Forecasts and Planning Tools

Seasonal to Interannual Forecasts

Climate Outlook

ARCHIVE COPY - NOV 2008

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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?

November 2008
Updated November 21, 2008 (posted November 24)

The climate outlook is reviewed monthly and updated as needed.

The Pacific Northwest (Oregon, Washington, and Idaho; PNW) experienced above normal temperatures and near-normal precipitation during October and early November. Temperatures were greater than 0.5°C above the 1971-2000 normal over the region (total and departure, HPRCC; days of freezing temperatures, WRCC). Heavy precipitation in early November produced flooding along the coast, around Puget Sound, and in some sections of Mount Rainier National Park (totals, departures; HPRCC). The warm temperatures have kept what precipitation has fallen in the form of rain, and the early season snowfall, as measured by snow water equivalent on 20 November, is well below normal over the region (map, map legend, NWRFC).

In contrast to the climate over land, the northeast Pacific Ocean has experienced large negative sea surface temperature anomalies since September 2007 (UW). The magnitude of the temperature anomalies in this region is approximately twice that associated with typical annual-mean fluctuations in the Pacific Decadal Oscillation (PDO, not shown). Monthly values of the PDO have been negative since September 2007 and in excess of 1 standard deviation negative since April of 2008 (the beginning of the climatological upwelling season along the Oregon and Washington coast) (1900-93 climatology, digital values). [For a normally distributed variable, only 32% of the values exceed one standard deviation in magnitude.] While the PDO explains much of the variance along the coast, the Oregon and Washington near-coast temperatures have also fluctuated strongly from one month to the next (animation, Coastwatch). Alongshore wind estimates for the northern Washington coast (48°N) indicate strong upwelling-favorable monthly-mean winds from April through July (the last month of estimates) (analysis [Monthly means are yellow bars; positive values indicate southward winds which force upwelling.], PFEL).

Sources:

  • High Plains Regional Climate Center (HPRCC)
  • Western Regional Climate Center (WRCC)
  • Northwest River Forecast Center (NWRFC)
  • Pacific Fisheries Environmental Laboratory (PFEL)


    Current indicators for Pacific climate

    El Niño/Southern Oscillation (ENSO). Last winter's strong, cold ENSO peaked in December-January-February (Niño 3.4 region (5°N-5°S, 170-120°W) SST anomaly of -1.73°C, 1971-2000 climatology), and the anomalies diminished to negligible amplitude during the Northern Hemisphere spring and summer. September and October have seen the reestablishment of weak, cold SST anomalies (mean August-September-October Nino 3.4 SST of -0.11°C), which NOAA classified on 6 November as neutral ENSO conditions (definition, latest report). Fifteen of the 23 ENSO forecast models polled by the International Research Institute for Climate and Society predict a continuation of ENSO neutral conditions in December-January-February (mean anomaly < 0.5°C in magnitude), and 16 of 21 models indicate a continuation of ENSO neutral through March-April-May.

    Pacific Decadal Oscillation (PDO). The conceptual model of PDO ocean variability has been very useful in characterizing the northeast Pacific Ocean conditions in 2008 (above), with the PDO in a significant cold phase. The NOAA Earth System Research Laboratory's statistical Linear Inverse Model PDO forecast is for continued cold polarity, but of smaller magnitude, through the end of the forecast period (November 2009) (forecast).

    What does the outlook mean for the PNW in coming months?

    The December-January-February climate forecast by the NOAA Climate Prediction Center is for an equal chance of above, normal, or below normal temperature and preciptation for the PNW (temperatures, precipitation). The skill of the precipitation forecast is derived from ENSO-related changes in precipitation. The model precipitation forecast has no useful skill in ENSO neutral years, like this one. 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.


    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