Typhoon Oliwa (1997)
Encyclopedia
Typhoon Oliwa was one of a record eleven super typhoons
in the 1997 Pacific typhoon season
. It formed in the central Pacific Ocean
on September 2 to the southwest of Hawaii
, but it became a typhoon in the western Pacific. Oliwa explosively deepened
on September 8, increasing its winds from 85 mph to 160 mph in a 24 hour period. Afterward, it slowly weakened, and after passing east of Okinawa, Oliwa turned northeast and struck Japan
with winds of 80 mph (130 km/h). There, it affected 30,000 people and killed 13; thousands of houses were flooded, and some were destroyed. Offshore South Korea
, the winds and waves wrecked 28 boats, while one boat went missing with a crew of 10 people. Typhoon Oliwa dissipated on September 19 in northern Pacific Ocean near the International Date Line.
in late August 1997. The tropical disturbance organized southwest of Hawaii
, and slowly organized. On September 2, the Central Pacific Hurricane Center
(CPHC) initiated advisories on Tropical Depression Two-C about 590 miles (950 km) southwest of Johnston Island, slightly east of the International Date Line
. The depression quickly attained tropical storm status, and the CPHC gave it the name "Oliwa", meaning "Oliver" in the Hawaiian language
.
A moderately powerful ridge
persisted north of Tropical Storm Oliwa, which caused a slow west to west-northwest track. Water temperatures were slightly warmer than usual, and there was a favorable upper-level environment for strengthening. Initially, however, Oliwa was somewhat disorganized on satellite imagery, and on September 4, as it crossed the International Date Line, there may have been multiple circulations. Upon entering the western Pacific Ocean, the Joint Typhoon Warning Center
(JTWC) and the Japan Meteorological Agency
(JMA) began issuing advisories on the system. Despite the favorable conditions, further intensification was slow, and it reached typhoon status - winds of at least 75 mph (120 km/h) - on September 8. Prior to that time, Oliwa co-existed with a weak tropical cyclone that formed in a similar location in the south Pacific.
About twelve hours after reaching typhoon status, Oliwa began to undergo unexpected explosive deepening
. In a 24 hour period, the JTWC assessed the typhoon as nearly doubling in intensity, from 85 to 160 mph (135 to 260 km/h 1-min winds), while the pressure dropped 69 mbar
to a minimum of 898 mbar; based on the estimated intensity, the JTWC classified Oliwa as a super typhoon
. The JMA, which is the official agency of the western Pacific, assessed Oliwa as reaching a peak of 115 mph (185 km/h 10-min winds), with a pressure of 915 mbar. Around that time, satellite imagery indicated a possible eyewall mesovorticy
, which is a small scale rotational feature found in the eyewall of an intense tropical cyclone. Additionally, concentric eyewalls
developed in the center of Oliwa, which typically occur in strong typhoons.
After maintaining peak intensity for 36 hours, Oliwa gradually weakened as it continued to the west-northwest, during which it passed through the Northern Marianas Islands. On September 14, the typhoon slowed to the north of Okinawa, and it turned to the northeast toward Japan
. As a weakened typhoon, Oliwa moved ashore on Kyushu
with winds of 85 mph (135 km/h) late on September 15. It weakened to tropical storm strength while crossing Japan, and deteriorated further to tropical depression status on September 16. On September 17, the JTWC issued the final advisory on Oliwa while it was in the eastern portion of the Sea of Japan
. The JMA maintained advisories as the storm crossed northern Japan, and it accelerated over the open Pacific Ocean. On September 19, Oliwa dissipated near the International Date Line to the south of the Aleutian Islands.
in the Northern Marianas Islands. Sustained winds on the island reached 75 mph (120 km/h), with gusts to 85 mph (135 km/h). The winds downed two coconut trees onto a radio antenna, which left the island temporarily without contact to the outside world. On the Japan
ese island of Kyushu
, where Oliwa made landfall as a weakened typhoon, thousands of homes were flooded, and dozens were destroyed. Its slow movement caused heavy rainfall that created a mudslide in Tashiro, Kagoshima
, killing three people. Across Kagoshima Prefecture
, officials issued evacuations due to flooding, although many did not heed the warnings. In the prefecture, the typhoon destroyed 131 buildings and damaged about 1,700 more. Damage there was estimated at 14 million yen
(1997 JPY, $150,000 in 1997 USD). Across Japan, Typhoon Oliwa caused 12 fatalities and displaced a total of 30,000 people. Total damage amounted to 4.36 billion yen ($50.1 million USD). Offshore the South Korea
coast, the winds and strong waves wrecked 28 vessels, and 10 people were reported missing from one ship.
