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Southwest Indian Ocean Cyclone Scale
Category Wind speed
Knots
Tropical Disturbance 28 <
Tropical Depression 28–33
Moderate Tropical Storm 34–47
Severe Tropical Storm 48–63
Tropical Cyclone 64–89
Intense Tropical Cyclone 90–115
Very Intense Tropical Cyclone > 115

Australian Cyclone Scale
Category Wind speed
Knots
Tropical Low 33 <
Tropical Cyclone 34–63
Severe Tropical Cyclone > 64

South Pacific Cyclone Scale
Category Wind speed
Knots
Tropical Disturbance N/A
Tropical Depression 33 <
Tropical Cyclone > 34

The 2005-06 Southern Hemisphere tropical cyclone season ran year-round. It started on July 1, 2005 and ended on June 30, 2006; it reached its peak between mid-February and mid-April.

Naming and scope

The scope of this article is limited to the Southern Hemisphere. Three major basins are located in the southern hemisphere (Southwest Indian Ocean, Australian Region, South Pacific Ocean). South Atlantic tropical cyclones rarely develop due to cooler waters, the lack of an ITCZ, and wind shear.

Southern Hemisphere adopted a naming system slightly different from the Atlantic one and is explained below. Names are assigned by Madagascar, Mauritius, Australia, Papua New Guinea or Fiji.

Tropical depressions in the Southern Hemisphere are assigned an "S" suffix if formed in the Indian Ocean, a "P" suffix (South Pacific), an "F" suffix (Fijian area of responsibility), a "U" suffix (Australian area of responsibility), or an "R" suffix (La Réunion AOR).

Storms

Southwest Indian Ocean

Tropical Storm 01S (02R)
Tropical Disturbance 02M formed approximately 860 nautical miles (1,590 km) east of Diego Garcia on October 12. It became more organised and the JTWC upgraded it to a Tropical Cyclone with a peak intensity of 35kt between October 14 and October 15. Due to growing wind shear, the system dissipated over water on October 15.
  • Météo France's archive on the system, in French. The system never reached Tropical Storm strength based on Météo France's advisories.

Overland Depression (07R)
A zone of disturbed weather developed on December 29. Moving southwestwards, it became an overland depression with maximum sustained winds of 25kt in Mozambique on January 5. The system tracked along the southern coast of Mozambique and became extratropical on January 8. The depression caused torrential rains in Mozambique and swept away 26 people.*
  • Météo France's archive on the system, in French.

Intense Tropical Cyclone Boloetse
A zone of disturbed weather developed northeast of Magadascar on January 20. The system organized into a Tropical Depression on January 24 and further intensified into Moderate Tropical Storm Boloetse on 25 January. The name was contributed by Lesotho. On 26 January, Boloetse briefly became a severe tropical storm with maximum sustained winds 50kt (92 km/h) near center. On January 29, Tropical Storm Boloetse crossed the coast near the village of Mananjary. On January 30, its remnants emerged into Mozambique Channel and reorganized. The system strengthened into a Severe Tropical Storm again on February 2, and strengthened further into an intense tropical cyclone. Boloetse passed just southwest of Magadascar on February 4 and became extratropical on February 5.

Moderate Tropical Storm 12S (09R)
A tropical disturbance formed just west of Madagascar on February 15. It moved south-east, towards Mauritius and became more organized. On February 19, it was designated as Tropical Disturbance 09. The midget system quickly strengthened but its status was under dispute. Météo France upgraded it to a moderate tropical storm while JTWC classified it as a Tropical Storm equivalent. In contrast, Mauritius did not upgrade and name the system. The storm was short-lived, it rapidly weakened on February 20 and dissipated over water on February 23.

