Tuesday, September 23, 2014

University climatologist: Cool end to summer doesn't lead to early winter

MANHATTAN, KAN. — Does a colder fall mean a harsher winter? A Kansas State University climatologist says not necessarily.

Mary Knapp, service climatologist in the university's agronomy department, says temperatures in late September are typically 10-15 degrees cooler than in the beginning of the month, so cooler weather now is not a sign of a tough winter.

Knapp says predicting how much snowfall will occur this winter isn't about the temperatures — it's about the global weather patterns.

"In particular, we are looking at the Atlantic oscillation because that's what triggers these cooler temperatures," Knapp said. "If it switches its phases, the oscillation could move a little farther east. That would mean the warmer than normal conditions in the west would move to the central part of the United States."

If an El Nino forms, it also would affect winter weather conditions. Knapp says the probability of an El Nino occurrence has declined somewhat, but still remains high at a 65 percent chance. An El Nino is expected to form in late fall to early winter and would bring wetter than normal conditions and a milder winter for the southern plains.

Much like the ups and downs of the seasonal temperatures, beating the heat earlier this season has brought both positives and negatives. Cool nights and mild days cut down on the energy demands, saving some money for consumers. However, the early freeze has done some damage to growing crops like soybeans and sorghum.

"They really won't be able to rebound," Knapp said. "When you have that freezing temperature, most of the time what you're going to see is the dropping of leaves. The leaves are basically the fuel for that crop, so you're going to end up with damaged plants that produce less yield."

Knapp says most row crops won't be able to recover from the freeze, but that alfalfa could and that corn was not as affected.