Another La Niña winter might be on tap
If you’re wondering how the weather might be shaping up for this winter, just think back to last winter and plan for that.
La Niña conditions have returned for the second consecutive year, says Indiana state climatologist
Dev Niyogi. The presence of La Niña raises the prospect of weather similar to that of last winter, when numerous states endured extreme cold and frequent snowstorms.
Studies conducted by the Indiana State Climate Office, based at Purdue University, show that typical effects from La Niña’s cool Pacific air are an autumn of drought and a transition to conditions colder and wetter than normal across the northern states during the second half of winter.
Farmers will be watching weather patterns closely during the winter months. That is because effects from the last La Niña extended into June of this year, bringing frequent rain that delayed planting for a month or longer. That, in turn, is resulting in lower yields.
Whether the Midwest has a winter as severe as the last one will depend also on the North Atlantic Oscilla-tion (NAO), a weather system that controls the strength and direction of westerly winds and storms. The severe start to 2011 was caused by "the one-two punch" of La Niña and the NAO, Niyogi says.
"If we have that again, the weather will certainly be a thing to watch," he cautions.
The effects of the NAO are difficult to predict because its cycle usually is shorter than that of
La Niña. But they can extend for a season or longer, as they did last winter.
"Even for a landlocked state such as Indiana, what happens in the oceans still has a profound impact," Niyogi says.
Crop Shifts. What that means for farmers is that they should probably consider hybrids with a longer growing season maturity date. Pro-ducers might also have to deal with new pests due to increased moisture and variable prevailing winds carrying insects and pathogen spores.
Gene Takle, a climatologist at Iowa State University, believes there will be a continued shift of the Corn Belt further north for both corn and soybeans, possibly even into Canada, as conditions there are likely to be warmer and wetter. In addition, he sees the Corn Belt moving further west, although much of the corn grown there will need irrigation.
"It’s likely we will not return back to conditions of the 20th century," Takle states. "It will be either hotter or more humid, or both."
Measurable Weather Shifts. Though there is year-to-year variability, "in Illinois, the first fall freeze seems to be later, and in the spring, the last freeze seems to be earlier, so we have been experiencing a slightly longer growing season," says Illinois state climatologist Jim Angel.
- December 2011