Seasonal to Interannual Forecasts
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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 July 1, 2008 (posted July 3)
The climate outlook is reviewed monthly and updated as needed.
Spring (March-May) was unseasonably cool throughout the Pacific Northwest (PNW). The average temperature for March-May was 43.6°F, 1.9°F cooler than the 20th century average and the 15th coldest on record. In many parts of the PNW, Spring temperature departures were generally 2-3°F below normal (1971-2000 average) with greater departures of 4-5°F in parts of central Oregon and southern Idaho. While many daily low maximum temperatures were set, Spring was not without its usual heat waves. Snowmelt from one such heat wave in May resulted in flooding for parts of eastern Washington and Northern Idaho, washing out roads and a dam along Strong Creek.
Cool weather continued through the first half of June, which began by setting a record for the coldest first week of June in Seattle. In the Washington Cascades, snowplows were clearing snow on the major highways around June 10th as an unseasonably cool storm system brought several inches of snow to the mountains and eastern Washington (Pullman, WA reported 1.5" of snow while Oroville, WA reported 3.0"). At the time, June was on track to be one of the coldest June's on record, but that was before summer weather arrived and a dominant ridge of high pressure moved over the area. Temperature departures for the month of June were generally 1°F below average throughout the PNW, with greater departures of 2-4°F in western Washington and Oregon.
While Spring weather was mostly cool and cloudy, Spring precipitation was below normal throughout the PNW. Only a few areas received above normal precipitation, with most of the region below 70% of normal. Thunderstorms in parts of eastern Washington, northeast Oregon, and northern Idaho resulted in above normal June precipitation in those areas. Others areas that received above normal precipitation include northwest interior Washington, the Washington Cascades, and parts of the Washington and Oregon coast. Central Washington, eastern Oregon, and southern Idaho are being monitored closely for the development of a drought due to the continued lack of precipitation in these areas. Currently, southern Idaho and southeast Oregon have been classified as moderate drought areas by the Drought Monitor.
Strong coastal upwelling winds (ERD Coastal Upwelling Indices, WA & OR) led to exceptionally cold ocean temperatures (4-6°F departures) along the Washington and Oregon shores in May and June. Elsewhere, coastal sea-surface temperatures (SSTs) along the west coast remain anomalously cool with temperature departures of 1-2°F. The pattern of colder than normal west coast SSTs is consistent with the cold ENSO conditions that have dominated the equatorial Pacific this year (April-June 2008 anomalies, NOAA Earth System Research Laboratory).
Current indicators for Pacific climate
El Niño/Southern Oscillation (ENSO). Since late February, Niño 3.4 (5N-5S, 170-120W) sea-surface temperatures (SSTs) in the tropical Pacific have been gradually warming up. The current Niño 3.4 region SSTs are 0.3°C below average and, as the majority of models suggested earlier this year, ENSO neutral conditions are present. According to the latest model forecasts, ENSO neutral conditions are expected to remain through August. Thereafter, considerable uncertainty exists, with some models suggesting the development of warm ENSO and others suggesting the return of cold ENSO.
Pacific Decadal Oscillation (PDO). The cold polarity of the PDO has been present since September 2007 and was -1.52 and -1.37 in April and May, respectively. The NOAA Earth System Research Laboratory's statistical Linear Inverse Model PDO forecast is for a continuation of cold PDO throughout the rest of 2008 (forecast).
For More Information
- Current conditions: weekly NRCS drought monitor/snowpack update reports
- Read the latest expert analysis of the current state of ENSO from NOAA's Climate Prediction Center
- European Centre for Medium-Range Weather Forecasts ENSO forecast
- View the International Research Institute for Climate Prediction's ENSO QuickLook
- How is an El Niņo/La Niņa event defined?
What does the outlook mean for the PNW in coming months?
Temperatures for western Oregon and Washington will likely remain below normal for the next three months (greater than a 33% chance) according to the Climate Prediction Center's (CPC) temperature outlook for July-August-September. However, in southern Idaho and southeast Oregon, the CPC outlook calls for an increased probability of above normal temperatures (greater than a 33% chance) with equal chances elsewhere in the region. There is an increased chance of below average precipitation through summer for much of the PNW, with a greater than a 40% probability in Idaho and greater than 33% in Oregon and eastern Washington. The only exception is western Washington, where equal chances of above, below, and normal precipitation exist.
The forecasts should be interpreted as the tilting of odds towards general categories of conditions, and should not be viewed as a guarantee that the specified conditions will be realized. The precipitation forecasts have marginal skill in ENSO neutral seasons, like this one.
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)
- NOAA El Niño and La Niña definitions (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 and North Pacific Conditions
- Seasonal Niño3.4 sea surface temperature anomaly plume forecasts (from the European Center for Medium-Range Weather Forecasts)
- Statistical Probabilistic ENSO Predictions (from the International Research Institute for Climate Prediction)
- Sea surface temperature forecasts (from the International Research Institute for Climate Prediction)
- Experimental PDO and Pacific Seasonal Forecasts (from NOAA's Earth System Research Laboratory)
The Current State of the Globe
- Climate diagnostics bulletin (from NOAA’s Climate Prediction Center)
- The North Atlantic Oscillation (NAO) (from NOAA’s Climate Prediction Center)
- 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)
- State of the Climate report (from the National Climatic Data Center)
- Northern Hemisphere snow report (from the National Climatic Data Center)
- 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
- Temperature and precipitation maps (from the High Plains Regional Climate Center)
- 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)
- monthly snowpack maps for the region (from the National Resource Conservation Service)
State Climatologist Offices
- Drought in central and southwest Asia (from the International Research Institute for Climate Prediction)