Theme for 1998:
Predicting California Precipitation and Floods

June 27, 1998
Sierra College, Rocklin, CA

Speaker Presentations

Weather Patterns and American River Floods

Gary W. Estes
Auburn, CA


Eleven of the 12 largest floods on the American River from 1905 through 1997 were caused by the same weather pattern, or storm type. Sorting of the 12 floods is based upon the 3-day mean river flow measured and/or computed at the Fair Oaks gaging station. The use of weather pattern/storm type knowledge appears to provide an opportunity to increase the reliability of Sacramento's flood management system.

Experimental Regional Scale Climate Forecast Over California

Su-Tzai Soong, Ph.D.
Atmospheric Science
Dept. of Land, Air, & Water Resources
University of California, Davis
Davis, CA


Back in May 1997, as the El Niño was getting stronger, a group of scientists in the Campus Laboratory Collaboration (CLC) Program on California Water Resources met at UCD and decided on an ambitious project of making an experimental seasonal climate prediction for the winter season of 1997-98. UC Davis participated in this experiment as a partner with Lawrence Livermore National Laboratory (LLNL), National Center for Environmental Prediction (NCEP) and UCLA. The climate prediction starts from the Sea Surface Temperature (SST) prediction by NCEP, which drives the global general circulation model of UCLA, which in turn drives the Mesoscale Atmospheric Simulation (MAS) model of UC Davis/LLNL. All of the predictions are made using observed weather and SST data from October 1997. The prediction of the MAS model is made over the area of California using a 20 km grid resolution. The prediction period is from November 1997 to April 1998.

Paleoflood Perspectives on Flood Hazards in Western United States

Dean A. Ostenaa
Geophysics, Paleohydrology, & Seismotectonics Group
U.S. Bureau of Reclamation
Denver, CO


[This paper is not available. The essence of the paper was to be included in the Folsom Dam Paleoflood Study conducted by the Bureau of Reclamation. This Study is designed to assess the flood hazard posed to Folsom Dam by large and extremely rare floods. The paleoflood information was to be used to characterize the probabilities of flood magnitudes greater than those represented by the historical record.]

Use and Expansion of an Objective Orographic Quantitative Precipitation Forecasting Aid

J. Owen Rhea
California-Nevada River Forecast Center
National Weather Service
Sacramento, CA


Quantitative precipitation forecasts (QPF's) for river basins are of great importance to river forecast centers and reservoir operators. QPF's in topographically complex areas like California must account for terrain effects on precipitation. Mean annual precipitation ranges from less than 15 inches in parts of the Sacramento Valley to over 80 inches in some of the wettest locations in the Sierra Nevada at the same latitude. This paper briefly describes an objective orographically-based QPF aid which the California-Nevada River Forecast Center (CNRFC) has been running for the last four years. The method produces QPF's in six-hour blocks and is also converted to input for use with new QPF preparation software (Mountain Mapper) from the Colorado Basin River Forecast Center (CBRFC). See Henkel and Peterson, 1996. An example of results for the flood period of late December, 1996 to early January, 1997 is given and some verification statistics from 1995 are mentioned.

Evolution of Flood Forecast Technologies Between The 1986 and 1997 Floods in California

Rob Hartman
California-Nevada River Forecast Center
National Weather Service
Sacramento, CA

Ira Bartfeld
National Weather Service (retired)
Carmichael, CA

David C. Curtis, Ph.D.
DC Consulting
Folsom, CA


During the intervening decade [1986-1997], flood-warning technologies changed significantly. For example, the National Weather Service modernization program, highlighted by the WSR-88D radar system, was implemented, automated gauge networks expanded, and quantitative precipitation forecasts improved significantly. This paper compares and contrasts the technological landscape for flood forecasting during the 1986 event in California with the tools available to forecasters in 1997.

CAL-JET Research and Improvements to Weather Forecasting Computer Models

Norm Hoffmann
National Weather Service
Monterey, CA


I'm going to talk about some of the data and interface that we did with the California Landfall Jet Experiment (CAL-JET), how it got started, some of the opportunities we had, and since I saw Alan Fox here, I've thrown in a Southern California example as well. So, we'll do a Southern California and a Northern California example.

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