Typhoon Keith (1997)
Encyclopedia
Typhoon Keith was the tenth of a record eleven super typhoons to develop during the unusually intense 1997 Pacific typhoon season
. Originating from a near-equatorial
trough
on October 26, the precursor depression to Keith slowly organized into a tropical storm. After two days of gradual strengthening, the storm underwent a period of rapid intensification
on October 30 as winds increased to 195 km/h (120 mph). On November 1, the storm further intensified into a super typhoon
and later attained peak winds of 285 km/h (180 mph). The following day, the powerful storm passed between Rota
and Tinian
in the Northern Mariana Islands
. After fluctuating in strength over the following few days, a steady weakening trend established itself by November 5 as the typhoon accelerated towards the northeast. On October 8, Keith transitioned into an extratropical cyclone
and was last noted early the following day near the International Dateline.
Despite Typhoon Keith's close passage to the islands of Rota and Tinian as a powerful storm, neither island received sustained winds over 160 km/h (105 mph). However, these winds resulted in significant damage across the island chain. More than 800 homes were damaged or destroyed by the storm and losses amounted to $15 million (1997 USD). There were no reports of fatalities in relation to the storm; however, one person was injured.
trough
near the Marshall Islands
. Along with its Southern Hemisphere twin, convection
persisted around a weak low-level circulation, beginning on October 18. Slowly tracking westward, the system remained fairly disorganized before conditions allowed it to develop. By October 26, convection consolidated around the center of circulation and symmetrical outflow
became established over the storm. Later that day, the JTWC issued a Tropical Cyclone Formation Alert
(TCFA) for the system as they anticipated development
into a tropical cyclone
. Hours later, the Japan Meteorological Agency
(JMA) began monitoring the system as a tropical depression. Despite favorable conditions, the low initially failed to develop further, prompting the issuance of a second TCFA on October 27. Later that day, the JTWC issued their first advisory on the depression, classifying it as 29W.
Early on October 28, the depression intensified into a tropical storm, at which time it was named Keith by the JTWC. Tracking west-northwestward in response to a subtropical ridge
, the storm slowly intensified at roughly half the rate initially forecast. However, on October 30, the storm suddenly underwent a period of rapid intensification
, with sustained winds increasing from 100 km/h (65 mph) to 195 km/h (120 mph) in a 24 hour span. Additionally, the barometric pressure decreased by 43 mbar
(hPa
; 1.27 inHg) during this time. Throughout the following day, the typhoon continued to intensify, becoming a super typhoon – a storm with winds of at least 240 km/h (150 mph) – late on October 31. Later, the system attained its peak winds of 285 km/h (180 mph) and an estimated pressure of 878 mbar (hPa; 25.93 inHg). According to the JMA, however, Keith's peak ten-minute sustained winds were 205 km/h (125 mph) and the pressure was 910 mbar (hPa; 26.87 inHg).
Maintaining super typhoon status, Keith moved through the Northern Mariana Islands
between 0600–1200 UTC
on November 2 with winds of 260 km/h (160 mph). The center of the typhoon moved between the islands of Rota
and Tinian
; however, it was discovered that the storm had a very compact field of intense hurricane-force winds, estimated to be 55 km (35 mi) across. After moving through the islands, Keith briefly weakened below super typhoon status on November 3 as the eye became partially obscured due to an eyewall replacement cyclone
. However, it re-attained winds of 250 km/h (155 mph) the following day as it began to turn towards the north and later northeast. Once the storm completed its turn, Keith accelerated and steadily weakened as it entered the westerly flow north of the ridge previously steering it westward. Early on October 8, the storm transitioned into an extratropical cyclone
as it was downgraded to a tropical storm. The extratropical remnants of Keith were last noted by the JMA on October 9 near the International Dateline.
.
On November 2, Typhoon Keith passed through the 95 km (60 mi) wide channel between Rota and Tinian. Despite the storm's close passage between both islands, the maximum sustained winds above 115 mph (185 km/h) did not extend far enough out to reach either island. However, maximum sustained winds on Saipan were 158 km/h (98 mph) with gust to 175 km/h (109 mph). On Rota, winds reached 93 km/h (58 mph) with gust to 130 km/h (81 mph). On Tinian winds reached 111 km/h (69 mph) with gust to 130 km/h (81 mph). The strongest winds reported across Guam were 66 km/h (41 mph) with gust to 101 km/h (63 mph).
