THE El Nino bringing drought conditions to much of Australia may be reaching its peak but is now one of the strongest on record.
THE Bureau of Meteorology says the El Nino, a warming of sea surface temperatures in the central and eastern tropical Pacific Ocean that tends to bring drier weather to Australia, now matches the strength of record El Ninos in 1997/98 and 1982/83.
Both of those events brought severe droughts to eastern Australia, and the 1982/83 drought was a major factor in the Ash Wednesday bushfires that killed 71 people in Victoria and South Australia on February 16, 1983.
“The (current El Nino) event is comparable to the record events of 1997/98 and 1982/83,” the BOM’s latest fortnightly El Nino Southern Oscillation Wrap Up says.
“International climate models suggest that El Nino sea surface temperatures are approaching their peak, and will decrease in the first quarter of 2016.
“With such warm sea surface temperatures, models suggest the tropical Pacific is unlikely to return to neutral until at least autumn 2016, although impacts on Australian climate are likely to decline prior to this.
” The influence of El Ninos varies at this time of year, depending on how quickly they begin to break down, but most deliver below-average rainfall and a continuing drying influence on southeastern Australia but more rain in inland Western Australia.
Meanwhile, a warming of Indian Ocean sea surface temperatures known as the Indian Ocean Dipole is decaying rapidly, the BOM says. It set sea surface temperature records in October and offset some of the drying influence of the El Nino during winter.
WHAT IS AN EL NINO?
* Warming of sea surface temperatures in eastern and central tropical Pacific Ocean that disrupts weather patterns across the Pacific
* Can cause ocean cooling in the western Pacific and around northern Australia
* Can deliver more rain to the west coast of North and South America
* Can disrupt trade winds that blow moisture-laden air towards eastern Australia
WHAT ARE THE EFFECTS IN AUSTRALIA?
* Lower rainfall through winter and spring, especially in the north and east
* Temperature extremes
* Warmer-than-average weather, particularly in southern Australia in the second half of the year
* Decreased cloud and low rainfall
* Worsening heat extremes for cities such as Adelaide and Melbourne, increase in extreme hot days and heatwaves further north
* Increased frost
* Increased bushfire risk
* Fewer tropical cyclones, especially for Queensland
* Later northern monsoon rains
* Below-average wet season rains early
* Reduced winter snowfall
(Source: Bureau of Meteorology)