Timeline of the 1990–91 South Pacific cyclone season

Track map of all the tropical depressions monitored by the Joint Typhoon Warning Center and the Naval Western Oceanography Center during the season

The 1990–91 South Pacific cyclone season was a below-average season; only two tropical cyclones occurred within the South Pacific to the east of 160°E.[A 1] The season officially ran from November 1, 1990, to April 30, 1991, but the first disturbance of the season formed on November 23 and the last dissipated on May 19.[A 2] This is the period of the year when most tropical cyclones form within the South Pacific Ocean.[1] During the season, no one was killed from tropical disturbances within the South Pacific. However, six people were killed by Cyclone Joy when it made landfall on Australia. The only tropical cyclone to cause any damage while within this basin was Sina, which caused at least $18.5 million (1991 USD) worth of damage to Fiji and Tonga.[2] As a result of the impacts of both Joy and Sina, the names were retired from the tropical cyclone naming lists.[1]

Within the South Pacific, tropical cyclones were monitored by the Tropical Cyclone Warning Centers (TCWC) at the Fiji Meteorological Service in Nadi and by the Meteorological Service of New Zealand Limited in Wellington. Tropical cyclones that moved to the west of 160°E were monitored as a part of the Australian region by the Australian Bureau of Meteorology. Both the United States Joint Typhoon Warning Center (JTWC) and the Naval Western Oceanography Center (NWOC) issued unofficial warnings within the southern Pacific. The JTWC issued warnings between 160°E and the International Date Line, while the NWOC issued warnings for tropical cyclones forming between the International Date Line and the coasts of the Americas. Both the JTWC and the NWOC-designated tropical cyclones with a number and a P suffix with numbers assigned in numerical order to tropical cyclones developing within the whole of the Southern Hemisphere. TCWC Nadi and TCWC Wellington both use the Australian Tropical Cyclone Intensity Scale, and measure windspeeds over ten minutes, while the JTWC and the NWOC measured sustained winds over one minute and use the Saffir–Simpson Hurricane Scale.

This timeline includes information from post-storm reviews by TCWC Nadi, TCWC Wellington, the JTWC, and the NWOC. It documents tropical cyclone formations, strengthenings, weakenings, landfalls, extratropical transitions, and dissipations during the season. Reports among warning centers often differ; therefore, information from all three agencies has been included.

Seasonal summary

As a result of the South Pacific Convergence Zone being both weaker and located further to the north than in previous seasons and the Madden–Julian oscillations being weaker and less regular defined than in previous tropical cyclone seasons.[2] As a result only three tropical cyclones occurred within the South Pacific basin between 160°E and 120°W, which made the season one of the least active on record.[2][3] The first tropical cyclone was first noted as a shallow depression on November 20 before it was named Sina on November 24 after it had intensified into a tropical cyclone.[4] After peaking as a category three severe tropical cyclone on the Australian tropical cyclone intensity scale, Sina affected Fiji, Tonga, Niue and the Southern Cook Islands with total damage estimated at over 18.5 million before it was last noted on December 4, as it was absorbed by an advancing trough of low pressure near 50°S.[2][5] During December 15, the precursor tropical low to Cyclone Joy developed near the Solomon Islands.[5] Over the next two days the system moved westwards, before it moved into the Australian region during December 17.[2] The system was subsequently named Joy on December 19, before it made landfall on Queensland during December 26.[2]

The basin then remained quiet until March when three significant tropical depressions including 15 and 16P were observed within the Coral Sea/Australian region, which did not develop into tropical cyclones but were subject to gale warnings.[6] 15P was first noted on March 3, while it was located about 900 km (560 mi) to the east of the Solomon Islands and over the next couple of days subsequently moved south-westwards and out of the South Pacific basin during the next day.[7] 16P was first noted on March 14, while located about 300 km (185 mi) to the southeast of Honiara in the Solomon Islands.[8][A 3] Over the next couple of days the system moved towards the south-east before the JTWC designated the system 16P and initiated advisories on it during March 18 after it had moved into the South Pacific basin.[9] Over the next couple of days the system, moved towards the south-southeast before it turned towards the southwest and passed over New Caledonia on March 20, before it was last noted during the next day moving out of the basin.[8] The final tropical cyclone of the season, Lisa, moved into the Southern Pacific on May 11 at its peak intensity of 110 km/h (75 mph).[2][5] During the next day as the storm moved towards the subtropical jet, Lisa rapidly weakened into a tropical depression before passing over Anatom Island without causing any significant damage.[2] After the season both the names Sina and Joy were retired from the naming lists for the region, while it was determined that a weak gale force tropical cyclone had affected Tonga between December 14–17.[1][3][10]

Timeline of storms

November

November 1
November 24
November 25
November 26
Sina formed in the upper center of the map and generally moved to the south. The storm then curved to the east and became extratropical.
Track map of Severe Tropical Cyclone Sina
November 27
November 28
November 29
November 30

December

Joy formed in the upper left of the map and headed generally to the west. The storm then curved to the southwest and then to the southeast before curving southwest again and dissipating.
Track map of Severe Tropical Cyclone Joy (06P)
December 1
December 4
December 15
December 17