Across the Northern Mariana Islands, more than 800 homes were damaged or destroyed and power was lost to most of the islands, leaving roughly 25,000 people without electricity. Most of the damage took place on Saipan
, where 130 homes were destroyed, 436 had major damage, and 226 others received minor damage. On Rota, 24 homes were destroyed and 156 others were damaged to varying degrees. Despite the severity of damage, there were no reports of loss of life and only one injury in relation to the typhoon. Throughout the Northern Mariana Islands, monetary losses from Keith amounted to $15 million (1997 USD).
In the wake of the typhoon, President Bill Clinton
declared the Mariana Islands as a disaster area, allowing the affected islands to receive government aid. Red Cross workers were deployed to the islands to assist with relief efforts days after the storm. Typhoon Keith was one of 23 events in the United States during the 1997-98 El Niño event which warrented federal aid; combined, the disasters cost $289.1 million, of which $5,813,784 was attributed to Keith.
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...
. Originating from a near-equatorial
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
on October 26, the precursor depression to Keith slowly organized into a tropical storm. After two days of gradual strengthening, the storm underwent a period of rapid intensification
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 October 30 as winds increased to 195 km/h (120 mph). On November 1, the storm further intensified into 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...
and later attained peak winds of 285 km/h (180 mph). The following day, the powerful storm passed between Rota
Rota (island)
Rota also known as the "peaceful island", is the southernmost island of the United States Commonwealth of the Northern Mariana Islands and the second southernmost of the Marianas Archipelago. It lies approximately 40 miles north-northeast of the United States territory of Guam...
and Tinian
Tinian
Tinian is one of the three principal islands of the Commonwealth of the Northern Mariana Islands.-Geography:Tinian is about 5 miles southwest of its sister island, Saipan, from which it is separated by the Saipan Channel. It has a land area of 39 sq.mi....
in the Northern Mariana Islands
Northern Mariana Islands
The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands , is a commonwealth in political union with the United States, occupying a strategic region of the western Pacific Ocean. It consists of 15 islands about three-quarters of the way from Hawaii to the Philippines...
. After fluctuating in strength over the following few days, a steady weakening trend established itself by November 5 as the typhoon accelerated towards the northeast. On October 8, Keith transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
and was last noted early the following day near the International Dateline.
Despite Typhoon Keith's close passage to the islands of Rota and Tinian as a powerful storm, neither island received sustained winds over 160 km/h (105 mph). However, these winds resulted in significant damage across the island chain. More than 800 homes were damaged or destroyed by the storm and losses amounted to $15 million (1997 USD). There were no reports of fatalities in relation to the storm; however, one person was injured.
Meteorological history
Typhoon Keith originated during the third week of October 1997 from a near-equatorialEquator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
near the Marshall Islands
Marshall Islands
The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...
. Along with its Southern Hemisphere twin, convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
persisted around a weak low-level circulation, beginning on October 18. Slowly tracking westward, the system remained fairly disorganized before conditions allowed it to develop. By October 26, convection consolidated around the center of circulation and symmetrical outflow
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather...
became established over the storm. Later that day, the JTWC issued a Tropical Cyclone Formation Alert
Tropical Cyclone Formation Alert
A Tropical Cyclone Formation Alert is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Naval Maritime Forecast Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone forming from a tropical disturbance that has been...
(TCFA) for the system as they anticipated development
Tropical cyclogenesis
Tropical cyclogenesis is the term that describes the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which mid-latitude cyclogenesis occurs...
into a tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
. Hours later, 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 monitoring the system as a tropical depression. Despite favorable conditions, the low initially failed to develop further, prompting the issuance of a second TCFA on October 27. Later that day, the JTWC issued their first advisory on the depression, classifying it as 29W.
Early on October 28, the depression intensified into a tropical storm, at which time it was named Keith by the JTWC. Tracking west-northwestward in response to a subtropical ridge
Subtropical ridge
The subtropical ridge is a significant belt of high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere. It is characterized by mostly calm winds, which acts to reduce air quality under its axis by causing fog overnight, and haze during...
, the storm slowly intensified at roughly half the rate initially forecast. However, on October 30, the storm suddenly underwent a period of rapid intensification
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...
, with sustained winds increasing from 100 km/h (65 mph) to 195 km/h (120 mph) in a 24 hour span. Additionally, the barometric pressure decreased by 43 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...
(hPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
; 1.27 inHg) during this time. Throughout the following day, the typhoon continued to intensify, becoming a super typhoon – a storm with winds of at least 240 km/h (150 mph) – late on October 31. Later, the system attained its peak winds of 285 km/h (180 mph) and an estimated pressure of 878 mbar (hPa; 25.93 inHg). According to the JMA, however, Keith's peak ten-minute sustained winds were 205 km/h (125 mph) and the pressure was 910 mbar (hPa; 26.87 inHg).
Maintaining super typhoon status, Keith moved through the Northern Mariana Islands
Northern Mariana Islands
The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands , is a commonwealth in political union with the United States, occupying a strategic region of the western Pacific Ocean. It consists of 15 islands about three-quarters of the way from Hawaii to the Philippines...
between 0600–1200 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on November 2 with winds of 260 km/h (160 mph). The center of the typhoon moved between the islands of Rota
Rota (island)
Rota also known as the "peaceful island", is the southernmost island of the United States Commonwealth of the Northern Mariana Islands and the second southernmost of the Marianas Archipelago. It lies approximately 40 miles north-northeast of the United States territory of Guam...
and Tinian
Tinian
Tinian is one of the three principal islands of the Commonwealth of the Northern Mariana Islands.-Geography:Tinian is about 5 miles southwest of its sister island, Saipan, from which it is separated by the Saipan Channel. It has a land area of 39 sq.mi....
; however, it was discovered that the storm had a very compact field of intense hurricane-force winds, estimated to be 55 km (35 mi) across. After moving through the islands, Keith briefly weakened below super typhoon status on November 3 as the eye became partially obscured due to an eyewall replacement cyclone
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...
. However, it re-attained winds of 250 km/h (155 mph) the following day as it began to turn towards the north and later northeast. Once the storm completed its turn, Keith accelerated and steadily weakened as it entered the westerly flow north of the ridge previously steering it westward. Early on October 8, the storm transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
as it was downgraded to a tropical storm. The extratropical remnants of Keith were last noted by the JMA on October 9 near the International Dateline.
Impact
Prior to the storm's arrival, more than 1,000 residents evacuated to storm shelters set up in the Northern Marianas Islands. Women who were more than seven months pregnant were also urged to check-in to hospitals, as doctors warned that changes in pressure could trigger laborChildbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
.
On November 2, Typhoon Keith passed through the 95 km (60 mi) wide channel between Rota and Tinian. Despite the storm's close passage between both islands, the maximum sustained winds above 115 mph (185 km/h) did not extend far enough out to reach either island. However, maximum sustained winds on Saipan were 158 km/h (98 mph) with gust to 175 km/h (109 mph). On Rota, winds reached 93 km/h (58 mph) with gust to 130 km/h (81 mph). On Tinian winds reached 111 km/h (69 mph) with gust to 130 km/h (81 mph). The strongest winds reported across Guam were 66 km/h (41 mph) with gust to 101 km/h (63 mph).
Across the Northern Mariana Islands, more than 800 homes were damaged or destroyed and power was lost to most of the islands, leaving roughly 25,000 people without electricity. Most of the damage took place on Saipan
Saipan
Saipan is the largest island of the United States Commonwealth of the Northern Mariana Islands , a chain of 15 tropical islands belonging to the Marianas archipelago in the western Pacific Ocean with a total area of . The 2000 census population was 62,392...
, where 130 homes were destroyed, 436 had major damage, and 226 others received minor damage. On Rota, 24 homes were destroyed and 156 others were damaged to varying degrees. Despite the severity of damage, there were no reports of loss of life and only one injury in relation to the typhoon. Throughout the Northern Mariana Islands, monetary losses from Keith amounted to $15 million (1997 USD).
In the wake of the typhoon, President Bill Clinton
Bill Clinton
William Jefferson "Bill" Clinton is an American politician who served as the 42nd President of the United States from 1993 to 2001. Inaugurated at age 46, he was the third-youngest president. He took office at the end of the Cold War, and was the first president of the baby boomer generation...
declared the Mariana Islands as a disaster area, allowing the affected islands to receive government aid. Red Cross workers were deployed to the islands to assist with relief efforts days after the storm. Typhoon Keith was one of 23 events in the United States during the 1997-98 El Niño event which warrented federal aid; combined, the disasters cost $289.1 million, of which $5,813,784 was attributed to Keith.