Seasonal to Interannual Forecasts
ARCHIVE COPY - MARCH 2007
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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?
Updated March 1, 2007 (posted 3.3.07)
The climate outlook is reviewed after the 20th of each month and updated as needed.
Wild winter continues
The wet, windy, and icy conditions in November and December continued in January. Just in the first week, two windstorms struck the Puget Sound region and heavy snow fell in the Palouse area of southeastern Washington and north Idaho (8 inches reported in Moscow, ID). Then on January 10 a vigorous cold air outbreak dropped as much as a foot of snow in the Puget Sound area, and 6-7" in places around Spokane. Temperatures throughout the Pacific Northwest plunged well below freezing and remained cold for several days, with daytime highs near or below freezing in western Washington and southern Idaho, and overnight lows below zero Fahrenheit in some locations in eastern Washington and north Idaho.
Since mid-January the weather has been more seasonable. For January and February averaged together, temperatures were close to or somewhat below the long-term average around the Northwest. Precipitation has been below to much below average at most locations in the PNW. Mountain snowpack, which got off to a good start, did not build well and was below average in most of the interior Pacific Northwest as of February 28. In the Oregon Cascades, basins were reporting at 80-102% of average; 60-80% in eastern Oregon; 72-83% in southern Idaho; around 90% in north Idaho and northeastern Washington; and 103-127% in the Washington Cascades. Colder, wet conditions after February 28 have helped snowpack averages slightly in some of these regions.
Wasn't the El Niño supposed to bring warmer and drier conditions? Yes, in a typical warm ENSO episode the Pacific Northwest often experiences a milder, drier winter. ENSO is the strongest determinant of how our winter climate varies from one year to the next, but it does not explain all or even half of how one winter differs from another. In addition, this ENSO episode was moderate in magnitude, and so its effect on our climate is weaker than in a stronger ENSO episode.
Current indicators for Pacific climate
El Niño / Southern Oscillation (ENSO). During January, the El Niño event was substantially weakened as an equatorial oceanic Kelvin wave pumped cold water to the surface in the eastern Pacific, leading to a rapid transition to ENSO-neutral conditions. The cold anomalies just below the surface raise the possibility of a La Niña. Forecasts of ENSO are more guarded about this transition, but also missed the rapid demise of the El Niño.
Pacific Decadal Oscillation (PDO). The Fall PDO index values were negative with respect to the 1900-93 mean, but are now neutral, and are likely to remain small now that El Niño is gone (more information on PDO forecasting).
For More Information
What does the outlook mean for the PNW in coming months?
The Climate Prediction Center's outlook for March-April-May is for a greater than 33% chance of warmer than normal temperatures for eastern Washington, central Oregon, and far northern Idaho, and a greater than 40% chance of warmer than normal temperatures in southeast Washington, eastern Oregon, and Idaho. The near-term precipitation forecast is equal chances for above, below, or near normal precipitation throughout the Pacific Northwest with a tilt in the odds for above average precipitation for April through June for much of the region based on recent trends. The CPC forecasts should be interpreted as the tilting of odds towards warmer conditions, and not viewed as a guarantee.
For More Information
Pacific Northwest Resource Outlooks
- Water Resources Forecasts (streamflow and other hydrologic conditions)
- Salmon survival forecast
- Forecast of extreme weather events
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
- Real-time data from moored ocean buoys (from NOAA’s TAO array)
- ENSO diagnostic discussion (from NOAA’s Climate Prediction Center)
- Weekly ENSO update (from NOAA’s Climate Prediction Center)
- ENSO Quick Look (from the International Research Institute for Climate Prediction)
- Monitoring El Niño/La Niña (from NOAA’s Climate Prediction Center)
Predictions of Tropical Pacific Conditions
- Seasonal Niño3 sea surface temperature anomaly plume forecasts (from the European Center for Medium-Range Weather Forecasts)
- ENSO forecast forum (from NOAA’s Climate Prediction Center)
- Statistical Probabilistic ENSO Predictions (from the International Research Institute for Climate Prediction)
- Sea surface temperature forecasts (from the International Research Institute for Climate Prediction)
The Current State of the Globe
- Climate diagnostics bulletin (from NOAA’s Climate Prediction Center)
- Monitoring climate in the Extratropics and Tropics (from NOAA’s Climate Prediction Center)
- The North Atlantic Oscillation (NAO) (from NOAA’s Climate Prediction Center)
- Monthly climate information digest (from the International Research Institute for Climate Prediction)
- Accumulated daily precipitation time series graphs (from NOAA’s Climate Prediction Center)
- Daily global and regional precipitation analysis (from NOAA’s Climate Prediction Center)
- Index of Climate Prediction Center’s climate monitoring activities and data
Current and Predicted U.S. Conditions
- Monthly to seasonal climate outlooks (from NOAA’s Climate Prediction Center)
- Northern Hemisphere snow report (updated monthly by NOAA/NCEP)
- Spring and summer streamflow forecasts (from the USDA Natural Resources Conservation Service)
- Drought in the US
- Water supply forecasts and snowpack conditions for the Western U.S.
- Experimental seasonal fire risk forecasts (from the U.S. Forest Service)
- Western U.S. climate conditions and forecasts (from the Western Regional Climate Center)
Pacific Northwest Conditions
- Western Washington water and snowpack (from Seattle City Light)
- Seattle water supply conditions and outlook (from Seattle Public Utilities)
- Coastal conditions (from NOAA’s CoastWatch)
- Data on PNW snowpack (from the Western Regional Climate Center)