Tropical Pacific neutral for reminder of summer (Bureau of Meteorology, Australia)

Tropical Pacific neutral for reminder of summer (Bureau of Meteorology, Australia)

18

Published

18 December 2012
Press Release Number:
N/A

The tropical Pacific Ocean remains neutral—neither El Niño nor La Niña. The central to eastern Pacific has cooled somewhat over the past month, with sea surface temperatures (SSTs) now close to their long-term average. Atmospheric indicators of ENSO, such as the Southern Oscillation Index (SOI), trade winds and cloudiness near the Date Line have shown some fluctuations recently, but have also continued at neutral levels. Further falls are expected in the SOI over the coming days, as a result of the tropical weather system which spawned Tropical Cyclone Evan. Large fluctuations in the SOI over summer due to tropical weather systems are not uncommon.

Climate models surveyed by the Bureau of Meteorology indicate that the tropical Pacific is likely to remain ENSO neutral through the southern hemisphere summer. This means that in contrast to the two prior summers, Australian rainfall and temperatures are unlikely to be strongly influenced by ENSO. Given current conditions and outlooks, this will be the first ENSO-neutral summer since 2005–06.

The influence of the Indian Ocean Dipole (IOD) on Australian rainfall is limited during summer and autumn, though near-record ocean temperatures off the northwest Australian coast may have at least a local influence. >> More

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