) Friday, July 17, Tropical Storm Nangka was tracking northeast over the southern Sea of Japan at 25 km/h (16 mph) with maximum sustained winds of about 65 km/h (40 mph). The Japan Meteorological Agency is forecasting heavy rains to continue over the next few days, bringing continued risk of flooding and landslides.

Insurance Impact

Typhoons are the most frequent type of natural disaster to cause property loss in Japan. While winds are typically the predominant driver of loss from most typhoons, Japan does have strict and well-enforced construction codes and significant structural damage from Nangka is unlikely. In Japan, wind damage is typically automatically covered under standard fire insurance policies, but flood damage is not, despite the fact that Japan regularly experiences “wet” storms that deliver extreme precipitation and flooding that contribute substantially to damage. Property owners who want flood coverage can purchase it as an add-on to a standard policy or select a comprehensive policy.

AIR’s tropical cyclone team will continue to monitor Tropical Storm Nangka and provide additional information if events warrant.

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Posting Date: July 17, 2015, 12:30:00 PM