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Summary The National Weather Service (NWS) has the primary responsibility among the federal agencies to provide advanced flood alerts and warnings in the United States. Because hydrologic services generate nearly $2 billion of benefits each year (NHWC, 2002) through timely flood and weather forecasting, the NWS has made hydrologic understanding and forecasting a priority at national and regional scales. In 1997, the NWS Office of Hydrologic Development began the Advanced Hydrologic Prediction Service (AHPS) program to advance technology for hydrologic services. AHPS is a congressionally funded program that is intended to provide incremental advancements to hydrologic services over its implementation from 1997 to 2013. AHPS' overarching objectives are to increase the current river and flood forecasting capability and improve communication among NWS staff and offices, cooperating federal and other entities, and NWS partners and collaborators (NWS, 2002). AHPS has seven stated goals (NWS, 2004): 1. Produce more accurate products incorporating advanced hydrologic science into NWS models 2. Provide more specific and timely information on fast-rising floods with increased lead time 3. Create new formats, including graphics, for products that are easier to use 4. Create more information that is useful to assess risk to flooding, including forecast probability 5. Provide products with forecast horizons two weeks or further into the future 6. Increase the distribution of products using advanced information technologies (such as the internet and web- based GIS formats) to provide broader and more timely access to and delivery of information; and 7. Expand outreach and engage partners and customers in all aspects of hydrologic product improvement. Through AHPS, the NWS seeks to provide accurate forecasts that can support timely warnings for all users of hydrologic predictions. Throughout history, and even recent history (i.e., Hurricanes Nora in 1997 and Katrina in 2005), there are examples of the important role that accurate, effectively communicated warnings play in keeping people and property safe from water- related disasters. Specifically, prediction and response together make hydrologic predictions the most valuable. AHPS, as described by the NWS, strives to provide the information needed at the right time to facilitate adequate responses to mitigate damages to life, livelihoods, and property. This provision would include predictions from the climate-scale to short-term weather-scale events with the appropriate representation of uncertainties so that AHPS users can respond to the information presented to them in the best ways possible. AHPS is slated to be fully implemented nationwide in 2013. With seven years still remaining in its development and implementation timeline, a review of the program now is timely and poised to provide the NWS with information it needs to maximize AHPS usefulness. In 2003, the NWS requested a National Research Council (NRC) study of the science, technology, and programmatic aspects of AHPS to help ensure that the program is well founded for successful implementation and operation. To carry out the study, the NRC's Water Science and Technology Board appointed a committee to address the tasks outlined in Box S-1. The committee produced this report after reviewing documentation about AHPS, models used in AHPS applications, and other relevant information. 1

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2 Toward a New Advanced Hydrologic Prediction Service (AHPS) BOX S-1 Statement of Task The study will review the new program of NOAA's National Weather Service, known as the "Advanced Hydrologic Prediction Service" (AHPS). The study will assess the full scope of the program, aimed at improving the nation's river forecasts, in respect to hydrologic science and technology research, river routing and mechanics, "systems" engineering aspects, and implementation. Specifically, the study will assess and make recommendations in respect to: 1. the nation's needs in respect to operational flood and drought forecasting and the overall strategy of AHPS to meet these needs, with emphasis on promoting advances in climate and weather forecast and the application of modern hydrology, hydraulics, and modeling techniques and technologies to enhance predictions; 2. assessment of research aspects of AHPS, priorities for science and technology, and means to facilitate application of research results into hydrologic operations; 3. opportunities to assure optimal communication of warnings and other information generated by AHPS, including potential new uses of information provided; and 4. the level of coordination with other agencies and entities engaged in flood and drought warning. KEY CONCLUSIONS AND RECOMMENDATIONS Overall, this study found AHPS to be an ambitious program that promises to provide services and products that are timely and needed. This report identifies several opportunities to help AHPS fulfill its goals. These findings and recommendations are presented in bold text and in terms of programmatic, scientific and technical, and user-related aspects of AHPS. Programmatic Conclusions and Recommendations The programmatic paradigm of AHPS includes the elements needed for administrative structure: clearly stated purpose, goals, and objectives; administrative organization; development and implementation plans; measurable criteria against which to determine success of meeting goals; and adequate human and fiscal resources. NWS documents (NWS, 2002; 2004) and website1 present clearly the goals of AHPS that aim to increase current river and flood forecasting capability, timeliness, and accuracy. The NWS is commended for presenting clear and well-articulated goals for AHPS. If AHPS succeeds in providing more timely and accurate hydrologic forecasts, the program will bring significant benefits to hazards mitigation and water resources management. Therefore, developing and implementing AHPS should continue to be a high priority for the NWS. AHPS program administration is managed through the AHPS Review Committee (ARC) to work from the national headquarters level down through the regional River Forecast Centers (RFCs) to the local Weather Forecast Offices (WFOs). Committee site visits to RFCs and WFOs suggest 1http://www.nws.noaa.gov/om/water/ahps/Ahps-back.shtml.

