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Executive Summary Floods are by far the most devastating of all weather- related hazards in the United States. The National Weather Service (NWS) is charged by Congress to provide river and flood forecasts and warnings to the public to protect life and property and to promote the nation' s economic and environ- mental well-being (such as through support for water re- sources management). As part of a modernization of its tech- nologies and organizational structure, the NWS is undertak- ing a thorough updating of its hydrologic products and ser- vices and the activities that produce them. The role of the 13 River Forecast Centers (RFCs) is be- coming more central in the provision of hydrologic services, and the interaction of the RFCs with 119 newly restructured Weather Forecast Offices (WFOs) will be much closer and more complex. All RFCs will now be collocated with a WFO. New technologies such as the Next Generation Weather Radar (NEXRAD) and the Advanced Weather In- teractive Processing System (AWIPS) will provide more detailed and timely data and facilitate the processing of data into products. A key feature of the modernization program is the inte- gration of hydrology and meteorology in a new hydrometeo- rological focus, which is expected to enable the provision of more efficient operations and more effective services. As part of this integration, the NWS has established a hydro- meteorological analysis and support unit at each RFC to fa- cilitate the increased emphasis on hydrometeorology and the interaction with WFOs. The roles and responsibilities of ex- isting meteorological forecasters and service hydrologists at WFOs will change in accordance with this enhanced focus on hydrometeorology. The National Weather Service Modernization Committee of the National Research Council undertook a comprehen- sive assessment of the NWS' plans and progress for the modernization of hydrologic and hydrometeorological op- erations and services. The committee's conclusions and rec- ommendations and their related analysis and rationale are presented in this report. The committee commends the NWS for the strides it has made in modernizing the NWS hydrology program. The ef- fort has been well planned and diligently pursued. The imple- mentation of major new hydrologic and meteorological tech- nologies presents an opportunity to integrate and signifi- cantly improve NWS weather and hydrology warning and forecast services (e.g., through an increased focus on hydro- meteorology). Although the committee has identified a number of as- pects of the modernization of the NWS hydrology program in which improvements are needed, the overall results of its assessment are quite positive. The modernization is incorpo- rating recent technological advances into field offices and thereby laying the groundwork for major benefits to be real- ized from improved hydrologic products and services. The availability of new tools and techniques is also having a strong, positive effect on the spirit and outlook of NWS personnel. Chapters 1 and 2 of this report provide an introduction and background information on hydrology and hydrometeo- rological programs in the NWS. Chapters 3 and 4 contain the evaluation of the NWS program as well as its management and operational support and present all of the conclusions and recommendations. The 40 recommendations in this re- port cover a wide variety of topics. The committee has placed a relatively higher priority on 14 of these recommendations, which are presented consecutively in this summary as found in Chapters 3 and 4 along with supporting discussion. How- ever, each of the recommendations in the report is important, and the reader is urged to review them all. It is important that each recommendation be understood in the context of the committee's analysis; therefore, this summary provides the section heading, and the chapter and recommendation num- ber where it can be found. It should be noted that the order of presentation does not imply any ranking or prioritization among the recommendations. Again, the reader is encour- aged to review the entire report, especially the conclusions, recommendations, and supporting information in Chapters 3 and4.

