2011–12 South Pacific cyclone season

2011–12 South Pacific cyclone season

Season summary map
First storm formed	November 13, 2011
Last storm dissipated	April 11, 2012
Strongest storm	Jasmine – 942 hPa (mbar), 185 km/h (115 mph) (10-minute sustained)
Total disturbances	20
Total depressions	16
Tropical cyclones	3
Severe tropical cyclones	1
Total fatalities	13
Total damage	> $17.2 million (2011 USD)
South Pacific cyclone seasons 2009–10, 2010–11, 2011–12, 2012–13, 2013–14
Related articles
2011–12 Australian region cyclone season 2011–12 South-West Indian Ocean cyclone season

The 2011–12 South Pacific cyclone season was one of the least active South Pacific tropical cyclone seasons on record, with only three tropical cyclones occurring during the season. The season ran from November 1, 2011 to April 30, 2012, however, any tropical cyclones that form before June 30, 2012 will count towards the season total. Within the basin, tropical cyclones are monitored by the Regional Specialized Meteorological Center (RSMC) in Nadi, Fiji, and the Tropical Cyclone Warning Center (TCWC) in Wellington, New Zealand. RSMC Nadi attaches an F designation to tropical disturbances that form in or move into the South Pacific. The United States Joint Typhoon Warning Center (JTWC) issues unofficial warnings within the South Pacific, designating tropical cyclones with a number and a P suffix. RSMC Nadi and TCWC Wellington both use the Australian Tropical Cyclone Intensity Scale, and measure windspeeds over a period of ten minutes, while the JTWC measures sustained winds over a period of one minute and uses the Saffir–Simpson Hurricane Scale.^[1]

Seasonal forecasts

During October 2011, both RSMC Nadi and New Zealand's National Institute of Water and Atmospheric Research (NIWA) issued seasonal forecasts which contained information on how many tropical cyclones were predicted to develop within the upcoming season.^[3] Both agencies expected that the season would see a below average amount of tropical cyclone activity within the South Pacific basin due to a weak La Niña during the first half of the season before ENSO neutral conditions prevailed during the second part of the season. As a result of these conditions, RSMC Nadi and NIWA both predicted that 5–8 tropical cyclones would exist within the basin.

Risk forecasts

In their October 2011, forecasts both RSMC Nadi and NIWA assessed the risk of a tropical cyclone affecting each island group within the South Pacific, based on a number of factors including what happened in certain previous seasons. The agencies felt that both New Caledonia and Vanuatu, had a high risk of a tropical cyclone affecting them while Fiji, Tonga, the Cook Islands had a moderate to high risk. Other island groups including Niue, Wallis & Futuna, Samoa, the Solomon Islands, Tuvalu and Tokelau each had a very low to moderate risk of being affected by a cyclone. RSMC Nadi also forecasted that Vanuatu, Fiji, New Caledonia, Tonga had a moderate to high risk of being affected by a Severe Tropical Cyclone while other areas had a low to moderate risk. NIWA issued an update for the southwest Pacific seasonal tropical cyclone activity in early February 2012, indicating normal or below normal risk for many island groups across the region for the February to April period. The expectation was that approximately 6 to 8 named storms would form during the late season.

Seasonal summary

During the first half of the season no tropical cyclone existed within the basin, which made the season only the second season since 1969–70 to have no named tropical cyclones before February.^[4] On February 6, Cyclone Jasmine moved into RSMC Nadi's area of responsibility, and became the first named tropical cyclone since Tropical Cyclone Bune, the previous March, to exist in the South Pacific basin.

Storms

Tropical Disturbance 01F

Tropical disturbance (Australian scale)
Duration	November 13 – November 16
Intensity	Winds unknown,  1004 mbar (hPa)

On November 13, an area of low pressure located within the South Pacific convergence zone started to rapidly develop further.^[5][6] RSMC Nadi then declared the low pressure area: Tropical Depression 01F later that day, while it was located about 400 km (250 mi) to the north of Suva, Fiji.^[7] During the next day, the disturbance moved towards the southwest and onto the main Fijian Islands before convection surrounding the system started to weaken due to land interaction. The disturbance remained over the Fijian Islands until November 16, before RSMC Nadi issued their final advisory on the system as 01F had dissipated.^[8] Within Fiji, torrential rainfall was experienced on November 14, over the whole of the Fijian islands, which lead to widespread flooding of low lying areas, while during the next day strong winds prevailed over the Lau and Lomaiviti group of islands as the rain gradually eased.^[5]

