Forecasts and Planning Tools

Seasonal to Interannual Forecasts

Forecasting and Resource Management

A key component of the Climate Impact Group's (CIG) effort to provide decision-support to Pacific Northwest (PNW) resource managers is development of seasonal to interannual forecasts and planning tools for use in decision-making processes.

Seasonal to interannual climate and resource forecasts provide resource managers the opportunity to consider how projected near-term variations in climate may affect operational decisions. A fall forecast for a warmer and drier winter, for example, could lead to more conservative management of snowmelt dependent reservoirs. The lead time provided by these forecasts for decision making can prove crucial, a finding documented both in case study and research, particularly in the water resources sector.

• Economic value of long-lead streamflow forecasts for the Columbia River system. Research conducted by the CIG finds that the use of seasonal streamflow forecasts for the Columbia River in the August-December period could increase hydropower revenue on the order of 4%, or $150 million, per year on average without compromising other operational objectives (Hamlet et al. 2002).
• Integrating El Niño/Southern Oscillation forecasts into Seattle reservoir management decisions. Efforts by Seattle Public Utilities (SPU) to incorporate the fall 1997 El Niño forecast into winter reservoir operations contributed to SPU’s ability to manage the resulting summer drought with no supply shortages to the public. This experience stands in sharp contrast to previous summer droughts (1987, 1992) during which water use curtailments were required.

ENSO Forecasts/PDO Status

El Niño/Southern Oscillation (ENSO) forecasts are freely available to the public through more than a dozen forecasting centers around the world (see box below). The forecasts are updated monthly.

The Pacific Decadal Oscillation (PDO) index is updated on a monthly basis by CIG researcher Nathan Mantua (see http://www.jisao.washington.edu/pdo/). The index is an up-to-date accounting of the current state of the PDO, not a forecast. PDO forecasts are not available at this time due to the lack of information on what triggers PDO regime shifts.

ENSO Forecast Centers

• International Research Institute for Climate and Society
• National Weather Service’s Climate Prediction Center
• NOAA Climate Diagnostics Center

PNW Climate and Resource Forecasts

The CIG annually produces climate and resource forecasts for the PNW using the latest ENSO forecast, the PDO state, and information on other climate patterns relevant to PNW climate. Current seasonal to interannual forecast products include:

• Outlook for PNW climate
• Water resources outlooks (includes Columbia River streamflow forecasts)
• Salmon survival forecast
• Forecast of extreme weather events

Forecasts Under Development

CIG’s research on climate impacts and potential forecast applications is ongoing. Forecast tools currently under development include:

• Ensemble forecasts of PNW temperature, precipitation, snowpack and soil moisture
• Seasonal flood risk forecast
• Mid-range (6-month) ensemble streamflow forecasts based on climate forecasts from the National Center for Environmental Prediction (NCEP)

Other Forecasts

Additional climate and resource forecast products of relevance to the PNW that are made available by other groups can be found on CIG’s climate outlook page.