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Seasonal to Interannual Forecasts

Climate Outlook

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The Climate Impacts Group (CIG) translates global-scale climate forecasts and conditions into regional-scale climate forecasts for Pacific Northwest (PNW) resource managers and the general public. The El Niño/Southern Oscillation (ENSO) is the most important factor for seasonal forecasting, changing the odds for different types of winter and spring weather (e.g. warmer/drier, cooler/wetter) in the PNW. Another important climate variable for Pacific Northwest climate is the Pacific Decadal Oscillation (PDO). The climate outlook also provides the basis for natural resource forecasts, including the CIG's annual streamflow forecasts.


What's Next for the Pacific Northwest?

Fall 2005 / Winter 2006
Updated November 17, 2005
The climate outlook is reviewed monthly and updated as needed.

Current indicators for Pacific climate:

El Niño/Southern Oscillation (ENSO). In the past two months, sea surface temperature (SST) patterns in the tropical Pacific have trended away from El Niño. In fact, SST in the eastern equatorial Pacific is now cooler than average, and NOAA scientists believe that the next 6-9 months will likely see either ENSO-neutral or weak La Niña conditions.

Pacific Decadal Oscillation (PDO). As with ENSO, the last two months have brought a change to the SST patterns used to determine the state of the PDO. SST patterns in the North Pacific have trended away from warm phase PDO to a negative PDO state that will very likely persist at least through November. Given the updated ENSO outlook, it is likely that the PDO will be near neutral or negative for the coming winter and spring (see note on PDO forecasting).

A note on PDO forecasting: Seasonal to interannual forecasts for the state of the PDO index (based on a pattern of North Pacific sea surface temperatures (SSTs)) are an emerging science. A major source of uncertainty in developing PDO forecasts is our lack of understanding of what causes the observed multi-year persistence in the PDO index and, more importantly, what triggers PDO regime shifts. However, a strong tendency for year-to-year persistence of the PDO index along with a well-established statistical relationship with the state of ENSO provides a means for making skillful 1-year projections of the PDO index. (For more information on this one-year lead-time PDO forecast method, see Newman, M., G. P. Compo, and M. A. Alexander, 2003. ENSO-forced variability of the Pacific Decadal Oscillation, Journal of Climate 16: 3853-3857).

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What will it mean for the PNW in coming months?

The recent changes in Pacific SST patterns suggest that large scale influences of ENSO and PDO patterns will likely favor near-normal odds for fall/winter/spring precipitation and temperatures, if not a weak tilt in the odds for cool-wet conditions in the next few seasons. The potential for a weak tilt in the odds to cool conditions will be tempered by the past decade's trends for warm fall/winter temperatures in the Pacific Northwest.

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Pacific Northwest Resource Outlooks

Climate Prediction Resources

The links below provide access to the latest information on the current state of global and regional climate, as well as links to global and regional climate predictions.

The Current State of the Tropical Pacific

Predictions of Tropical Pacific Conditions

The Current State of the Globe

Current and Predicted U.S. Conditions

Pacific Northwest Conditions

State Climatologist Offices

Special Areas