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2 ASSESSMENT OF HYDROLOGIC AND HYDROMETEOROLOGICAL OPERATIONS AND SERVICES PRECIPITATION PROCESSING SYSTEM Recommendation 3-1. The NWS should continue its efforts to incorporate additional real-time precipitation data (both ground-based and remotely sensed) into hydrologic prod- ucts and services. The methods used for multisensor detec- tion and estimation of precipitation should enable accurate characterization of precipitation patterns that span seasonal, geographic, and range diversity. A capability to distinguish reliably between rain and snow must be developed. The Pre- cipitation Processing System (PPS) methodology should be upgraded to a more scientifically sound and dynamic meth- odology to improve seasonal and geographic performance, especially during light rain and snow events and in moun- tainous areas. One of the most important inputs to NWS hydrologic models is the spatial and temporal distribution of precipita- tion, derived from a three-stage PPS. Weather radars, along with rain gauges, have long been used to estimate the amount of precipitation that falls to the Earth's surface. Although radar technology and the associated computer processing have improved immensely in recent years, our knowledge about the amount of precipitation that actually reaches the surface remains primitive. As a result, the PPS provides in- consistent results for certain types of rainfall in different geographical areas and has seasonal variations as well. Successful modernization of NWS hydrologic services depends on the ability of the NEXRAD network to provide accurate estimates of precipitation that benefit from im- proved spatial and temporal resolution. Furthermore, the current approach for analyzing precipitation patterns is flawed and based on outdated research. It lacks the scientifi- cally sound and dynamic methodology needed to improve the seasonal performance of the PPS in light rain or snow and in mountainous areas. PRECIPITATION FORECASTS Recommendation 3-4. The NWS should accelerate its fledgling efforts to redesign, develop, evaluate, and verify quantitative precipitation forecasts (QPFs) and probabilistic QPFs (pQPFs) and assess their use in hydrologic forecast models across a range of geographic and seasonal condi- tions. The Office of Hydrology should determine the time and space resolution of QPFs that hydrologic models require. Users of products that incorporate QPF data should be kept informed about these developments and their potential im- pact on user operations. QPFs and pQPFs represent, along with NEXRAD, an opportunity to improve significantly both flash flood pre- diction and regional runoff estimates that, in turn, impact hydrologic forecasts for larger basins. Thus they are of great value for the development of improved hydrologic services that have longer forecast lead times. However, the produc- tion of an accurate QPF is considered to be among the most difficult challenges in operational meteorology. The chal- lenge increases substantially when hydrologists attempt to use the QPF as part of the precipitation input to their hydro- logic models, which require forecasts of spatial coverage and amount of precipitation. Significant efforts are required to coordinate the possible redesign, production, and use of QPFs and pQPFs. In addi- tion, the current QPF focus to forecast the are al coverage of precipitation needs to be reevaluated. The impact of a mod- ernized QPF and pQPF on hydrologic models in various geo- graphic and seasonal conditions needs to be assessed. These sets of forecasts need to undergo extensive verification stud- ies to determine their proper design for a modern-day QPF (e.g., required time projections and spatial resolution for hydrologic models of the twenty-first century before QPF input becomes routine). FLASH FLOOD GUIDANCE Recommendation 3-12. The NWS should improve the sci- entific basis that underpins the forecasting of floods that occur in the zero to six-hour time frame. WFO and RFC staff should be enabled to contribute to this effort by facilitating their access to adequate training, continuing education, and univer- sity cooperative programs. Furthermore, they should be able to access state-of-the-art geographic information systems, digi- tal elevation models, and drainage and land-use data. The scientific foundations of both flash flood guidance and threshold runoff (another type of guidance product) are derived from decades-old techniques that need significant revisions. Yet few of the existing NWS research programs are related to operational flood forecasting. In addition, threshold runoff is currently estimated based on limited data. The Weather Forecast Office Hydrologic Forecasting Sys- tem (WHFS), with its capabilities for both site-specific and area-wide modeling of the flash flood hazard, has great po- tential for dealing with the zero to six-hour flood problem if technical and scientific, training, and operational procedures problems are resolved. WEATHER FORECAST OFFICE HYDROLOGIC FORECASTING SYSTEM Recommendation 3-14. The NWS should reevaluate the staffing needs of WFOs with regard to their hydrologic re- sponsibilities. The number of service hydrologists should be increased so that each WFO has a program leader for WFO hydrologic operations, at least for the first year or two fol- lowing implementation of the AWIPS at each field office. (A related recommendation is provided in the Qualifications section of this summary.) Overall, the NWS has done an excellent job of defining the requirements and planning the staffing needed in the hy- drology and hydrometeorology functions of the modernized

