What's Next for the Pacific Northwest?
Weak La Niña Conditions
Neutral ENSO conditions are still present in the tropical Pacific Ocean, but sea surface temperatures (SSTs) have cooled over the last few weeks. Current weekly SST departures from normal are between 0.4 and 0.7 degrees Celsius below normal in the central and east-central tropical Pacific Ocean. Low-level easterly wind anomalies have also been persisting in parts of the western and central tropical Pacific over the last couple of months. On November 10, the Climate Prediction Center upgraded its "La Niña Watch" to a "La Niña Advisory". Models are now indicating about a 55% chance of La Niña conditions during the December through February period, and higher chances (~70%) this fall. Overall, the CPC is calling for a weak La Niña for the upcoming winter.
What does this mean for Washington in the coming months?
The CPC December temperature outlook has higher chances of above normal temperatures for the entire state. The chances of above normal temperatures are slightly higher for western WA compared to eastern WA. December precipitation, on the other hand, is a toss up for for a majority of the state. A portion of eastern WA has increased chances of above normal precipitation.
The CPC 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 for the eastern half of the state.
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: 11/17/2016
Climate Prediction Resources
NWS Local 3-Month Temperature Outlook
The links below provide access to global and regional climate predictions.