Seasonal to Interannual Forecasts
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.
Recent PNW Climate
August 1 2011
Updated 1 August 2011 (posted 4 August)
The 90 days ending on July 25 were cooler than normal across the entire Pacific Northwest. Figure 1 shows the temperature departures from the 1971-2000 normal (in Fahrenheit) for the western US, indicating that much of the Pacific Northwest was between 2 and 4°F cooler than normal. A few locations were even cooler than that, specifically parts of eastern WA and the OR Cascades, ranging between 4 and 6°F below normal. These negative temperature anomalies represented a continuation of relatively cool temperatures for the region beginning in February 2011.
The distribution of precipitation in the Pacific Northwest during the last 90 days, in a relative sense, is shown in Figure 2. Most locations had close to normal precipitation, but a few areas were wetter than normal. Central WA and southwestern and southeastern OR, for example, received between 150 and 200% of normal precipitation. There were some drier than normal spots as well, such as south central OR and eastern ID. These locations ranged between 33 and 91% of normal precipitation. The source of both temperature and precipitation data presented here are from The Western Regional Climate Center.
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The equatorial Pacific is now in an ENSO-neutral state, according to the Climate Prediction Center. Figure 3 shows the sea surface temperature (SST) anomalies for several regions of the equatorial Pacific since August 2010. In recent months, the SSTs have been very close to normal except for the easternmost portion of the tropical Pacific (Niņo 1+2 region) where SSTs have been warmer than normal. As for the state of ENSO for winter 2011-12, a majority of the models indicate a continuation of ENSO-neutral conditions. A just-released run of the Coupled Forecast System (CFS) model, however, indicates an ensemble mean with weak La Niņa conditions for the 2011-12 winter. These results point towards a higher likelihood that the equatorial Pacific will be on the cool side and a lower likelihood of an El Niņo developing for next winter. These predictions will be fine-tuned in the coming months and by early fall, more definitive forecasts for ENSO should be available.
What's next for the Pacific Northwest? Despite the cooler than normal conditions that have persisted, the Climate Prediction Center (CPC) August-September-October (ASO) seasonal temperature outlook (Figure 4) has equal chances of below, equal to, or above normal temperatures for most of the region. In other words, the probability is split evenly into a 33% chance for each of the three outcomes. The exception is most of western OR in which there is an increased likelihood of below normal temperatures.
The ASO precipitation outlook also has equal chances of below, equal to, or above normal precipitation for most of the region (Figure 5). Southeastern OR and southwestern ID have a slightly greater than 33% chance of below normal precipitation for the period, tilting the odds towards drier conditions there.
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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
- Real-time data from moored ocean buoys (NOAA’s TAO array)
- ENSO diagnostic discussion (NOAA’s Climate Prediction Center)
- Weekly ENSO update (NOAA’s Climate Prediction Center)
- ENSO Quick Look (International Research Institute for Climate and Society
- Monitoring El Niño/La Niña (NOAA’s Climate Prediction Center)
Predictions of Tropical Pacific and North Pacific Conditions
- Seasonal Niño3.4 sea surface temperature anomaly plume forecasts (European Center for Medium-Range Weather Forecasts)
- Statistical Probabilistic ENSO Predictions (International Research Institute for Climate and Society)
- Sea surface temperature forecasts (International Research Institute for Climate and Society)
- Experimental PDO and Pacific Seasonal Forecasts (NOAA's Earth System Research Laboratory)
The Current State of the Globe
- Climate diagnostics bulletin (NOAA’s Climate Prediction Center)
- The North Atlantic Oscillation (NAO) (NOAA’s Climate Prediction Center)
- Accumulated daily precipitation time series graphs (NOAA’s Climate Prediction Center)
- Daily global and regional precipitation analysis (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 (NOAA’s Climate Prediction Center)
- State of the Climate report (National Climatic Data Center)
- Northern Hemisphere snow report (National Climatic Data Center)
- Spring and summer streamflow forecasts (USDA Natural Resources Conservation Service)
- Drought in the US
- Water supply forecasts and snowpack conditions for the Western U.S.
- Large fire incidents (National Interagency Fire Center)
- Experimental seasonal fire risk forecasts (U.S. Forest Service)
- Western U.S. climate conditions and forecasts (Western Regional Climate Center)
- Monthly temperature and precipitation maps (National Climatic Data Center)
Pacific Northwest Conditions
- Temperature and precipitation maps (Western Regional Climate Center)
- Temperature and precipitation maps (High Plains Regional Climate Center)
- Western Washington water and snowpack (Seattle City Light)
- Seattle water supply conditions and outlook (Seattle Public Utilities)
- Monthly snowpack maps for the region (National Resource Conservation Service)
- Snotel River Basin Snow Water Content (Western Regional Climate Center)
- River forecasts (NOAA Northwest River Forecast Center)
- Wildland fires (Incident Information System -- InciWeb)
- Oregon and Washington wildland fires (Northwest Interagency Coordination Center)
- Coastal conditions (NOAA’s CoastWatch)
State Climatologist Offices
- Drought in central and southwest Asia (International Research Institute for Climate and Society)