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Seasonal to Interannual Forecasts

Climate Outlook

January 2010 - Archive Copy

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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?

January 2010
Updated 26 January 2010 (posted January 26)

The climate outlook is reviewed monthly and updated as needed.

The 7 January NOAA El Niño Southern Oscillation (ENSO) diagnostic discussion alert system status is that of an "El Niño Advisory" that tropical Pacific El Niño conditions exist and are expected to continue. NOAA anticipates the continuation of warm ENSO conditions through Northern Hemisphere Spring. A review of tropical Pacific observations and more recent ENSO forecasts is found below.

ENSO typically affects the climate of Oregon, Washington, and Idaho during the Fall through Spring. Guidance on what to expect in the coming months is also available from seasonal forecasts produced by the NOAA Climate Prediction Center (CPC). The February-March-April CPC temperature forecast is for a greater than 50% chance of above normal temperatures in northern Idaho, eastern Washington, Puget Sound, and northeastern Oregon; a greater than a 40% chance of the same in central Idaho, central Oregon, and along the Washington coast; and a greater than a 33% chance of above normal temperatures in southwest Oregon and southeast Idaho.

The CPC precipitation forecast for February-March-April is for a greater than 40% chance of below normal precipitation in northwest Idaho, northeast Oregon, eastern Washington, and western Washington with the exclusion of the coast. The forecast is for a greater than 33% chance of below normal precipitation in central and northeast Idaho, central Oregon, and on the Washington coast. The temperature and precipitation forecasts for the PNW and the continental U.S. are consistent with the expectation that ENSO will be the dominant form of climate variability in the coming months (Observed typical November through April ENSO-related temperature and precipitation anomalies (UW).)

The seasonal 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 only have skill during periods of significant warm or cold ENSO conditions.

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Recent Pacific Northwest Climate

The 30 days ending 19 January were much warmer than the 1971-2000 mean over the Pacific Northwest and, in general, over the western U.S. (temperature departures, WRCC). Temperatures were at least 2 °F (1 °C) and, in places, in excess of 4 °F (2 °C) above normal over the PNW. The potential exists for this to be a record warm January in Seattle (Cliff Mass Weather Blog; 25 January National Weather Service update). Precipitation during the same period was near normal over the three state area with the exception of the northern coast of Washington, which received over 20 inches (50 cm) of precipitation or 150 to 200% of normal (total, departure, percent normal).

Averaged from the 1 October beginning of the Water Year through 21 January, precipitation has been below normal over the PNW (with the exception of western Washington) and temperatures within 2 °F (1 °C) of the long-term mean (precipitation percent normal, departure; temperature departure). The snow pack conditions on 21 January, as measured in snow water equivalent (SWE), are near normal to slightly below normal SWE over the Canadian portion of the Columbia Basin, and the northern and southern Washington Cascades; and deficits in SWE are observed over the remainder of the Columbia Basin, most notably the SWE is 25 to 75% of normal over the Oregon Cascades, and the southern and southeastern portions of the basin (21 January analysis, legend; today's analysis; NWRFC). The 21 January analysis also shows 10 to 25% above normal SWE for the Olympic Penninsula of Washington State. The longstanding drought conditions in northern Idaho and the eastern portions of Oregon and Washington continue unabated (19 January Drought Monitor). The storm that brought heavy and welcome precipitation to the southwest U.S. during 17-23 January did not produce noticeable changes to the PNW water-year precipitation accumulation or snow water equivalent (not shown).

December coastal sea surface temperatures (SSTs) (PFEL) were cooler than the 1985-97 mean from the northern tip of Washington State to at least 30°N on the Baja Penninsula with warmer than normal temperatures over the Salish Sea and the west coast of Vancouver Island. The largest anomalies at the coast, in excess of -1°C, were found at the mouth of the Columbia River and between Cape Blanco in southern Oregon and Point Conception (34°N) in southern California. Larger magnitude anomalies, in excess of -2°C, were observed several hundred kilometers offshore of the California coast. The mean global SST anomalies (ESRL) for the more recent 30-days ending in mid-January gives a different impression, with small anomalies near the coast (<0.5°C in magnitude), and warm anomalies offshore. Comparison with the 30-day mean ending in mid-December indicates that the ocean conditions are rapidly changing.

At this posting extraordinary storm events are sweeping across California and the southern states, but the strong low pressure , Arizona, and Nevada, with (More updated statistics: precipitation percent normal, departure; temperature departure).

Sources:

  • Western Regional Climate Center (WRCC)
  • Northwest River Forecast Center (NWRFC)
  • Drought Monitor
  • Pacific Fisheries Environmental Laboratory (PFEL)
  • Earth System Research Laboratory (ESRL)

  • Recent and Projected Changes in Key Indicators for Pacific Climate

    El Niño/Southern Oscillation (ENSO).The NOAA El Niño/Southern Oscillation (ENSO) Diagnostic Discussion employs the average sea surface temperature (SST) anomaly over 5°N-5°S, 170-120°W in the equatorial Pacific, in what is called the "Niño 3.4" region, as a key indicator of tropical Pacific climate. The Nino 3.4 SST anomaly for October, November, and December was 1.01, 1.65, and 1.85 °C, respectively, and represents an intensification of the warm ENSO.

    NOAA employs mechanistic and statistical models to forecast how ENSO will evolve over the next several seasons. Mechanistic models solve equations for ocean and atmosphere motions, precipitation, cloud and radiative processes to forecast the future from present conditions. Statistical models, on the otherhand, are constructed from observations of past climate, and apply regression coefficients to present climate conditions to forecast the future. Agreement of the forecasts from these two types of models increases our confidence in the forecast.

    The ENSO model forecasts are summarized by the International Research Institute for Climate and Society. The October-November-December mean Nino 3.4 SST was 1.5°C, and the models are initialized with ocean and atmosphere data through December. Fourteen of the 22 models predict a diminution of ENSO in the next 3 months, with a model average February-March-April SST anomaly of 1.1°C. ENSO is predicted to further diminish during the Northern Hemisphere Spring, with the average SST forecast of 0.5°C (the minimum amplitude for an "El Niño condition") in May-June-July.

    Pacific Decadal Oscillation (PDO). Much of the past 2.5 years have seen strong negative PDO values relative to the 1900-93 mean, which was manifested by colder than normal temperatures along the North American coast. This run ended in July of 2009, and the index has been small in magnitude and usually positive in subsequent months ( historical digital values in units of standard deviations). [For a normally distributed variable, only 32% of the values exceed one standard deviation in magnitude.]

    The existence of the present "El Niño" (warm ENSO) in the equatorial Pacific and its forecast persistence through the Northern Hemisphere Spring is consistent with the development of a PDO warm phase in the coming months. NOAA employs both statistical and mechanistic models to forecast the PDO and coastal ocean conditions. The statistical linear inverse model forecast is for the PDO to be weak and negative through July-August-September (the end of the forecast period). The coupled forecast system, a mechanistic ocean-atmosphere model, predicts warm SST anomalies along the Washington, Oregon, and northern California coasts through June-July-August, with the warmest anomalies, in excess of 0.5°C, along the Oregon and Washington coasts through April-May-June. Cool SST anomalies are predicted offshore during the same period. This pattern of SST anomalies is consistent with the positive phase of the PDO (20 January forecast, more recent forecasts).

    For More Information


    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