1997–98 Australian region cyclone season

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1997–98 Australian region cyclone season
Season summary map
First system formed 19 November 1997
Last system dissipated 19 April 1998
Strongest storm Tiffany – 940 hPa (mbar), 170 km/h (105 mph) (10-minute sustained)
Total storms 10 official, 1 unofficial
Tropical cyclones 4
Total fatalities Unknown
Total damage Unknown
Australian region tropical cyclone seasons
1995–96, 1996–97, 1997–98, 1998–99, 1999–00
Related articles

The 1997–98 Australian region cyclone season was an event in the ongoing cycle of tropical cyclone formation. It ran from 1 November 1997 to 30 April 1998. The regional tropical cyclone operational plan also defines a tropical cyclone year separately from a tropical cyclone season, and the "tropical cyclone year" ran from 1 July 1997 to 30 June 1998.

Tropical cyclones in this area were monitored by four Tropical Cyclone Warning Centres (TCWCs): the Australian Bureau of Meteorology in Perth, Darwin, and Brisbane; and TCWC Port Moresby in Papua New Guinea.


Storms[edit]

Tropical Cyclone Nute[edit]

Category 2 tropical cyclone (Australian scale)
Category 1 tropical cyclone (SSHWS)
Duration 19 November – 21 November
Peak intensity 110 km/h (70 mph) (10-min)  975 mbar (hPa)

On 19 November, TCWC Brisbane and the JTWC reported that Cyclone Nute had crossed 160°E and moved into the Australian region at its peak intensities.[1]

Tropical Cyclone Sid[edit]

Category 2 tropical cyclone (Australian scale)
Tropical storm (SSHWS)
Duration 24 December – 29 December
Peak intensity 95 km/h (60 mph) (10-min)  985 mbar (hPa)

A low-pressure system formed over the Northern Territory in late December and moved into the Timor Sea as the monsoon trough developed near Australia. A tropical depression had formed on 26 December near Darwin, Australia.[2] The storm reached gale force six hours after developing and was named Sid by the Tropical Cyclone Warning Center in Darwin. Sid moved to the east, affecting the Northern Territory. Sid turned southestward, crossing the Northern Territory. Sid moved fully southward, in which it weakened due to wind shear. By 28 December, Sid had weakened to below gale-status and residual low meandered around for a few days.[2]

By 3 January, the low re-entered the Western Gulf and the TCWC in Darwin began to re-issue advisories on the low, which was forecast to re-intensify. The low became a depression and drifted around for another day. On 4 January, scatterometer data at 1330 UTC indicated the presence of 30-35 mph winds over the water. The depression weakened back into a low on 5 January and advisories were stopped again. However, on 7 January, the TCWC in Darwin re-issued advisories for a third time and was forecast to re-intensify, but this did not occur. The last warning was issued on the depression at 1800 UTC. The remnant low moved into the Gulf of Carpentaria and across Queensland. The TCWC in Brisbane, Australia issued bulletins on 10 January for the low which was once Sid. The low remained quasi-stationary ro a couple of days near Townsville. The bulletins were discontinued the next day. Heavy rains fell and several rivers flooded when it was the remnant low on 11 January.[3]

Severe Tropical Cyclone Selwyn[edit]

Category 3 severe tropical cyclone (Australian scale)
Category 1 tropical cyclone (SSHWS)
Duration 26 December – 2 January
Peak intensity 140 km/h (85 mph) (10-min)  960 mbar (hPa)

Tropical Cyclone Selwyn formed 650 kilometers east-southeast of Christmas Island within the monsoon trough.[4] Selwyn rapidly strengthened into a tropical cyclone on 27 December and reached its maximum intensity of 70 mph (110 km/h) on 28 December. Selwyn went at a west-southwesterly motion, bringing it to a position almost 1,000 nautical miles (2,000 km) west of Broome by mid-day 29 December.[4] After this point, Selwyn began to weaken rapidly as it moved west-northwesterly slowly. Warnings were discontinued by the Tropical Cyclone Warning Center in Perth, Australia on 31 December because winds were forecast to fall below gale-force. The remnant low drifted westward and then to the southwest with convection flaring up once in a while. Warnings were re-issued in early January due to forecasts that Selwyn would re-intensify, but this did not occur. The remnant low (formerly known as Selwyn) was tracked until 3 January.[4]

Severe Tropical Cyclone Katrina–Victor–Cindy[edit]

Category 4 severe tropical cyclone (Australian scale)
Category 2 tropical cyclone (SSHWS)
Duration 1 January – 24 January
Peak intensity 165 km/h (100 mph) (10-min)  940 mbar (hPa)
Category 3 severe tropical cyclone (Australian scale)
Category 2 tropical cyclone (SSHWS)
Duration 4 February – 19 February
Peak intensity 120 km/h (75 mph) (10-min)  970 mbar (hPa)

