Theme for 2006:
Forecasting Advances Since the 1986 Flood
University of California, Davis
Special Recognition Award
The 2006 Special Recognition Award was presented to Johannes J. DeVries, Ph.D., P.E., P.H., D.WRE. See the award language and some biographical information on the Symposium's Johannes J. DeVries award page.
Hydrologic Modeling: The more things change … the more they stay the same
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In this presentation Joe looks back well past the 1986 flood (looking back to the start of his career four and one-half decades ago) and review some major changes that have occurred in computational tools used in hydrologic analyses during this period. Joe started in the era of the slide rule and has over the years witnessed the major changes provided by the increasingly high-powered computer-based systems of the 21st century.
Some of the basic modeling techniques developed in these early days, however, are still being employed in our rainfall-runoff computations. Also, the fact that we rely on data collection using rain gages means that what was our most important data source in the past is still essential today. The challenge Joe proposes for future workers in this field is for the basic data-collection systems to be expanded to keep up with the sophisticated computational systems that we currently have.
Advanced Hydrologic Prediction Services: Ensemble Streamflow Prediction
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[Abstract not available]
Forecasting and Operations Advances from a Reservoir Operator's Perspective
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The Central Valley Project (CVP) is the largest integrated water development project in the nation. It consists of 20 dams and reservoirs, 500 miles of canals, and other facilities located mainly in California's Central Valley. Operating the CVP to meet the multitude of project objectives relies on both short range and long range weather and stream flow forecasts. Improved interagency coordination, more accurate and timely forecast products, and new forecasting tools have contributed to enhancing the operation of the CVP over the past decades. 1986 was a time of hand written spreadsheets, teletype machines, and mainframe computer use. Although the general nature of the products has not changed over the years, we have seen significant improvements in the number of basins analyzed, greater accuracy in the precipitation and runoff forecasts, an extension of the forecast window, and access to a large variety of forecast model outputs. These improvements to forecasting products and tools combined with improved interagency coordination have resulted in greater water supply for the CVP, reduced impacts to the fishery, increased power generation, and improved public safety.
A Chronology of Events Leading to the Accurate Prediction of the Storms of December 24, 2005 – January 3, 2006
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The winter of 2005-06 will go down in the record books as one of the wettest ever for northern California. In fact, the Northern Sierra 8-Station Precipitation Index ranks the water year among the top five. What made this past winter especially problematic is that a large percentage of the precipitation fell during two distinct periods; one in late December and another in April.
This presentation will focus on the challenges of dealing with the high impact event that affected northern California in late December from the perspective of a National Weather Service (NWS) field office. A chronology of events will be provided detailing some of the proactive measures that were taken by the NWS staff in advance of the wet season. These measures proved helpful in the successful identification of the pattern change that led to the excessively wet period. Finally, the well-coordinated effort that was displayed by multiple agencies leading up to the event and the outcome will be discussed.
Precipitation Forecasting: Past, Present, and Future
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This presentation reviews the changes in precipitation forecasting that have taken place since the 1986 floods in northern California. Most if not all of these changes are attributed to changes in our tools and techniques to gather and display data information, as well as steady advancements in numerical weather prediction. Over the years, our skill at forecasting precipitation has shown a slow but steady improvement.
The NOAA Hydrometeorological Testbed Program: Overview, Progress to Date and Future Plans
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The Hydrometeorological Testbed (HMT) of the National Oceanic and Atmospheric Administration (NOAA) is a demonstration program intended to accelerate the infusion of new technologies, models, and scientific results from the research community into daily forecasting operations of the National Weather Service (NWS) and its River Forecast Centers (RFCs). The program focuses the use of advanced tools on quantitative precipitation estimation (QPE) and quantitative precipitation forecasting (QPF) for the purpose of improving hydrologic forecasts and warnings. The testbed concept has been identified as a key R&D approach for improving streamflow and flood forecasts based on recent guidance from NOAA's Strategic Plan, the NWS Hydrology Science and Technology Infusion Program (STIP) and the U.S. Weather Research Program (USWRP).
The HMT plan calls for a sequential deployment of advanced research tools in different regions of the United States to address different hydrologic forecasting problems. Field work will be conducted for a few years in each regional demonstration to determine which new tools are the most useful for improving QPE, QPF and associated hydrologic forecasts and warnings. The most successful tools will become HMT legacy facilities that will remain in place in the first region and will be duplicated in the next region as the project moves. Preliminary work for HMT was mostly conducted in the coastal mountains of California during the winters of 2003-2004 and 2004–2005. Starting in the winter of 2005–2006 the primary emphasis shifted inland to the western slopes of the much taller Sierra Nevada for the first full-scale deployment of HMT. Intensive operations focused on the North Fork of the American River Basin between Sacramento and Reno. Water from the American River Basin is a critical resource for California's economy and natural habitats, and the threat of flooding poses an extremely serious concern for the heavily populated downstream area. The frequent impact of prolonged, heavy winter precipitation from concentrated "atmospheric rivers" of moisture, originating in the tropical Pacific, underscores the area's flood vulnerability.
The Madden-Julian Oscillation: Can it Play a Significant Role in Improving Forecasts of Hydrologically Significant Rainfall for Week Two?
Tropical influences can have a profound impact on California precipitation. Specifically, hydrologically significant events can occur along the West Coast during the cool season when tropical seasonal oscillations (such as the Madden-Julian Oscillation or MJO) occur. This paper discusses one of the clearer cases that occurred in late 2004 and again in early 2005. The examples presented show how one can monitor the location and phase of the MJO as it progresses across the Western Pacific. This coupled with an understanding of the concurrent large scale circulation may make it possible to determine if this MJO activity will have a significant impact in amplifying the pattern such that enhanced westerly's, with above normal moisture content, will impact the West Coast with some 10-to-14 day lead times. It will be noted that the key forcing on the circulation pattern is from the direct impact of the tropical convection. It is not just an MJO that can impact the circulation. Recurving tropicals in the western Pacific can directly inject large amounts of heat into the Eastern Asian Jet thus amplifying the large scale pattern via Rossby wave dispersion. These intra-seasonal tropical convective systems act similarly to how El Nino and La Nina work, but on shorter time scales. Tools such as Hovmoeller diagrams of filtered outgoing long wave radiation anomalies and monitoring ensemble forecasts of the circulation pattern 10-to-14 days out will greatly aid the operational forecaster in assessing future flood potential.
Atmospheric Rivers: A Key to Understanding California Extreme Precipitation Events
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[Abstract not available]
Forecast-Coordinated Operations for the Yuba-Feather River and Reservoir System: Interagency Cooperation
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- American River Watershed Institute
- Center for Watershed Sciences, University of California Davis
- Placer County Water Agency
- Sacramento Area Flood Control Agency
- Sierra College Natural History Museum