The 1970 Pacific typhoon season has no official bounds; it ran year-round in 1970, 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.
The scope of this article is limited to the Pacific Ocean, north of the equator and west of the International Dateline. Storms that form east of the date line and north of the equator are called hurricanes; see 1970 Pacific hurricane season. 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.
Seasonal summary
27 tropical depressions formed this year in the Western Pacific, of which 24 became tropical storms. 12 storms reached typhoon intensity, of which 7 reached super typhoon strength.
Systems Typhoon Nancy (Atang)
Nancy originated from the interaction between an active ITCZ and a cold front near the Caroline Islands and the equator in mid February. An increase in convection was shown by weather satellites on February 18 and by the following day a recon aircraft found a weak depression to the south of the Caroline Islands. The depression moved west, suppressed south by a high pressure ridge to the north, and gradually strengthened into a tropical storm and was given the name Nancy early on February 20. Nancy became a typhoon on the 22 about 100 miles northwest from Woleai. On February 23 Nancy passed to the north of Yap where strong gale winds occurred. Continuing to encounter more favorable conditions Nancy was able to achieve a peak intensity of 140 mph (220 km/h) and a pressure of on February 24. This was the equivalent of a category four hurricane. It is rare to have a typhoon of this magnitude during the month of February, as noted by the JTWC, only Irma of the 1953 season reached the same intensity at the time. As Nancy approached the Philippine Islands the typhoon traversed to the western ambit of the ridge that had kept it to the south, allowing it to move farther in a north direction. During the 25 Nancy passed east off the coast of the easternmost islands of the Philippines. On the island of Catanduanes, the edge of the eye brushed the eastern coast. A U. S. Coast Guard loran station on Catanduanes recorded intense winds, at which point the equipment malfunctioned. The storm encountered a hostile environment to the northeast of Luzon and began to weaken. By February 26 Nancy had become a tropical storm and shortly afterward had transitioned into an extra tropical cyclone and moved off into open ocean. By the 28 what remained of Nancy was a frontal trough.
Nancy caused significant damage to the Philippines and surrounding islands. Particularly hard hit were the islands of Catanduanes and Samar. Damage was estimated near a million dollars with 5,000 families homeless. On the Island of Yap heavy storm surge caused $160,000 in damages, luckily no one was killed. A 6,065 ton American ship, Antinous, encountered the full brunt of the typhoon shortly before midnight, February 24. Ship logs record sea swells of over 40 feet, winds over 100 knots, a central pressure of 953 millibars, and three of the ships large butane tanks on the main dock broke free during the storm along with a portion of its bulwark.
Super Typhoon Olga (Deling)
In mid-June a change in the jet stream over a large part of the Pacific Ocean caused an increase in tropical wave frequency; one becoming the precursor to Olga. The wave was first noticed near the Marshall Islands, particularly the Island of Majuro on June 24. As it moved west weather satellites depicted the wave had begun to organize with considerable convection and spiraling storm bands as it neared the Central Caroline Islands. Due to the waves close proximity to a high pressure area to the north, strong easterlies accelerated it to the west. The increased forward speed inhibited the establishment of a circulation until it was south of Guam early on June 29. Later that day reconnaissance found a closed center and gale-force winds, prompting the JTWC to upgrade the low into a tropical storm and was given the name Olga. As it entered the Philippine Sea the ridge that had kept it to the south began to weaken allowing Olga to move in a northwestward direction. As Olga entered an increasingly favorable environment, the storm slowed its forward speed and strengthened into a typhoon late on June 29. Rapid intensification followed as the system bottomed out at a pressure of and winds of 160 mph (260 km/h) on July 1. The rapid 62 millibar drop between June 30 and July 1 caused an intense wind profile surrounding the small eye. The storm followed a break in the ridge and moved north while gradually weakening. As Olga was passing to the east of Taiwan a short wave from the China mainland gave an eastward component to the storm's motion. A low developed following the short wave and began to influence Olga, causing the typhoon to weaken. Dry air soon entered the circulation, reducing the systems overall convection. During July 5 Olga made landfall on the Kansai region of Japan, south of Osaka, as a tropical storm. The system continued into the Sea of Japan, and merged with a cold front. The remaining low tracked over South Korea before completely dissipating on July 7.
Olga was a very intense typhoon, causing an estimated ten million dollars to Japan alone. While passing through the Ryukyu Islands wind measurements were as high as 130 mph (205 km/h) on July 4. Heavy rains occurred over Japan, up to 14 inches in some areas, caused landslides and extensive flooding; killing 20. In South Korea 29 deaths were caused by the heavy rainfall associated with Olga's remnants.
Tropical Storm Pamela (Klaring)
Forming on June 28, Pamela slowly travelled towards the Philippines, and made landfall late on June 30. The tropical storm brought rains and winds to the Philippines, but no major damage was reported. Having greatly weakened after landfall, Pamela degenerated into a remnant low and dissipated over the South China Sea on July 1, just as Category 5 Super Typhoon Olga reached its peak.
