The 1997 Pacific typhoon season was a record-breaking season featuring eleven tropical cyclones reaching super typhoon intensity, tying the record with 1965 with the most intense tropical cyclones globally, and was the ninth and last consecutive year of above-average tropical cyclone activity that started in 1988. Its extremely high activity produced the highest ACE index ever recorded in a single tropical cyclone season. In addition, this season had ten Saffir-Simpson Category 5-equivalent tropical cyclones, the most ever recorded in a single regional tropical cyclone season. The 1997–98 El Niño event was a contributing factor to this unusually high activity. Despite this, the season produced an average number of tropical storms, spawning 28 tropical storms.
It has no official bounds; it ran year-round in 1997, but most tropical cyclones tend to form in the northwestern Pacific Ocean between May and November.Gary Padgett. May 2003 Tropical Cyclone Summary. Retrieved on 2006-08-26. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean. The first named storm, Hannah, developed on January 20 while the last named storm, Paka, dissipated on December 23. Tropical Storm Linda became the worst tropical cyclone to hit Vietnam, killing over 3,000 people.
The scope of this article is limited to the Pacific Ocean to the north of the equator between 100°E and 180th meridian. Within the northwestern Pacific Ocean, there are two agencies which assign names to tropical cyclones which can often result in a cyclone having two names. The Japan Meteorological Agency (JMA) will name a tropical cyclone if it has 10-minute sustained wind speeds of at least anywhere in the basin, while the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) assigns names to tropical cyclones which are active in the Philippine Area of Responsibility (PAR), located between 135°E and 115°E and between 5°N–25°N, regardless of whether or not a tropical cyclone has already been given a name by the JMA. Tropical depressions that are monitored by the United States' Joint Typhoon Warning Center (JTWC) are given a number with a "W" suffix.
Seasonal summary
The accumulated cyclone energy (ACE) index for the 1997 Pacific typhoon season as calculated by Colorado State University using data from the Joint Typhoon Warning Center was 570.4 units, which is the highest ACE for a single season ever recorded. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of .
The season was unusual and exceptional in the number of super typhoons that occurred in the basin. According to the Joint Typhoon Warning Center, eleven tropical cyclones attained super typhoon status, ten of which became Category 5 Super Typhoons, marking the highest number of Category 5 storms in a single season on record. Eleven typhoons reached winds of at least 135 knots. They were Isa, Nestor, Rosie, Winnie, Bing, Oliwa (from Central Pacific), Ginger, Ivan, Joan, Keith, and Paka (also from the Central Pacific). This was due to the 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. This is also due to the El Niño during that time, which tends to shift typhoon tracks east. When Severe Tropical Storm Peter made landfall in southern Japan on June 27, it marked the first time that two tropical cyclones made landfall in mainland Japan during the month of June since reliable records began in 1951.
Systems
Tropical Depression Hannah (Atring)
In early January, an area of convection developed along a near-equatorial trough just west of the International Date Line. It tracked steadily westward, and remained disorganized for about week. On January 18, deep convection increased as a low-level circulation began to form, and at 0000 UTC on January 19 it developed into Tropical Depression 01W while located to the southwest of Guam. Based on satellite imagery estimates, the Joint Typhoon Warning Center upgraded it to Tropical Storm Hannah six hours after first forming. The deep convection quickly organized into well-defined cyclonic bands, and early on January 20 Hannah attained its peak intensity of 60 mph near the island of Yap. Increased southeasterly wind shear weakened the storm, leaving its dwindling convection situated along the northern portion of the circulation. Interaction with a large and powerful extratropical cyclone left the storm moving erratically, and on January 22 Hannah weakened to tropical depression status. Its motion turned to a steady southwestward motion, and on January 27 Hannah dissipated a short distance east of the Philippine island of Mindanao.
Near the end of its duration, the Philippine Atmospheric, Geophysical and Astronomical Services Administration began issuing warnings on Hannah when was a tropical depression; the institution named the storm Tropical Depression Atring. Hannah was not considered a tropical storm by the Japan Meteorological Agency. There were no reports of significant damage or injuries.
Typhoon Isa
Isa developed from a disturbance in the monsoon trough near the Caroline Islands on April 12. It moved erratically at first, though after attaining tropical storm status it curved westward due to the subtropical ridge to its north. Isa very gradually intensified, and on April 20 the typhoon reached peak 1-min winds of , as reported by the Joint Typhoon Warning Center; Japan Meteorological Agency reported maximum 10-min winds of . After turning northward, it accelerated to the northeast, and merged with a larger extratropical cyclone on April 24.
Early in its duration, Isa caused light rainfall and moderate winds on Pohnpei. Later, a stationary rainband from the typhoon dropped heavy precipitation on Guam during its dry season. Damage in the Guam National Weather Service area of responsibility totaled $1 million (1997 USD, $1.3 million 2006 USD), the majority of it from crop damage. No deaths were reported.
