Dr. Jeff Masters ·

Above: Windows of a commercial building damaged by Typhoon Mangkhut on Sept. 16, 2018, in Hong Kong. City officials raised the storm alert to T10, its highest level, as Typhoon Mangkhut landed on Hong Kong. (Lam Yik Fei/Getty Images).

Mangkhut made landfall in China at the Guangdong city of Taishan at 5 pm Sunday local time (9Z or 5 am EDT). At the time of the 6Z advisory, three hours prior to landfall, the Joint Typhoon Warning Center (JTWC) rated Mangkhut a Category 1 storm with 90 mph winds. Given the large amount of destruction Mangkhut caused during this landfall, the typhoon was likely stronger than that: the China Meteorological Agency (CMA) put Mangkhut’s maximum sustained 2-minute average winds at 6Z at 108 mph (48 m/s); this is equivalent to a borderline Category 2/Category 3 hurricane with 1-minute-average sustained winds of 110 – 115 mph. China’s Xinhua news service reported the storm had winds of 100 mph (162 kph) at landfall.

The official agency responsible for advisories in the Northwest Pacific, the Japan Meteorological Agency (JMA), put Mangkhut’s 6Z maximum sustained 10-minute winds at 85 mph, which is roughly equivalent to a borderline Category 1/Category 2 hurricane with 1-minute-average sustained winds of 95 mph.

Sea water pours into dining hall of a hotel in Shenzhen, China.#TyphoonMangkhut pic.twitter.com/0MJIkiHGEY — China Xinhua News (@XHNews) September 16, 2018

Mangkhut was a huge storm at landfall, with hurricane-force winds that extended out up to 100 miles (160 km) from the center, and tropical storm-force winds that extended out up to 315 miles (510 km) from the center. This huge wind field was able to generate a significant storm surge. In Macau, which the typhoon’s eye passed about 40 miles (70 km) to the west of, a storm surge of 1.9 meters (6.2 feet) flooded the entire inner harbor, according to South China Morning Post. A pressure of 970 mb was measured there, along with peak sustained winds of 65 mph (105 kph).

Figure 1. MODIS image of Super Typhoon Mangkhut on Sunday afternoon, September 16, 2018, just before making landfall in South China. Image credit: NASA Worldview.

In Hong Kong, the No. 10 signal--their highest level of danager alert--remained in place between 9:40 am and 7:40 pm on Sunday, only one hour shorter than the record set by Typhoon York, which ravaged the city for 11 hours in September 1999. At the 12 monitoring stations in Hong Kong, which the center passed 80 miles (130 km) to the west of, the pressure fell low as 971 mb, and winds as high as 101 mph (163 kph) were measured.

According to senior science officer Lee Suk-ming of the Hong Kong Observatory, Mangkhut “brought Hong Kong a record-breaking storm surge, which was more severe than those brought by Typhoon Wanda and Typhoon Hope.” The maximum storm surges recorded at Quarry Bay and Tai Po Kau were 2.35 meters and 3.38 meters respectively, higher than the 1.77m surge bought by Typhoon Wanda in 1962 to Quarry Bay, and the 3.23m surge in Tai Po Kau under Typhoon Hope in 1979. Storm surge records in Hong Kong extend back to 1904. Lee said the stronger storm surge in the Victoria Harbour could be attributed to years of reclamation. “It’s common sense that such works will make the seas higher when extreme weather hits,” he said. Fortunately, Hong Kong is not especially vulnerable to storm surge, since it has few low-lying areas. However, Guangzhou, China, with a metro-area population of 25 million, was in the strong right front quadrant of the typhoon, and may have experienced a significant storm surge. Guangzhou is the #1 most vulnerable city on the planet to damage from sea level rise and coastal flooding, according to a World Bank report.

At least 64 dead in the Philippines

Typhoon Mangkhut barreled into the island of Luzon in the Northern Philippines early Saturday as a Category 5 hurricane with 165 mph winds, killing at least 64, with 45 missing. Mangkhut brought extreme rains to the Philippines, with Baguio in western Luzon picking up more than 26 inches of rain through 8 am EDT Saturday. Mangkhut, the Thai word for mangosteen fruit, is known as Ompong in the Philippines. On Wednesday, Mangkhut was a Category 5 storm with 180 mph winds, making it Earth’s strongest storm so far in 2018.

Mangkhut was the most powerful typhoon to hit the typhoon-prone Philippines this year, and the first Category 5 to hit Luzon since Super Typhoon Megi of 2010. Mangkhut slammed ashore before dawn in Cagayan province on the northeastern tip of Luzon island, a breadbasket that is also a region of flood-prone rice plains and mountain provinces with a history of deadly landslides. The airport terminal in Cagayan’s capital, Tuguegarao, was badly damaged, its roof and glass windows shattered by strong winds, which also sent chairs, tables and papers flipping about inside.

On Monday, Mangkhut struck Rota in the Mariana Islands on Monday as a Category 2 storm with 105 mph winds. Wind gusts in excess of 80 mph were reported in Guam. To the north in Saipan, wind gusts topped 60 mph.

Figure 2. Radar image of Typhoon Mangkhut taken at 5 pm local time Sunday, September 16, 2018, when it was making landfall in South China. Image credit: CMA.

A top-ten most damaging typhoon in Asian history?

Given the large amount of development that has occurred in the region in recent years, Mangkhut could rank as one of the top-ten most expensive typhoons on record in Asia, if its damages reach $5 billion. According to EM-DAT, the most expensive typhoons on record (in dollars adjusted for inflation) are:

1) $18.4 billion, Typhoon Mirelle, Japan, 1991

2) $12.0 billion, Typhoon Songda, Japan, 2004

3) $10.8 billion, Typhoon Haiyan, Philippines, 2013

4) $8.7 billion, Praparoon, Korea, 2000

5) $7.5 billion, Bart, China, 1999

6) $7.2 billion, Typhoon Fitow, 2013

7) $6.2 billion, Typhoon Maemi, 2003, China

8) $6.0 billion, Typhoon Flo, Japan, 1999

9) $5.9 billion, Typhoon Rusa, Korea, 2002

10) $4.2 billion, Typhoon Rammasun, China, 2014

Many of these official numbers are almost certainly too low, according to experts I’ve talked to. In addition, this list leaves out what was possibly the most destructive Chinese typhoon of all-time, Typhoon Nina of 1975. Nina stalled out and dumped prodigious rains for two days in the Ru River drainage basin upstream of the Banqiao Dam, leading to its collapse and the loss of 171,000 lives, with an area 34 miles long and 8 miles wide wiped out.

The South China Morning Post has an excellent summary of the history of typhoons in Hong Hong.