Very Intense Tropical Cyclone Carina
Tropical depression 14S (10R) formed far southeast of Diego Garcia on February 23. It became more organized and was upgraded to Moderate Tropical Storm Carina by Réunion at 1800 UTC February 23. The name was contributed by Mauritius. Carina moved southwards, and became a tropical cyclone on February 26. Carina remained over open waters and quickly intensified, becoming an intense tropical cyclone on February 27. At 0000Z Feb 28, Carina was moving west-southwest and nearing Category 5 strength on the Saffir-Simpson hurricane scale. Carina moved into an area with high wind shear on February 28, started to weaken and dissipated over open water on March 3.

Severe Tropical Storm Diwa
On March 2, Météo France identified a broad area of low pressure between 45°E and 55°E and from 8°S to 15°S. Within this area, two lows were detected. The main one (11R) was north of Mascarnes Islands while the other one was north of Madagascar.

11R became a tropical depression on March 3 and was later named Diwa. The name was contributed by Malawi. At first Diwa was classfied as a moderate tropical storm by Mauritius, but as a tropical depression by Météo France, but a few hours later, Météo France also classified it as a tropical storm. This made the fourth documented case of a tropical cyclone being named before reaching tropical storm strength.

On the other hand, the other low briefly developed into a tropical disturbance (12R) on March 4. The two systems were less than 700 km away and Météo France said that Diwa might be partially influenced by a slight Fujiwhara effect with 12R. 12R was short-lived and Diwa remained the dominant system. Diwa came very near to Réunion but never made landfall. The outer edges of Diwa did caused some subtantial rainfall on the island. The strongest gust reported was 194 km/h at the top of the Sainte-Rose Large-Piton. The highest rainfall in three days was 2720 mm in Commerson. After this, Diwa moved southwards and strengthened into a severe tropical storm on March 7. Eventually, Diwa became extratropical and reached its peak intensity on March 9.

Moderate Tropical Storm Elia
The unusually tenacious disturbance that would develop into Elia was first identified by NRL on April 2. It lingered around and organized very slowly. After waiting for nine days, it gathered gales in southern quadrants and Australian Bureau of Meteorology issued a shipping warning on April 11. It entered Météo France's area of responsibility as a Moderate Tropical Storm and was named Elia on April 13. The name was contributed by Madagascar. Elia encountered unfavourable shear conditions on April 15 causing the low level circulation to decouple from the convection. It degenerated into a remnant low the following day and finally dissipated on April 17.

Other Systems

Southeast Indian Ocean/Western Australia

Tropical Cyclone 02S (04R)
TCWC Perth issued a gale warning on a Tropical Low near 8.3S 97.1E on November 5. According to JTWC, the low developed into a tropical cyclone and reached its peak intensity of 45kt on the same day. It moved southwestward into Météo France (Réunion)'s area of Responsibility on November 7 and gradually weakened afterwards. The last JTWC warning was released the next day. Météo France tracked its remnants until November 9.
  • Météo France's archive on the system, in French. The system never reached Tropical Storm strength based on Météo France's advisories.

Severe Tropical Cyclone Bertie-Alvin
TCWC Perth issued a gale warning on a Tropical Low near 3.5S 94.0E, which later became Bertie on November 17. Bertie gradually strengthened and became a Severe Tropical Cyclone on November 21, before entering the Southwest Indian Ocean on November 23 and being renamed Alvin. According to the JTWC, the cyclone reached its peak intensity of 115 kt (210 km/h) - which equates to a marginal Category 4 on the Saffir-Simpson hurricane scale - on the same day. Alvin weakened significantly afterwards and the last JTWC warning was released on November 26. Météo France tracked its remnants until November 30.
  • Météo France's archive on the system, in French.

Tropical Cyclone 04S (06R)
TCWC Perth issued a gale warning on a Tropical Low near 9.5S 91.9E on December 22. Moving west-southwestward, the low entered Météo France (Réunion)'s area of responsibility on December 23. During its long journey to the west, it became more organised and JTWC upgraded it to a Tropical Cyclone with peak intensity of 35kt between December 24 and December 25. The system then skirted east of Réunion as a zone of disturbed weather. Météo France tracked its remnants until December 30.
  • Météo France's archive on the system, in French. The system never reached Tropical Storm strength based on Météo France's advisories.

