Australia wheat production
© USDA and Climate Prediction Center

The Climate Prediction Center June 4th issued an El Niño alert indicating that "Conditions are favorable for a transition from ENSO-neutral to El Niño conditions during June − August 2009."

El Niño occurs when sea surface temperatures warm up in the central equatorial Pacific Ocean, but this is only one aspect of a broad scale shift in wind, air pressure and rainfall patterns that alters the climate in the tropics and sub-tropics. A classic symptom of El Niño is drought in Australia wheat states New South Wales and Victoria.

Below is a look at Australia wheat production in years when El Niño was in effect. Production was low in 11 out of 14 cases and seemed worst in the second year of a 2-season episode (1976-77 and 1986-87). Really severe damage occurred in recent El Niño cases 2002 and 2006 when less than half a normal wheat crop was gathered.

To be classified as an El Niño wheat season in Australia, the El Niño had to be in effect from August through October, encompassing key development stages in wheat -- tillering, jointing and heading. In many cases the El Niño effect began much earlier in May and June, hampering farmer efforts to plant wheat. Thus, not only was the yield reduced, but also the wheat area planted.

At the current time, sea surface temperatures are close to the El Niño threshold in the Niño 3.4 sentinel region. Equatorial surface temperatures must be .5 C above normal or higher for several overlapping months, in order to be classified as a full blown El Niño by the Climate Prediction Center.
Sea Surface Temp
© StromX

Storm Exchange scientist Jeremy Ross points out that what seemed to be an emerging El Niño last year late in summer never came to fruition and , in fact, the equatorial sea chilled down rapidly in the fall, turning into a winter La Niña. Ross gives El Niño a 60% chance for occurrence in the summer of 2009.

A drier weather pattern has resumed in Australia's drought-prone southeastern wheat state New South Wales in recent weeks, suggesting that a weak El Niño influence may be in effect. The top wheat state Western Australia is especially dry on the May-June rainfall map.
Australia 45 day precip
© StormX

Australia wheat growing areas
© StormX