La Nina foretells warm, dry summer

A weak and waning El Nino, such as the one currently lingering around the international date line in the Pacific Ocean, usually means a coolerthan-normal summer for large parts of the Midwest and South. However, an atmospheric scientist at the University of Missouri, Columbia, predicts a warm, dry summer in store for both of those regions. Tony Lupo, associate professor of atmospheric sciences in the College of Agriculture, Food and Natural Resources, points out that, in 2004, the Midwest experienced rather regular rainfall and mild temperatures, which are common conditions that occur before El Nino.

El Nino is an irregular warming of the Eastern Pacific equatorial waters, stretching west from South America toward the South Sea Islands. Its counterpart, La Nina, describes the cooling of the same waters. Each profoundly affects U.S. weather.

"I consider drought to be the biggest issue," asserts Lupo. "I would not be shocked to see it be drier than normal" this summer.

Researchers have discovered that, in La Nina years, or when the climate is in transition to La Nina, dry spells last longer in mid-to-late summer--typically about three weeks. "When an El Nino dies out, as this one currently is, data typically points toward warmer and drier than normal conditions.... Drought is a possibility. Frequent, lighter rains are better for agricultural and other purposes than gully-washers that can be associated with dry summers."

Lupo adds that it would be a mistake to read too much into any longrange forecast--including his own--regarding the 2005 growing season. "We can't really rely on it," he admits.

"Long-range weather forecasting still is a dicey proposition, and I've rolled snake-eyes before."

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