El Niño Conditions

El Niño conditions have developed in the tropical Pacific Ocean, according to the CPC, and are expected to persist. The most recent 4-week sea surface temperature anomalies in the equatorial Pacific have reached 1 degree C. Most of the models predict that the El Niño conditions will continue to intensify and develop into a moderate warm ENSO event by winter.

What does this mean for Washington in the coming months?

The Climate Prediction Center's (CPC) 3-month outlook (November-December-January) predicts at least a 33% chance of above normal temperatures for the eastern third of the state. The NDJ precipitation outlook calls for at least a 40% chance of below normal precipitation on the Olympic Peninsula and at least a 33% chance of below normal precipitation for the remainder of western WA through the Cascades. Eastern WA, however, has an equal chance of below, equal to, or above normal precipitation for NDJ. The winter (December-January-February) outlook shows the intensification of El Niño conditions with at least a 33% chance of above normal temperatures for the western half of the state and at least a 40% chance of above normal temperatures for the eastern half. There is at least a 40% chance of below normal precipitation for the Olympic Peninsula for DJF and at least a 33% chance of below normal precipitation for the remainder of the state.

Another factor is the Pacific Decadal Oscillation, which had a negative polarity from September 2007 through July 2009 (PDO index values). The August PDO value was slightly positive (0.09 standard deviations) and the September PDO value even more so (0.52 standard deviations), which is consistent with the El Niño conditions that have developed. A positive polarity is associated with southerly winds and warm water along the Pacific coast of WA. The NOAA Earth System Research Laboratory's PDO forecast model suggests a shift to weak, positive/warm PDO anomalies this winter.

More information on the climate outlook for the entire Pacific Northwest can be found at the UW's Climate Impacts Group website.

Last Updated: 11/4/2009

NWS Local 3-Month Temperature Outlook
Select a location plotted on the map to view the local outlook.

The links below provide access to global and regional climate predictions.

• The Current State of the Tropical Pacific:
• Climate Prediction Center
• Climate Prediction Center - ENSO Discussion
• Pacific Marine Environmental Laboratory
• Predictions of the Tropical Pacific:
• Climate Prediction Center - ENSO Outlook
• International Research Institute for Climate Prediction
• European Center for Medium-Range Weather Forecasts
• NOAA/ESRL/PSD Linear Inverse Modeling SST Anomalies Forecast
• Predictions of U.S. Climate Anomalies
• Climate Prediction Center - U.S. Outlooks
• NOAA/ESRL/PSD Seasonal Forecast Guidance
• International Research Institute for Climate Prediction