The slow developing El Nino event of the El Nino/La Nina cycle is still developing, long-term forecasters say. At one point over the last year it appeared that it might fall apart. Instead, forecasters now believe it will strengthen as the calendar moves deeper into 2015.
The El Nino cycle refers to warm water developing off the coast of the tropical Pacific over a vast mass of ocean. The sea surface temperature affects barometric pressure, which in turn affects air circulation patterns aloft. The patterns affect how weather cycles set up around the globe.
Indiana saw the effects of what happens when a weather pattern blocks fronts and forces them to go a different direction this spring. Ken Scheeringa, associate climatologist with the Indiana state climate office, says storms came up with moisture from the Gulf of Mexico, and were diverted across Indiana, primarily from early June through Late July.
That's what gave Indiana such high rainfall totals during the two months. However, he's not sure that the effect was related to the developing El Nino event. Scientists still have a lot to learn about how an El Nino impacts Indiana weather in the summer, he says.
There is a more known impact on Indiana winters when an El Nino event is underway, and sea surface temperatures in the tropical Pacific Ocean are above normal.
As the calendar moves into autumn and winter, Scheeringa believes that the El Nino will continue to get stronger. That's based on predictions from long-range weather forecasters, and those who study La Nina events.
El Nino impacts tend to be greater in winter than in summer in Indiana, he says. They are also more predictable in their impact on weather patterns. Strong El Nino events typically bring milder winters to Indiana. Often the snowfall is about half of what falls during a normal winter in the state.