Weakening La Niña Conditions

Last winter's weak-to-moderate La Niña in the equatorial Pacific Ocean substantially weakened during March, according to the Climate Prediction Center (CPC). Warming sea-surface temperatures (SSTs) have become evident in the eastern equatorial Pacific Ocean and in the upper 300 meters of the equatorial Pacific Ocean as a whole (oceanic heat content). Models are indicating that a return to ENSO-neutral conditions will occur soon and that these conditions will persist through the summer. The "La Niña Advisory" that was released by the CPC last fall in still in effect, however, and has more details on the current state of ENSO.

What does this mean for Washington in the coming months?

As we transition out of La Niña conditions and into a more neutral state, there is not as much signal to rely on for the seasonal forecast. The CPC three-class May-June-July (MJJ) temperature outlook has equal chances of below, equal to, or above normal temperatures for the entire state. The MJJ precipitation outlook does shift the odds toward a drier than normal 3-month period, however. There is at least a 33% chance of below normal precipitation statewide, with chances exceeding 40% for eastern WA.

The summer (June-July-August; JJA) CPC three-class temperature outlook also has equal chances of below, equal to, or above normal temperatures for the whole state. The JJA precipitation outlook has increased chances of below normal precipitation for nearly the whole state, except for the Olympic Peninsula and the central and northern Puget Sound locations which have equal chances of below, equal to, or above normal precipitation.

Another factor is the Pacific Decadal Oscillation, which has had a negative polarity since June 2010 (PDO index values). The negative values are consistent with the recent La Niña conditions and are associated with northerly winds and cold water along the Pacific coast of WA. The NOAA Earth System Research Laboratory's PDO forecast model suggests a continuation of negative/cold PDO anomalies.

Last Updated: 4/19/2012

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 and Society