Tuesday, September 28, 2010

La Niña Returning for Winter 2010-11

Headline: La Niña Returns
We are currently in a La Niña phase for the Pacific Ocean. Last Winter we were in an El Nino phase and we transitioned into the La Niña phase earlier this Summer. This oscillation back and forth is known as the El Nino Southern Oscillation (ENSO).

The attached graph shows the predictions from over a dozen computer models for the upcoming Winter 2010-11 through Spring 2011. The three letters on the bottom axis are clusters of three months (SON = September, October, November for example). The left axis shows the forecast temperature anomalies (with negative numbers indicating La Niña and positive numbers indicating El Nino.

All of the models show the La Niña peaking in intensity (most negative values on the left axis) in early to mid Winter. Indications are that this La Niña will be one of the more intense ones and it will also quickly begin to disappear by mid-Spring (with several models indicting neutral conditions, i.e. neither La Niña or El Nino by next Summer).

La Niñas can have a dramatic impact on our winter weather on the Plains and will be illustrated in the next BLOG posting at our site.

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