What's Next for the Pacific Northwest?
Neutral ENSO Conditions
Neutral El Niño-Southern Oscillation (ENSO) conditions are still present in the equatorial Pacific Ocean, but sea surface temperatures (SSTs) have warmed over the last 4 weeks. SST anomalies averaged over the last month in the equatorial Pacific Ocean are between 0.5 and 2 degrees Celsius and the "El Niño" Watch issued by the Climate Prediction Center is still in effect. ENSO forecast models strongly favor a weak to moderate El Niño for the upcoming winter, with chances of El Niño development for December-February at about 80%.
What does this mean for Washington in the coming months?
The expectation of El Niño development plays a role in the seasonal forecasts from the Climate Prediction Center (CPC) below. The CPC December temperature outlook has higher chances of above normal temperatures for all of WA state, with chances exceeding 50% on a three-tier system. The CPC December precipitation outlook has equal chances of below, equal to, or above normal precipitation statewide.
The CPC winter (December-January-February; DJF) outlook has increased chances of above normal temperatures statewide, with chances exceeding 60% on the three-tier system for the western two-thirds of the state. In other words, a location such as Seattle has a 60% chance of above normal winter temperatures, a 27% chance of near-normal winter temperatures, and only a 13% chance of below normal winter temperatures. For precipitation, there are equal chances of below normal, equal to, or above normal precipitation statewide.
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: 11/15/2018
Climate Prediction Resources
NWS Local 3-Month Temperature Outlook
The links below provide access to global and regional climate predictions.