Tropical Depression 02F

Tropical depression (Australian scale)
Duration	December 28 – January 1
Intensity	Winds unknown,  1002 mbar (hPa)

Early on December 28, RSMC Nadi reported that Tropical Disturbance 02F had developed within an area of moderate windshear, about 140 km (90 mi) to the southeast of Alofi on the island of Niue.^[9] During the next day, the disturbance moved towards the east, before it developed into a tropical depression during the next day.^[10]

Tropical Disturbance 03F

Tropical disturbance (Australian scale)
Duration	January 7 – January 8
Intensity	Winds unknown,  1001 mbar (hPa)

On January 7, RSMC Nadi started to monitor a tropical disturbance that had developed about 240 km (150 mi), to the southeast of Lifuka, Tonga.^[11] Over the next 24 hours the disturbance persisted in a weekly sheered environment to the southeast of an upper level outflow centre.^[11] However late the next day, RSMC Nadi reported that the disturbance was not expected to develop any further and issued their final advisory on the system, since convection had been irregularly surrounding the system during that day.^[12]

Tropical Depression 04F

Tropical depression (Australian scale)
Duration	January 8 – January 9
Intensity	Winds unknown,  1000 mbar (hPa)

On January 8, RSMC Nadi reported that Tropical Depression 04F had developed, about 465 km (290 mi) to the west of Papeete on the French Polynesian island of Tahiti.^[12] 04F had an exposed low level circulation centre and was situated to the east of a trough of low pressure and to the west of an area of enhanced convection.^[12] Over the next 24 hours, convection surrounding the system became increasingly displaced to the far east of the exposed low level circulation centre because of strong vertical windshear.^[13] As a result, RSMC Nadi issued their final warning on 04F, late on January 9.^[13]

Tropical Disturbance 05F

Tropical disturbance (Australian scale)
Duration	January 8 – January 10
Intensity	Winds unknown,  1000 mbar (hPa)

Late on January 8, RSMC Nadi reported that Tropical Disturbance 05F had developed within a trough of low pressure, about 460 km (285 mi) to the southeast of Apia, Samoa.^[12] Over the next few days the disturbance did not develop any further, before RSMC Nadi issued their final advisory on the disturbance during January 10.

Tropical Depression 06F

Tropical depression (Australian scale)
Duration	January 19 – January 25
Intensity	Winds unknown,  1001 mbar (hPa)

On January 19, RSMC Nadi reported that Tropical Disturbance 06F, had developed along an active trough of low pressure to the north of Fiji.^[14] Over the next couple of days, the disturbance moved towards the south before it developed into a tropical depression and moved across Vanua Levu during January 21.^[14] Over the next few days the depression, remained near stationary over central parts of the country and caused widespread heavy rainfall and strong winds, over Fiji's Northern and Eastern divisions which lead to flooding.^[14] The depression was last noted on January 25, as it weakened and moved off Fiji and started to move towards the southeast.^[14]

Tropical Depression 07F

Tropical depression (Australian scale)
Duration	January 26 – February 2
Intensity	55 km/h (35 mph) (10-min),  994 mbar (hPa)

The RSMC Nadi reported that a tropical disturbance formed near Vanuatu on January 26, and strengthened into a tropical depression on January 29. But on February 1, 07F rapidly became disorganized, and as it began an extratropical transition, the RMSC Nadi issued their last advisory on the storm.^[15] On February 2, 07F completed its extratropical transition, and thus it was dropped from the RMSC Nadi's advisories.

Tropical Depression 08F

Tropical depression (Australian scale)
Duration	January 25 – January 28
Intensity	Winds unknown,  1001 mbar (hPa)

On January 25, RSMC Nadi reported that a shallow tropical depression, had developed over the northern Lau Islands, within a weak surface trough of low pressure.^[14][16] Over the next couple of days the depression moved southwards through the Lau and Lomaiviti islands and moved into an area of moderate to high vertical windshear.^[14][17] The depression was last noted by RSMC Nadi on January 28, as it moved out of the Fijian archipelago.^[14]

Tropical Depression 09F

Tropical depression (Australian scale)
Duration	January 30 – January 31
Intensity	55 km/h (35 mph) (10-min),  998 mbar (hPa)