Tropical Storm Ruby (Emang)
Tropical Storm Ruby formed as a disturbance east of the Philippines. It slowly traveled west-southwest, becoming a tropical storm on the 12th. It crossed the northern part of Luzon before making landfall in China on the 15th. The storm became extratropical over China, and proceeded northwest, crossing Hokkaido before dissipating over the Aleutian Islands.
Tropical Storm Sally
Tropical Storm Sally was a tropical cyclone that formed in the Western Pacific Ocean during the 1970 Pacific typhoon season . It developed from a tropical disturbance on July 19 and gradually intensified into a tropical storm. It became a tropical storm on the 21st, then became extratropical on the 22nd Sally moved generally westward, remaining at sea throughout its lifespan. The storm reached its peak intensity as a tropical storm with maximum sustained winds of 75 kilometers per hour (45 miles per hour). Sally eventually weakened and dissipated on July 23. Due to its offshore track, Tropical Storm Sally did not cause any significant impact on land. The storm primarily affected open waters, generating rough seas and strong winds in the vicinity of its path.
Tropical Storm 07W (Gading)
Tropical Storm 07W, also known in the Philippines as Gading, was a tropical cyclone that formed in the Western Pacific Ocean during the 1970 Pacific typhoon season. It originated from a tropical depression that developed on July 25. The system gradually organized and intensified, reaching tropical storm strength. 07W generally moved westward, passing the Philippine Area of Responsibility (PAR), bringing rainfall in Taiwan, and hitting Eastern China. The storm maintained its intensity for a short period before weakening and dissipating on August 2. Due to its relatively weak intensity and offshore track, 07W did not cause any significant impact on land areas but still bringing rainfall. The storm primarily affected open waters, generating rough seas and gusty winds in the vicinity of its path.
Tropical Storm 06W Tropical Storm 06W was a short-lived tropical storm that moved westward through the Philippine Sea before dissipating over the South China Sea on August 1. Due to its offshore path and relatively weak intensity, it did not cause significant impacts to land.
Tropical Storm Therese
Tropical Storm Therese remained far at sea during its life. It formed as a disturbance on the July 30, then turned northwestward and became a tropical storm, before undergoing extratropical transition and dissipating over the Bering Sea.
Tropical Storm Violet (Heling)
Tropical Storm Violet formed east of the Philippines, then traveled westward, becoming a tropical storm before making landfall on Luzon. Violet then crossed the South China Sea before making landfall in China as a weak tropical storm. It dissipated over China shortly after.
Typhoon Wilda (Iliang)
A broad surface trough developed into Tropical Storm Wilda on August 9. After drifting to the west-southwest, it turned to the north, where it reached a peak of 120 mph winds on the 12th near Okinawa. Wilda continued northward, and weakened slightly to a 105 mph typhoon before making landfall on western Kyūshū on the 14th. Wilda accelerated to the northeast, and became extratropical on the 15th. The typhoon caused heavy rain, killing 11 people.
Super Typhoon Anita
An upper-level low contributed to the formation of Tropical Depression 11W on August 16 over the northern Marianas Islands. It quickly intensified, reaching typhoon status that night. Anita's intensification rate slowed initially, but as it continued northwestward late on the 18th and 19th, Anita rapidly strengthened to a 155 mph super typhoon. It weakened as it accelerated to the north-northwest, and hit western Shikoku in Japan on the 21st as a 115 mph typhoon. Anita, which became extratropical on the 22nd, caused 23 deaths and sank 31 vessels.
Typhoon Billie (Loleng)
Typhoon Billie formed in the Philippine Sea as a weak depression. It intensified while heading northwards, becoming a tropical storm on the 23rd, a typhoon on the 25th, and reaching its maximum intensity of 110-knot winds and a 945-millibar central pressure as it passed the Ryukyu Islands on the 27th. The storm brushed South Korea as a category-1-equivalent typhoon on the 29th before making landfall in North Korea on the 30th. The remnants of Billie dissipated over the Sino-Soviet border shortly after.
Typhoon Clara
Tropical Storm Clara developed on August 26 southeast of Japan from an upper tropospheric circulation that separated from the Mid-Pacific trough. It quickly strengthened, and became a typhoon on the 27th at 31.9º North, one of only 16 Western Pacific typhoons to reach that strength north of 30ºN. Clara peaked at 95 mph before coming close to Japan, when a shortwave trough forced it sharply eastward. The storm maintained its intensity until becoming extratropical on September 3. An interesting fact about Clara was a reconnaissance mission flown into Hurricane Dot in the central Pacific also flew into Clara on the same flight, an unusual accomplishment not normally seen.
Tropical Depression Miding