Katrina formed on 1 January 1998 340 nautical miles (630 km) east-northeast of Cairns and 425 nautical miles (787 km) southeast of Port Moresby, Papua New Guinea.[5] Katrina became a tropical storm on 3 January and was moving slowly to the east-northeast. The cyclone was affected by Cyclone Susan which was 1,000 nautical miles (1,900 km) east of Katrina. On 7 January, Susan moved further south allowing Katrina to intensify as it neared the Solomon Islands, this proved to be the northernmost point of Katrina's track as the storm turned east-southeast and then southeast, fluctuating in hurricane strength. On 9 January, Cyclone Katrina threatened Vanuatu when it stalled about 200 nautical miles (370 km) west-northwest of Port Vila and reversed direction and moved west due a high pressure system. On 11 January, Katrina moved south of Rennell Island and then crossed back into the Brisbane area six hours later where it crossed the 160E on its eastward journey, then the storm turned west where it maintained that course until 15 January.[5] On the 15th, the storm moved south-southwest where it reached Category 2 strength with a barometric pressure of 940 mbar. Katrina weakened rapidly and slowed before making a tight loop on 17 and 18 January.[5] After completing the loop, Cyclone Katrina moved east for 12 hours before moving east-southeast for three days. During that time, Katrina briefly reached Category 1 strength once more before slowing down and being affected by wind shear. By 24 January, Katrina had weakened to a tropical depression.

A low from Cyclone Katrina continued to move to the west across Northern Australia, and emerged in the Indian Ocean where it strengthened into Cyclone Victor in early February.[6] The weakening Tropical Cyclone Victor accelerated to the middle of the Indian Ocean where it was again renamed Cindy by the Mauritius Tropical Cyclone Warning Centre, and then finally weakened on 17 February. The time from the beginning of Cyclone Katrina to the ending of Cyclone Cindy was around 50 days.

Severe Tropical Cyclone Tiffany[edit]

Category 4 severe tropical cyclone (Australian scale)
Category 4 tropical cyclone (SSHWS)
Duration 22 January – 31 January
Peak intensity 170 km/h (105 mph) (10-min)  940 mbar (hPa)

Tropical Cyclone Tiffany began as a tropical low about 1,000 nautical miles (2,000 km) northeast of Broome.[7] TCWC in Perth, Australia started issuing advisories on the low 24 January. The system was of land origin and had entered the ocean. A brief surge of southeasterly flow helped the system strengthen and was given the name Tiffany the next day. Tiffany was a small system and strengthened rapidly with an estimated 40 mph (60 km/h) gain in a 12-hour period on 26 January.[7] Hurricane-status was reached at 1200 UTC about 125 nautical miles (232 km) north of Port Hedland. The peak intensity of 930 millibars was recorded on 27 January with the maximum sustained winds of 115 mph (140 by the JTWC). Tiffany remained at 115 mph (185 km/h) for 18–24 hours before beginning to weaken. The cyclone went to the west-southwest, farther and farther away from the Australian coastline. By 29 January, the system fell below hurricane-status and Perth issued its last warning the next day. The Joint Typhoon Warning Center followed the next day. No damage was reported with the system.[7]

Tropical Cyclone Les[edit]

Category 2 tropical cyclone (Australian scale)
Tropical storm (SSHWS)
Duration 22 January – 1 February
Peak intensity 110 km/h (70 mph) (10-min)  976 mbar (hPa)
Main article: Cyclone Les (1998)

Les formed on 23 January 1998 near Darwin, Australia. The storm moved westward reaching Category 1 status before making landfall on the eastern gulf coast of the Northern Territory. Moving back out over the Timor Sea, Les hugged the coast and regained strength before making a second landfall and dissipating. Les caused extensive flooding and damage in the town of Katherine and there was one death.[8]

Tropical Cyclone May[edit]

Category 1 tropical cyclone (Australian scale)
Tropical storm (SSHWS)
Duration 25 February – 26 February
Peak intensity 75 km/h (45 mph) (10-min)  990 mbar (hPa)

May formed from an area of low pressure on 25 February 1998 near the Australian coast. May moved southward before making landfall near Mornington Island on 26 February. After that the storm dissipated while moving inland.[9] There were no reports of deaths or damage from Tropical Storm May.

Tropical Low Elsie[edit]

Tropical low (Australian scale)
Clockwise vortex
Duration 7 March – 9 March (crossed basin)
Peak intensity 35 km/h (25 mph) (10-min) 

Tropical Cyclone Nathan[edit]

Category 2 tropical cyclone (Australian scale)
Category 1 tropical cyclone (SSHWS)
Duration 20 March – 26 March
Peak intensity 95 km/h (60 mph) (10-min)  990 mbar (hPa)

Tropical Cyclone Nathan formed from a tropical low embedded weak monsoon trough that had formed when Tropical Cyclone Yali had reached cyclone intensity. Upper-level outflow was favorable, but wind shear made it restricted for rapid development. Nathan started off developing rapidly, the first warning, issued on 21 March, classified the system as a 45 mph (72 km/h) tropical cyclone. Nathan was a small system in an environment of weak steering flow, causing the storm to move erattically but slowly to the east. Nathan turned southward, coming to within 100 nautical miles (190 km) of Cooktown, Australia on 23 March. The TCWC in Brisbane kept Nathan's wind speed at 50-60 mph, whereas the Joint Typhoon Warning Center boosted it up to hurricane-strength on 23 March.

