La Nina follows El Nino -- be ready for rough winterWEST LAFAYETTE, Ind. -- With mild temperatures and little snowfall, Hoosiers seemed to skate past a typical Indiana winter last year. But this year, Hoosiers may be skating literally.
El Nino, the weather pattern caused by warm currents in the Pacific Ocean, has given way to its climatological opposite, La Nina.
Ken Scheeringa, acting state climatologist for Indiana who is stationed at Purdue University, said that comparing September's weather with past El Nino-La Nina transitions indicates that Indiana is already in a La Nina weather pattern. "September historically is one of the driest months of the year in most of Indiana, with rainfall averaging three to three-and-a-half inches across the state," he said. "Most of the state is well below that at this time. This is indicative of La Nina weather characteristics."
Tom Priddy, Extension Service Agricultural Meteorologist for the University of Kentucky, said that people in the upper third of the United States should expect a very different winter than last year's. "After a very El Nino-controlled weather pattern for the past 12 months, it's time for it's wicked sister -- La Nina," he said. "She leaves an entirely different footprint for the middle United States and Ohio Valley."
Priddy said that the fall and winter months ahead will be dominated by a La Nina-driven weather pattern. "Typically, La Nina brings mild, dry conditions to the southern third of the U.S. and cold, wet weather conditions to the northern third of the U.S.," he said. "Indiana can expect cold, wet conditions for November, December and part of January. Temperatures should reverse by February, though, to mild conditions for the remainder of the winter."
Scheeringa said there were two recent El Nino-La Nina transition winters for which weather analogies are available: the winters of 1958-59 and 1983-84. These years brought autumns that were cooler than normal, with temperatures taking a severe drop in November and December.
"In the summer of 1958 we had an El Nino event, which was followed by a La Nina later that year," Scheeringa said. "That November we had a record low in Indiana of 12 degrees below zero."
The Indiana State Climatologist's official weather summary for January 1959 reported a furious La Nina:
"The month will be remembered for its numerous snow and ice storms. Losses totaled several million dollars. On the fourth, winds and moisture from Lake Michigan were such as to cause drifts up to four feet in height in the Michigan City area. In southern Indiana, three to six inches of rain on frozen soil flooded lowlands and places seldom exposed to high water."
Scheeringa said that 1983 was another El Nino-La Nina transition year. "On Christmas Day in '83, everybody in Indiana was snowed in," he said. "Traveling was strongly discouraged due to severe wind chill factors and iced-over highways. This was quite a contrast to the balmy El Nino Christmas Day weather just a year earlier. This was something I lived through and will never forget."
Priddy said that besides rough weather, another distinguishing characteristic of La Ninas is the fluctuating temperatures. "That means cold blasts from the Arctic as well as mild periods interspersed," he said. "That could average out to near normal."
Sources: Ken Scheeringa, (765) 494-8105; e-mail, firstname.lastname@example.org
Tom Priddy, (606) 257-3000, ext. 245; e-mail, email@example.com
Purdue News Service: (765) 494-2096; e-mail, firstname.lastname@example.org