Cyclone Kathy
Encyclopedia
Severe Tropical Cyclone Kathy was a powerful tropical cyclone
that devastated the Sir Edward Pellew Group of Islands
in March 1984. Originating from a tropical low off the southern coast of Papua New Guinea
. Tracking westward, the system attained gale-force winds by 18 March before striking the Cape York Peninsula
. After crossing the area, Kathy entered the Gulf of Carpentaria
where environmental conditions favoured significant development. On 22 March, the storm attained its peak intensity as a Category 5 severe tropical cyclone (Australian tropical cyclone intensity scale) with ten-minute sustained winds of 205 km/h (125 mph). By this time, the storm had been tracking towards the southwest and struck the Sir Edward Pellew Group of Islands later on 22 March before moving over the Australian mainland as a slightly weaker system. Once over land, Kathy rapidly degraded, losing gale-force winds within 24 hours; the storm dissipated over the Northern Territory
on 24 March.
Moving through the Pellew Islands as a powerful cyclone, Kathy generated a maximum storm surge
of 4.2 metres (13.8 ft) and winds exceeding 232 km/h (144.2 mph). Offshore, 20 vessels were affected, one of which sank and resulted in the death of its captain. In mainland Australia, the system struck a relatively sparsely populated area, with only Borroloola being significantly impacted by the cyclone. Additionally, mangrove
s at along the McArthur River
sustained substantial damage. Overall, losses from the storm were placed at A$12 million (A$30.5 million 2011 AUD; US$24.1 million 2011 USD). Following its usage, the name Kathy was retired and will never be used again to name an Australian cyclone.
began monitoring a tropical low
off the southern coast of Papua New Guinea
for possible development into a tropical cyclone
. Over the following day, the system quickly developed and attained gale-force winds as it neared the Cape York Peninsula
. Attaining a pressure of 990 hPa
(mbar
; 29.23 inHg), the weak system made landfall
just north of Weipa, Queensland
on 19 March before losing strength. Though already considered a tropical cyclone for two days by the Bureau, the Joint Typhoon Warning Center
(JTWC) issued their first advisory on the system just prior to its landfall; however, they considered it to be a tropical depression rather than a storm. After roughly 12 hours over land, a weakened Kathy emerged over the warm waters of the Gulf of Carpentaria
on 20 March. Once over water, the JTWC classified the system as a tropical storm. Turning southwestward, the storm entered a region favoring significant development
and soon began a period of rapid intensification
.
Intensification took place through 22 March as convection
deepened around Kathy's centre and a well-defined eye
formed. The system reached its peak strength as a Category 5 severe tropical cyclone on the Australian tropical cyclone intensity scale with ten-minute sustained winds
of 205 km/h (125 mph). Operational analysis of the storm indicated a minimum pressure of 920 hPa (mbar; 27.17 inHg); however, a reassessment in 2009 concluded that Kathy's pressure had been slightly lower, bottoming out at 916 hPa (mbar; 27.05 inHg). Additionally, the JTWC assessed the system to have been slightly stronger, estimating peak one-minute sustained winds at 250 km/h (155 mph). At this time, the storm was estimated to have a Dvorak technique
rating of 7.0, equivalent to a Category 5 on the Saffir–Simpson Hurricane Scale;
As Cyclone Kathy neared the Australia coastline later on 22 March, it began to weaken as it interacted with land. Radar imagery
depicted the system as having an eye 10.8 km (6.7 mi) in diameter. Roughly 5 hours after peaking, the storm passed directly over the Sir Edward Pellew Group of Islands
, resulting in a degrading structure. Near midnight, the system weakened to a Category 4 cyclone and made landfall in a remote region near Borroloola. Based on a wind gust to sustained ratio of 1.4, Kathy was estimated to have moved onshore with winds between 165 and 185 km/h (105 and 115 mph). In the hours after landfall, Kathy rapid weakened, no longer retaining gale-force winds once 200 km (124.3 mi) away from the Gulf on 23 March. Later that day, the system turned south-westward and persisted for another 24 hours before dissipating.
, Kathy brought moderate rainfall and strong winds to much of the region. No measurements from the centre of the storm were made, although a wind gust of 60 km/h (37.3 mph) was recorded in Batavia Downs, Queensland, about 55 km (34.2 mi) south-southeast of the cyclone. Between 18 and 21 March, a total of 126.7 mm (5 in) of rain fell near Batavia Downs. Due to the relatively low intensity of the storm, damage was minimal and mainly confined to trees.