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Summary 3 that this top-down structure has yet to reach its full potential, and regional and local offices should play a larger role in the administration and management of AHPS activities. AHPS is designed to provide products and services across offices in the NWS, the National Oceanic and Atmospheric Administration (NOAA), the federal government, and entities outside of the federal government. A plan is needed to ensure that AHPS product development and implementation are well-integrated and communicated across these different users. The NWS document, Draft: Advanced Hydrologic Prediction Service (AHPS) Development and Implementation Plan (NWS, 2004), was reviewed by the committee and found to be very general and in need of implementation schedule specifics, measures of success, mechanisms for incorporating user feedback, and facilitation of outreach and training. Because this is a draft document, the following recommendation is made for its next revision: AHPS should develop a detailed and comprehensive, multi-year implementation plan that is updated on an annual basis and includes the following: 1. a detailed prioritization of milestones and schedule for implementation; 2. itemized fiscal and human resources allocated to each task; 3. specific metrics to measure progress towards meeting objectives; 4. methods for incorporating user feedback into the AHPS program for improving AHPS products and services; and 5. follow-on strategies to achieve longer range goals. Human and fiscal resources for AHPS are programmatic areas of concern. In terms of human resources, the need remains for trained hydrologic scientists to conduct hydrologic work in the NWS, just as a meteorological background is required for NWS meteorological work and forecasts. Therefore, as recognized in a previous NRC report (NRC, 1996): the NWS should require a degree or extensive formal education in hydrology for positions that involve a hydrologic emphasis. For fiscal resources, the budgetary history and current allocation seem misaligned with the ambitious goals of the program, and the program's goals and budget should be brought into closer alignment. The AHPS goal of expanding outreach to collaborating federal and non-federal entities was evaluated and determined to have a very healthy start. Examples of successful collaboration are noted with organizations such as the U.S. Geological Survey and hydrologic community activities, such as the Distributed Model Intercomparison Project (DMIP), Community Hydrologic Prediction System (CHPS), and Model Parameter Estimation Experiment (MOPEX). There are difficulties inherent in working across agencies and institutions to fulfill internal goals, and the NWS should focus its collaborations with federal, academic, and private sector organizations to advance the AHPS program and product development. Scientific and Technical Conclusions and Recommendations The scientific and technical aspects of AHPS include the hydrologic science, data, and models used to generate hydrologic forecasts. The NWS uses the National Weather Service River Forecast System (NWSRFS) as its primary modeling engine for hydrologic forecasts. Developed in the 1970s and 1980s, it is a modular modeling framework that is based on FORTRAN code. For AHPS to fulfill its scientific and technical goals, numerous, specific recommendations are made to improve NWSRFS, and the major recommendations are noted here within three broad observations.

