1. Climate Prediction Applications Science Workshop Des Moines, IA – March 3, 2011 Andy Wood NWS Colorado Basin River Forecast Center Also: John Schaake, John Lhotak, Kevin Werner, Michelle Schmidt 1 Incorporating weather and climate predictions from NCEP GFS and CFS into operational water supply forecasts for the Western U.S.

2. Outline Motivation – applications of probabilistic prediction ESP overview and new developments CFS-based water supply forecast example

3. Applications of Probabilistic Flow Forecasts  Western water supply  Water Utilities, Mgmt Districts: Denver, S. Calif.  USBR 24-month study  BOR Midterm Probabilistic Model Others  Pacificorps operation on Bear River (UT and ID)  BPA and USACE operation on Columbia River  INFORMS in CA

4. Western Water Supply Forecasts Forecasts for spring runoff amounts from snow melt dominated basins in western US Routinely produced at 6 RFCs and coordinated with other agencies NWS forecast program began in 1940s Primary forecast tools: –Ensemble Streamflow Prediction –Multivariate Linear Regression Applications of Probabilistic Flow Forecasts

5. Denver Water: Long history of using ensemble forecasts for risk management Download CBRFC ensemble forecasts into reservoir operations spreadsheet (right) Optimize reservoir operations by minimizing negative impacts Southern CA MWD: Requested forecast for probability of equalization releases from Lake Powell USBR determines inflow volume required to trigger equalization from 24 month study CBRFC uses regulated ESP forecast to determine probability of reaching the required volume Applications of Probabilistic Flow Forecasts

6. 4,035 cfs Mar 15 Forecast 570 KAF Applications of Probabilistic Flow Forecasts Upper Colorado Reservoir Management

7. Lake Powell & Lake Mead Operational Diagrams for 2010 11.4 1/1/10 Projection 3,635 1/1/10 Projection 15.4 1/1/010Proj ection 1,098 1/1/10 Projection Major releases depend on CBRFC April 1 Forecasts Applications of Probabilistic Flow Forecasts Upper Colorado Reservoir Management Note discontinuous decision rules – ill-suited to deterministic forecasts

8. CBRFC – BOR Cooperation The past The future Efforts in parallel --  CBRFC working to improve probabilistic flow forecasts  BOR working to implement probabilistic water management model

9. Current forecast framework 9

10. Target, multi-forecast framework 10

11. Current forecast performance  CBRFC/NRCS official forecasts have plenty of skill at times, but…

12. Applications of Probabilistic Flow Forecasts …little of that skill comes from traditional climate forecasts, currently (JFM Precip correlation with Nino 3.4)

13. 1970198019902000 ESP first used at California-Nevada River Forecast Center NWS/HRL begins ESP development ESP first presented at the Western Snow Conference ESP used for drought assessment ESP used for water supply forecasts ESP released with NWSRFS ESP Analysis and Display Program (ESPADP) development started ESPADP deployed to the field Water Resources Forecasting Services (WARFS) quantifies value of ESP Climate Prediction Center (CPC) forecast pre-adjustment developed for use in ESP Historic development of ESP Medium to long-range ESP short-medium- long range ESP Experimental Ensemble Forecast System (XEFS) work begins Western Snow Conference paper, 1977 Work to incorporate climate forecasts

14. © The COMET Program An ESP Upgrade: The NWS Hydrologic Ensemble Forecast Service (HEFS) Pre- processor Weather Input Ensembles Ensemble Streamflow Prediction System Hydrologic Model Output Statistics processor Verification system Post processed Hindcaster/ reforecaster Input flow data Streamflow Operational Forecast System Product generation system Verification products Ensemble products “Raw” Post processor flow ensembles

15. HEFS climate forecast calibration 15 Limin Wu, Generation of Precipitation Ensemble Forecasts from Single-Value QPF via Mixed-Type Meta-Gaussian Model, AGU Fall Meeting 2010 Key Point GFS & CFS ensemble forecast means are used to generate calibrated, seamless ensemble time- series of RFC model inputs (P, T), 6- hourly!

16. The HEFS WSF Input 16

17. 17 Example: CFS climate forecasts, late 2010 November

18. Water Supply Forecast Results (Dec 1, 2010) 18 Average contribution to Lake Powell Apr-Jul inflow: Green River34% Colorado River50% San Juan River13%

19. Returning to the framework 19  The water supply forecast approach may become ‘messier’, but also, we hope:  more transparent  better informed by climate forecasting  We are still evaluating approaches, but making real progress

20. Lastly … Gaps Skillful climate forecasts in Upper Colorado –2 weeks to 2 years (medium range to interannual) –Need to go “beyond ENSO”, given weak ENSO-index skill in upper Colorado –CBRFC & BOR organizing an SI-to-Year2 Climate/Flow Forecasting workshop/testbed later this month Improved land surface analysis (snow, soil moisture) –A critical part of every forecast (initial conditions) –Can collaborative efforts improve this information? Connect decision frameworks with forecast characteristics –Ensembles enable risk-based analysis –Forecast skill varies in space and time: decisions should account for this property

21. Thank You! 21 Lake Powell Inflow forecast with GFS and CFS based inputs Daily updating, experimental Contact: Andy.Wood@noaa.gov