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Recap of WY 2006. ENSO is typically very stable from Oct-Jan. Evaluation of Sept 1 ECMWF Nino3.4 Forecast for WY 2003-2005. WY 2003. WY 2004. WY 2005. Evaluation of Aug 1 ECMWF Nino3.4 Forecast for WY 2006. Used range: Jan3.4 >= -0.4 Jan3.4 <= 0.6.
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Evaluation of Sept 1 ECMWF Nino3.4 Forecast for WY 2003-2005 WY 2003 WY 2004 WY 2005
Evaluation of Aug 1 ECMWF Nino3.4 Forecast for WY 2006 Used range: Jan3.4 >= -0.4 Jan3.4 <= 0.6
Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2006. (Nino3.4 anomalies between -0.4 and 0.6) Black = Climatological Extremes Gray = Forecast Ensemble Members Red = Observed Blue = Ensemble Mean Naturalized Flow (cfs) Nino3.4 -0.4 to 0.6
Evaluation of Sept 1 ECMWF Nino3.4 Forecast for WY 2006 Used range: Jan3.4 >= 0.0 Jan3.4 <= 0.6
Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2006. (Nino3.4 anomalies between 0.0 and 0.6) Black = Climatological Extremes Gray = Forecast Ensemble Members Red = Observed Blue = Ensemble Mean Naturalized Flow (cfs) Nino3.4 0.0 to 0.6
ColSim Reservoir System Storage Forecast All Years from 1916-2003 for which J. Nino3.4 Anom. >= -0.4 AND <= 0.6 Obs. System Storage Sept 28, 2006
http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/plumes/http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/plumes/
April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies. 1916-2002
Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2007. (Nino3.4 anomalies between 0.7 and 1.5) Black = Climatological Extremes Gray = Forecast Ensemble Members Red = LTM from 1950-1999 Blue = Ensemble Mean Modified Flow (cfs)
ColSim Reservoir System Storage Forecast All Years from 1960-1999 for which J. Nino3.4 Anom. >= 0.7 AND <= 1.5 2007
Selected References on Compositing Techniques: Hamlet, A.F., Lettenmaier, D.P., 1999: Columbia River Streamflow Forecasting Based on ENSO and PDO Climate Signals, ASCE J. of Water Res. Planning and Mgmt., 125 (6) : 333-341 Werner K, Brandon D, Clark M, et al., 2004: Climate index weighting schemes for NWS ESP-based seasonal volume forecasts, J. of Hydrometeorology, 5 (6): 1076-1090
Conclusions: The WY 2006 ESP forecast predicted a range of flows centered around near normal conditions. Actual flows in 2006 were towards the upper range of this forecast, probably due in part to an unusually large ENSO forecast error. A moderate warm ENSO event is expected for the winter of 2006-2007. ESP traces from 1960-1999 associated with a forecasted range of Nino3.4 anomalies from 0.7-1.5 suggest elevated drought risks for WY 2007.