Sunday, June 15, 2008

{News} 080604 ENSO Wrap-Up

ENSO Wrap-Up
A regular commentary on the El Niño-Southern Oscillation

Australia Bureau of Meteorology, June 4, 2008
Summary: Pacific ENSO-state neutral, but ocean warms

Pacific climate patterns remain neutral, although some aspects of the 2007/08 La Niña lingered in the western Pacific during the past fortnight. The tropical Pacific has been warming gradually during the past few months, with central Pacific temperatures now near-normal and eastern Pacific temperatures about one-half to one degree warmer than average.
The warming in the east has been caused in part by a weakening of the Trade Winds in that region, an effect that has been gradually spreading further west during the past several months. In addition, the Southern Oscillation Index (SOI) has been falling and now sits a little below zero for the past 30 days.
Computer model predictions show central and western Pacific temperatures continuing to increase over the next two seasons, but mainly remaining less than about 0.8°C above average, that is, neutral. No model is predicting a return to La Niña conditions, and while the chance of an El Niño developing is small, it can't be ruled out, especially as ENSO events can evolve rapidly at this time of the year.
Furthermore, several models are predicting a positive mode of the Indian Ocean Dipole (IOD), an effect which often hinders the formation of northwest cloudbands which are an important source of winter/spring rainfall in southeast Australia.

Source: http://www.bom.gov.au/climate/enso/

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