Hydrologic Modeling Strategy National Water Center Hydrologic Modeling Strategy Presented By: Brian Cosgrove (NWS/NWC) Contributors: David Gochis (NCAR/RAL), Michael Ek (NWS/NCEP)

Operational System Attribute(s) System Name Acronym Areal Coverage Horz Res Cycle Freq Fcst Length (hr) WRF-Hydro Data Assimilation System WRF-Hydro Analysis CONUS+ 1km / 250m / 2.7 million catchments & reaches 1-Hr 6-Hr Analysis WRF-Hydro Short Range Forecast System WRF-Hydro 3-Hr 2 days WRF-Hydro Medium Range Forecast System 1km / 250m / 2.7 million catchments & reaches 24-Hr 10 days WRF-Hydro Long Range Forecast System 1km / 2.7 million catchments & reaches 48-Hr 30 days System Data Assimilation or Initialization Technique System Attributes WRF-Hydro Analysis Initialized with states from previous WRF-Hydro analysis cycle. Streamflow observations assimilated with nudging-based method. WRF-Hydro Initialized with states taken from most recent WRF-Hydro analysis cycle.

Why System(s) are Operational Primary stakeholders and requirement drivers Flash flood forecasts (NWS service assess., FEMA, stakeholder summits) Street-level flood forecasts (NWS service assess., FEMA, emerg. mgrs) Operational extended water resource forecasts (Army Corps, RBC) Fully coupled river-to-estuary modeling (NOAA strat. goals, serv. assess.) What products are the models contributing to? Guidance from WRF-Hydro will support NWS flood and flash flood forecasts, FEMA emergency responses, Army Corps reservoir management, interagency drought monitoring, ecological forecasting and National Ocean Service modeling What product aspects are you trying to improve with your development plans? We are improving flood forecast products in a transformational way, supporting street-level impact-based predictions of hazards Water supply and drought products, along with coastal modeling will be improved Top 3 System Performance Strengths 1) Street-level resolution of hydrologic processes, 2) Representation of multiple hydrologic routing processes, 3) Modularity and connectivity of system Top 3 System Performance Challenges 1) Long-term data storage and delivery to end users, 2) Rapid growth of computational requirements, 3) Universal challenge of verification

System Evolution Over the Next 5 Years Major forcing factors Drive for coupled process modeling (ocean, atmosphere, river, estuary) Hyper-local information required in increasingly populated and vulnerable areas Science and development priorities Expanded data assimilation capabilities Coupled hydraulic, coastal modeling Hyper-resolution modeling Addition of hydrologic processes for higher fidelity simulations Development of upscaling/downscaling approaches to connect EMC/NWC What are your top challenges to evolving the system(s) to meet stakeholder requirements? Computational resources and communications bandwidth Availability of data for forcing, verification and assimilation Potential opportunities for simplification going forward WRF-Hydro integration into NEMS (in progress) Where possible, integrate model and forcing evaluation system driven by development of NWC Water Resource Evaluation Service (WRES) and efforts at NCEP/EMC Where possible, leverage a common NCEP/NWC forcing data engine

Top 3 Things You Need From the UMAC Continuation of efforts to integrate total water prediction into fabric of NOAA Earth system modeling and reduce cross-office and cross-agency barriers Neutral input into vision of cross-office and interagency modeling strategy Support for links to projects and programs in the broader national and international land surface hydrology community