Severe Tropical Cyclone Clare

A tropical low formed north of Northern Territory and tracked roughly parallel to the coast. On January 7, TCWC Perth started issuing tropical cyclone advisories on this system. The low became Tropical Cyclone Clare when it was located 250 km north of Cape Leveque or 430 km north of Broome. A steady strengthening trend continued and Clare peaked as a 70 mph storm, or a Category 3 cyclone on the Australian scale, with an unusually low pressure of 960 mbar. On January 9 the cyclone made landfall near Karratha and Dampier next day, and dissipated on the 10th as it continued inland.

In preparation of the storm, 1,500 people were evacuated, while incoming flights and mining operations were closed. Although sustained wind speeds of 131km/h and gusts of up to 142km/h were recorded, the towns affected by TC Clare escaped with only minor structural damage. The rain depression associated with Ex-Tropical Cyclone Clare caused extensive flooding in the towns of Walkaway and Lake Grace over the weekend of 14-15 January. * Overall, damage was minor, and Clare was responsible for no deaths.

Severe Tropical Cyclone Daryl
On January 17, TCWC Perth started issuing tropical cyclone advices for a tropical low overland. The low tracked into Kuri Bay next day and developed into Tropical Cyclone Daryl. It continued to strengthen, and on January 21 briefly became a Severe Tropical Cyclone. Over the next two days, Daryl tracked parallel to the West Australian coast, mostly as a Category 2 system. Daryl continued tracking in a south-westerly direction before being downgraded to a low-pressure system on January 23. The cyclone did not cross the coast.

Tropical Cyclone Emma
On February 26, TCWC Perth started issuing tropical cyclone advices as a tropical low was developing far north of Exmouth. The low moved slowly southward at first, and then accelerated. The Tropical Low became a category 1 cyclone on the Australian scale on February 27. Emma accelerated southwards and crossed the coast near Mardie on February 28. At that time, Emma only had peak winds of about 35 mph. But since Emma covered a very large area, her effects were felt in almost the entire western extent of Australia. The heavy rain associated with Emma caused substantial flooding in the Pilbara region, where she came ashore. In Wittenoom, Western Australia, 7.8 inches of water fell from the sky in 48 hours 15 days after Emma made landfall, overflowing rivers still threatened cities such as Kalbarri in Western Australia [http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=13415. No fatalities were reported from Emma.

Severe Tropical Cyclone Floyd
On March 21, TCWC Perth started issuing advises on a Tropical Low. That low later strengthened to Tropical Cyclone Floyd as a Category 1 on the Australian scale. Overnight on March 22, it became a severe tropical cyclone. Strengthening further, Floyd reached Australian Category 4 at 8 p.m. AWST (1200 UTC) on March 23. Floyd attained its peak intensity with maximum sustained winds up to 105 knots (10-minute average) on March 24. A steady weakening trend occurred thereafter and Floyd became a tropical low about 285 kilometres west northwest of Exmouth on March 27.

Severe Tropical Cyclone Glenda
A tropical low entered Joseph Bonaparte Gulf on March 21. The low made landfall just west of Northern Territory/Western Australia border. Though slightly inland, the low showed potential for development and TCWC Darwin started issuing tropical cyclone advisories on this system on March 24. The low tracked westward across North Kimberley District and into Indian Ocean late March 26. On the next day, it strengthened quickly into Tropical Cyclone Glenda. The strethening trend went on and its sustained winds increased from 35 knots to 115 knots with pressure dropping from 990hPa to 915hPa in just 32 hours. It attained Category 5 status on the Saffir-Simpson Scale on 28 March 2006 before weakening slightly.

