Wet Spring, Dry Summer Are Forecast

Odds favor a wet spring giving way to increased chances of drought this summer, says ISU climatologist.

Published on: Mar 26, 2007

Odds are this year's planting season will get off to a wet start, then the growing season will turn quite dry.

"Soil moisture reserves this spring are good to excessive in Iowa and in the rest of the Midwest," says Elwynn Taylor, an Iowa State University Extension climatologist. Taylor, who has been speaking at meetings across the Corn Belt in recent weeks, says farmers report tile lines are running in 90% of the fields.

The strong flow of moist air from the Gulf of Mexico is continuing to head into the Midwest "which means here in Iowa and in the rest of the Corn Belt we might be wet this spring," he says. Taylor is also paying attention to weather conditions in Arkansas. Generally, weather patterns in that state provide about a three-week look ahead on possible rainfall amounts for Iowa.

Cycle signals dry growing season

Looking at the longer-term weather indicators, the chance of a significant drought occurring somewhere in the Corn Belt during the 2007 growing season is increasing. "The risk of drought is higher for 2007 as well as for the next six years because of where we are in the 19-year weather cycle," he explains.

In addition, it appears that La Nina conditions are developing. If a La Nina event does indeed form during the next 60 days, weather will turn dry and temperatures will be more extreme than normal--especially in the western Corn Belt.

If La Nina establishes itself before mid-May, the risk of severe drought would increase from 25%, which is the chance now, to about 33%, says Taylor. That would mean about a 70% chance that the U.S. average corn yield for 2007 would be below the trendline of 148.4 bushels per acre. Weather conditions so far in March translate into a projected U.S. average corn yield of 146 bu. per acre for 2007, slightly below the trendline.

A number of weather experts are predicting that a La Nina will develop during the 2007-growing season. Fred Gesser, senior meterologist for Plananalytics, a weather forecasting firm, says as far as he's concerned, La Nina is already here. He predicts dryness this summer will be centered in the Great Plains and could stretch into Northwest Iowa too. "As the calendar moves forward this year, it's important to watch what happens in early summer, " says Gesser.