The 1964 Pacific typhoon season was the most active tropical cyclone season recorded globally, with a total of 39 tropical storms forming. It had no official bounds; it ran year-round in 1964, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
Tropical Storms formed in the entire West Pacific basin were assigned a name by the Joint Typhoon Warning Center. Tropical depressions in this basin have the "W" suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric, Geophysical and Astronomical Services Administration or PAGASA. This can often result in the same storm having two names.
Notable storms include Typhoon Joan, which killed 16,000 people in Vietnam, mostly from catastrophic flooding; Typhoon Louise, which killed 570 people in the Philippines, Typhoons Sally and Opal, which both peaked at 1-minute sustained speeds of 195 mph, Typhoons Flossie and Betty, which both struck the city of Shanghai, China, and Typhoon Ruby, which hit Hong Kong as a powerful Category 4 storm, killing over 700 and becoming the second worst typhoon to affect Hong Kong.
Season summary From the summer of 1964 until the end of spring 1965, the La Niña phase remained weak. In the year following the end of La Niña, the unofficial number of recorded super typhoons reached a record high of 11. This indicates that 1964 and 1965 were the years with the most intense low-pressure systems and storm activity ever-record documented in the Northwest Pacific region, as well as across the entire basin.
Timeline of tropical activity in 1964 Pacific typhoon season
The 1964 typhoon season was the most active Pacific typhoon season on record. All months between and including May and November were featured an above-average number of typhoons relative to the 1959–1976 period. The China Meteorological Administration (CMA), Hong Kong Observatory (HKO), Japan Meteorological Agency (JMA), and Joint Typhoon Warning Center (JTWC) each maintain tropical cyclone databases that include their respective intensity and path analyses for 1964, resulting in disparate storm counts and intensities. Total tropical cyclone counts for the 1964 season include 40 from the CMA, 34 from the JMA, and 52 from the JTWC (including 7 considered "suspect cyclones"). There were more named storms in the northwestern Pacific in 1964 than in any other year or in any other basin.
A recommendation was made at the 20th session of the United Nations Economic Commission for Asia and the Far East (now known as the UN Economic and Social Commission for Asia and the Pacific [ESCAP]) in March 1964 for the United Nations Secretariat and World Meteorological Organization to investigate the feasibility of a multinational program for monitoring typhoons. This led to the formation of the ESCAP/WMO Typhoon Committee, which held its inaugural session in 1968. Prior to the inception of the Typhoon Committee, the United States Indo-Pacific Command had designated the U.S. Fleet Weather Central in Guam as the JTWC in May 1959. The JTWC was tasked with warning U.S. government agencies on tropical cyclones in the northwestern Pacific, in addition to researching and orchestrating aircraft reconnaissance into such storms. Boeing B-47 Stratojets were deployed from the 54th Weather Reconnaissance Squadron to carry out airborne reconnaissance. The JTWC issued 730 warnings on 26 typhoons, 14 tropical storms, and 5 tropical depressions. The number of typhoons was a new record, topping the 24 set in 1962. Ten of these occurred in the South China Sea, compared to the annual average of 3.2 in the five years preceding 1964. The anomalous strength of tropical waves observed during the latter-half of the year may have contributed to season's high activity. Ten of the year's tropical cyclones—Grace, Helen, Nancy, Pamela, Ruby, Fran, Georgia, Iris, Kate, Louise, and Opal—were first detected using meteorological satellites.
The active typhoon season was also impactful. More storms passed near Hong Kong in 1964 than in any prior year. The Royal Observatory Hong Kong issued tropical cyclone warning signals 42 times for ten different storms; these warnings were in effect for 570 hours. Two of these storms, Ruby and Dot, prompted the highest warning signal, signal no. 10. No year prior to 1964 featured more than two typhoons affecting Hong Kong on record. Ten typhoons impacted the Philippines, including Winnie (known as Dading in the Philippines), Luzon's severest typhoon since 1882. The effects of typhoons in 1964 led to a 3.1 percent decrease in rice output from the Philippines. Six typhoons and two tropical storms struck Vietnam, including three tropical cyclones in a twelve-day period in November. The combined effects of Iris and Joan killed as many as 7,000 people and led to the worst floods in six decades.
In May 1964, the western Pacific was characterized by anomalously high geopotential heights towards the northern part of the basin and low geopotential heights in the tropical regions. This configuration was favorable for tropical cyclogenesis and led to the development of typhoons Tess and Viola, the first storms of the 1964 typhoon season. Shower activity in the tropics west of Hawaii was above average between May 10–20. The first half of June marked a reversal of this pattern as a large area of low pressure became established over the mid-Pacific. The average sea-level pressure for the month was below normal for most of the northern Pacific. Typhoons Winnie and Alice formed in the second half of the month when the initial height patterns returned. July 1964 featured more tropical cyclones than any other July on record, though this was superseded by the 1971 Pacific typhoon season. A strong high pressure area south of Japan caused most storms during July to take slow and westward paths.
