El Nino Warning Raised by Australia as Tropical Pacific Sizzles.

http://www.bloomberg.com/news/2014-11-18/el-nino-warning-raised-by-australia-as-tropical-pacific-sizzles.html

Australia raised an El Nino warning after the Pacific Ocean showed renewed signs of the pattern that can bring drought to parts of Asia and heavier-than-usual rain to South America.

Climate models suggest current conditions will persist or strengthen, prompting the status to be elevated from watch to alert, the Bureau of Meteorology said on its website today. The alert indicates at least a 70 percent chance of El Nino, it said.

The bureau had previously pushed back projections for the onset of El Nino as changes to the atmosphere failed to develop consistently. The odds of the event during the Northern Hemisphere winter are 58 percent, the U.S. Climate Prediction Center said on Nov. 6. El Ninos can roil agricultural markets worldwide as farmers contend with drought or too much rain.

“Above-average temperatures in the tropical Pacific Ocean have warmed further in the past fortnight, while the Southern Oscillation Index has generally been in excess of El Nino thresholds for the past three months,” the Australian bureau said. “International climate models expect the warm tropicalPacific Ocean temperatures to persist, with most models predicting values will remain near or beyond El Nino thresholds for the next two to three months.”

El Ninos, caused by periodic warmings of the tropical Pacific, occur every two to seven years and are associated with warmer-than-average years. The last El Nino was from 2009 to 2010, and the Pacific has either been in its cooler state, called La Nina, or neutral since then.

The weather bureau previously issued an El Nino alert on May 6, predicting an event may develop as early as July. That was downgraded to watch on July 29.

Not all indicators have shifted toward El Nino, with tropical cloudiness near the Date Line and trade wind strength close to average, suggesting the atmosphere is still not firmly linked with the warmer ocean, the bureau said today.