2010 Pacific typhoon season

A record-quiet year

By any agency's measure, 2010 was exceptionally inactive. The Joint Typhoon Warning Center warned on only 19 tropical cyclones of all strengths, against a long-term average of 31, and described the year as record-low activity that continued a downward trend dating from 2005. Its own averages for 1959 to 2010 are close to 27 tropical storms and typhoons and 17 typhoons a year, so the season's tally fell well short on both counts.

The quiet was not caused by cool water. Sea surface temperatures were above normal during the ongoing La Niña, but reduced low-level spin and suppressed thunderstorm activity worked against formation, and upper-level winds shifted much of the summer convection in southeastern Asia toward the northern Indian Ocean. Forecasters caught the trend only gradually: Tropical Storm Risk began the year expecting near-average activity and by August was calling for a season 25 to 30 percent below normal.

The 16 tropical storms, 9 typhoons and 4 major typhoons shown here count one-minute sustained winds from US agencies, so they differ from other tallies. The Japan Meteorological Agency, which uses ten-minute winds, named 14 storms and ranked 7 as typhoons, the fewest named storms it had recorded in a season. JTWC's own warnings in the basin also include 14 tropical storms and 9 typhoons. The archive adds two systems that other centers assign to neighboring basins: Jal, which JTWC warned on as a North Indian Ocean cyclone, and Omeka, which the Central Pacific Hurricane Center named.

How the season unfolded

The year opened with a short-lived tropical depression that formed on January 18 and came ashore in southern Vietnam, where rough seas were blamed for three deaths. Tropical Storm Omais followed in March, passing near several Micronesian islands before dissipating short of the Philippines. From April through June no tropical storm formed at all, and the season's first typhoon did not arrive until July 12, when Conson reached that strength east of Luzon.

Late July and August brought the first sustained run. Conson and Chanthu crossed Luzon within a week of each other, Dianmu moved north toward Korea, and Mindulle struck Vietnam. At the end of August three systems formed almost together: Lionrock in the South China Sea, Kompasu northwest of Guam and Namtheun east of Taiwan. JTWC concluded that Lionrock and Namtheun rotated around each other in a direct interaction while outflow from Kompasu helped weaken Namtheun, which was drawn into Lionrock and dissipated in the Taiwan Strait.

September kept the pace with Malou, Meranti, Fanapi and Malakas. Malou's track was bent by a weaker companion circulation that JTWC failed to recognize in real time, so it passed west of Okinawa later than forecast and stayed well below its expected intensity. October produced the season's two strongest storms, Megi and Chaba, after which activity collapsed. Only Jal in early November and Omeka, a system that began as a subtropical storm near the International Date Line, reached tropical-storm strength in the final two months, and the last tropical-stage observation came on December 21.

Strongest storms

Typhoon Megi stood far above the rest of the season. It formed west of Guam, became a typhoon on October 14 and intensified rapidly to peak one-minute winds of 160 knots on October 17, with a minimum pressure of 903 hPa. It was the year's only super typhoon and its only Category 5 storm, and it was also the longest-lived storm of the season. After crossing northern Luzon it weakened, reorganized over the South China Sea to a second peak on October 21, then deteriorated before its final landfall at Zhangpu in Fujian on October 23.

Typhoon Chaba, which formed while Megi was over the South China Sea, peaked at 115 knots on October 28 and became extratropical near Japan on October 30. Kompasu and Fanapi each reached 105 knots, Kompasu on September 1 and Fanapi on September 18 just before it struck Taiwan. Malakas peaked at 90 knots on its way past Japan before becoming a powerful extratropical cyclone. The other four typhoons, Conson, Chanthu, Mindulle and Meranti, peaked at Category 1.

Notable landfalls and impacts

The Philippines took repeated blows. Typhoon Conson came ashore in Quezon province on July 13 and passed over Metro Manila, where power was cut across the capital region; the national disaster agency later put the Philippine death toll at 38. Chanthu followed days later with flooding in Aurora and elsewhere on Luzon that killed eight people. In October, Typhoon Megi killed 31 people in Luzon, and PAGASA retired its local name, Juan, after the storm caused more than 1 billion pesos of damage in the country.

Southern China and Vietnam absorbed a string of costly storms. Chanthu's rain bands flooded Hong Kong and southern China, where 9 people died and economic losses reached 5.54 billion yuan (about US$818 million in 2010). Lionrock forced 160,000 people into shelters in Guangdong and caused losses of 441 million yuan (US$65 million), while Meranti, whose thunderstorms set off a record 13,102 lightning strikes in one hour over Hong Kong, killed 3 people in eastern China with losses of 800 million yuan (US$118 million). Mindulle killed at least 10 people in Vietnam, with losses of 850 billion dong (US$43 million).

Typhoon Fanapi was the most damaging storm to strike directly. It made landfall in Hualien County, Taiwan, early on September 19, crossed the island and hit Zhangpu in Fujian the next day; the account reports 105 deaths across Taiwan and China and about US$1 billion in damage in 2010 dollars. A month later, moisture linked to Megi combined with a weather front to bring torrential rain to northeastern Taiwan, where 38 people died in Yilan, and Megi's overall losses were estimated at US$709 million in 2010 dollars.

Farther north, Typhoon Kompasu crossed Okinawa as a strong typhoon and then came ashore on Ganghwa Island near Incheon as a minimal typhoon, the strongest storm to hit the Seoul area in 15 years; it killed at least four people there and 29 over its lifetime. Dianmu had earlier brought flooding to South Korea that killed at least five people, including the first rain-related death in Seoul in nine years. In Japan, Malou's downpours topped 100 millimeters an hour and caused flash flooding without loss of life, ending one of the country's longest and hottest heat waves.

Records, research and retired names

Megi coincided with the ITOP/TCS-10 field campaign, a research program on how typhoons affect the ocean that brought extra observations to the western Pacific from August to early October. US Air Force Reserve WC-130J aircraft flew into the storm, and on one pass the Step Frequency Microwave Radiometer measured a wind of 172 knots, which JTWC described as the highest tropical cyclone wind speed ever recorded.

The late-August three-storm interaction also exposed a gap in forecasting. JTWC wrote that the lack of reliable tools for diagnosing direct cyclone interaction limited its support to military operations, and its review of Malou noted that scatterometer analysis often showed a single elongated circulation where several smaller vortices were present.

Fanapi, used for the first time in 2010, was retired by the Typhoon Committee in 2011 and replaced with Rai. In the Philippines, PAGASA retired Juan, its name for Megi, and removed Katring, its name for Chaba, from the list reused in 2014.