Typhoon Oliwa was one of eleven super typhoons
in the western Pacific, which broke the previous record of seven; a typical typhoon season has four super typhoons. The period of heightened activity was the result of one of the most powerful El Niño events on record. The track Oliwa was unusual, due to its origin as a cyclone from the central Pacific Ocean and its path over the Northern Marianas Islands and Japan
. The typhoon was one of only two during the season to undergo explosive deepening
, which is a decrease in barometric pressure of ≥2.5 mbar
per hour for a period of at least 12 hours. In 24 hours, the pressure dropped 69 mbar, which averages 2.9 mbar per hour; such values are usually estimated in the western Pacific using the Dvorak technique
.
The name was not retired, although due to the low activity in the central Pacific Ocean, the name will not be used for several years.
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
in the 1997 Pacific typhoon season
1997 Pacific typhoon season
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 May and November. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern...
. It formed in the central Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
on September 2 to the southwest of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, but it became a typhoon in the western Pacific. Oliwa explosively deepened
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
on September 8, increasing its winds from 85 mph to 160 mph in a 24 hour period. Afterward, it slowly weakened, and after passing east of Okinawa, Oliwa turned northeast and struck Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
with winds of 80 mph (130 km/h). There, it affected 30,000 people and killed 13; thousands of houses were flooded, and some were destroyed. Offshore South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
, the winds and waves wrecked 28 boats, while one boat went missing with a crew of 10 people. Typhoon Oliwa dissipated on September 19 in northern Pacific Ocean near the International Date Line.
Meteorological history
The origins of Typhoon Oliwa were from an unusually eastward extension of the monsoon troughMonsoon trough
The monsoon trough is that portion of the Intertropical Convergence Zone which extends into or through a monsoon circulation, as depicted by a line on a weather map showing the locations of minimum sea level pressure, and as such, is a convergence zone between the wind patterns of the southern and...
in late August 1997. The tropical disturbance organized southwest of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, and slowly organized. On September 2, the Central Pacific Hurricane Center
Central Pacific Hurricane Center
The Central Pacific Hurricane Center of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central North Pacific Basin...
(CPHC) initiated advisories on Tropical Depression Two-C about 590 miles (950 km) southwest of Johnston Island, slightly east of the International Date Line
International Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...
. The depression quickly attained tropical storm status, and the CPHC gave it the name "Oliwa", meaning "Oliver" in the Hawaiian language
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...
.
A moderately powerful ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
persisted north of Tropical Storm Oliwa, which caused a slow west to west-northwest track. Water temperatures were slightly warmer than usual, and there was a favorable upper-level environment for strengthening. Initially, however, Oliwa was somewhat disorganized on satellite imagery, and on September 4, as it crossed the International Date Line, there may have been multiple circulations. Upon entering the western Pacific Ocean, the Joint Typhoon Warning Center
Joint Typhoon Warning Center
The Joint Typhoon Warning Center is a joint United States Navy – United States Air Force task force located at the Naval Maritime Forecast Center in Pearl Harbor, Hawaii...
(JTWC) and the Japan Meteorological Agency
Japan Meteorological Agency
The or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
(JMA) began issuing advisories on the system. Despite the favorable conditions, further intensification was slow, and it reached typhoon status - winds of at least 75 mph (120 km/h) - on September 8. Prior to that time, Oliwa co-existed with a weak tropical cyclone that formed in a similar location in the south Pacific.
About twelve hours after reaching typhoon status, Oliwa began to undergo unexpected explosive deepening
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
. In a 24 hour period, the JTWC assessed the typhoon as nearly doubling in intensity, from 85 to 160 mph (135 to 260 km/h 1-min winds), while the pressure dropped 69 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
to a minimum of 898 mbar; based on the estimated intensity, the JTWC classified Oliwa as a super typhoon
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
. The JMA, which is the official agency of the western Pacific, assessed Oliwa as reaching a peak of 115 mph (185 km/h 10-min winds), with a pressure of 915 mbar. Around that time, satellite imagery indicated a possible eyewall mesovorticy
Mesovortices
Mesovortices are small scale rotational features found in convective storms, such as those found in bow echos, supercell thunderstorms and the eyewall of tropical cyclones.-Eyewall mesovortices:...