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EXECUTIVE SUMMARY NWS. However, although service hydrologists will manage the hydrology programs at all future WFOs, only 80 of the planned 1 19 WFOs will have a service hydrologist assigned full time; these 80 service hydrologists will cover all 119 WFOs. WFO service hydrologists are program leaders within their offices, not operational forecasters. But most WFO weather forecasters currently do not perceive hydrology as part of their operational duties. Furthermore, during severe weather conditions, hydrometeorological forecasting at WFOs may at times produce an excessive workload for the planned staffing; as a result, the use of interactive hydrologic forecast programs might receive less attention than is warranted. Sufficient staff must be in place who have the appropriate training to take advantage of these modernized capabilities. The committee remains concerned about the vital and in- creasingly important role that the service hydrologist will play in the modernized NWS. It is possible that most, if not all, WFOs may require a full-time position. At offices where operational tests and evaluations are conducted, additional hydrologic expertise will be needed to ensure a thorough, effective test of the new systems and techniques. Recommendation 3-15. Guidelines and procedures should be in place to ensure that the hydrologic and hydrometeoro- logical forecasts meet NWS requirements (e.g., for accuracy and timeliness) even under the most challenging of opera- tional circumstances. Operational tests should be performed to confirm that these requirements are met. A suite of powerful new software tools has been devel- oped to assist in the development of guidance and forecast products. However, during severe weather conditions, WFO forecasters are concerned primarily with generating severe weather warning products, which result in the new interac- tive hydrologic forecast programs receiving less attention than is warranted. There is a risk that RFC guidance prod- ucts on flooding potential might sometimes be released to the user community with little modification or enhancement by WFO forecasters. The potential is even greater when fac- tors such as hydraulic structures (e.g., dams), small-scale land-use patterns, and urban surfaces complicate the local hydrologic picture. The full capability of an application such as the WHFS can be realized only when WFO forecasters are prepared adequately to deal with hydrologic forecasting during flood water crises and concurrent severe weather conditions. The WHFS in particular needs to be tested in the most challeng- ing of operational environments, for example, during com- plex, severe weather situations when forecast and warning workloads are heavy. DATA ARCH IVING, VERIFICATION, AND QUALITY ASSURANCE Recommendation 3-22. The suite of precipitation prod- ucts produced by the NEXRAD network, along with 3 accompanying surface rain and stream gauge information, should be archived by the NWS for future use when new hydrologic models require calibration before they can be implemented. The NWS should ensure that appropriate ac- cess, storage, and visualization methods, such as those planned in the National Oceanic and Atmospheric Adminis- tration (NOAA) Hydrologic Data System, are developed or adapted for use with the entire spectrum of hydrologic data. An essential element of the foundation for future improve- ments in the NWS hydrologic forecast system is the avail- ability of a comprehensive data archiving and retrieval sys- tem. Although the NOAA Hydrologic Data System, now under development, is expected to meet the data archiving needs of some NWS operational activities, nevertheless the current system fails to archive and efficiently retrieve most of the data that will be needed for twenty-first century im- provements in NWS hydrology. A lengthy archive of all basin data is essential to calibrate hydrologic models (old and new) and improve model perfor- mance during critical high-water and low-water situations. For example, hydrologic models can be improved using data on the distribution in space and time of precipitation that produced floods or led to drought conditions. Yet NEXRAD precipitation estimates provide a unique opportunity to pro- duce hydrologic guidance and forecasts with an unprec- edented level of detail. With increasing demands for hydrometeorological data n an interactive forecast environment, efficient methods for accessing, storing, and viewing these data are required. i] Recommendation 3-23. The NWS should implement and provide the sustained support that is needed to continue the development and operation of the National Hydrologic Fore- cast Verification Program. An essential ingredient to improve hydrologic services