The 2004–05 South Pacific cyclone season was a near average tropical cyclone season, that contained nineteen tropical disturbances and nine tropical cyclones. The season got of to an early start, when Tropical Depression 01F developed near the Solomon Islands on October 28, three days before the official start of the season on November 1. The final disturbance of the season dissipated as the season was drawing to a close on May 1, 2005. Tropical cyclones between 160°E and 120°W and north of 25°S are monitored by the Fiji Meteorological Service in Nadi. Those that move south of 25°S are monitored by the Tropical Cyclone Warning Centre in Wellington, New Zealand.
The 2004–05 South Pacific cyclone season, got off to an early start with the first tropical depression of the season forming on October 28 about 420 km, (260 miles) to the northeast of Honiara in the Solomon Islands. This came about four days before the official start to the season. The Depression gradually moved towards the west and moved into TCWC Brisbane'sarea of responsibility late on October 30. The South Pacific remained quiet during November with no tropical disturbances forming. This quietness lasted until December 3 when Tropical Depression 02F formed to the north of Vanautu. After being relocated a couple of times the depression then dissipated on December 14 with no impact being reported from the depression. Whilst 02F was active another weaker tropical depression formed to the northwest of Fiji. Remaining weak the depression lasted until December 10 when Nadi issued their final advisory on it as it had dissipated.
On October 28, RSMC Nadi reported that Tropical Depression 01F had developed within a weak monsoon trough, about 420 km, (260 mi) to the northeast of Honiara on the Solomon island of Guadalcanal. The depressions low level circulation center at this time was located under the deep convection and lied in a weak monsoonal trough which had a low to moderate amount of wind shear. Over the next couple of days the system moved towards the west until late on October 30, when RSMC Nadi released their final advisory on the depression as it was now located within TCWC Brisbane’s area of responsibility. TCWC Brisbane mentioned the depression in their tropical weather outlooks for a couple of days but never released any full warnings on the system.
Late on December 3, RSMC Nadi reported that Tropical Depression 02F had formed about 280 km (170 mi) to the north of Port Villa in Vanuatu. The depression was located within an area of moderate shear, as a consequence of this major convection was displaced to the east of the low level circulation center. Over the next few days the depression moved towards the east and gradually weakened. However late on December 9 RSMC Nadi reported that the depression had re-intensified and had reached its peak wind speeds of 55 km/h (35 mph). Early the next day RSMC Nadi reported that a new circulation center had developed and relocated the depression's position to about 600 km (370 mi) to the northeast of Fiji. However later that day RSMC Nadi relocated the disturbance to about 600 km (370 mi) to the northwest of Fiji. During December 12 as the depression moved to the south and was located a few hundred miles to the east of northern Vanuatu, the depression's low level circulation center consolidated and thus Nadi started to issue gale warnings on the depression however the depression then weakened and Nadi issued their final warning on December 14. There was no impact reported from Tropical Depression 02F.
Early on December 5, a weak tropical disturbance formed within a moderately sheared environment to the northwest of Fiji. Later that day it was designated as Tropical Depression 03F by RSMC Nadi. Deep convection was detached from the Low level circulation center and remained to the north and south of the depression. Over the next couple of days the depression remained weak reaching a peak pressure of 1003 hPa, before being absorbed into a trough of low pressure on December 8. RSMC Nadi then issued its final advisory on December 10 as the depression had dissipated after remaining weak throughout its lifetime.
On December 21, RSMC Nadi reported that Tropical Disturbance 04F had developed, along an active and slow-moving monsoon trough near French Polynesia. The depression was in an area of high shear, with the deep convection located to the northeast of the center. The low level circulation center at this time was exposed but was developing despite the high shear associated with the system. Early on December 24 deep convection associated with the system moved over the low level circulation center whilst the system was getting better organized. Later that day at 1800 UTC the Depression was upgraded to a category one tropical cyclone and was named Judy whilst located about 510 km (320 mi) southeast of Tahiti and moving towards the southwest. During the next few hours under strengthening shear, Judy struggled to maintain itself. However as it moved further to the south if came under a strengthening steering field which was being enhanced by a trough of low pressure to the west of the steering field which helped to neutralize the effect of the shear over the cyclone. Judy then intensified slightly further and reached its peak intensity of 85 km/h, (50 mph), with a peak pressure of 989 hPa late on December 25 whilst turning towards the south towards TCWC Wellington's area of responsibility. RSMC Nadi then released their final advisory on Cyclone Judy early the next day as they passed primary warning responsibility of the cyclone to TCWC Wellington. The cyclone had started to weaken by this time due to it moving in to cooler waters. TCWC Wellington kept Judy as a tropical cyclone for 12 hours before declaring it had become extratropical. The remnants of Judy eventually merged with a low pressure system to the southeast of Tahiti.
