Typhoon Mangkhut: A Weekend of Destruction

From the small city of Baggao, Cagayan Province in the Philippines, to Hong Kong and further into China — locations across these two countries look to recover after Typhoon Mangkhut (25W). After landfall in Guam on Monday, September 10, Mangkhut — known locally as Ompong in the Philippines, made landfall again at 2 a.m. Saturday local time (18:00 UTC, Friday, September 14) near Baggao, as the equivalent of a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale (SSHWS).

Maximum sustained wind speeds at landfall were 133 miles per hour (214 kilometers per hour) according to the Japan Meteorological Agency (JMA). The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) reported similar results to the JMA with maximum sustained wind speeds of 134 miles per hour (215 kilometers per hour), but the Joint Typhoon Warning Center (JTWC) reported 166 miles per hour (268 kilometers per hour), equivalent to a Category 5 major hurricane on the SSHWS.

Philippines — Mangkhut Hits Vulnerable Northern Luzon

For the Philippines, this was the strongest storm to impact the country since Haiyan (Yolanda) in 2013 and was stronger than Haima (Lawin) which impacted northern Luzon in October 2016.

The size of Mangkhut saw hurricane-force winds extending 110 miles (175 kilometers) from the center of the system at landfall, and tropical storm-force winds some 327 miles (527 kilometers) from the center. The biggest impact was felt across a broad swathe of northern Luzon, the largest and most populous island of the Philippines. The northern Philippines and southern portions of Taiwan also experienced damage.

But it was the remote northeast of Luzon that saw extensive damage to unreinforced and poorly constructed buildings. At least 64 people have died, according to local authorities. The majority of the buildings in the cities of Tuguegarao (pop. ~ 153,000), Baggao (pop. ~ 82,000), and Alcala (pop. ~ 39,000), according to local officials, sustained some damage, ranging from minor roof damage to structural failure. Early estimates state that the 48,000 homes impacted by the typhoon’s strongest winds were constructed of light materials; in Tuguegarao, the tin roofs of most homes are reportedly removed from their structures. The system has brought down trees and powerlines, leading to widespread power outages and debris in the streets.

House destroyed in rural northern Luzon, Philippines, after Typhoon Mangkhut. Image credit: Twitter/CatholicRelief

The typhoon, combined with the seasonal monsoon rains, has triggered at least 42 landslides. Heavy rainfall led to localized flash and river flooding; with five dams opened to release water. Insured losses likely to be low as this is a sparsely populated and very rural part of the Philippines, but there is concern about the wider economic impact of the storm as corn and rice crops were destroyed in this important agricultural region.

Hong Kong, Macau, and China

After its journey across the South China Sea, the center of Mangkhut bypassed approximately 60 miles (100 kilometers) southwest of Hong Kong, before making landfall at around 5:00 p.m. local time (09:00 UTC) on Sunday, September 16, on the Taishan coast of Jiangmen City in Guangdong Province, according to the China Meteorological Association (CMA). Landfall was around 62 miles (100 kilometers) west-southwest of Macau. The JMA and the CMA analyzed maximum sustained wind speeds of 109 miles per hour (175 kilometers per hour) and 101 miles per hour (162 kilometers per hour) respectively, both equivalent to a Category 2 hurricane on the SSHWS. The Hong Kong Observatory (HKO) reported slightly higher maximum sustained wind speeds at landfall of 114 miles per hour (184 kilometers per hour), equivalent to a Category 3 hurricane on the SSHWS.

Hurricane-force winds extended up to 90 miles (150 kilometers) from the center of the storm, which impacted Hong Kong, Macau, and coastal areas of Guangdong Province. A record-breaking wind gust of 138 miles per hour (223 kilometers per hour) was observed in Hong Kong, though the observation point is in an exposed location and is not a true representation of the storm’s surface wind speed. At the center of the storm during landfall, Mangkhut produced stronger winds than Hato last year (195 kilometers per hour) and the strongest winds experienced in Hong Kong since Typhoon Rose in 1971.

Hong Kong: T-10 warning

For Hong Kong, in anticipation of the storm, the HKO issued a T-10 warning — the highest warning level, for ten hours; Typhoon York in 1999 holds the record with eleven hours. The Secretary for Security in Hong Kong called the damage “serious and extensive”, stating damage may be several times greater than from Typhoon Hato, with at least 500 homes and high-rise buildings, including apartment complexes and office blocks, severely damaged according to local media. High-rise buildings swayed in the strong winds, with smashed windows in high-rise buildings; the One Harbour office tower was damaged up to the twentieth floor. Multiple construction scaffolding and crane collapses have contributed to building damage. Around 1,500 trees, twice as many as Hato, were downed across Hong Kong, which have also damaged homes and infrastructure, and 1,500 people sought refuge in the aftermath of the event.