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4 Toward a New Advanced Hydrologic Prediction Service (AHPS) First, precipitation inputs to the AHPS hydrologic models need improvements. The quality of the hydrologic forecast depends on the quality of its precipitation inputs, and improvements to precipitation inputs will advance the AHPS goal of creating information that is useful to assess risk to flooding through better, more accurate forecasts. Therefore, AHPS should strengthen quantitative precipitation estimation (QPE) and quantitative precipitation forecasts (QPF) for hydrologic prediction through an end-to-end evaluation that assesses QPE/QPF quality and impacts on flood and streamflow products for basins of diverse size and topography. In addition to improving QPE and QPF, AHPS developers are encouraged to work closely with satellite precipitation groups to ensure that AHPS hydrologic requirements for precipitation are considered in other federal activities, such as the National Aeronautics and Space Administration's Global Precipitation Measurement mission. Second, the current modeling capability in NWSRFS needs improvements for AHPS to produce more accurate products and incorporate advanced hydrologic science in the NWS hydrologic models. A gap exists between the state-of-the-art hydrologic modeling capabilities and those used in AHPS product development. The current AHPS NWSRFS model needs updates, better verification, and closer alignment with models that have finer spatial and temporal resolution. The NWS should invest in the next generation of NWSRFS that includes a flexible framework that allows alternative models, methods, or features that can be tested, verified, and implemented expediently. A total redesign of the NWSRFS is needed for AHPS to fulfill its scientific and technical goals. The NWS should clarify the criteria and decisionmaking process for selecting the next generation of hydrologic model(s) for AHPS, using an advisory group that involves modeling experts from inside and outside of the NWS to ensure that the state-of-the-art modeling advances are incorporated objectively into NWSRFS. CHPS, DMIP, and other collaborative activities to address the modeling capability of AHPS are commended. The NWS should strengthen connections between these activities and AHPS goals. Finally, a recurrent finding in the evaluation of AHPS was that very few scientific and technical aspects of AHPS in general and the NWSRFS, in particular, are documented in written, citable form. The AHPS program needs greater publication, peer review, and dissemination of its current and recent activities to improve the hydrologic science and technology used in AHPS product development and operation. User-related Conclusions and Recommendations AHPS technical products and services will succeed only if they are scientifically strong and useful. The development of the AHPS program and the dissemination of AHPS products require the NWS to involve users and the public in the same way that it involves scientists and engineers in advancing the science and technology that underpins AHPS products. As AHPS products and services will be implemented in phases over several years, a similar phased approached is reasonable for the user side of AHPS, as well. The first phase could address the needs of the RFCs and WFOs and integrate the RFC and WFO personnel into the AHPS program. Needs of these internal NWS users and designers should be addressed first because RFCs and WFOs play important roles in developing and disseminating AHPS information; RFCs and WFOs are the primary AHPS users; and the external user base is still small. The NWS expects the AHPS user base to expand to more external users as advanced products are developed and distributed; for now, AHPS users are primarily internal to the NWS. Therefore, the NWS should focus AHPS development and implementation initially on the activities and needs of the

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Summary 5 RFCs and WFOs. In subsequent User Phases, the NWS can focus on the needs of new and/or external users, as enhanced and partnered services are developed, refined, and implemented. The user interface to access AHPS information is central to creating new formats for products and widely distributing AHPS products and services. The AHPS website is the primary portal for all of its hydro-meteorological information, and the NWS has done an excellent job in providing web access to AHPS observational data and products. Different formats of AHPS information are visible on different AHPS web pages and through different RFCs, and greater presentation uniformity is needed to increase AHPS identity and effectiveness of presenting hydrologic information. While the NWS is making progress towards its goal of creating new formats for AHPS products, graphical formats need greater consistency across all AHPS web pages. AHPS has used the internet to a great extent to increase the distribution of products using advanced information technologies (such as the internet and web-based geographic information system (GIS) formats) to provide broader and more timely access and delivery of information. GIS holds great promise for some of the AHPS products, such as mapping flood inundated areas, areas prone to landslides or debris flows, or intensity and duration of droughts, but the degree to which GIS is used in the development and presentation of AHPS products is difficult to ascertain. In planning for AHPS product distribution, it is critical that the products and modes of presentation, whether GIS based or not, are communicating what is intended. The NWS should consult a communications specialist to assist with developing consistent and clear modes of presentation. User feedback is essential to AHPS. User feedback should: involve outreach and training programs, include measures of success, and improve AHPS products and services. Site visits by our committee indicate that better communication and education about AHPS products, development, and protocol are needed for both internal NWS users and some external users, as well. Site interviews also reveal a wide range of understanding and acceptance of AHPS products among RFC and WFO personnel and suggest a need to bring all RFC and WFO personnel to a comparable level of understanding of AHPS products. An AHPS outreach, education, and training program should be designed to ensure that AHPS products are used properly and to their fullest potential. With respect to measuring success, it is important to know the extent to which forecasts were correct, whether they were communicated in optimal ways, and how they were used to assess risks and minimize losses. The purpose of user feedback is to continually improve the AHPS program, its products and services. The NWS should develop specific measures of success and a strategy to systematically collect and integrate feedback into a continuous loop of improved AHPS products and services.

