Update on West Wide Hydrologic Forecasting at the University of Washington Dennis P. Lettenmaier, Andrew W. Wood, Ted Bohn, George Thomas Univ. of Washington Components of Real-time Forecasting Approach OBJECTIVE The forecasting system was created to evaluate the use of distributed macroscale hydrologic models for hydrologic forecasting, and provide a testbed for assessing the use of climate predictions and data assimilation in a streamflow forecasting context. OVERVIEW Forecasts are made once monthly, using simulated initial conditions based on real-time observations of temperature and precipitation. Experimental hydrologic forecasts are also made using the climate forecast ensembles derived from the NCEP Climate Prediction Center Seasonal Climate Outlooks. Benchmark hydrologic forecasts are also constructed via the well-known Extended Streamflow Prediction (ESP) method of the U.S. National Weather Service. The ESP forecasts are also categorized to provide ENSO and PDO-conditioned ensembles, which past work has shown can improve seasonal forecast accuracy. Climate Forecasts Hydrologic Model (Liang et al., 1994) Snow Assimilation Hydrologic Forecasting Simulations Forecast Products streamflow soil moisture runoff snowpack derived products model spin-up forecast ensemble(s) climate forecast information climatology ensemble 1-2 years back start of month 0 end of mon 6-12 NCDC met. station obs. up to 2-4 months from current LDAS/other real-time met. forcings for remaining spin-up data sources snow state information ESP and ESP/ENSO forecasts NRCS SNOTEL / Env. Canada ASP observed SWE anomalies are merged with simulated anomalies to adjust the forecasts’ initial hydrologic state, e.g.: VIC model resolution (1/8 degree) use ensemble of historical 12 month daily sequences taken from 1960-99 use subsets based on ENSO category corresponding SWE adjustment example obs. SWE anomalies NCEP CPC Official Outlooks derived from Probability of Exceedence seasonal precipitation and temperature forecasts for US climate divisions ensembles of precipitation and temperature generated by non-parameteric resampling approach called the Schaake Shuffle Forecasts from Climate Model Output from NCEP CFS (in re-development) Major Products of Westwide Forecasting System Current Activities Forecast Web Page Collaboration with Operational and Research Groups During the last year, forecast system activities have included: the continued production of monthly forecasts implementation of automatic calibration approach an expansion of forecast products increasing interaction with NOAA groups (EMC and NWS WRSC) a major effort to re-stage the system on a Linux cluster, including: fully automated daily updates, rather than semi-automated monthly development of additional forecast points in new domain areas Current conditions nowcasts for soil moisture / SWE http://www.hydro.washington.edu/forecast/westwide/ Notable interactions with external groups: Forecast inter-comparison with RFC and NRCS Interaction with NCEP EMC Interaction with USBR on lower Colorado R. Spatial Forecasts for P, T, SWE, Soil Moisture, Runoff Expansion of Nowcast simulation domain Prior evolution of water balance for drainage area of each forecast location Nowcasts of WY 2006 showing response to strong North American monsoon precipitation Missouri R. basin added in August Mexico also added to daily update simulations, but a modified approach is needed to accommodate unreliable forcing Other Changes / Ongoing Work re-evaluating the NASA/NOAA NLDAS 1/8 degree forcing product as a potential real-time forcing in Western U.S. automating nowcast / initial condition simulation over the US westward of the Mississippi River adopting selected experimental reservoir system forecasts as routine products comparing nowcasts with retrospective simulations now in progress extending back to 1915 Expanding the set of streamflow forecast points to the Great Basin, Missouri, and upper Rio Grande Rivers West-wide overview map of current water supply period volume forecast References / Acknowledgements Wood, A.W., E.P. Maurer, A. Kumar and D.P. Lettenmaier, 2002. Long Range Experimental Hydrologic Forecasting for the Eastern U.S., JGR, 107(D20). Liang, X., D. P. Lettenmaier, E. F. Wood and S. J. Burges, 1994. A Simple hydrologically Based Model of Land Surface Water and Energy Fluxes for GSMs, JGR., 99(D7). Wood, A.W. and D.P. Lettenmaier, 2006, A testbed for new seasonal hydrologic forecasting approaches in the western U.S., BAMS (in press). The authors gratefully acknowledge the support of NOAA/OGP (now the Climate Program Office) CDEP and CPPA programs. This map clicks through to forecast hydrographs at right, and water balance plots above