The signs of an actual drought weren't yet visible in mid-spring. Yet one well-known ag climatologist says that the risk for a major drought in the Corn Belt is up. He adds, however, that just because the risk is up doesn't mean that a drought will materialize.
Elwynn Taylor, ag climatologist at Iowa State University, notes that one factor is the El Nino/La Nina cycle. That's the one the popular press dwells on. The cool phase of the cycle is the La Nina phase, and it's often been associated with increased drought risk.
In mid-spring, the La Nina was still active, but Taylor classified it as a moderate La Nina historically. If it should decrease in intensity as spring moves on, it's importance as a factor in determining what summer weather patterns might be like would also decrease, he notes.
Signs of a typical La Nina later-winter period include a wet Ohio Valley, although that was beginning to change in early May. Dry high plains also often result from a La Nina, as does extremes in temperatures during the winter.
What popular pres weather reporters often forget is that there are other factors that can influence long-range weather forecasting. Taylor says another important consideration in looking toward summer '08 in the Corn Belt is the existing drought in South Carolina.
While the drought there is a bit unusual in how it developed, the connection between drought in South Carolina and drought the same year or following year in the Corn Belt is fairly strong, Taylor explains. "The correlation is definitely there," he notes.
Drought in Georgia, particularly around Atlanta, ahs attracted more media attention over the past several months. A major lake north of Atlanta dropped so much in water level that some boats were stranded on dry land. Water levels in the lake remain far below normal today.
However, there is far less correlation between droughts there and the Corn Belt and a drought in South Carolina and the Corn Belt, the ag climatologist explains. Droughts in Georgia and Alabama may result from different situations than what cause drought in South Caroline.
Besides, it's important to note what's considered a true drought, he adds. Atlanta's population has tripled since the 1960's, but their water supply remains virtually the same. Due to changes in laws, the city is no longer allowed to draw a nearby river to near-dry stream bed conditions either.
Major drought factor
The third factor in play is that the average time between droughts in the Corn Belt is 19 years. That's based on information from tree rings going back 800 years, Taylor insists. The longest period between two major droughts is 23 years.
"The last major drought across the Corn Belt was in 1988," Taylor recalls. "So we've used up our 19 years." Based on this theory, unless the gap proves wider than ever before, a major drought in the Corn Belt could occur before 2011.
"Overall, as an ag climatologist I can say that the risk of drought this year is up based on these three factors," he concludes. "If a large portion of corn planting is delayed beyond May 10, that would be another factor favoring a drought that impacts crop yields."
By mid-spring actual signs of drought in the Corn Belt weren't on the table yet.
"But it's going to be a tight year in terms of weather and one worth watching," Taylor concludes.