October 1st, 2018

Super Typhoon Trami

Posted at 6:53 PM ET

trami-2-bigIn the West-Pacific Basin, Typhoon Trami made landfall in the city of Tanabe, Japan (Wakayama prefecture) on 30 September at around 11 UTC (8 PM local time), according to media reports. Before reaching Honshu, the typhoon had rendered considerable impacts while making close approach to Okinawa, Kyūshū and Shikoku Islands. Trami brought significant flood impacts as a result of heavy rainfall and storm surge, as well as variable property damage due to wind. Significant power outages and transportation disruption have been reported by media. Over 4.3 million people were given evacuation orders or advisories. Media reports indicate at least four fatalities and 120 injured. It will take time to fully assess the complete scope and severity of the event, and our first thoughts and concerns are with those directly affected.

Meteorological Discussion

Typhoon Trami originated at around 18 UTC on 20 September as a tropical depression south of Guam. The system strengthened as it headed north and west across the warm waters of the Philippine Sea. According to the Joint Typhoon Warning Center (JTWC), the feature was upgraded to a tropical storm on 21 September at 06 UTC, with 1-minute sustained winds of around 65 km/h (40 mph). The storm continued to follow a general west-northwesterly motion while gaining strength. Trami was classified as a typhoon by the JTWC on 22 September at 18 UTC, with 1-minute sustained winds of around 120 km/h (75 mph). The system continued a general west-northwest to northwesterly motion over the next day or so, while undergoing a period of rapid intensification. Trami was classified as a super typhoon on 24 September at 06 UTC, with 1-minute sustained winds of around 240 km/h (150 mph). Trami then reached its peak intensity at 00 UTC on 25 September, with 1-minute sustained winds of around 260 km/h (160 mph), a Category-5 on the Saffir-Simpson Scale. trami-2smallHazard data illustrated in the CAT-i map was taken from GC AdvantagePoint®, Guy Carpenter’s web-based risk management platform. GC AdvantagePoint users can view impacted areas on any map as well as see how their portfolios were affected. Please contact your broker or cat modeling analyst for further information.

At this time, Trami experienced a considerable reduction in forward speed and began to drift in a northerly direction between two adjacent ridges. During this time, Trami was in an environment of low wind shear and good storm ventilation, but over cooler waters from upwelling due to the slow forward motion of the storm. Trami began to weaken as a result and was downgraded to a typhoon at 18 UTC on 25 September. As the ridge to the northeast of the storm began to strengthen, the resulting steering flow caused Trami to begin to drift to the north and then northwest while following the western edge of the ridge through 27 September. By this time Trami had weakened to carry 1-minute sustained winds of around 165 km/h (105 mph), a Category-2 on the Saffir-Simpson Scale.

As the storm rounded the western axis of the ridge it began to make a gradual turn to the northeast on 28 September. According to JTWC position reports, Trami passed on close approach to Okinawa around 06 UTC on 29 September, maintaining 1-minute sustained winds of around 165 km/h (105 mph). The Okinawa province experienced strong winds, with gusts well in excess of 160 km/h (100 mph) unofficially reported by media.

On 30 September, as the system made close approach to the coasts of the Kyūshū and Shikoku Islands, JTWC reported a decrease of 1-minute sustained winds from 165 km/h (105 mph) at 00 UTC to 150 km/h (90 mph) at 06 UTC. According to media reports, over 400 mm (16 inches) of rainfall was unofficially recorded for certain areas of the two islands, and a record wind gust of 197 km/h (122 mph) was observed in Tokara (Kagoshima prefecture, Kyūshū). On 30 September at around 11 UTC (8 PM local time) Trami made landfall on Tanabe (Wakayama prefecture), about 100 km (62 miles) south of Osaka, according to media reports. Prior to landfall at 06 UTC on 30 September, the JTWC reported 1-minute sustained winds of around 150 km/h (90 mph), a Category-1 on the Saffir-Simpson Scale.

At the same time the JMA reported equivalent 1-minute sustained winds of around 165 km/h (100 mph) (equivalent offshore), a Category-2 on the Saffir-Simpson Scale. The system was then moving rapidly to the northeast at a speed of about 52 km/h (32 mph), while undergoing extratropical transition and weakening due to land interaction and wind shear. At 15 UTC Trami had reached Gifu and Nagano prefectures. According to media reports the city of Gero (Gifu prefecture) experienced unofficial gusts of 144 km/h (89 mph). At 18 UTC Trami had reached the Fukushima prefecture. At around 21 UTC the system crossed the Iwate prefecture and then moved into the Pacific Ocean, before making close approach to the east coast of Hokkaido. The storm then moved rapidly to the northeast while weakening.

Impacts

According to media reports, Trami left at least four dead, two missing, and over 120 injured. One person was killed by a landslide in Tottori prefecture, and another man was found dead in a river in Yamanashi. Authorities issued evacuation orders and advisories affecting over 4.3 million people, and many municipalities in western Japan set up shelters for residents. Our thoughts and concerns are with those lost and directly affected by this event. The JMA issued warnings and advisories across Honshu for heavy rain, landslides, and storm surge. A river was reported to overflow its banks in Miyazaki prefecture, flooding farms and houses, as well as National Route 10. A 79-meter cargo ship that was anchored off the coast of Yokohama was carried about 4 kilometers and eventually washed ashore in the city of Kawasaki, striking a seawall and causing damage; no injuries were reported. Minor building damage due to wind was reported across the country, and several people were injured by windows shattered by strong winds and windborne debris. Nearly 1.6 million households were affected by power outages throughout the country. Tokyo Electric Power Co. reported that over 385,000 households in Ibaraki, Tochigi, Tokyo and Yamanashi prefectures were affected by power outages. According to data made available by Chubu Electric Power Co. another blackout affected about 750,000 households in Shizuoka, Aichi and Mie prefectures. Power outages also affected over 3,000 houses in Fukushima and Iwate.

Before making landfall on Honshu, the typhoon also rendered downed power lines in Kyūshū, leaving more than 275,000 homes and offices without power, and in Okinawa where 175,000 buildings were left without power. Trami also disrupted transportation services across the country. The event forced Central Japan Railway Co. to suspend all high-speed trains between Tokyo and Osaka on 30 September. Shinkansen trains between Osaka and Hiroshima were also suspended along with other local railway services. East Japan Railway Co. suspended all trains in the Tokyo Metropolitan area Sunday evening. Overnight Sunday into Monday wind gusts left downed trees and windborne debris and damaged traffic lights in the Tokyo region, causing considerable transportation disruption to both road and rail.

The Kansai International Airport in Osaka was closed Sunday morning and reopened Monday. Sandbags were used to offset flooding in the airport (located on an artificial island), following earlier impacts from Typhoon Jebi. Over 1,200 flights were cancelled at major airports across Japan, including those in Akita, Sendai and Sapporo, as well as Tokyo’s Narita and Haneda. Japan Airlines and All Nippon Airways cancelled more than 400 flights to and from Okinawa and Kagoshima prefectures, affecting over 38,000 passengers.

Sources: Japan Meteorological Agency, Joint Typhoon Warning Center, NOAA, The Weather Company, The Japan Times, The Mainichi, Reuters, BBC, NHK, Bloomberg.

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Guy Carpenter publishes CAT-i reports for major natural catastrophes worldwide. These reports cover catastrophes including worldwide tropical cyclones, earthquakes, major UK and European floods and any other natural event that is likely to incur a significant loss to the (re)insurance industry. Please email CAT.i@guycarp.com if you wish to be added to the free email distribution list.

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