On January 30, RSMC Nadi reported that a tropical depression had developed about 250 km (150 mi) to the northeast of Port Vila, in Vanuatu. On January 31, RSMC Nadi issued their last advisory on 09F, as the system rapidly became disorganized.^[18]

Between February 1 and 4, a convergence zone associated with the remnants of Tropical Depression 09F, affected Fiji and caused widespread rainfall over the islands.^[19]

Tropical Depression 10F

Tropical depression (Australian scale)
Duration	February 2 – February 6
Intensity	35 km/h (25 mph) (10-min),  991 mbar (hPa)

On February 2, the RSMC Nadi reported that a tropical depression had formed east of New Caledonia. For the 4 few days, 10F began to accelerate towards the southeast. However, late on February 6, the storm weakened below tropical disturbance intensity, and the RSMC Nadi issued their last advisory on the storm.

Tropical Cyclone Cyril

Category 2 tropical cyclone (Australian scale)
Tropical storm (SSHS)
Duration	February 5 – February 8
Intensity	95 km/h (60 mph) (10-min),  985 mbar (hPa)

On February 5, RSMC Nadi reported that a tropical disturbance had developed about 310 km (190 mi) to the southeast of Nadi, Fiji.^[20] During that day the system moved towards the east and passed through the Fijian islands, while convection surrounding the system increased and organized before it was declared a tropical depression early the next day.^[19][21] Later that day as the system started to move towards the southeast it rapidly consolidated further with the JTWC and RSMC Nadi both reporting that the depression had developed into a tropical cyclone, with the later naming it Cyril as it passed through the Tongan islands.^[22][23] After Cyril had moved through Tonga, the cyclone continued to move towards the southeast before RSMC Nadi reported during February 7 that Cyril had reached its 10-minute peak windspeeds of 95 km/h (60 mph) which made it a category two tropical cyclone on the Australian scale.^[22][24]

The JTWC also reported later that day that Cyril had peaked as a tropical storm with 1-minute windspeeds of 100 km/h (65 mph).^[25] Later that day, RSMC Nadi issued their final warnings on Cyril because it was about to move into TCWC Wellington's area of responsibility.^[26] After moving into TCWC Wellington's area of responsibility, Cyril continued to move towards the southeast and weakened into a category 1 tropical cyclone before it became extratropical and embedded in the westerlies on February 8 while located over 3,000 km (1,900 mi) to the northeast of Wellington, New Zealand.^[22][27][28] Within the northern Fijian Islands, Cyril caused heavy rain, strong and gusty winds, before it brought gale force winds and torrential rain to Tonga. As a result some flooding and minor damage to vegetation and plantations was reported in parts of the Vava'u group of islands with fruit bearing trees such as breadfruit and banana trees, severely affected.^[19][22][29]

Severe Tropical Cyclone Jasmine

Category 4 severe tropical cyclone (Australian scale)
Category 4 tropical cyclone (SSHS)
Duration	February 6 (entered basin) – February 19 Became extratropical on February 16.
Intensity	185 km/h (115 mph) (10-min),  942 mbar (hPa)

On February 6, Tropical Cyclone Jasmine moved into RSMC Nadi's area of responsibility while rapidly intensifying into a Category 4 severe tropical cyclone, while showing annular characteristics.