Striking the Sir Edward Pellew Group of Islands
as a high-end Category 4 cyclone, Kathy wrought significant damage in the region. A storm surge
of 4.2 m (13.8 ft) struck Vanderlin Island
, destroying much of the nesting ground for sea turtle
s. Winds were recorded up to 232 km/h (144.2 mph) before the station's anemometer
failed. Several camps across the islands were destroyed. Offshore, 20 vessels were caught in the storm, one of which sank and three others ran aground. One person perished on board the ship that sank during the storm. Losses sustained by the ships were placed at A$5 million (A$12.7 million 2011 AUD; US$10 million 2011 USD).
Though a powerful storm, only light to moderate rains fell along the cyclone's path with totals generally less than 100 mm (3.9 in). The remnants, however, triggered thunderstorms near Tennant Creek
that produced 325 mm (12.8 in) of rain in 24 hours. Reports indicate that several sea turtles and dugong
s were washed up to 8 km (5 mi) inland by Kathy's surge. The only population center significantly affected by the storm was Borroloola, where moderate to severe damage took place. At least one home was destroyed and many more were damaged in the town. Along the mouth of the McArthur River
, near where Kathy struck the mainland, the combination of severe winds and storm surge killed 80% (±20%) of the Rhizophoraceae
mangrove
trees in the region. Along the entire length of the river, 45% (±15.3%) of the Rhizophoraceae, Bruguiera
and Ceriops
as well as 18.5% (±11.4%) of the Exoecaria agallocha, Lumnitzera racemosa
and Avicennia marina
perished. In all, losses from the storm were placed at A$12 ,million (A$30.5 million 2011 AUD; US$24.1 million 2011 USD).
In the wake of the storm, Australian Prime Minister Bob Hawke
promised residents of Borroloola that they would receive all possible help from the government. About 400 people in the town were left homeless by Cyclone Kathy. By 25 March, an Royal Australian Air Force
aircraft was sent to the region carrying emergency supplies for sheltering displaced persons. Two patrol boats from the Royal Australian Navy
were also sent to assist in relief efforts. One brought fuel and medical supplies and the other assisted trawlers set adrift or grounded by the storm. Following its usage, the name Kathy was retired from Brisbane's
list of cyclone names and will never be used again.
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...
that devastated the Sir Edward Pellew Group of Islands
Sir Edward Pellew Group of Islands
The Sir Edward Pellew Group of Islands is situated in the south-west corner of the Gulf of Carpentaria, off the northern coast of Australia.-History:They were named in 1802 by Matthew Flinders in honour of Sir Edward Pellew, a fellow naval officer...
in March 1984. Originating from a tropical low off the southern coast of Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
. Tracking westward, the system attained gale-force winds by 18 March before striking the Cape York Peninsula
Cape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
. After crossing the area, Kathy entered the Gulf of Carpentaria
Gulf of Carpentaria
The Gulf of Carpentaria is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the Arafura Sea...
where environmental conditions favoured significant development. On 22 March, the storm attained its peak intensity as a Category 5 severe tropical cyclone (Australian tropical cyclone intensity scale) with ten-minute sustained winds of 205 km/h (125 mph). By this time, the storm had been tracking towards the southwest and struck the Sir Edward Pellew Group of Islands later on 22 March before moving over the Australian mainland as a slightly weaker system. Once over land, Kathy rapidly degraded, losing gale-force winds within 24 hours; the storm dissipated over the Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
on 24 March.
Moving through the Pellew Islands as a powerful cyclone, Kathy generated a maximum storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
of 4.2 metres (13.8 ft) and winds exceeding 232 km/h (144.2 mph). Offshore, 20 vessels were affected, one of which sank and resulted in the death of its captain. In mainland Australia, the system struck a relatively sparsely populated area, with only Borroloola being significantly impacted by the cyclone. Additionally, mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
s at along the McArthur River
McArthur River
The McArthur River is a river in the Northern Territory of Australia which flows into the Gulf of Carpentaria at Port McArthur, opposite the Sir Edward Pellew Group of Islands. The river was named by Ludwig Leichhardt while he explored the area in 1845...
sustained substantial damage. Overall, losses from the storm were placed at A$12 million (A$30.5 million 2011 AUD; US$24.1 million 2011 USD). Following its usage, the name Kathy was retired and will never be used again to name an Australian cyclone.
Meteorological history
On 16 March 1984, the Bureau of MeteorologyBureau of Meteorology
The Bureau of Meteorology is an Executive Agency of the Australian Government responsible for providing weather services to Australia and surrounding areas. It was established in 1906 under the Meteorology Act, and brought together the state meteorological services that existed before then...
began monitoring a tropical low
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
off the southern coast of Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
for possible development 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...
. Over the following day, the system quickly developed and attained gale-force winds as it neared the Cape York Peninsula
Cape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
. Attaining a pressure of 990 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...
(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...
