If you're wondering how the weather might be shaping up for this winter, just think back to the last one and plan for that.
La Nina conditions have returned for the second consecutive year, said State Climatologist Dev Niyogi
. The presence of La Nina raises the prospect of weather similar to last winter when Indiana endured extreme cold and frequent snowstorms.
"There is a good probability that we could have the same thing that we had last winter," Niyogi said.
Studies by the State Climate Office, based at Purdue University, show that typical effects from La Nina's cool Pacific air are an autumn of drought, which Indiana had until recently, 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 over the winter. That is because effects from the last La Nina extended into June this year, bringing frequent rain that delayed planting of crops for a month or longer. That, in turn, is resulting in projections of yields lower than what would be expected with normal weather.
Whether Indiana has a winter as severe as the last one will depend also on the North Atlantic Oscillation, a weather system that controls the strength and direction of westerly winds and storms. Indiana's severe winter this year was caused by "the one-two punch" of La Nina and the North Atlantic Oscillation, Niyogi said.
"If we have that again, that will be a thing to watch," he said.
The North Atlantic Oscillation and its effects are difficult to predict because its cycle usually is shorter than that of La Nina. But they can extend over a season or longer, as they did last winter.
"Even for a landlocked state like Indiana, what happens in the oceans still has a profound impact," Niyogi said.
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