Cyclone warnings had been issued for Malampa Province, Shefa Province and Tafea Provinces in Vanuatu.^[30] The system passed between New Caledonia and Efate.^[31] A few small islands of both New Caledonia and Vanuatu suffered high winds and torrential rain through February 8 as the system passed^[31] including Anatom island.^[32] The system continued to move southeastward on February 8, even as it intensified into the SSHS equivalent of a Category 4 tropical cyclone.^[32] Later on February 9, Jasmine began to weaken, as it began to undergo and eyewall replacement cycle. Late on February 9, Jasmine moved into TCWC Wellington's area of responsibility, prompting RSMC Nadi to issue their last advisory on the storm, even as Jasmine continued to weaken.^[33] After completing the replacement, late on February 10, Jasmine slowly began to restrengthen, with a larger eye, which formerly extended 40 kilometers across at peak intensity, and was now 75 kilometers across.^{[citation needed]} However, shortly after the event, Jasmine quickly began to weaken again. A few days later, a high pressure area south of Jasmine, began to push the system eastwards.^{[citation needed]} Late on February 11, Jasmine weakened back into a Category 1 tropical cyclone, even as the system turned towards the northeast. Early on February 12, Jasmine moved back into RSMC Nadi's area of responsibility, which prompted the agency to begin reissuing advisories on the storm.^[34] On February 14, Jasmine began to turn towards the north, even as the system slightly organized. By February 15, a warning had been issued for Tonga, with Jasmine bringing strong winds, heavy rain, and flooding to the island of Tongatapu, and Nuku'alofa.^[35] Later on that same day, Jasmine began to execute a loop, first by moving westward, and then by moving southward. Jasmine then turned southeast, and continued to move in that same direction, for the rest of the storm's duration. Later on February 16, Jasmine weakened below tropical disturbance intensity, due to the strong wind shear. Soon afterwards, Jasmine transitioned into an extratropical cyclone. As a result, RSMC Nadi issued their last advisory on the storm.^[36] However, TCWC Wellington continued to track the remnants of Jasmine, over the next few days, as the storm continued to move towards the southeast. On February 19, the remnants of Jasmine dissipated, and thus the storm was dropped from TCWC Welington's bulletins.

Tropical Depression 14F

Tropical depression (Australian scale)
Duration	March 16 – March 18
Intensity	Winds unknown,  1003 mbar (hPa)

On March 16, RSMC Nadi reported that Tropical Depression 14F had developed about 525 km (325 mi) to the south of Vanuatu's Tanna Island.^[37] However during the next day, it was dropped from RSMC Nadi's warnings as it moved south, into TCWC Wellington's area of responsibility.^[38][39] As the depression left RSMC Nadi's area of responsibility, it degenerated into a subtropical depression, before degenerating further into a deep mid-latitude baroclinic low pressure system during March 18, as it affected New Zealand's North Island.^[40] During 14F's time at New Zealand, the storm killed a total of 5 people.

Tropical Disturbance 15F

Tropical disturbance (Australian scale)
Duration	March 19 – March 20
Intensity	Winds unknown,  1004 mbar (hPa)

On March 19, RSMC Nadi reported that a Tropical Disturbance had developed at the western edge of their area of responsibility, west of New Caledonia.^[41] During the next day, the storm accelerated towards the southeast. The disturbance dissipated on the next day, to the southeast of New Caledonia.

Tropical Disturbance 16F

Tropical disturbance (Australian scale)
Duration	March 23 – March 27
Intensity	Winds unknown,  1003 mbar (hPa)

On March 23, RSMC Nadi reported that a tropical disturbance had developed within a trough of low pressure near the Samoan Islands, and gave it the identification 16F. During the next few days, the storm slowly moved moved towards Fiji, eventually moving southeastwards, just east of Fiji. During the next 2 days, the storm looped back northwestwards, as the system began to weaken. During the rest of the storm's duration, 16F accelerated towards the southeast, as it continued to fall apart. Late on March 27, RSMC Nadi issued their last advisory on Tropical Disturbance 16F, weakened below tropical disturbance intensity, which was now located to the far south of Niue. Early on March 28, the storm was drawn into a neightboring extratropical cyclone, to the east of 16F. Early on March 29, the remnant of 16F was completely absorbed by the extratropical cyclone.

Tropical Depression 17F

Tropical depression (Australian scale)
Duration	March 25 – March 31
Intensity	Winds unknown,  1000 mbar (hPa)

On March 25, RSMC Nadi reported that Tropical Disturbance 17F, had developed within a trough of low pressure about 100 km (60 mi) to the northwest of Rotuma.^[42] Over the next few days, the depression moved towards the southwest before it moved on to Northern Fiji during March 28. After moving onto Fiji, 17F rapidly developed further which prompted RSMC Nadi to declare the system a tropical depression.

As the storm rapidly developed further, it triggered widespread rainfall and thunderstorms in Fiji, which led to flooding within Fiji. Within the next few days, 17F slowly left Fiji, with 5 people dead, and slowly moved towards the south. On April 1 the Fijian government announced that at least three people have been killed and almost 4,000 forced into evacuation centers after record floods hit the island nation. ^[43] The next day these numbers rose to at least five dead and more than 8,000 in evacuation shelters. ^[44] On March 30, 17F left Fiji, and began moving south-southeastward. Within the next day, Tropical Depression 17F turned to the southwest, and later accelerated towards the southeast again, before dissipating late on March 31.

