One year lead-time experimental streamflow forecasts for the Columbia River at The Dalles
Forecasts shown here were produced in real time in June preceeding the
water year since 1998. Observed streamflow was added (red dashed line)
after the fact to produce these figures. Note that different hydrologic
model versions were used to produce forecasts in different years.
To display a retrospective forecast click on the links below, which are
identified by water year. Red line in the 2002 forecast is simply the
long term simulated mean, not the actual observed streamflow.
Archive of Retrospective Forecasts
Forecasts shown here were produced retrospectively using the latest 1/4
degree hydrologic model and are based on driving data for the hydrology
model from 1950-2000. There is no overlap of the driving data and the
forecast for each year. The forecasts assume perfect foreknowledge of
the ENSO state (and soil moisture in September preceding the water year)
based on the observed December-February Nino3.4 index (+-0.5 standard
deviations from the mean). The PDO state is assumed to persist from the
previous year unless an April-September average streamflow event greater
than or less than 1.5 standard deviations from the long-term mean in opposition
to the dominant phase of the PDO occurs, in which case the phase of the
PDO is assumed to change. In the retrospective forecasts below, the PDO
is assumed to shift from warm phase following the high flow event in water
year 1997. Water year 1997 is assumed to be warm phase PDO, since this
is the information available in June of 1996. Note that the forecast ensembles
contain different numbers of ensemble members for different climate categories
since these climate states have different frequencies in the period from
The figures are keyed as follows:
- grey lines: forecast ensemble members
- black lines: maximimum and minimum simulated streamflows
- blue lines: observed naturalized streamflow
- red lines: simulated observed streamflow.
- Units are cfs.
Note that errors in the PDO forecast are reproduced in these forecasts.
For more information on the retrospective forecasts see:
Retrospective Forecast Poster