is an adequate forecast verification system. Such a system must provide a baseline that documents previous forecast skill lev- els and also detects small improvements in forecast skills that result from new models being developed, calibrated, and implemented. Currently the verification of hydrologic forecast products is inadequate. Hydrologic model development and the incor- poration of new scientific tools into a modernized work en- vironment should be accompanied by a rigorous verification program to document what progress has been achieved. The National Hydrologic Forecast Verification Program is a re- cent initiative in the NWS and represents an important set of plans for overcoming verification deficiencies in the hydrol- ogy program of the NWS. DATA SOURCE RELIABILITY Recommendation 3-25. The NWS, along with other federal agencies and local and state governments, should coordinate hydrologic and hydrometeorological data requirements, data

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4 ASSESSMENT OF HYDROLOGIC AND HYDROMETEOROLOGICAL OPERATIONS AND SERVICES collection, and processing. Priorities among these data should be set and appropriate funding allocated by the par- ties involved to maintain a consistent, reliable set of data for national and local flood forecasting programs. The NWS should exert leadership to forge an explicit partnership for sharing these data collection resources. Data for use in hydrologic and hydrometeorological analyses and models are the lifeblood of NWS river fore- casts and flash flood guidance and warning products. Sources of these data include stream gauges, precipitation gauges, cooperative observers, flood warning systems, satellite-relayed data, telemetered data and, most impor- tantly, data from the NEXRAD network. But ownership of these data sources is distributed across various federal, state, and local government or private networks. Abrupt funding changes and uncertainties cause some data sources to be unstable, unreliable, or subject to short-notice curtailment or elimination, sometimes with no apparent coordination or consideration for the impact of their loss on NWS opera- tions. It is essential that a shared ownership exist for the nation's water management and flood warning infrastruc- ture, lest this infrastructure lose its ability to meet growing operational demands. Strengthening the vitality of the surface-observing net- works is also essential; the modernization of NWS hydrology will be hindered without the real-time availability of stream and rain gauge data from a larger number of locations. PRODUCTS AND SERVICES Recommendation 3-26. The NWS should continue to work with the user community to determine community needs. In particular, the NWS should focus on user concerns that may develop in regions where political boundaries and basin boundaries do not coincide. In addition, improved commu- nication technologies should be employed to share data and to disseminate warnings. A service agency such as the NWS is known by the qual- ity, relevance, and ease of access and use of its products. Nowhere are these traits more critical than in river and flash flood situations where lives and property are threatened situations that often arise late at night and in rural areas. In these situations, a forecast and warning system provides an unacceptable level of service when the forecasts and warn- ings are inaccurate or difficult to decipher or when they fail to reach the population at risk. To achieve the dividends of modernization requires that the NWS and its myriad of users understand each other's needs, capabilities and responsibili- ties, establish highly efficient telecommunication linkages, and support or advocate mutually beneficial programs. The NWS forecast and warning system can be fully effective only if local communities accept responsibility to acquire and act on the information. PROG RAM RES PONS I Bl LITI ES AN D PERCEPTIONS Recommendation 4-1. The NWS must communicate the objectives of the hydrologic and hydrometeorological as- pects of the modernization program and progress that has been made in the program more effectively to its employees as well as to users of its services. In particular, the NWS should ensure that responsibilities for the integrated hydrol- ogy and hydrometeorology programs are clearly assigned and understood at all levels of the NWS. Interdisciplinary advisory or working groups such as the Service Hydrologist Working Group could be essential intermediaries in this communication process. In its contacts with field office personnel, the committee found considerable misunderstanding or distrust of modern- ization activities relating to hydrologic and hydrometeoro- logical functions, products, and services. In particular, the benefits of the integration of certain hydrologic and meteo- rological duties and responsibilities are neither clearly understood nor readily accepted in many field offices. These misunderstandings about roles and responsibilities- particularly with respect to hydrometeorological duties- need to be resolved at all levels of the organization. AVAILABILITY OF ADVANCED WEATHER INTERACTIVE PROCESSING SYSTEM Recommendation 4-2. The AWIPS implementation pro- gram