Tropical Depression 18F

Tropical depression (Australian scale)
Duration	March 30 – March 31
Intensity	Winds unknown,  1004 mbar (hPa)

Tropical Cyclone Daphne

Category 2 tropical cyclone (Australian scale)
Tropical storm (SSHS)
Duration	March 31 – April 3
Intensity	95 km/h (60 mph) (10-min),  985 mbar (hPa)

On March 31, RSMC Nadi reported that Tropical Depression 19F had developed about 410 km (255 mi), to the south of Honiara on the Solomon Island of Guadalcanal.^[45] This low gradually strengthened and on April 2, it strengthened into a tropical cyclone and RSMC Nadi named it Daphne. Daphne moved southeastwards rapidly and moved into TCWC Wellington's area of responsibility late on April 2. The next day, the storm moved into the mid-latitudes and became extratropical.

Power to the main island of Viti Levu and Nadi International Airport had been cut as thousands of stranded tourists scrambled to leave for home.

Tropical Depression 20F

Tropical depression (Australian scale)
Duration	April 9 – April 11
Intensity	Winds unknown,  1009 mbar (hPa)

On April 9, RSMC Nadi reported that Tropical Disturbance 20F had developed in the vicinity of New Caledonia. As the storm moved southeast, over New Caledonia, 20F began to intensify. On March 10, RSMC Nadi reported that 20F had strengthened into a tropical depression.^[46] Later on the same day, 20F reached its peak intensity.^[47] On March 11, Tropical Depression 20F turned to the southwest, and exited New Caledonia. Soon afterwards, the storm turned eastwards, and began to weaken, due to the moderate wind shear displacing 20F's convection, to the east of the storm.^[48] As the storm continued moving eastwards, the wind shear eroded away more of the storm's convection. Late on April 11, RSMC Nadi issued their last advisory on 20F as the storm dissipated.

Other systems

The following weak tropical disturbances and depressions were also monitored by RSMC Nadi, however all of these systems were either short lived or did not develop significantly.

Early on February 14, Tropical Depression 13F developed within an area of low vertical windshear about 850 km (530 mi) to the northwest of Noumea, New Caledonia.^[49] During that day the depression moved towards the east-southeast, before during the next day it slowly moved towards the west-southwest.^[49][50][51] The final advisory on Tropical Depression 13F was then issued on February 17, as the depression was moving into the Australian region and was not expected to develop into a tropical cyclone.^[52]

Season effects

This table lists all the storms that developed in the South Pacific to the east of longitude 160°E during the 2011–2012 season. It includes their intensity on the Australian Tropical cyclone intensity scale, duration, name, landfalls, deaths, and damages. All data is taken from RSMC Nadi and/or TCWC Wellington, and all of the damage figures are in 2012 USD.

Storm names

Within the Southern Pacific a tropical depression is judged to have reach tropical cyclone intensity should it reach winds of 65 km/h, (40 mph) and it is evident that gales are occurring at least halfway around the center. With tropical depressions intensifying into a tropical cyclone between the Equator and 25°S and between 160°E – 120°W named by the Regional Specialized Meteorological Center in Nadi, Fiji (RSMC Nadi). However should a tropical depression intensify to the south of 25°S between 160°E and 120°W it will be named in conjunction with RSMC Nadi by the Tropical Cyclone Warning Center in Wellington, New Zealand (TCWC Wellington). Should a tropical cyclone move out of the basin and into the Australian region it will retain its original name.^[1]

See also

Tropical cyclones portal

• List of Southern Hemisphere cyclone seasons
• Atlantic hurricane seasons: 2011, 2012
• Pacific hurricane seasons: 2011, 2012
• Pacific typhoon seasons: 2011, 2012
• North Indian Ocean cyclone seasons: 2011, 2012

Notes

References

External links

• World Meteorological Organization
• Fiji Meteorological Service
• Meteorological Service of New Zealand
• Joint Typhoon Warning Center

• v
• t
• e

Tropical cyclones of the 2011–12 South Pacific cyclone season
01F 02F 03F 04F 05F 06F 07F 08F 09F 10F C Ja 13F 14F 15F 16F 17F 18F D 20F		South Pacific Tropical Cyclone Scale TDI TDE 1 2 3 4 5

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