Close to the coast, with hurricane force winds already over the coast, Glenda took a more westerly track and moved closer to Onslow before finally crossing the coast near Onslow. The prolonged interaction with land likely weakened the system to Category 3 intensity prior to reaching Onslow. After landfall, the storm decayed fairly quickly and was downgraded to a tropical low on the morning of March 31.

The impact could be seen as early as March 24 when pre-tropical cyclone Glenda, together with the active monsoonal trough that gave birth to it, brought heavy rain to North Kimberley District. Flooding washed out many roads around Kununurra, including part of the Great Northern Highway.*

On March 28, an Australian oil and gas producer shut down production at its Mutineer-Exeter oil field off the coast due to the cyclone.*

On March 30, power lines were down and more than 2,000 homes were without electricity and in Karratha. There were hundreds of evacuations in Karratha and further south in Exmouth.and there was a minor fire in an evacuation centre.[http://news.bbc.co.uk/1/hi/world/asia-pacific/4863352.stm

During the storm passage, Mardie reported a sustained wind speed of 72 knots (133 km/h). Storm force winds were recorded in Adele Island, Legendre Island, Karratha and Onslow Airport. Near gale force winds were observed far inland in Gascoyne Junction. Also, 206mm of rain fell at Onslow, representing the sixth wettest day on record for the town.

Tropical Low
Cocos Islands faced their first cyclone threat this cyclone season on March 25 when a tropical low developed to its east-northeast. Fortunately, the low passed well to their east and did not develop further. The maximum sustained winds near the low were 30 knots and the minimum pressure was 994 hPa.

Tropical Cyclone Hubert

TCWC Perth issued a gale warning for a Tropical Low off Northwest Australia on April 4. The low moved erratically at first, and then towards southwest. It strengthened into Tropical Cyclone Hubert (Australian Category 1) on April 5 and to Australian Category 2 on April 6. Prior to landfall, Hubert weakened rapidly in an unfavourable atmospheric environment, and the surface circulation was poorly defined. Eventually, Hubert was downgraded to a tropical low with maximum sustained winds to 33 knots as it crossed the coast during the night of April 7 (based on AWST).

Arafura Sea and Gulf of Carpentaria/Northern Australia

Tropical Low
A tropical low developed off the north coast of the Top End in late January. It made landfall in the Darwin area and drifted down the western border of the Northern Territory. The low brought heavy falls to many parts of the western Northern Territory. The low continued to move south through the Victoria River District and into the Tanami Desert. The Victoria Highway was cut by floodwaters, isolating Timber Creek and the Victoria River Crossing. On January 31, the low deepened producing near gale force winds.

Tropical Low
A tropical low formed in the Arafura Sea north of Nhulunbuy on the February 24. It moved northwest into the Banda Sea and deepened during the next two days. Through the remainder of February it moved slowly southsouthwest into the Timor Sea. The low persisted into March but did not reach cyclone intensity. A cyclone watch was issued for portion of Western Austrlia though the maximum sustained winds of the low were just 25 knots.

Other Systems

Coral Sea/Eastern Australia

Severe Tropical Cyclone Jim
TCWC Brisbane issued a gale warning for a Tropical Low off the Queensland east coast on January 26. It was upgraded to Tropical Cyclone Jim on the morning of January 28 as it moved in an easterly direction. Jim moved out of Brisbane's area of responsibility on January 30 and was then monitored by Fiji. Jim gradually turned south-southeastward and became extratropical on February 1.

The extratropical remnants of Jim (08F) lingered around and then moved northwest. On February 3, 08F was again mentioned in a bulletin issued by Fiji. However, on the following day, the number 08F was dropped in Fiji bulletin while Brisbane called it a tropical low instead of Ex-Jim. The low was quasi-stationary and gradually weaken afterwards. It is questionable whether this system is a continuation of Jim.

Despite being well to the west of that country, Cyclone Jim was blamed for extensive flooding in Fiji, with the western coast of the island of Viti Levu - including the city of Lautoka - inundated by floodwaters on January 29. * Fortunately, no fatalities were reported in any of the areas affected by the cyclone.