; 29.23 inHg), the weak system made landfall
Landfall (meteorology)
Landfall is the event of a tropical cyclone or a waterspout coming onto land after being over water. When a waterspout makes landfall it is reclassified as a tornado, which can then cause damage inland...
just north of Weipa, Queensland
Weipa, Queensland
Weipa is the largest town on the Gulf of Carpentaria coast of the Cape York Peninsula in Queensland, Australia. At the 2006 census, Weipa had a population of 2,830; the largest community on Cape York Peninsula. It exists because of the enormous bauxite deposits along the coast...
on 19 March before losing strength. Though already considered a tropical cyclone for two days by the Bureau, 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) issued their first advisory on the system just prior to its landfall; however, they considered it to be a tropical depression rather than a storm. After roughly 12 hours over land, a weakened Kathy emerged over the warm waters of the Gulf of Carpentaria
Gulf of Carpentaria
The Gulf of Carpentaria is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the Arafura Sea...
on 20 March. Once over water, the JTWC classified the system as a tropical storm. Turning southwestward, the storm entered a region favoring significant 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...
and soon began 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...
.
Intensification took place through 22 March as 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...
deepened around Kathy's centre and a well-defined eye
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...
formed. The system reached its peak strength as a Category 5 severe tropical cyclone on the Australian tropical cyclone intensity scale with ten-minute sustained winds
Maximum sustained wind
The maximum sustained winds associated with a tropical cyclone are a common indicator of the intensity of the storm. Within a mature tropical cyclone, they are found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are...
of 205 km/h (125 mph). Operational analysis of the storm indicated a minimum pressure of 920 hPa (mbar; 27.17 inHg); however, a reassessment in 2009 concluded that Kathy's pressure had been slightly lower, bottoming out at 916 hPa (mbar; 27.05 inHg). Additionally, the JTWC assessed the system to have been slightly stronger, estimating peak one-minute sustained winds at 250 km/h (155 mph). At this time, the storm was estimated to have a 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...
rating of 7.0, equivalent to a Category 5 on the Saffir–Simpson Hurricane Scale;
As Cyclone Kathy neared the Australia coastline later on 22 March, it began to weaken as it interacted with land. Radar imagery
Weather radar
Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...
depicted the system as having an eye 10.8 km (6.7 mi) in diameter. Roughly 5 hours after peaking, the storm passed directly over the Sir Edward Pellew Group of Islands
Sir Edward Pellew Group of Islands
The Sir Edward Pellew Group of Islands is situated in the south-west corner of the Gulf of Carpentaria, off the northern coast of Australia.-History:They were named in 1802 by Matthew Flinders in honour of Sir Edward Pellew, a fellow naval officer...
, resulting in a degrading structure. Near midnight, the system weakened to a Category 4 cyclone and made landfall in a remote region near Borroloola. Based on a wind gust to sustained ratio of 1.4, Kathy was estimated to have moved onshore with winds between 165 and 185 km/h (105 and 115 mph). In the hours after landfall, Kathy rapid weakened, no longer retaining gale-force winds once 200 km (124.3 mi) away from the Gulf on 23 March. Later that day, the system turned south-westward and persisted for another 24 hours before dissipating.
Impact
In Far North QueenslandFar North Queensland
Far North Queensland, or FNQ, is the northernmost part of the Australian state of Queensland. The region, which contains a large section of the Tropical North Queensland area, stretches from the city of Cairns north to the Torres Strait...
, Kathy brought moderate rainfall and strong winds to much of the region. No measurements from the centre of the storm were made, although a wind gust of 60 km/h (37.3 mph) was recorded in Batavia Downs, Queensland, about 55 km (34.2 mi) south-southeast of the cyclone. Between 18 and 21 March, a total of 126.7 mm (5 in) of rain fell near Batavia Downs. Due to the relatively low intensity of the storm, damage was minimal and mainly confined to trees.
Striking the Sir Edward Pellew Group of Islands
Sir Edward Pellew Group of Islands
The Sir Edward Pellew Group of Islands is situated in the south-west corner of the Gulf of Carpentaria, off the northern coast of Australia.-History:They were named in 1802 by Matthew Flinders in honour of Sir Edward Pellew, a fellow naval officer...
as a high-end Category 4 cyclone, Kathy wrought significant damage in the region. A storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
of 4.2 m (13.8 ft) struck Vanderlin Island
Vanderlin Island
Vanderlin Island is an island in the Gulf of Carpentaria, Northern Territory, Australia. It is the largest island in the Sir Edward Pellew Group. Its area is 264 km².-See also:*List of islands of Australia...
