1997 Pacific typhoon season: Difference between revisions

Template:Infobox typhoon season nopic The 1997 Pacific typhoon season has no official bounds; it ran year-round in 1997, 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 date line. Storms that form east of the date line and north of the equator are called hurricanes; see 1997 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.

1997 was the year of the super typhoons, with eleven typhoons reaching winds of at least 135 knots. They were Isa, Nestor, Rosie, Winnie, Bing, Oliwa (from Central Pacific), Ginger, Ivan, Joan, Keith, and Paka (from Central Pacific). This was due to the strong El Niño of 1997-1998, which contributed to the record amounts of not only super typhoons but also tropical storms in the Western and Eastern Pacific. Fortunately, most of the stronger systems remained at sea. Only storms that are notable in some way are mentioned below.

Tropical Depression 5W drifted eastward through the Philippines in late May. The heavy rain it brought caused mudslides that killed 33 people. The depression continued northeastward, becoming a tropical storm, and transitioning to an extratropical storm on May 30.

On July 18, Tropical Depression 10W formed near Caroline Islands. 10W was upgraded to Tropical Storm Rosie and became a Category 5 Super Typhoon on July 22. Rosie moved northward and began to weaken. Rosie made a landfall as a Category 1 typhoon at Shikoku, Japan on July 26. Two people were killed because of Rosie.

On August 5, a tropical depression formed near the Marshall Islands. It headed northwestward, slowly strengthening to a tropical storm on the 9th. Intensification became more rapid as conditions became more favorable, and Winnie reached typhoon strength on the 10th. 2 days later, it became the 4th Super Typhoon of the season with peak winds of 160 mph. Soon after, the eye became ragged and large, with an outer eyewall reaching 200 miles in diameter. On the 18th, a minimal Typhoon Winnie passed north of Taiwan and hit eastern China, where it winded down until dissipating on the 19th. The remnant continued northeastward, bringing heavy rain and damage across China until the 23rd. Winnie caused 64 deaths, 39 of which were in Taiwan from the heavy rain.

On August 28, the monsoon formed into Tropical Depression 2C in the Central Pacific. It headed slowly westward, becoming a tropical storm on the 3rd. It crossed the International Date Line, and continued to slowly strengthen to become a typhoon on the 8th. Oliwa rapidly strengthened on the 9th to reach a peak of 160 mph winds; the 6th Super Typhoon of the year. Oliwa slowly weakened as it moved westward, and hit Japan on the 15th and 16th. It turned to the northeast, and dissipated on the 17th after causing 7 deaths and widespread damage from flooding.

Two near-equatorial troughs of low pressure, having formed from westerly low-level winds, developed into Tropical Depressions 27W and 28W on October 9 and October 11th, respectively. Both poorly organized, they headed generally westward without much convection. On the 13th, 27W became Tropical Storm Ivan and on the 14th, 28W became Tropical Storm Joan. The two were within 500 nautical miles (930 km) of each other, but they were separate enough to strengthen on their own. On the 15th, while crossing the Northern Mariana Islands, they both reached typhoon intensity. Rapid intensification came soon after, and Ivan and Joan became the 8th and 9th Super Typhoons of the year on the 17th. The two underwent the Fujiwhara effect, bringing Ivan more westerly and Joan more northerly. After reaching peaks of 300 km/h (185 mph) winds within 12 hours of each other, they slowly weakened to Category 4's. Ivan struck the northern Philippines at this intensity causing 1 death, while Joan restrengthened to a Category 5. They both turned to the northeast, and slowly dissipated.

How they reached their extreme intensities are unknown. When two systems are relatively close to each other, one typically shears the other. Here, they both maintained Category 5 intensity for at least a day within a relatively close distance of each other. The monsoon trough, which typically helps intensify Western Pacific typhoons, was absent from these storms. Pressures were higher than normal, and the initial disturbances were very poorly organized. Regardless, they are among the strongest Super Typhoons of the world with 300 km/h (185 mph) winds each.

The tenth of eleven TCs to attain super typhoon intensity in the western North Pacific during 1997, Keith formed at low latitudes in the Marshall Islands. It was one of ten TCs which formed east of 160° E and south of 20° N — within the "El Niño". Keith was a recurving TC which passed between the Islands of Rota and Tinian (only 50 nm (93 km) apart) on the west-bound leg of its recurving track. NEXRAD imagery from Guam indicated the eye wall cloud of Keith never touched land as it threaded the narrow channel between these two islands. As such, the Mariana Islands were spared the full force of Keith Keith's compact wind and cloud structure were revealed by Guam's NEXRAD Equatorial westerly winds bounded by twin near-equatorial troughs preceded the formation of Keith and a Southern Hemisphere twin.

Keith's Maximum sustained winds were 190 mph and had a minimum pressure of 872.

Typhoon Linda, after moving through the Philippines and the South China Sea, hit the Malay Peninsula on November 3. It restrengthened in the Bay of Bengal, but vertical shear caused Linda to dissipate on the 9th. Linda caused 330 deaths from flooding and heavy damage.

The final super typhoon of the year developed in the Central Pacific on November 28. It moved westward, strengthening into a tropical storm before crossing the International Date Line on December 7. Conditions were marginally favorable for development, and Paka remained a tropical storm until the 10th, when it was able to become a typhoon. 5 days later, Paka reached Super Typhoon strength, the 11th of the year. The next day it crossed over Guam, and on the 18th, Paka reached a peak of 185 mph winds. After causing major damage across the Western Pacific islands, Paka rapidly weakened and dissipated on the 22nd.

Western North Pacific tropical cyclones were named by the Joint Typhoon Warning Center. The first storm of 1997 was named Hannah and the final one was named Mort.

Two central pacific storms, Tropical Storms Oliwa and Paka, crossed into this basin. They became Typhoons Oliwa and Paka, keeping their original name and "C" suffix.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) uses its own naming scheme for tropical cyclones within its area of responsibility. Lists are recycled every four years. This is the same list used for the 1993 season.

• 1997 Pacific hurricane season
• 1997 Atlantic hurricane season
• 1997-98 Southern Hemisphere tropical cyclone season

• Typhoon2000 Philippine typhoon website.
• Philippine Area of Responsibility.
• Joint Typhoon Warning Center.
• Meaning of Tokyo Typhoon Centre names.

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