Tropical Storm Jimmy
A low-level equatorial westerly wind system developed an area of convection on April 18, the same system that previously developed Typhoon Isa. It drifted west-northwestward, and on April 21 separated from the westerly wind system. At 0400 UTC on April 22, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert on the system, and two hours later the JTWC issued the first warning on Tropical Storm Jimmy about southeast of Guam. Coinciding with its first warning, the Japan Meteorological Agency (JMA) classified it as a tropical depression.
Jimmy continued northwestward through a break in the subtropical ridge caused by Isa, and it steadily intensified as it tracked through an area of light vertical wind shear. It recurved to the northeast, and shortly after reaching its westernmost point Jimmy attained its peak intensity of 55 mph on April 24. Conversely, JMA assessed Jimmy as remaining a minimal tropical storm throughout its duration. After maintaining peak winds for about 18 hours, to increased southwesterly winds aloft quickly weakened the storm, and late on April 25 JTWC issued its final advisory on Jimmy after its low-level circulation center became completely exposed from the deep convection. On April 26, Jimmy was absorbed by an approaching frontal trough over the open Pacific Ocean. The storm had little effects on land.
Tropical Storm Kelly
A low-level equatorial trough developed an area of convection on May 4. The low strengthened as it became more organized over the next two days. Late on May 5, the JTWC issued a TCFA and the system was declared Tropical Depression 04W shortly after. The depression slowly intensified and was upgraded to a Tropical Storm early on May 8 and was named Kelly. Kelly was able to intensify slightly before strong vertical wind shear displaced the center, weakening Kelly. Kelly was downgraded to a Tropical Depression on May 10 and the remnant circulation dissipated the next day.
Tropical Storm Levi (Bining)
Tropical Depression 5W drifted eastward through the Philippines in late May. The depression continued northeastward, becoming a tropical storm, and transitioning to an extratropical storm on May 30.Joint Typhoon Warning Center. Tropical Storm Levi. Retrieved on 2007-01-07. In the Philippines, Levi killed 53 people and displaced 210,000 others.
From May 26–29, Philippine Atmospheric, Geophysical and Astronomical Services Administration tracked the storm, and named it Bining.
Typhoon Marie
On May 23, a large area of convection grouped together to form a low pressure, over the Mariana Islands. It strengthened into a tropical depression on May 26, before intensifying into a category 1 typhoon 2 days later. Marie then reached its peak intensity on May 31, as a category 2 typhoon, before undergoing an Eyewall replacement cycle. The storm developed double eyewalls during the process. On June 2, the system degenerated into an extratropical cyclone.
Typhoon Nestor
In late May, an area of convection developed near the Marshall Islands, and rapidly became a low-pressure area. On June 1, the low-pressure area organized into a tropical depression. Nestor intensified into a category 1 typhoon on June 7, as it started to affect the Mariana Islands. Nestor continued to intensify, and on June 10, Nestor reached its peak intensity as a category 5 super typhoon, as the storm began to affect the Northern Mariana Islands. At this time, Nestor began showing annular characteristics. Nestor began to weaken slowly, as typical annular typhoons do, while it developed an eye measuring 65 kilometers across. On June 15, Nestor transitioned into an extratropical cyclone.
Typhoon Opal (Kuring)
From June 15–18, Philippine Atmospheric, Geophysical and Astronomical Services Administration tracked the storm, and named it Kuring.
In preparation for Opal, Japanese airlines cancelled 107 domestic flights and port officials halted all ferry traffic. Throughout Japan, 6,750 schools were closed due to the typhoon. One person drowned after being knocked off his boat by rough seas while trying to secure it at port. Heavy rains flooded streets throughout the region. The storm triggered 14 landslides, flooded 50 homes and cut power to 800 residences. In all, three people were killed in Japan by Typhoon Opal. Damages totaled to ¥392 million (US$3.24 million).
Typhoon Peter (Daling)
From June 22–26, PAGASA tracked the storm, and named it Daling.
Ahead of the storm, international and domestic flights were cancelled throughout Japan and ferry service was suspended. Heavy rains produced by the storm triggered landslides throughout Japan, resulting in three fatalities. A landslide caused a train derailment that left 28 people injured after covering the tracks. One of the fatalities from the storm was that of a United States soldier stationed in Iwakuni. The JMA estimated that upwards of of rain fell due to Typhoon Peter. Damages totaled to ¥231.6 million (US$1.91 million).
Typhoon Rosie (Elang)
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.Joint Typhoon Warning Center. Super Typhoon Rosie (10W). Retrieved on 2007-01-07. In Japan, five people were killed and 1,200 were displaced by the storm. Damages totaled to ¥11.1 billion (US$91.7 million).
From July 22–26, PAGASA tracked the storm, and named it Elang.
Tropical Storm Scott