ENSO stands for El Niño Southern Oscillation and refers to oscillation back and forth from El Niño to La El Niño conditions. The attached graph produced by the International Research Institute (IRI) shows the various computer model projections of the current La Niña
On the graph, anything below the -0.5 line indicates a La Niña phase, and above the +0.5 line indicates the El Niño phase and in between +0.5 and -0.5 would be classified as "neutral".
Some of the models have the La Niña lingering into next Summer while some models have La Niña ending and a return to "neutral" conditions by next Summer. It is interesting to note that some of the models have a repeat performance of the La Niña conditions for next Autumn going into Winter 2011-12
Although there are many variables that can be used in predicting seasonal weather patterns, the existence of a La Niña, or El Niño can play a major role in our ability to produce seasonal outlooks.