The U.S. Climate Prediction Center (CPC) said the La Nina pattern blamed for a crippling drought in Texas and severe dry spells in South America has vanished as expected and is unlikely to reappear later this year.
U.S. government forecasters are still uncertain if a feared El Nino anomaly will develop later in the year.
To the relief of U.S. farmers, La Nina has been fading since February and had disappeared by the end of April, the CPC said in a monthly report released on Thursday. This is inline with its forecasts over the last few months.
"La Nina dissipated during April 2012," said the CPC, an office under the National Oceanic Atmospheric Administration.
La Nina is an abnormal cooling of waters in the equatorial Pacific which can last for years and wreaks havoc on weather conditions in Asia and the Americas, where it mainly causes crop-killing drought.
Its more infamous counterpart, El Nino, leads to a heating of those waters, triggering drought in Southeast Asia and Australia and floods in South America.
"The current and evolving conditions . . . suggest that La Nina is unlikely to redevelop later this year," CPC said.
But the CPC could not pin down whether La Nina would be followed by an El Nino event this year.
"There is considerable forecast uncertainty as to whether neutral or El Nino conditions will prevail, due largely to the inability to predict whether the warmer sea surface temperatures will result in the ocean-atmosphere coupling required for a sustained El Niño event," it explained.
For now, there should be neutral conditions in the Pacific from July to September, and then this would be "followed by approximately equal chances of neutral or El Niño conditions for the remainder of the year," the CPC concluded.
La Nina's lingering sting could still cause problems for crops like corn, soybeans and cotton that are sown in the U.S. Midwest and the south. The worst drought in a century in 2011 hit Texas, the biggest cotton growing state in the country.
La Nina has affected Latin America, where estimates for the 2011/12 corn crop from Argentina, the world's No. 2 supplier, have been cut. Brazil's soy crop has also been hit.
La Nina's dissolution came just before the start of the annual Atlantic hurricane season on June 1. The U.S. crude oil industry is particularly worried about storms in the Gulf of Mexico that could topple platforms and rigs there.
In the last two years when La Nina was present, more storms formed in the Atlantic Ocean, but most veered away from the U.S. mainland. An exception was Hurricane Irene which caused severe damage in states from New Jersey to Vermont last year.
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