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6 Toward a New Advanced Hydrologic Prediction Service (AHPS) Recommendations Developing and implementing AHPS should continue to be a high priority for the NWS (Chapter 2, p. 18). Regional and local offices should play a larger role in the administration and management of AHPS activities (Chapter 2, p. 20). The NWS should require a degree or extensive formal education in hydrology for positions that involve a hydrologic emphasis (Chapter 2, p. 21). The program's goals and budget should be brought into closer alignment (Chapter 2, p. 22). AHPS should develop a detailed and comprehensive, multi-year implementation plan that is updated on an annual basis and includes the following (Chapter 2, p.26): o a detailed prioritization of milestones and schedule for implementation; o itemized fiscal and human resources allocated to each task; o specific metrics to measure progress towards meeting objectives; o methods for incorporating user feedback into the AHPS program for improving AHPS products and services; and o follow-on strategies to achieve longer range goals. The NWS should focus its collaborations with federal, academic, and private sector organizations to advance the AHPS program and product development (Chapter 2, p. 29). AHPS developers are encouraged to work closely with satellite precipitation groups to ensure that AHPS hydrologic requirements for precipitation are considered in other federal activities, such as the National Aeronautics and Space Administration's Global Precipitation Measurement mission (Chapter 3, p. 32). The NWS should strengthen quantitative precipitation estimation (QPE) and quantitative precipitation forecasts (QPF) for hydrologic prediction through an end-to-end evaluation that assesses QPE/QPF quality and impacts on flood and streamflow products for basins of diverse size and topography (Chapter 3, p. 33). REFERENCES NHWC (National Hydrologic Warning Council). 2002. Use and Benefits of the National Weather Service River and Flood Forecasts. Available on-line at http://www.nws.noaa.gov/ oh/ahps/AHPS%20Benefits.pdf. Accessed May 26, 2005. NRC (National Research Council). 1996. Toward a New National Weather Service: Assessment of Hydrologic and Hydrometeorological Operations and Services. Washington, D.C.: National Academy Press. NWS (National Weather Service). 2002. Advanced Hydrologic Prediction Service Concept of Services and Operations. Silver Spring, MD: NWS. NWS. 2004. Draft: Advanced Hydrologic Prediction Service (AHPS) Development and Implementation Plan. Available on-line at http://www.nws.noaa.gov/oh/rfcdev/docs/AHPS %20%20Plan%208_2_04-1.pdf. Accessed May 26, 2005.

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Summary 7 The NWS should strengthen connections between DMIP Phase I/DMIP Phase II and AHPS goals (Chapter 3, p. 37). The NWS should clarify the criteria and decisionmaking process for selecting the next generation of hydrologic model(s) for AHPS, using an advisory group that involves modeling experts from inside and outside of the NWS to ensure that the state-of-the-art modeling advances are incorporated objectively into NWSRFS (Chapter 3, p. 37). The NWS should invest in the next generation of NWSRFS that includes a flexible framework that allows alternative models, methods, or features that can be tested, verified, and implemented expediently. A total redesign of the NWSRFS is needed for AHPS to fulfill its scientific and technical goals (Chapter 3, p. 44). The NWS should focus AHPS development and implementation initially on the activities and needs of the RFCs and WFOs (Chapter 4, p. 53). An AHPS outreach, education, and training program should be designed to ensure that AHPS products are used properly and to their fullest potential (Chapter 4, p. 54). While the NWS is making progress towards its goal of creating new formats for AHPS products, graphical formats need greater consistency across all AHPS web pages (Chapter 4, p. 55). The NWS should consult a communications specialist to assist with developing consistent and clear modes of presentation (chapter 4, p. 58). The NWS should develop specific measures of success and a strategy to systematically collect and integrate feedback into a continuous loop of improved AHPS products and services (Chapter 4, p. 63).