should be expedited to enable NWS offices to exploit the use of data from new technologies and to realize improve- meets in the river and flash flood forecasts and warnings. The AWIPS (Advanced Weather Interactive Processing System) is essential for data collection, quality control, and processing and telecommunication of hydrologic and hy- drometeorological data. The AWIPS is essential to the inte- gration of data, analyses, and models that enable improve- ments in river and flash flood forecasting programs. De- spite consistent efforts by the NWS, a variety of technical, funding, and political setbacks have slowed the AWIPS de- velopment and implementation program. At this point in the modernization and restructuring, the absence of an AWIPS is preventing full realization of the benefits of the modernization program. As data from other new technol- ogy systems have become available, the lack of AWIPS workstation capabilities presents a bottleneck in data pro- cessing and data integration that will result in less accurate and timely warnings than would otherwise be possible with the new work-station technologies. RES EARC H AN D D EVEL0 PM ENT Recommendation 4-5. The NOAA and the NWS should develop a formal, long-term plan for hydrologic science

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EXECUTIVE SUMMARY research that includes establishing priorities and is relevant to flood and flash flood forecasting. The NOAA and the NWS should request sufficient funding to implement and sustain the research. The plan should be communicated to field personnel so as to improve the overall NWS vision for hydrologic services in the twenty-first century. In addition, NWS headquarters should disseminate regularly to its field offices updates on research and development activities, their specific objectives, and timetables. Considering its relatively small size, the NWS supports a significant research and development program that has pro- duced very useful results. For example, interactive hydrol- ogy forecast applications such as the WHFS and the NWS River Forecast System are quite innovative. However, rela- tively little effort is under way on research issues related to the scientific underpinning of hydrologic procedures and models used in day-to-day operations. The committee concludes that although a modest amount of hydrology research is in progress or planned within the Office of Hydrology, the overall objectives are unclear. Fur- thermore, the priorities, relevance, and cohesiveness of those research activities are lacking to some extent. In addition, information on NWS research and development activities is not received at field offices in a timely manner and often is not considered credible by field office staff. ADVISORY GROUPS Recommendation 4-8. The NWS should use internal advi- sory groups consistently throughout major planning, devel- opment, test, and implementation phases of the hydrology modernization program. These groups should include field office members and be encouraged to advise NWS head- quarters on matters relating to research and development, operational test and evaluation, and overall modernization implementation. Early in the modernization planning, the NWS established various working groups, consisting of field office and head- quarters personnel, to review requirements and to develop s plans to improve products and services in hydrology and hydrometeorology. The contributions of these groups are seen almost universally as having been beneficial and effec- tive in the establishment of a sound modernization program. One or more similar advisory or working groups need to be reestablished with respect to the hydrometeorological as- pects of the modernization and restructuring. Such a group could provide important feedback on data quality control, forecast verification, hydrologic modeling, and precipitation processing techniques. QUALIFICATIONS Recommendation 4-11. The NWS should review and, if warranted, modify its qualification standards for hydrology positions. The NWS should require a degree or extensive formal education in hydrology for positions that involve a hydrology emphasis. Hydrometeorological personnel with duties that have a meteorological emphasis are required to have an extensive education in meteorology. However, those personnel that have duties with a hydrology emphasis are not required to have a comparable level of education in hydrology. NWS forecasters with a degree or extensive formal education in meteorology but no comparable training in hydrology usu- ally are not qualified for hydrologist positions. A more sub- stantial educational background in hydrology is necessary for personnel working in such positions. OUTL00K Overall, the NWS hydrology program has taken a posi- tive leadership role in the use of new observation networks and in developing state-of-the-art interactive forecasting sys- tems. To be sure, there are barriers that must be overcome- financial, technological, operational, and organizational. However, the committee is confident that if the changes rec- ommended in this report are made, there is a high likelihood that the hydrologic and hydrometeorological goals of the modernization program will be achieved.