August was another above-average month for tropical activity in the basin. Pressures across most of the western Pacific were lower than average, particularly around Okinawa where tropical cyclone activity was high during the month. Between August 10–19, a progression of cyclones in the upper troposphere triggered wind perturbations closer to the ocean surface, leading to the genesis of Tropical Storm June, Typhoon Kathy, Tropical Storm Lorna, and Tropical Storm Nancy. Typhoons Kathy and Marie were involved in a Fujiwhara interaction that led both storms to rotate counterclockwise around each other, ending with Marie's absorption into Kathy's circulation. A paper published in the Quarterly Journal of the Royal Meteorological Society described the resulting paths of the two storms as an "archetypal example" of the Fujiwhara interaction. In September, tropical cyclone activity was high across the Northern Hemisphere in both the Atlantic and Pacific. Subtropical ridging in the Pacific was extended zonally throughout the month, resulting in strong easterly winds in the subtropical latitudes and providing conducive conditions for storm development. The extensive ridging also prevented most of September's storms from taking curved paths into the westerlies; while approximately half of September typhoons curve into the westerlies on average, only one typhoon, Wilda, took such a trajectory in 1964. The strong substropical ridging continued into October, leading to similar storm paths.
Systems Typhoon Tess (Asiang) + Peak intensity estimates Agency Wind(kt) Pressure(hPa)c CMA 97 966 HKO 75 965 JMA 960 JTWC 85 965
The first tropical cyclone of 1964 developed from a segment of the polar trough. A wind circulation was first identified near Woleai by the JTWC on May 9. This initial disturbance traveled west-northwest, passing near Ulithi and Yap. On May 14, it organized further into a tropical depression and took an erratic track over the next four days, including a looping course. During this process, it strengthened into a tropical storm, weakened to a tropical depression, and reattained tropical storm intensity before heading on an east-northwestward to northeastward trajectory. On May 19, a reconnaissance flight investigating Tess observed two eyes: the first and innermost eye measured across while the second was asymmetrical, with axes roughly across. Shortly after finding this feature, Tess was estimated to have attained typhoon status.
Tess tracked towards the northeast after reaching typhoon intensity. Its center passed between Alamagan and Guguan on May 20 while maximum sustained winds in the typhoon were . Farther southeast, in Guam, the passing storm produced of rain. The next day, Tess reached its peak intensity with winds of and a minimum barometric pressure of 960 hPa (mbar; 28.35 inHg). A seabee stationed on the island was presumed to have drowned after being swept away by the rough seas generated by the storm; two landing crafts were also destroyed by the rough seas. At noon on May 21, the center of Tess passed west of Marcus Island, bringing squalls accompanied by heavy rain and winds of . Gusts reached and rainfall accumulations reached on the island, though there was "little damage." Gradual weakening followed, with winds diminishing below typhoon intensity on May 22. The system then began to curve east as it transitioned into an extratropical cyclone by May 24, and was last noted three days later.
Typhoon Viola (Konsing) + Peak intensity estimates Agency Wind(kt) Pressure(hPa) CMA 68 980 HKO 65 980 JMA 980 JTWC 70 980
According to data from the Japan Meteorological Agency (JMA), the progenitor to Typhoon Viola emerged in the South China Sea just east of Vietnam on May 21. This system initially moved towards the north before curving sharply east. Three days later, the system organized into a tropical depression after the JTWC identified a surface wind circulation. Viola reached tropical storm strength on May 25 and then curved northwest, strengthening further into a typhoon on May 27 and peaking in strength with winds of . These winds diminished to —just under typhoon intensity—as Viola made landfall approximately west of Hong Kong at 03:00 UTC on May 28. The storm weakened over mainland China and dissipated on May 30.
The Royal Observatory Hong Kong issued typhoon signal No. 8 ahead of Viola's approach, signifying gale-force conditions, a peak gust of over 140 km/h recorded in Waglan Island, the highest ever in May. Ferry services were suspended in the territory. Hong Kong recorded of rain in five days from the passing typhoon. The rainfall brought an end to an over two-year-long drought that had prompted a year-long water rationing in the territory. More rain fell in roughly 24 hours than in 1964 prior to Viola's arrival. The storm uprooted trees, triggered landslides, and put over 6,000 telephones out of commission. Vegetable crops were badly damaged. Viola generated a storm surge at Quarry Bay and grounded four ships, including three freighters at Hong Kong. Forty-one people were hospitalized by the storm and over a thousand were left homeless. Further inland, the storm relieved drought conditions in the Chinese province of Guangdong.
Typhoon Winnie (Dading) + Peak intensity estimates Agency Wind(kt) Pressure(hPa) CMA 87 955 HKO 90 970 JMA 968 JTWC 100 950