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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 is now provided by the Office of the Washington State Climatologist on a quarterly basis with the CIG newsletter.

Recent PNW Climate

August 2012
Updated 23 August 2012 (posted 30 August)

The 90 days ending on August 21 were cooler than normal for western WA, western OR, and northern CA, as shown in the average temperature departure from 1971-2000 normal (Figure 1). This is a continuation of the generally cooler than normal conditions that have prevailed since late fall 2011. While some of these areas had temperatures less than 1°F below normal, some other locations had temperatures between 1 and 3°F below normal for the last 90 days. The rest of the Pacific Northwest, however, has had average temperatures on the warmer side of normal in the last 90 days. Like the areas west of the Cascades, most locations had average temperatures that were close to normal (within 1°F) while other had average temperatures between 1 and 3°F above normal.

Precipitation during the last 90 days was variable across the Pacific Northwest (Figure 2). Eastern WA, the ID panhandle, and northwestern MT were much wetter than normal during this period, receiving between 150 and 250% of normal precipitation. Northern OR and most of western WA received normal to above normal precipitation as well, while southwestern OR had much above normal precipitation (between 150 and 200% of normal) in the last 90 days. The remainder of the Pacific Northwest, specifically southeastern OR and the rest of ID, had below normal precipitation, between about 25 and 75% of normal.

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ENSO Conditions

Neutral ENSO conditions have existed in the equatorial Pacific Ocean during the last 90 days, according to the Climate Prediction Center (CPC). The sea-surface temperatures (SSTs) have been warming, however, especially in the east-central equatorial Pacific. Most of the dynamical ENSO forecast models are now predicting continued warming, resulting in a weak-to-moderate El Niņo during the upcoming fall and winter. Some statistical models are still indicting the neutral conditions will persist through the winter, but the consensus of the model solutions indicate warming. The chances for a La Niņa, which would be the third in a row, are small.


Climate Outlook

What can we expect for the Pacific Northwest? The expected El Niņo is influencing the CPC seasonal outlooks toward drier predictions for the region. The CPC September-October-November (SON) three-class temperature outlook calls for increased chances of below normal temperatures along the western seaboard (Figure 3) due to the presence of colder than normal sea surface temperatures. Equal chances of below, equal to, or above normal temperatures for the rest of WA and OR are expected for SON, while the majority of ID has increased chances for warmer than normal temperatures. Precipitation is expected to be below normal for most of the Pacific Northwest during the SON period, with the highest chances for the western two-thirds of WA and OR (Figure 4). Eastern ID has equal chances of below, equal to, or above normal precipitation.

 

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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 and North Pacific Conditions

The Current State of the Globe

Current and Predicted U.S. Conditions

Pacific Northwest Conditions

State Climatologist Offices

Special Areas