Tropical Cyclone Kate
TCWC Brisbane issued a gale warning for a Tropical Low near the northern tip of Cape York Peninsula on February 22. The low moved in an easterly direction. It quickly strengthened and became Tropical Cyclone Kate on the same day. Kate moved eastwards and weakened into a tropical low on February 24.

Severe Tropical Cyclone Larry

TCWC Brisbane issued a gale warning for a Tropical Low in the Coral Sea on March 16. On the same day, RSMC Nadi classified it as a deepening tropical depression (15F). On March 17, the tropical low strengthened into Tropical Cyclone Larry. Larry moved towards the Queensland coast and gradually intensified to Category 5 on the Australian scale, making landfall with that strength on March 20 over Innisfail. Larry was downgraded to a tropical low that night.

Cyclone Larry is considered to be the worst cyclone to hit Queensland since 1931. The total damage caused by Larry was estimated to be $1 billion (2006 AUD).

Severe Tropical Cyclone Monica

On Monday April 17 TCWC Brisbane issued an advice on the newly formed Tropical Cyclone Monica in the extreme north Coral Sea. The system began to establish a westward track, reaching Category 3 on the Australian scale on April 18. The very destructive core of Monica crossed the coast with hurricane force wind on April 19. There were no immediate reports of injuries or damage though torrential rain and flood were reported. In the wake of Monica, Cairns broke its April rainfall record of 550 millimetres (21.7 inches).***

Monica moved off the Cape York Peninsula and reformed southwest of Aurukun on April 20. As it moved across the Gulf of Carpentaria, it strengthened and became the strongest tropical cyclone worldwide so far this year. On April 23, the storm made landfall on small islands northeast of Arnhem Land and the southern side of the storm affected the extreme northern part of Australia's Northern Territory, which is very sparsely populated. Most of the residents were evacuated or located in shelters, mainly in Nhulunbuy. The town escaped significant damage, however, as the storm track was well offshore. *

At peak strength on April 23 the TCWC in Darwin reported a minimum pressure of 905 mbar. The Joint Typhoon Warning Center issued an advisory on April 23 which pinned the pressure at a southern hemisphere record-tying 879 mbar, and sustained winds at 155 kt (180 mph). Some estimated unofficial preliminary data suggested that this cyclone could have produced the lowest atmospheric pressure ever recorded in the world, with a reported minimum pressure of 869 mbar, surpassing Typhoon Tip's 870 mbar record. *

Monica then made a third landfall, to the northwest of Maningrida. Fortunately the storm weakened quickly overland and spared Darwin, which was devasted by Cyclone Tracy in 1974, a direct hit from a severe tropical cyclone. The remnant low of Monica dissipated on April 26 over the Timor Sea.

Other System

Solomon Sea and Gulf of Papua/Papua New Guinea

No storms have occurred in the Solomon Sea/Gulf of Papua/Papua New Guinea area.

South Pacific/Fiji

Tropical Cyclone Tam
Tam originated as Tropical Depression 04F near 15S 179.5E on January 6. The system then lingered around for a few days, appearing to significantly weaken, only to strengthen later. As Tam moved southeastward on January 12, a gale warning was issued for Tonga and later for Niue as well as American Samoa. Tam accelerated towards south-southeast and became extratropical on January 14. Tam was the first tropical cyclone to occur within the area of responsibility of TCWC Wellington this year.

Tropical Cyclone Urmil
Urmil formed near 14S 174E as Tropical Depression 06F on January 13 and erupted overnight with rapid development. A Tropical cyclone warning was then issued for Tonga. Urmil continued to strengthen and broke the constraints for Dvorak technique. It almost reached hurricane intensity on January 14. Urmil accelerated towards southeast and was declared extratropical once it entered the area of responsibility of TCWC Wellington on January 15.