January and February

March

March 15
March 21

April

April 30

May

Lisa formed in the upper center of the map and headed generally to the southeast before dissipating.
Track map of Tropical Cyclone Lisa (21P)
May 11
May 12
May 19

Notes

  1. ↑ An average season has nine tropical cyclones, about half of which become severe tropical cyclones.
  2. ↑ TCWC Nadi warned on systems in the South Pacific, which is located from the equator to 25°S and from 160°E to 120°W. TCWC Wellington warns on systems from 25°S to 40°S and from 160°E to 120°W
  3. ↑ The figures for maximum sustained winds and position estimates are rounded to the nearest 5 units (miles, or kilometers), following the convention used in the Fiji Meteorological Service's operational products for each storm. All other units are rounded to the nearest digit.
  4. ↑ UTC stands for Coordinated Universal Time.
  5. ↑ FST stands for Fiji Standard Time, which is equivalent to UTC+12.
  6. ↑ The figures for maximum sustained winds and position estimates are rounded to the nearest 5 units (knots, miles, or kilometers), following the convention used in the Fiji Meteorological Service's operational products for each storm. All other units are rounded to the nearest digit.

References

  1. 1 2 3 4 5 RA V Tropical Cyclone Committee. "Tropical Cyclone Operational Plan for the South Pacific and South-East Indian Ocean" (PDF) (2012 ed.). World Meteorological Organization. Archived from the original on May 21, 2014. Retrieved June 16, 2010.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 Bannister, Anthony J; Smith, K. J (December 4, 1993). "The South Pacific and Southeast Indian Ocean Tropical Cyclone Season 1990–1991" (PDF). Australian Meteorological Magazine. Australian Bureau of Meteorology. 42 (4): 111–121. Retrieved June 16, 2010.
  3. 1 2 Terry, James P (2007). "Appendix 1". Tropical cyclones: climatology and impacts in the South Pacific. Springer. pp. 188–191. ISBN 978-0-387-71542-1. Retrieved May 15, 2011.
  4. ↑ Ward, Graham F.A (March 1, 1995). "Prediction of tropical cyclone formation in terms of sea-surface temperatures vorticity and vertical windshear" (PDF). Australian Meteorological Magazine. Australian Bureau of Meteorology. 44. Retrieved June 16, 2010.
  5. 1 2 3 4 5 6 7 8 9 10 11 MetService (May 22, 2009). "TCWC Wellington Best Track Data 1967–2006". International Best Track Archive for Climate Stewardship.
  6. ↑ Darwin Regional Specialised Meteorological Centre (1991). "March 1991" (PDF). Darwin Tropical Diagnostic Statement. Australian Bureau of Meteorology. 10 (3): 3. ISSN 1321-4233. Archived from the original on July 17, 2012. Retrieved August 19, 2013.
  7. ↑ Joint Typhoon Warning Center. "Tropical Depression 15P best track analysis". United States Navy, United States Air Force. Retrieved August 19, 2013.
  8. 1 2 3 4 Joint Typhoon Warning Center. "Tropical Depression 16P best track analysis". United States Navy, United States Air Force. Retrieved August 19, 2013.
  9. 1 2 3 4 Joint Typhoon Warning Center; Naval Western Oceanography Center (1992). 6. Tropical Cyclone Warning Verification Statistics: Southern Hemisphere (PDF) (1991 Annual Tropical Cyclone Report). United States Navy, United States Airforce. pp. 213–220. Archived from the original on March 18, 2012. Retrieved August 19, 2013.
  10. ↑ "The Kingdom of Tonga's Initial National Communication In response to its commitments under the United Nations Framework Convention on Climate Change" (PDF). The Government of Tonga. July 21, 2005. pp. 12–13. Archived from the original on February 20, 2012. Retrieved July 7, 2011.
  11. 1 2 3 4 5 Prasad, Rajendra; Nadi Tropical Cyclone Warning Center (July 3, 1992). Tropical Cyclone Sina, November 24 - 30, 1990 (PDF) (Tropical Cyclone Report 90/6). Fiji Meteorological Service. Archived from the original on September 19, 2013. Retrieved September 20, 2013.
  12. 1 2 3 4 5 6 7 8 9 "Tropical Cyclone Sina (03P) Best Track Analysis". Joint Typhoon Warning Center. 1992. Retrieved 2010-06-16.
  13. 1 2 "Tropical Cyclone Joy (06P) Best Track Analysis". Joint Typhoon Warning Center. 1992. Retrieved 2010-06-16.
  14. 1 2 Pandaram, Sudha (July 3, 1992). Tropical Cyclone Lisa, May 7 - 13, 1991 (PDF) (Tropical Cyclone Report 91/1). Fiji Meteorological Service. Archived from the original on March 19, 2013. Retrieved September 30, 2013.
  15. ↑ "Tropical Cyclone Lisa (21P) Best Track Analysis". Joint Typhoon Warning Center. 1992. Retrieved 2010-06-16.

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