2016–2017 Tropical Cyclone Season Outlook for Tonga Featured
2016–2017 Tropical Cyclone Season Outlook for Tonga
Summary
The tropical cyclone (TC) activity expected in the 2016/17 TC Season to affect Tonga is likely to be slightly higher than average. This means that Tonga could expect 2 to 3 cyclones this season with a chance that at least 1 of them could be Severe (Category 3 and above classified a Severe Tropical Cyclone or Category 3 or above).
Analysis and Outlook
The official 2016/17 TC Season will begin on 1st of November 2015, and will end on 30th April, 2016. It should be noted that tropical cyclones have occasionally formed outside this period e.g. Tropical Cyclone “Keli” which affected Northern Tonga in June 1997. The peak time for the occurrence of tropical cyclones in Tonga is from January to March with most events occurring in February.
Assessments of the current El Nino Southern Oscillation (ENSO) indicate that near neutral conditions currently prevail in the Pacific Ocean and global models remain undecided whether a La Nina is likely to develop in late 2016 into the first half of 2016. Tongan rainfall patterns in the last 4 to 6 months has been erratic with extreme drought conditions experienced in some months and very wet in some months. The outlook for the next 6 months is for normal conditions over most places.
Traditional knowledge indicates that when drought conditions are experience ahead of the cyclone season, enhanced tropical cyclone activity is usually expected in the upcoming cyclone season. On record, about 1.88 cyclones affect Tonga during El Nino, 1.63 during La Nina and 1.64 during neutral years.
The average number tropical cyclones that form in the Southwest Pacific is 10 to 12.
The outlook indicates that 8 to 10 named TCs are expected for the coming season. TC activity is elevated for island countries near Papua New Guinea and close to the International Date Line near Tonga and Niue.
Tropical Cyclone Risk in 2016/17
Figure 1: Map of tropical cyclone risk for the number of named Cyclones interacting with an island group based on the 2016-17 Island Climate Update tropical cyclone guidance.
Tropical Cyclone Outlook 2016-17
Figure 2: map of tropical cyclone overall seasonal outlook for the number of named cyclones interacting with an island group based on the 2016-17 Island Climate Update tropical cyclone guidance.
It should be noted that this outlook reflects an expectation of overall elevated activity during both the early season (November to January) and the late season (February to April) particularly west of the Dateline. Note that the TC activity outlook for islands like New Caledonia, Fiji, Vanuatu and Tonga indicates two or more cyclones could interact with each of those countries during the season despite subtle projected differences from normal.
At least 5-6 severe TCs (Category 3 or higher) are expected to occur anywhere across the Southwest Pacific during the season. All communities should remain vigilant and follow forecast information provided by the Meteorology Department throughout the season.
-MEIDECC