After approaching the coast of Queensland, Nathan came under the influence of the monsoon flow from Tropical Cyclone Yali. The storm moved east-northeasterly very rapidly and became more easterly on 25 March. By the morning of 26 March, the circulation was becoming sheared. The shear was possibly coming from an extratropical system (formerly known as Yali). Nathan turned to the south and the Brisbane TCWC downgraded the system into a tropical low, ceasing advisories. By 1200 UTC on 27 March, Nathan showed signs of redevelopment near the Chesterfield Islands. The JTWC reissued advisories and upped the winds to 50 mph (80 km/h). Nathan moved westward and approached Australia again, weakening slowly.

A scatterometer pass on 29 March indicated a small circulation with winds of about 40 mph (60 km/h) and a Willis Island report the next day indicated that Nathan only had 35 mph (56 km/h) easterly winds. The JTWC kept Nathan as a minimal tropical cyclone until 31 March when it was downgraded into a weakening low.

Tropical Cyclone Yali[edit]

Category 1 tropical cyclone (Australian scale)
Tropical storm (SSHWS)
Duration 25 March – 27 March
Peak intensity 80 km/h (50 mph) (10-min) 
Main article: Cyclone Yali

Entered the Australian region on 25 March (See 1997-98 South Pacific cyclone season).

Tropical Low (35S)[edit]

Tropical low (Australian scale)
Tropical storm (SSHWS)
Duration 19 April – 19 April
Peak intensity 65 km/h (40 mph) (10-min)  1002 mbar (hPa)

A low formed off the coast of Australia on 16 April 1998. The depression moved southwestward before making landfall in Western Australia on the 19th.[10] There were reports of heavy rain but no report of damage or deaths from the unnamed storm.

Storm names[edit]

Tropical cyclones are assigned names by the Australian Bureau of Meteorology or Papua New Guinea. Tropical cyclones are named if they are non-frontal low pressure systems of synoptic scale developing over warm waters, or if Dvorak intensity analysis indicate the presence of gale force or stronger winds near the centre. Therefore, tropical systems with gales in one or more quadrants, but not near the centre, are not named.[11] All names assigned in the Australian region are selected sequentially. Only the names used during this cyclone season are listed below. The complete list of names for each basin are found in the World Meteorological Organization's official lists.[12]

Each Australian Tropical Cyclone Warning Centre (Perth, Darwin, and Brisbane) maintains a list of names arranged alphabetically and alternating male and female. Tropical cyclones that develop in the South-East Indian Ocean are assigned names by the Tropical Cyclone Warning Centre in Perth. This region includes the areas east of 90°E, south of the Equator, and west of 125°E. Tropical cyclones that develop south of the Equator between 125°E and 141°E are assigned names by the Tropical Cyclone Warning Centre in Darwin, Northern Territory. This area includes most of the cyclones that form in the Arafura Sea and Western Gulf of Carpentaria. Tropical cyclones in the Coral Sea and Eastern Gulf of Carpentaria between 141°E and 160°E and south of 10°S are assigned names by the Tropical Cyclone Warning Centre in Brisbane, Queensland.[12]

Additionally, the Tropical Cyclone Warning Centre in Port Moresby, Papua New Guinea reserves the right to name cyclones that develop in the Solomon Sea and Gulf of Papua, north of 10°S between 141°E and 160°E. Names are selected randomly from their list and retired once they are used.[13] No cyclones were named by this warning centre during the 1997-98 season.

Perth

  • Selwyn - Tiffany - Victor

Darwin

  • Sid

Brisbane

  • Katrina - Les - May - Nathan

Additionally, two cyclones that were named by Fiji Meteorological Service - Nute and Yali - moved into Brisbane's area of responsibility.

See also[edit]

References[edit]

  1. ^ Naval Pacific Meteorology and Oceanography Center, Joint Typhoon Warning Center (2002). "Tropical Cyclone 05P (Nute) best track analysis". United States Navy, United States Air Force. Retrieved 30 May 2011. 
  2. ^ a b Sid Report
  3. ^ Tropical Depression (formerly TC Sid - 08S) 3-11 January
  4. ^ a b c Tropical Cyclone Selwyn (TC-09S)26 December-2 January
  5. ^ a b c Katrina report
  6. ^ WA Tropical Cyclone Season Summary 1997-98
  7. ^ a b c Tropical Cyclone Tiffany (TC-15S) 24-31 January
  8. ^ Les Report
  9. ^ May report
  10. ^ 35S report
  11. ^ "Tropical Cyclones: Frequently Asked Questions". Australian Government Bureau of Meteorology. Retrieved 15 August 2008. 
  12. ^ a b "Tropical Cyclone Operational Plan for the South Pacific and South-East Indian Ocean". World Meteorological Organization. 1999. Retrieved 15 August 2008. 
  13. ^ "Tropical Cyclone Operational Plan for the South Pacific and South-East Indian Ocean" (PDF). World Meteorological Organization. 2006. Archived from the original on 11 September 2008. Retrieved 15 August 2008. 

External links[edit]