The 2013–14 Australian region cyclone season was a slightly below-average tropical cyclone season, with 10 tropical cyclones occurring within the Australian region. It officially started on 1 November 2013, and ended on 30 April 2014. The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2013 and ended on 30 June 2014.
After two seasons with no cyclones of Category 5 intensity, this season saw two of the ten named storms reaching this level: Gillian and Ita. Of the two systems, Gillian rapidly intensified from a tropical low to a Category 5 in just 48 hours but caused only minor damage. Ita was ultimately the strongest and most intense system inside the basin and made landfall on the Far North Queensland coast near Cooktown, causing minor damage but significant flooding. In addition, significant damage was also caused by Christine in the towns of Wickham and Roebourne in Western Australia while Fletcher dumped over 1,250 mm of rainfall on the Queensland town of Kowanyama, making it the fifth-wettest tropical cyclone in the country on record.
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Seasonal forecasts Region Chance ofmore Averagenumber Actualactivity Whole57%1110 Western 53%73 North-Western 55%53 Northern 52%33 Eastern 53%33 Southern Pacific48%158 Western South Pacific56%84 Eastern South Pacific47%114Source: BOM's Seasonal Outlooks for Tropical Cyclones. Region Normalnumber Numberpredicted Actualactivity GCACIC Whole12-151310 GCACIC Western9-1095 GCACIC Eastern5-657 NIWA109-1010Sources:
Ahead of the cyclone season, the Australian Bureau of Meteorology (BoM), the New Zealand National Institute of Water and Atmospheric Research (NIWA) and various other Pacific Meteorological services, all contributed towards the Island Climate Update tropical cyclone outlook that was released during October 2013. The outlook took into account the ENSO neutral conditions that had been observed across the Pacific and analogue seasons with ENSO neutral conditions occurring during the season. The outlook called for a near average number of tropical cyclones for the 2013–14 season, with eight to twelve named tropical cyclones, to occur between 135°E and 120°W compared to an average of 10. At least four of the tropical cyclones were expected to become category 3 severe tropical cyclones, while three could become category 4 severe tropical cyclones, they also noted that a Category 5 severe tropical cyclone was unlikely to occur.
In addition to contributing towards the Island Climate Update outlook, the BoM issued eight seasonal forecasts during October 2013, for the Australian region and the Southern Pacific with each forecast covering the whole tropical cyclone year. Each forecast issued took into account the current neutral ENSO conditions that were forecast to continue during the season. For the basin as a whole they predicted that there was a 57% chance that the season would be near its average of around 11 tropical cyclones. For the Western region between 90°E and 125°E, the BoM forecast that the area would see activity near to or slightly below the average of 7, with a 53% chance of an above average cyclone season. TCWC Perth also noted that there was a likelihood of two tropical cyclones and a significant likelihood of at least one severe tropical cyclone impacting Western Australia.
For the North-Western subregion between 105°E and 130°E, it was predicted that activity would be near normal with a 55% chance of above average tropical cyclone activity. The Northern Territory which was defined as being between as being 125°E and 142.5°E had a 52% chance of an above average season, with TCWC Darwin noting that all of the climate drivers were pointing towards a typical tropical cyclone season for Northern Australia. The Eastern region between 142.5°E and 160°E had a 53% chance of having an above average tropical cyclone season. The BoM also issued 3 seasonal forecasts for the Southern Pacific between 142.5°E and 120°W, one for the Western Southern Pacific region between 142.5°E and 165°E and one for the Eastern Southern Pacific region between 165°E and 120°W. They noted that the tropical Pacific Ocean was currently experiencing neutral ENSO conditions which meant that there was no strong shift expected in the average location of tropical cyclone formation. They also noted that there was nothing in the broad climate drivers to suggest anything, but a typical tropical cyclone season for the South Pacific. As a result, they predicted that the region as a whole, would experience near average tropical cyclone activity during the coming season with a 48% chance of it being above average. The Western region was predicted to have 56% chance of being above average while the Eastern region had a 47% chance of being above average.
During November 2013 the Guy Carpenter Asia-Pacific Climate Impact Centre (GCACIC), issued seasonal forecasts for the whole basin and one each for the regions to the east and west of 135°E. For the overall basin they predicted that tropical cyclone activity in the entire Australian region was likely to be near normal with 13 tropical cyclones predicted to occur. However, it was suggested that the season could be below average since the region had been in an inactive era since around 2000, and two of the indicators they had used to predict the season suggested below average activity. For the Western region it was predicted that activity would be near normal with 9 tropical cyclones occurring, while the Eastern region was predicted to have 5 tropical cyclones occurring.
