Northwest River Forecast Center Seasonal Volume Forecasts Using Ensemble Streamflow Prediction for...
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Transcript of Northwest River Forecast Center Seasonal Volume Forecasts Using Ensemble Streamflow Prediction for...
Northwest River Forecast Center
Seasonal Volume ForecastsUsing Ensemble Streamflow Prediction
for the 2011 Water Year
Steve King, [email protected]
Topics for Presentation
Overview of Water Supply Models used at the NWRFC
Recap of WY 2010
2011 Volumetric Streamflow Outlook
Direction of NWRFC Water Supply Program
NWRFC Water Supply Models
Statistical Water Supply Seasonal Volumetric Forecasts
• Statistical Regression techniques (Legacy, SWS)• Based primarily on observation (Runoff, Snow, Precip)• NWS Driver for ‘Official’ Federal Coordinated
Forecasts
Ensemble Streamflow Prediction Many types of forecasts including
Seasonal Volumetric Forecasts• Probabilistic (ESP) technique built on top of real-time
hydrologic modeling system• Combines updated model states with QPF and
weather scenarios (typically based on climatology).
Seasonal Volume Forecasts (2010 Example)http://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi
http://www.nwrfc.noaa.gov/espws/espws.cgi
Statistical Water Supply ESP Volume Forecasts
WY 2010 Seasonal Precipitation
Above Grand Coulee ~ 92%Above Lower Granite ~ 95%Above The Dalles ~ 96%
WY 2010 Runoff Recaphttp://www.nwrfc.noaa.gov/runoff/runoff.cgi
Snake/Lower Granite
75%
Columbia/The Dalles
79%
Columbia/Grand Coulee
77%
Westside = Apr-SepEastside= Jan-Jul
PalisadesInflow
75%
Boise River
80%
OwyheeInflow
77%
Dworshak Inflow
73%
Jackson Lake Inflow
75%
Salmon River
98%
Verification of Fall Outlook (WY 2010)
Snake/Lower Granite
75%Columbia/The Dalles
79%
Columbia/Grand Coulee
77%
2010 Observed Runoff
Snake RLower Granite
96% 90%ColumbiaThe Dalles 95% 91%
Columbia RGrand Coulee
96% 91%
ESP Outlook w/o ENSOESP Outlook w/ ENSO
Spring 2011 Outlook
Ensemble Streamflow Prediction (ESP)
Driven by: Antecedent Snow/Soil Moisture
10 day Precip and Temp forecast
Precip and Temp climatology (1948-2002)
Published forecasts updated weekly
Capability of including climate forecasts/signals(unpublished)
Forecast input to ESP: Precipitation, Min and Max Temperature, Freezing Levels
6hr QPFavailable for day 1-3
24 hr Quantitative Precipitation Forecast for days 1-10
http://www.nwrfc.noaa.gov/weather/10_day.cgi
2011 Outlook* (ESP Forecasts)ttp://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi
50% Ex. Prob = 29 MAF97% of 30 yr Norm (30 MAF)
50% Ex. Prob = 103 MAF96% of Normal (107 MAF)
* Reflects current model states (antecendent conditions),10 day QPF, and climatology
2011 ESP Outlook*
Snake R/Lower Granite
89%
Columbia R/The Dalles
93%
Columbia R/Grand Coulee
96%
Jan-JulMedian Ensemble VolumePercent of ESP Normal
* Reflects 10/26/10 model states,10 day QPF, and ESP climatology
PalisadesInflow
102%
Boise River
102%
Dworshak Inflow
96%
Salmon River
110%
SST Predictions (Oct 2010)
SST observation and forecasts indicate that we are in a strong La Ninaclimate pattern that is expected to persist through the first half of 2011.
2011 ESP OutlookUsing La Nina Climatology
Snake RLower Granite
89% 97%
ColumbiaThe Dalles
93% 96%
Columbia RGrand Coulee
96% 102%
ESP for ALL yearsESP for La Nina yearsMedian Ensemble VolumePercent of ESP Normal
La Nina ClimatologyDJF ENSO ONI <= -1.0
11 cases in ESP record (1948-2002)
WY19511955195619651971197419761985198919992000
PalisadesInflow
102% 114%
Boise River
102% 109%
Dworshak Inflow
96% 110%
Salmon River
110% 125%
NWS Western Region / NWRFC Water Supply Directions
No operational changes for WY 2011
Examine potential for ESP as primary forecast tool.
Replace Legacy Raw model with SWS as supplementary forecast tool.
WS Model Verification Study2009-2010
• SWS similar to and often better performing than other models
• ESP stronger than others for late season forecasts
NWS Western Region / NWRFC Water Supply Directions
Work with users to determine forecast locations and forecast periods that are providing the most value for users.
Expand use of QPS in ESP
Investigate conversion of regulated forecasts to unregulated (natural) streamflow forecasts.