The weather outlook for the 2009 growing season: normal temperatures and precipitation for most of the Prairies. Maybe.
A weakening La Nińa effect could mean stable weather over much of the North American grain belt between June and August, with good crops possible, according to Mike Tannura, an American weather analyst.
Four of Canada’s five highest-yielding wheat crops occurred in years when La Nińa conditions prevailed in January, Tannura told the recent GrainWorld outlook conference in Winnipeg.
He stressed, however, that the link is far from foolproof.
La Nińa is a phenomenon in which surface-level water temperatures in the equatorial Pacific Ocean off South America are colder than average. Its opposite is El Nińo, in which temperatures are warmer than average. Both influence weather patterns worldwide.
A weak to moderate La Nińa is currently underway but is weakening, said Tannura, a meteorologist and commodity analyst with T-storm Weather in Chicago, Illinois.
The phenomenon is at least partially responsible for drought in Argentina and southern Brazil from November through mid-January. An upper-level high pressure system blocked rain-producing storm systems from key crop areas, Tannura said. However, several storm systems at critical times prevented a severe drought.
Here in Canada, there’s no necessary correlation between wheat yields and La Nińa events, said Tannura.
But of the five highest-yielding wheat crops since 1960, four (in 1976, 2008, 1963 and 1999) happened when La Nińa conditions occurred in January. Only one (1966) did not come after a January La Nińa.
By the same token, four of Canada’s five poorest-yielding wheat crops (in 1988, 1961, 2002 and 2001) occurred after ongoing La Nińas in January. Just one poor crop (1984) had no La Nińa.
La Nińas in January are poor indicators of yield potentials for U. S. corn, soybeans and wheat, Tannura said.
And La Nińas don’t necessarily mean drought in the soybean areas of Brazil and Argentina, although the threat is higher than usual, he said.
The U. S. Climate Prediction Center is forecasting near-average warmth and wetness throughout much of the continental United States this summer (and, by inference, the Canadian Prairies). Above-average temperatures are predicted for the western third of the U. S. and the extreme southeast, including Florida. Below-average precipitation is seen as likely for the extreme northwest and southeast.
Tannura admitted he doesn’t have much confidence in weather forecasts past 14 days.
However, he did point to several potential problem areas for drought. Those include southeastern Australia, where wildfires recently destroyed whole communities and killed over 200 people, and a belt stretching from southern China to the North China Plain and through to Manchuria.
The central U. S. Plains, where dry conditions are causing the Hard Red Winter wheat crop to break dormancy earlier than normal, is also one to watch, Tannura said. [email protected]