What's Next for the Pacific Northwest?
Neutral El Niño-Southern Oscillation (ENSO) Conditions
Neutral ENSO conditions are present in the tropical Pacific Ocean and are now projected to continue through the winter of 2016-17. The "La Niña Watch" that had been issued earlier by the Climate Prediction Center was cancelled on Sept 8 as the likelihood of neutral conditions continuing is now higher than the likelihood of a weak La Niña developing. During the last month, sea-surface temperatures (SSTs) have been near-normal to below normal in the central and eastern tropical Pacific Ocean. SSTs have warmed in the eastern Pacific over the last month, but the anomalies are still near-normal in the eastern tropical Pacific at the time of this writing. Models are now indicating that neutral conditions will continue through the winter. For example, in December-January-February, there's about a 55% chance of neutral conditions, and a 40% chance of La Niña conditions developing.
What does this mean for Washington in the coming months?
The CPC October-November-December (OND) temperature outlook has increased chances of above normal temperatures for the entire state, with chances exceeding 40% on the three-tiered scale for a majority of the state. For OND precipitation, there is little indication of how it will turn out over the course of the season. The CPC outlook is calling for equal chances of below normal, equal to, or above normal precipitation for the state. A small area in northeastern WA has slightly higher chances of above normal precipitation for OND.
The outlook for winter (December-January-February; DJF) has equal chances of below, equal to, or above normal temperatures statewide. For precipitation, Eastern WA has higher chances of above normal precipitation while Western WA has equal chances of below, equal to, or above normal precipitation 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: 9/15/2016
Climate Prediction Resources
NWS Local 3-Month Temperature Outlook
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