, destroying much of the nesting ground for sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
s. Winds were recorded up to 232 km/h (144.2 mph) before the station's anemometer
Anemometer
An anemometer is a device for measuring wind speed, and is a common weather station instrument. The term is derived from the Greek word anemos, meaning wind, and is used to describe any airspeed measurement instrument used in meteorology or aerodynamics...
failed. Several camps across the islands were destroyed. Offshore, 20 vessels were caught in the storm, one of which sank and three others ran aground. One person perished on board the ship that sank during the storm. Losses sustained by the ships were placed at A$5 million (A$12.7 million 2011 AUD; US$10 million 2011 USD).
Though a powerful storm, only light to moderate rains fell along the cyclone's path with totals generally less than 100 mm (3.9 in). The remnants, however, triggered thunderstorms near Tennant Creek
Tennant Creek, Northern Territory
Tennant Creek is a town located in the Northern Territory of Australia. It is the fifth largest town in the Northern Territory and it is located on the Stuart Highway, just south of the intersection with the western terminus of the Barkly Highway....
that produced 325 mm (12.8 in) of rain in 24 hours. Reports indicate that several sea turtles and dugong
Dugong
The dugong is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow , was hunted to extinction in the 18th century...
s were washed up to 8 km (5 mi) inland by Kathy's surge. The only population center significantly affected by the storm was Borroloola, where moderate to severe damage took place. At least one home was destroyed and many more were damaged in the town. Along the mouth of the McArthur River
McArthur River
The McArthur River is a river in the Northern Territory of Australia which flows into the Gulf of Carpentaria at Port McArthur, opposite the Sir Edward Pellew Group of Islands. The river was named by Ludwig Leichhardt while he explored the area in 1845...
, near where Kathy struck the mainland, the combination of severe winds and storm surge killed 80% (±20%) of the Rhizophoraceae
Rhizophoraceae
Rhizophoraceae is a family constituted by tropical or subtropical flowering plants. Among the better known members are mangrove trees of the genus Rhizophora...
mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
trees in the region. Along the entire length of the river, 45% (±15.3%) of the Rhizophoraceae, Bruguiera
Bruguiera
Bruguiera is a plant genus in the family Rhizophoraceae. It is a small genus of six mangrove species of the Indian and west Pacific Ocean region, its range extending from East Africa and Madagascar through coastal India, Sri Lanka and Southeast Asia to northern Australia, Melanesia and Polynesia...
and Ceriops
Ceriops
Ceriops is a genus of mangroves in family Rhizophoraceae.There are 5 species:*Ceriops australis *Ceriops decandra Ding Hou *Ceriops pseudodecandra Sheue, Liu, Tsai, and Yang...
as well as 18.5% (±11.4%) of the Exoecaria agallocha, Lumnitzera racemosa
Lumnitzera
Lumnitzera is an Indo-West Pacific mangrove genus in the family Combretaceae. The English common name is Black Mangrove. Lumnitzera, named after the German botanist, Stephan Lumnitzer , occurs in mangroves from East Africa to the Western Pacific , and northern Australia.The genus has two species of...
and Avicennia marina
Avicennia marina
Avicennia marina, commonly known as grey mangrove or white mangrove, is a species of mangrove tree classified in the plant family Acanthaceae...
perished. In all, losses from the storm were placed at A$12 ,million (A$30.5 million 2011 AUD; US$24.1 million 2011 USD).
In the wake of the storm, Australian Prime Minister Bob Hawke
Bob Hawke
Robert James Lee "Bob" Hawke AC GCL was the 23rd Prime Minister of Australia from March 1983 to December 1991 and therefore longest serving Australian Labor Party Prime Minister....
promised residents of Borroloola that they would receive all possible help from the government. About 400 people in the town were left homeless by Cyclone Kathy. By 25 March, an Royal Australian Air Force
Royal Australian Air Force
The Royal Australian Air Force is the air force branch of the Australian Defence Force. The RAAF was formed in March 1921. It continues the traditions of the Australian Flying Corps , which was formed on 22 October 1912. The RAAF has taken part in many of the 20th century's major conflicts...
aircraft was sent to the region carrying emergency supplies for sheltering displaced persons. Two patrol boats from the Royal Australian Navy
Royal Australian Navy
The Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...
were also sent to assist in relief efforts. One brought fuel and medical supplies and the other assisted trawlers set adrift or grounded by the storm. Following its usage, the name Kathy was retired from Brisbane's
Bureau of Meteorology
The Bureau of Meteorology is an Executive Agency of the Australian Government responsible for providing weather services to Australia and surrounding areas. It was established in 1906 under the Meteorology Act, and brought together the state meteorological services that existed before then...
list of cyclone names and will never be used again.
See also
- Lists of tropical cyclones
- List of retired Australian cyclone names