Seasonal summary
Systems
Tropical Cyclone Alessia
The first storm of the season originated from a developing low-pressure area south of Java in the Indian Ocean on 20 November. The system tracked southeastward, and organized only slowly due to moderate wind shear. However, at 0600 on 21 November, TCWC Perth initiated advisories on Tropical Low 01U. Over the course of the next day, the disturbance continued toward the east-southeast into an environment more conducive for further intensification, and as a result, its structure began to improve. At 0900 UTC, the JTWC designated the system Tropical Cyclone 02S, noting that the storm's center of circulation had become better-defined, with an improved convection pattern. Three hours later, the BoM upgraded the low to Category 1 Tropical Cyclone Alessia. Tracking toward the east around the southern periphery of a ridge to the north, the abnormally small cyclone approached the Kimberley coastline on 23 November.
Alessia remained a marginal Category 1 cyclone as it skirted the northern Kimberley coast, passing just south of Troughton Island before emerging into the Joseph Bonaparte Gulf. The JTWC issued its final warning on 02S at 0600 UTC on 24 November, Increased wind shear took its toll on the already disheveled cyclone, leaving the system vertically decoupled; it made its final landfall near the Anson Bay, Daly and Reynolds River Floodplains area of the Top End midday local time on 24 November. According to the BoM, Alessia deteriorated below tropical cyclone status by 1200 UTC.Tropical Cyclone Outlook Alessia reformed in the Gulf of Carpentaria on 27 November, around 100 km northeast of Borroloola. During the next day, Alessia moved ashore and turned towards the east. On 28 November, Alessia weakened below tropical cyclone intensity again, and turned towards the west again. On 29 November, Alessia completed a loop and re-entered the Gulf of Carpentaria. During the next several days, Alessia turned back towards the east, while continuing to weaken. On 1 December, Alessia moved over land once again, as the system continued moving westwards. Early on 2 December, Alessia was dropped from TCWC Perth's Tropical Weather Outlook, as the system dissipated.Tropical Cyclone Outlook for the Western Region
Rainfall was unusually light for even a weak tropical cyclone, with no major rain totals after Alessia's first landfall. Rainfall in the Gulf of Carpentaria was heavier, Centre Island recorded , the McArthur River Mine and Borroloola .
Severe Tropical Cyclone Bruce
In mid-December 2013, an active monsoon trough became established over the eastern Indian Ocean, near southwestern Indonesia. By 15 December, an area of low pressure developed about 535 km (330 mi) northeast of the Cocos Islands. Scatterometer passes revealed a well-defined circulation while satellite imagery showed fragmented convective banding features wrapping into the system. Situated to the north of a subtropical ridge, favorable diffluence supported convective development; however, concurrent moderate to high wind shear mitigated this. On 16 December, the BOM began monitoring the system as a tropical low, assigning it the identifier 03U. Tracking generally southwest over the following day, deep convection became increasingly organized around the centre of circulation and banding features steadily improved. Owing to this development, the JTWC issued a Tropical Cyclone Formation Alert. Environmental conditions improved markedly by 17 December, with wind shear lessening and excellent outflow into an upper-level low over Western Australia developing. Around 1800 UTC that day, the JTWC issued their first advisory on the system, designating it Tropical Cyclone 04S.
Early on 18 December, the BOM upgraded the low to a tropical cyclone and assigned it the name Bruce. At this time, Bruce was situated roughly 210 km (130 mi) north of the Cocos Islands. Near-gale-force winds were reported on the island despite its distance, indicating stronger winds were likely near its center. Maintaining a general southwest to west-southwest track along the subtropical ridge, Bruce steadily intensified. Increasingly rapid development took place later that day as the storm passed roughly northwest of the Cocos Islands. Periodic gale-force winds and heavy rains impacted the Cocos Islands; a peak gust of was measured on 18 December while gusts up to continued into the following day. During the same period, a total of of rain fell. No damage was reported in relation to the storm. With elevated oceanic heat content in the storm's path, Bruce attained severe tropical cyclone status — having sustained winds of at least — early on 19 December. A broad, ragged eye feature became apparent on visible satellite imagery that day, and deep convection soon consolidated around the eyewall. Around 1800 UTC, the cyclone crossed 90°E, leaving the BOM's area of responsibility and entering that of Météo-France. At this time, Bruce was estimated to be a high-end Category 3 on the Australian intensity scale with winds of and a barometric pressure of 961 mbar (hPa; ). On 25 December, the remnants of Bruce re-entered the Australian region basin.
Severe Tropical Cyclone Christine
On 25 December, TCWC Perth started to monitor a discrete center, that had developed within the broad monsoon circulation. Over the next couple of days the system intensified further and became a tropical cyclone on 28 December, gaining the name Christine. It intensified overnight and was upgraded to Category 2 status by the Bureau of Meteorology, before intensifying into a Category 4 system.
On 30 December, Christine made landfall near Port Hedland, directly between Roebourne and Whim Creek. The name Christine was retired and was replaced to Catherine.
Tropical Low 05U
On 10 January, TCWC Darwin reported that a weak tropical low had formed in the Arafura Sea north of the Arnhem Land. The low remained stationary on 11 January and continued to maintain its intensity. On 13 January, TCWC Darwin issued warnings for the coast of Northern Territory. The tropical low crossed the coast early on 14 January east of Darwin and moved inland.