Tropical Cyclone Vaianu
Tropical Depression 12F formed near 14.5S 176.1W on February 10 and a tropical cyclone alert was raised in Tonga. This is the third tropical system to threaten Tonga this season. At that time, another Tropical Depression (11F) was to its south causing unstable movements of the two depressions. On the next day, 12F became the dominant system and moved south. Strengthening into Tropical Cyclone Vaianu, it turned southwest and passed between Fiji and Tonga. On February 13, Vaianu resumed a southward track and reached hurricane intensity. Vaianu then struck the Tonga islands as a category 1 cyclone on the Saffir-Simpson scale, knocking down power lines and flattening crops, such as banana and mango trees. In Nuku'alofa, low lying areas were shut down because of flooding. On February 13, Vaianu reached it's peak intensity of 85 mp/h, but these peak winds were well away from the Tonga and Fiji islands, but Tonga still felt Vaianu's winds. Then, the cyclone accelerated towards the southeast, entered TCWC Wellington's area of responsibility and became extratropical on February 16.

Severe Tropical Cyclone Wati
Tropical Depression 16F formed on March 17 and strengthened into Tropical Cyclone Wati on March 19 north of New Caledonia. It moved westwards and slowly strengthened into a Category 3 cyclone on the Australian scale before coming to a near standstill over the Coral Sea. After remaining stationary for most of March 22, Wati took a southeasterly course on March 23, gaining speed and continuing that course on March 24. A cyclone watch was issued for Lord Howe Island and a cyclone warning was issued for Norfolk Island. Wati passed between the two islands and became extratropical on March 25.

The remains of Wati brought heavy rain and strong winds to the North Island of New Zealand on March 26, with gusts of 140km/h reported at Cape Reinga. *

Other Systems

South Pacific/New Zealand

2005-06 storm names

Southwest Indian Ocean

According to the operational plan, a tropical disturbance is named when reaching the stage of moderate tropical storm. Unlike in Atlantic, subtropical cyclones are not qualified to have names. Names are assigned by Sub-regional Tropical Cyclone Advisory Centre in Madagascar (for west of 55°E) or Mauritius (for 55°-90°E). A new annual list is used every year so there is no need to consider the retirement of names.
  • Alvin
  • Boloetse
  • Carina
  • Diwa
  • Elia

Southeast Indian Ocean and South Pacific

According to the operational plan, non-frontal low pressure systems of synoptic scale developing over warm waters are named whenever observations and/or Dvorak intensity analysis indicate the presence of gale force or stronger winds near the centre. It should be emphasized that an unnamed tropical system may have gales in one or more quadrants, but not near the centre. This is quite different from the Atlantic standard.

Names are assigned by the Australian Bureau of Meteorology or Papua New Guinea (for 90°E-160°E) or Fiji Meteorological Service (for 160°E-120°W). No tropical cyclone has ever been observed in South Pacific Ocean east of 120°W based on the JTWC's best track data. If there is one in the future, it is unclear how it will be handled. The most probable solution is to leave it unnamed like the South Atlantic tropical cyclone.

Only the names used during this cyclone season and the next few names on the sequential lists are listed below. For the complete list of names for each basin, see the WMO's official list. Names that have not yet been assigned are marked in gray. Bold names are currently active.

Southeast Indian Ocean/Western Australia
  • Bertie
  • Clare
  • Daryl
  • Emma
  • Floyd
  • Glenda
  • Hubert

Arafura Sea and Western Gulf of Carpentaria/Northern Australia

Coral Sea and Eastern Gulf of Carpentaria/Eastern Australia

Solomon Sea and Gulf of Papua/Papua New Guinea

South Pacific/Fiji
  • Tam
  • Urmil
  • Vaianu
  • Wati

See also

External links

 

This article is licensed under the GNU Free Documentation License. It uses material from the "2005-06 Southern Hemisphere tropical cyclone season".

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