Window damage from Typhoon Mangkhut viewed from Grand Harbour Kowloon Hotel in Hong Kong. Image: Wikipedia/Cybreshot

Mangkhut also brought a record-breaking storm surge to parts of Hong Kong, according to local officials. Several feet of storm surge impacted coastal areas of Hong Kong, flooding shopping centers and coastal buildings. Officials have attributed the increased impact from storm surge to land reclamation in the Victoria Harbor. Maximum storm surge amounts observed include 7.7 feet (2.35 meters) at Quarry Bay, and 11 feet (3.38 meters) at Tai Po Kau. Areas most affected by surge appear to be in the outlying islands or in the southeastern part of Hong Kong which was most exposed to the approaching typhoon. Strong coastal flood defenses in the highest exposure areas Hong Kong held up well. Levels of serious flooding were more than Hato, but waters receded relatively quickly.

High levels of insurance claims are expected for property, auto, hotel damage, and business interruption (BI).

Macau

Initial assessments by the Macau Government indicate damage from Typhoon Mangkhut is “significantly lower” than Typhoon Hato of 2017, which generated 8.3 billion Patacas (US$1 billion), of economic losses. Government officials state the most serious storm surge flooding was reported in the inner harbor area, where water levels reached up to 6.2 feet (1.9 meters) above normal, but this receded quickly. Maximum sustained winds were reported at 137 kilometers per hour, compared to 155 kilometers per hour for Hato.

20,000 households lost power, this compares to 250,000 during Hato, and that outage that lasted five days. Buildings immediately near the coastline, including several casinos in the harbor areas, were flooded and have sustained damage. All casinos in Macau closed simultaneously for first time in history on Sunday but reopened the next day. Macau is a large gambling hub with annual revenues seven times that of Las Vegas. Hato did see large BI losses, but Mangkhut should be much lower due to fewer power outages, less severe flooding, and better preparations.

Guangdong and Guangxi Provinces

A total of 3.1 million people were evacuated in Guangdong Province and Hainan Island in anticipation of the storm. Damage information across China is still emerging and there are currently no official damage statistics. According to local media, minor to moderate wind damage is reported across Guangdong, and authorities have said the storm will likely cause direct economic losses of at least 200 million yuan (US$29 million), though this is expected to rise as a full assessment of the damage is completed.

There is minor damage across western Guangdong and Guangxi, largely consisting of minor façade damage, commercial signage damage, minor street flooding, broken windows, and downed trees and powerlines. Local officials have indicated the damage was not as significant as Typhoon Hato, which impacted the region in 2017. In Shenzhen, around 10,000 vehicles are reportedly damaged, according to local news reports.

Along the Pearl River Delta, storm surge flooding has impacted commercial areas near the coastline. Ports, oil refineries and industrial plants in Guangdong have been shut, and power in other areas was reduced as a precaution. More than 20,000 construction projects were suspended, and shipping was halted in Pearl River delta. But there were no widespread power cuts, which could result in lower BI losses than Hato. Already 542 million yuan in insurance claims (US$79 million) had been received in Guangdong by Monday afternoon — some 30,000 claims, including 27,000 vehicle damage claims (233 million yuan) and 1,100 agricultural damage claims (105 million yuan).

With RMS producing a slew of recent model releases, it is supporting clients to manage these events through stochastic event selections released for Mangkhut for Guam, the Philippines, China and Hong Kong. For more details, RMS clients can contact their account representative.

Simon Athawes, Product Manager, Model Product Management

Based in London, Simon joined RMS in 2012 and works within the Model Product Management team, focusing on the Asia tropical cyclone suite of products. He is product manager for the RMS typhoon models for China, Taiwan, South Korea, Guam, and has most recently been involved in supporting the development and release of the Philippines Typhoon and Inland Flood Model. Simon holds a bachelor's degree in Geography from the University of Nottingham and a master's degree in Geological and Environmental Hazards from the University of Portsmouth.

James Cosgrove, Senior Analyst, Model Development

Based in London, James works within Model Development as a member of the RMS Event Response team, supporting real-time Event Response operations and assisting on various Event Response projects.

James holds a bachelor’s degree in Physical Geography and Geology from the University of Southampton and a master’s degree in Applied Meteorology from the University of Reading.

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