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NOAA's Climate Prediction Center on Thursday issued its monthly forecast for El Nino/La Nino (known officially as ENSO).

Over the summer computer models forecasted that a weak-to-moderate El Nino would develop for this coming winter, but in September changes in the sea surface temperatures (SST) of the tropical Pacific reversed course (went from warming to cooling) and computer models were split about 50-50 between forecasting a weak El Nino or a neutral winter (in a neutral winter the SSTs are close to their averages).

The latest computer model runs based on October s observations now seem to be settling on this being a neutral winter (as you can see by the bar graph below).



What does that mean for Western Washington s weather? Neutral winters tend to be near the averages in precipitation and temperature; however, more extreme events tend to occur during neutral winters (though not every neutral winter). For example, the December 2008 snowstorm that paralyzed the Northwest for several weeks occurred in the region's last neutral winter. (Though I should note that winter came within one-tenth of a degree in SST of being a La Nina winter, whereas this year we are closer to El Nino.

An average winter would see about 7-8 inches of snow in Seattle. So right now we should expect to see normal rainfall and average temperatures over the winter, but we will need to keep a close watch on our shorter-term computer models (which only go out 2 weeks) for any signs that something unusual is headed our way.

Right now there aren t any signs of any extreme weather events headed our way out through Thanksgiving Day (Turkey cookers take heart!), but stay tuned!

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