What's Next for the Pacific Northwest?
Weak La Niña Conditions
Neutral ENSO conditions are still present in the tropical Pacific Ocean, but due to a recent cooling in the eastern equatorial Pacific Ocean and stronger easterly winds across the tropical Pacific, a weak La Niña is now expected to develop. The "La Niña Watch" that had been issued earlier by the Climate Prediction Center was cancelled on Sept 8 but has since been reinstated as of Oct 13. During the last month, sea-surface temperatures (SSTs) have been below normal in the central tropical Pacific and near-normal in the eastern tropical Pacific. Models are now indicating higher chances of La Niña conditions developing this fall (between 60 and 70% chance) versus neutral conditions (between 30 and 35% chance). The probability that the La Niña will continue through the winter of 2016-17 is somewhat decreased, however, with chances at about 55%. Overall, the CPC is calling for borderline, weak La Niña or neutral conditions for the upcoming winter.
What does this mean for Washington in the coming months?
The CPC November temperature outlook has equal chances of below normal, equal to, or above normal temperatures for the entire state. November precipitation, on the other hand, has increased chances of higher than normal precipitation for the entire state.
The outlook for winter (December-January-February; DJF) shows little indication of how temperatures will turn out over the course of the season. There equal chances of below, equal to, or above normal temperatures statewide. For precipitation, there are higher chances of above normal precipitation statewide for DJF.
Remember that these outlook percentages are based on a tercile system, and therefore the chances of below, equal to, or above normal temperatures or precipitation are split into equal probabilities of 33%. When there is a greater than a 33% chance of an occurrence, it should be looked at as a slight tilting of the odds in favor of that outcome.
Last Updated: 10/20/2016
Climate Prediction Resources
NWS Local 3-Month Temperature Outlook
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