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Medium-range Hydrometeorological Forecasts of the Big Wood Basin in 2006 (plus a look forward at 2007…)

Medium-range Hydrometeorological Forecasts of the Big Wood Basin in 2006 (plus a look forward at 2007…). A Project for the Pacific Northwest Regional Collaboratory. Contributors. University of Idaho, Dept. of Geography: Troy R. Blandford, M.S. in 2006 Brian J. Harshburger, PhD Candidate

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Medium-range Hydrometeorological Forecasts of the Big Wood Basin in 2006 (plus a look forward at 2007…)

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  1. Medium-range Hydrometeorological Forecasts of the Big Wood Basin in 2006(plus a look forward at 2007…) A Project for the Pacific Northwest Regional Collaboratory

  2. Contributors University of Idaho, Dept. of Geography: Troy R. Blandford, M.S. in 2006 Brian J. Harshburger, PhD Candidate Karen S. Humes, Associate Professor Brandon C. Moore, M.S. in 2006 Von P. Walden, Associate Professor Idaho National Laboratory (INL): Ryan Hruska, Senior Engineer/Scientist

  3. SnowmeltRunoffModel • SRM is a semi-distributed, temperature index (degree-day) model designed to simulate and forecast streamflow in snowmelt-dominated (mountainous) basins. • Model inputs: • Current temperature and precipitation from SNOTEL sites • Snow-covered Area • Derived from MODIS images • INL (Ryan Hruska) • NSIDC (Tom Painter) • Forecasted Temperatures • Medium-range, 15-day from NCEP GFS (downscaled to SNOTEL sites) • Short-range, 7-day from NDFD (4 day - precipitation) • Temporal resolution: daily

  4. Downscaling of Met Forecasts • Example of downscaling of four NCEP Global Forecasting System (GFS) grid points (large yellow dots) to individual SNOTEL station locations (small black dots) Clark and Hay, (2004)

  5. Errors in NCEP and NDFD Temperatures Moore et al., 2006

  6. SRMEnhancements • The use of both maximum and minimum critical temperatures (Tcritmax and Tcritmin) to partition precipitation into rain, snow, and rain/snow mixed. • model currently uses a single critical temperature value • The use of an antecedent temperature index (ATI) method to track snowpack cold-content and account for the delay in melt associated with diurnal refreezing. • used to determine when the snowpack is ripe • also to determine when the rain falling on the snowpack should contribute to the runoff

  7. Forecasted Inputs 15 Day Downscaled Temperature Forecasts (Tmax, Tmin) Global Forecasting System NCEP 15 Day Downscaled Precipitation Forecasts Global Forecasting System NCEP Model Updating (Day n-1) Schaake Shuffle (reorder the ensembles) Observed Temperature (Tmax, Tmin) SNOTEL, NRCS Obtained 1 day after measured Snow-covered Area (SCA) (Obtained from snow depletion curves) Enhanced version of SRM Observed Precipitation SNOTEL, NRCS Obtained 1 day after measured Model Parameters (Retrospective Analysis) Observed Streamflow USGS Obtained 1 day after measured Snow Depth and SWE observations SNOTEL, NRCS (monitor degree-day factors) Ensemble Streamflow Forecasts SRMEnhancements Ensemble Streamflow Forecasts

  8. StudyArea for 2006 Big Wood River Basin Stream Gauge: Hailey, ID Contributing Area: 1,625 km2 Elevation Range: 250-3,630 m location of SNOTEL sites

  9. RetrospectiveForecastResults(2002) Coefficient of Determination (R2) Mean Absolute Error (cms) Mean Bias Error (cms)

  10. RetrospectiveForecastResults(2003) Coefficient of Determination (R2) Mean Absolute Error (cm) Mean Bias Error (cm)

  11. RetrospectiveForecastResults(2004) Coefficient of Determination (R2) Mean Absolute Error (cm) Mean Bias Error (cm)

  12. Real-time Forecasting in 2006

  13. Real-time Forecasting in 2006 • SRM correctly forecasted the timing of the peak discharge (May 22, 2006) out 6 days in advance. • Early by 1 day at a lead time of 7 days and 2 days at 10 days • The magnitude of the peak was slightly under-predicted for all of the lead-times illustrated here. • The forecasts of the secondary peak, which occurred in early June, require further investigation and may be due to errors in the input data (i.e. snow covered area). • The timing of the forecasts are off (timing of smaller peaks) during the early and late portions of the snowmelt season. • May be due to time lag between snowmelt and precipitation events and the resulting stream discharge

  14. Preparation for 2007 • Create a decision support system for interested parties that is • Easy to use • Accurate • Intention is to create tools for many basins, not just a single basin, for end-users (NRCS, COE) • UI training session on basin disaggregation and how to process snow-cover images (snow-covered area)

  15. Preparation for 2007 • Automation - Improved tools for ArcGIS

  16. ArcGIS Tools

  17. ArcGIS Tools

  18. ArcGIS Tools

  19. ArcGIS Tools

  20. Preparation for 2007 • Automation - Improved tools for ArcGIS • Additional basins

  21. Potential New Basins for FY07 • North Fork of the Clearwater • St. Joe River • Big Lost River • Little Wood River • Fisher River (Montana) • South Fork of the Flathead (Montana) • And perhaps basins in Washington and Oregon as well

  22. Preparation for 2007 • Automation - Improved tools for ArcGIS • Additional basins • Ensemble and Single-value (like 2006) forecasting • Downscaling of global climate model output for simulation of future stream flow conditions in the PNW

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