, which is a small scale rotational feature found in the eyewall of an intense tropical cyclone. Additionally, concentric eyewalls
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
developed in the center of Oliwa, which typically occur in strong typhoons.
After maintaining peak intensity for 36 hours, Oliwa gradually weakened as it continued to the west-northwest, during which it passed through the Northern Marianas Islands. On September 14, the typhoon slowed to the north of Okinawa, and it turned to the northeast toward Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. As a weakened typhoon, Oliwa moved ashore on Kyushu
Kyushu
is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....
with winds of 85 mph (135 km/h) late on September 15. It weakened to tropical storm strength while crossing Japan, and deteriorated further to tropical depression status on September 16. On September 17, the JTWC issued the final advisory on Oliwa while it was in the eastern portion of the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
. The JMA maintained advisories as the storm crossed northern Japan, and it accelerated over the open Pacific Ocean. On September 19, Oliwa dissipated near the International Date Line to the south of the Aleutian Islands.
Impact and records
While weakening after peaking in intensity, Oliwa passed about 60 miles (95 km) north of AgrihanAgrihan
Agrihan is a stratovolcano which forms an island in the Northern Mariana Islands in the Pacific Ocean. The entire island is a massive volcano which rises over from the ocean floor, and is the fifth largest in the Marianas volcanic arc. At , its summit is the highest point in Micronesia...
in the Northern Marianas Islands. Sustained winds on the island reached 75 mph (120 km/h), with gusts to 85 mph (135 km/h). The winds downed two coconut trees onto a radio antenna, which left the island temporarily without contact to the outside world. On the Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese island of Kyushu
Kyushu
is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....
, where Oliwa made landfall as a weakened typhoon, thousands of homes were flooded, and dozens were destroyed. Its slow movement caused heavy rainfall that created a mudslide in Tashiro, Kagoshima
Tashiro, Kagoshima
was a town located in Kimotsuki District, Kagoshima, Japan.On March 22, 2005 Tashiro was merged with the town of Ōnejime, also from Kimotsuki District, to form the new town of Kinkō....
, killing three people. Across Kagoshima Prefecture
Kagoshima Prefecture
is a prefecture of Japan located on the island of Kyushu. The capital is the city of Kagoshima.- Geography :Kagoshima Prefecture is located at the southwest tip of Kyushu and includes a chain of islands stretching further to the southwest for a few hundred kilometers...
, officials issued evacuations due to flooding, although many did not heed the warnings. In the prefecture, the typhoon destroyed 131 buildings and damaged about 1,700 more. Damage there was estimated at 14 million yen
Japanese yen
The is the official currency of Japan. It is the third most traded currency in the foreign exchange market after the United States dollar and the euro. It is also widely used as a reserve currency after the U.S. dollar, the euro and the pound sterling...
(1997 JPY, $150,000 in 1997 USD). Across Japan, Typhoon Oliwa caused 12 fatalities and displaced a total of 30,000 people. Total damage amounted to 4.36 billion yen ($50.1 million USD). Offshore the South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
coast, the winds and strong waves wrecked 28 vessels, and 10 people were reported missing from one ship.
Typhoon Oliwa was one of eleven super typhoons
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
in the western Pacific, which broke the previous record of seven; a typical typhoon season has four super typhoons. The period of heightened activity was the result of one of the most powerful El Niño events on record. The track Oliwa was unusual, due to its origin as a cyclone from the central Pacific Ocean and its path over the Northern Marianas Islands and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. The typhoon was one of only two during the season to undergo explosive deepening
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
, which is a decrease in barometric pressure of ≥2.5 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
per hour for a period of at least 12 hours. In 24 hours, the pressure dropped 69 mbar, which averages 2.9 mbar per hour; such values are usually estimated in the western Pacific using the Dvorak technique
Dvorak technique
The Dvorak technique is a widely used system to subjectively estimate tropical cyclone intensity based solely on visible and infrared satellite images. Several agencies issue Dvorak intensity numbers for cyclones of sufficient intensity...
.
The name was not retired, although due to the low activity in the central Pacific Ocean, the name will not be used for several years.