Tropical Cyclone Kerry developed from Tropical Depression 05F on January 5, 315 nautical miles (583 km) northeast of Port Vila, Vanuatu. Kerry moved to the southwest with 40-knot (70 km/h) winds as it moved over Vanuatu. Once past the island, Kerry moved on a west-southwest course and it began to intensify after turning to the west. The storm reached a peak intensity of 85 knots (157 km/h) before turning towards the south-southeast. The storm began to weaken under vertical shear and was downgraded to a depression on January 13.
Tropical Storm Lola developed from Tropical Depression 06F on January 31, 100 nautical miles (200 km) west-southwest of Tongatapu. Lola reached a peak intensity of 40 knots (70 km/h), but was downgraded to a depression on February 2.
On February 1, the RSMC Nadi began monitoring a tropical disturbance, which they designated as 07F, to the west of the northern Cook Islands. The next day, a small area of deep convection developed.
The most intense system of the season, Tropical Cyclone Olaf developed rapidly like Nancy. By February 16, Olaf had attained maximum sustained winds of 145 knots (269 km/h) and was thrashing American Samoa. However bad the damage was, it could have been worse as Olaf veered east, its eyewall missing the islands.
Cyclone Nancy formed on February 10 as Tropical Disturbance 09F, over the next couple of days. The disturbance gradually developed and was designated as Cyclone Nancy during February 12 due to its outflow improving and a small area of deep convection, developing over the center of circulation, whilst it was located about 485 km (301 mi) east-northeast of Pago Pago, American Samoa. During that day Nancy started to rapidly intensify becoming a Severe Tropical Cyclone late on February 13 as a small, irregularly shaped, eye had begun to develop.
The next day both RSMC Nadi, and the JTWC reported that Cyclone Nancy had attained its peak intensity of 175 km/h (110 mph 10-minute winds) and 230 km/h (145 mph 1-minute winds). Increasing wind shear then caused Nancy to weaken. Early on February 15, the storm passed directly over Manuae. Continued weakening took place as a trough of low pressure approached from the southwest. By February 16, Nancy weakened below hurricane intensity and turned to the southwest as it began to undergo a Fujiwhara interaction with Cyclone Olaf, strong shear associated with the outflow of Cyclone Olaf caused all convection associated with Nancy to be displaced to the southwest on February 16. Early on February 17, Nancy transitioned into an extratropical cyclone as it entered the area of responsibility of TCWC Wellington. Shortly afterwards, the low was absorbed into the larger circulation of Olaf however it was monitored by TCWC Wellington as a separate system until 1200 UTC on February 18.
Already impacted by Cyclone Meena a week earlier, the Cook Islands sustained significant damage from Cyclone Nancy. Several homes were damaged and destroyed throughout the islands. Downed trees and power lines blocked roads and cut power and minor flooding was reported along coastal areas.
Percy quickly formed from an area of low pressure on February 24 and reached Category 1 status north of American Samoa. The cyclone then moved eastward, peaking at Category 5 status before turning southward. Percy then passed through the southwestern Cook Islands causing severe damage before dissipating.
Late on February 26, RSMC Nadi reported that Tropical Depression 11F had formed about 1,200 km (750 mi), to the northwest of Henderson Island. The depression was located east of an 250hPa outflow channel and was poorly organised with major convection located to the northeast of the low level circulation center. During the next morning RSMC Nadi downgraded the depression to a tropical disturbance as they issued their final advisory on the depression.
Late on February 27, RSMC Nadi reported that a suspect tropical disturbance was developing near to the north of Rennel Island, in the Solomon Islands. Over the next couple of days the system gradually developed and before it was declared as a tropical disturbance early on March 1. At this time convection detached from the disturbance's low level circulation center, whilst vertical wind shear around the system remained weak. Early the next day, the Disturbance was then relocated to the northwest of Viti Levu in Fiji, before it was designated as Tropical Depression 13F later that day. The Depression remained weak reaching an estimated central pressure of 1001 hPa (mbar) early on March 3, however there were no winds reported by RSMC Nadi whilst they were monitoring it. RSMC Nadi then issued their last advisory on 13F early on March 4 after no persistent convection reported around the system since the depression reached its peak pressure.
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.
During April 20 Tropical Disturbance 16F developed within a monsoon trough, about 570 km (350 mi) to the southeast of Apia on the Samoan island: Upolu. During April 21, the disturbance moved towards the southwest and affected Niue while starting to rapidly weaken, before it was last noted during April 22 wrapping into Cyclone Shelia's circulation. Tropical Depression 17F then developed on April 26 while located about 710 km (440 mi) to the northeast of Pago-Pago in American Samoa.
During April 29, Tropical Depression 18F developed within a monsoon trough about 635 km (395 mi), to the northeast of Suva, Fiji. Over the next 24 hours the system moved towards the southeast while deep convection surrounding the system failed to become organized and started to weaken. The depression was last noted during the next day, as it dissipated about 445 km (277 mi), to the northeast of Suva.
This table lists all the storms that developed in the South Pacific to the east of longitude 160°E during the 2004–05 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 2005 USD.