Those who think that because Mother Nature didn't give us moisture this summer mans we will get pounded with snow this winter just might be off target. Ken Scheeringa, assistant state climatologist based at Purdue University, says that instead, it looks like below normal precipitation for the region on through late fall and into and through winter.
The La Nina cycle is in control as the driving factor, and we've had a typical La Nina fall for Indiana," he says. "Temperatures tend to average above normal and precipitation averages below normal. That's certainly what we've seen so far this fall."
La Nina is the cool phase of the El Nino-La Nina cycle. This process refers to warming or cooling of vast areas of the Pacific Ocean far off the coast. Exactly where the pocket of warm or cool water develops and how big it is determines the intensity of the event. The cycle of El Nino- neutral phase- La Nina repeats, but at irregular intervals. Overall, it's typically a four- to- five year process.
When vast areas of the Pacific Ocean water are cooler than normal, it impacts atmospheric pressures. The net result is that it impacts wind currents aloft in the atmosphere. These wind currents drive weather patterns around the globe. So in this particular case, the wind currents affect how many storms come through the Midwest, particularly across Indiana. Right now, and for the past three months, patterns have been such that storms have nor developed frequently in this region. Their movement is altered into other directions by air flow circulation patters aloft.
This doesn't mean there won't be any rain or snow, Scheeringa cautions. There can still be rain and snow, even a week or two of above normal rainfall or colder than normal weather, embedded within an overall trend that favors drier, warmer weather. The La Nina is one of the major factors that controls weather on a global scale. There are other important but much less all-inclusive factors that can control weather on a more daily scale where you live.
If the La Nina ends as anticipated, the trend may be back toward more rain in March and April. While it will be needed to recharge soils, it may not be the best news if it results in another long, wet spring.