If El Nino Fades, Expect Drought In 2007

We have El Nino-like conditions now, but what happens in January will tell the tale about drought possibility in 2007.

Big corn yields are needed with the increased demand for corn to be made into ethanol. Big yields start with great genetics, but they don't happen without getting good weather as well. There is concern about drought hitting the U.S. Corn Belt between now and the year 2010. The odds favor it, says Iowa State University Extension climatologist Elwynn Taylor.

What does the long-term weather picture look like for the 2007-growing season? What is El Nino going to do to us or for us in the U.S. Corn Belt? "El Nino is our concern," says Taylor, "mainly because it makes the coming season predictable. If we have an El Nino, that means we likely won't experience widespread drought. That's what's happened historically.

"If we have the opposite of El Nino, which is called La Nina, that weather pattern has been associated with our worst drought," he explains. "That's not predictable 100% of the time, but still La Nina years are when most of the worst droughts occur. Right now, we are in El Nino-like conditions and have been since the past July. It saved our crop in 2006, you might say, for much of the Corn Belt."

Keep an eye on the current El Nino

If the El Nino persists through 2007, it would do that again and mean that we'd have a pretty good or above trend corn yield. "However, the experts who watch El Nino closely and make weather forecasts are saying that this current one may fade," says Taylor. "This one may fade as fast as it came."

Taylor says he isn't going to make a judgement on that, however, until the calendar gets well into January. Because December and January are El Nino times, but the current one has weakened. The SOI index, which is how El Nino strength is measured, shows that the current one has weakened by minus 0.76 and the minus 0.8 is qualifying as El Nino. So it is now right at the edge of just barely qualifying as an El Nino, weaker than it has been in the past few months.

Odds favor drought in next few years

Taylor still thinks the odds are that we are in line to have a serious drought in the Midwest one of these years soon—between now and the end of 2010. "There are a few things there's no doubt about when you look at historical weather records," he says. "We have 17 years in every 100 years that qualify as drought years on the average. In one out of three of those droughts, it's usually a severe one. The last major drought in the Corn Belt was in 1988."

It's not uncommon if you look at 800 years of tree rings, to see when these drought periods have occurred. "Trees keep a pretty good record of how the weather has been," says Taylor. "The 800 year history of tree ring records show that it's not uncommon to go 18 or 19 years between major droughts. But the longest period of time between the droughts in the last 800 years was 23 years.

"So here we've been, since 1988, the 18 years have arrived," he notes. "If we reach 23 years we will have set a record long time without a serious drought in the U.S. Corn Belt."

What this means is that the longer-term odds aren't in our favor. "In fact, with about five or six of these major droughts occurring during a 100 year period, and that's gone on for 800 years, that's pretty high odds," says Taylor. "That is, that we're going to have a major drought sometime in the U.S. Corn Belt during this five-year period between now and 2010--or before the end of the year 2010."

TAGS: Extension
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