recap of wy 2006. enso is typically very stable from oct-jan
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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
Used range: Jan3.4 >= -0.4Jan3.4 <= 0.6
Evaluation of Aug 1 ECMWF Nino3.4 Forecast for WY 2006
Nino3.4 -0.4 to 0.6
Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2006. (Nino3.4 anomalies between -0.4 and 0.6)
Nat
ural
ized
Flo
w (
cfs)
Black = Climatological ExtremesGray = Forecast Ensemble MembersRed = ObservedBlue = Ensemble Mean
Used range: Jan3.4 >= 0.0Jan3.4 <= 0.6
Evaluation of Sept 1 ECMWF Nino3.4 Forecast for WY 2006
Nino3.4 0.0 to 0.6
Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2006. (Nino3.4 anomalies between 0.0 and 0.6)
Nat
ural
ized
Flo
w (
cfs)
Black = Climatological ExtremesGray = Forecast Ensemble MembersRed = ObservedBlue = Ensemble Mean
ColSim Reservoir System Storage ForecastAll Years from 1916-2003 for which J. Nino3.4 Anom. >= -0.4 AND <= 0.6
Obs. SystemStorage Sept 28, 2006
WY 2007 Forecast
http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/plumes/
150000
200000
250000
300000
350000
400000
450000
-3 -2 -1 0 1 2 3 4
NINO3.4 Index Anomaly
Ap
ril-
Se
pte
mb
er
Av
era
ge
S
tre
am
flo
w
1916-2002
April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies.
Mod
ified
Flo
w (
cfs)
Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2007. (Nino3.4 anomalies between 0.7 and 1.5)
Black = Climatological ExtremesGray = Forecast Ensemble MembersRed = LTM from 1950-1999Blue = Ensemble Mean
ColSim Reservoir System Storage ForecastAll 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.