Weather forecasts and warnings are the most important services provided by the meteorological profession. As one aspect of these services, a year-round fog forecasting objective is selected for California coastal sites and their surrounding areas, both alongshore and offshore. The effort was to provide a simple, straightforward forecasting method using primarily data from the coastal site, which might be supplemented and improved using the forecaster's experience, any new technology, and new results of research. The meteorological objective is to forecast light, moderate, and dense fog, the probability of each occurring, and the expected times of beginning and ending of each period of reduced visibility, both for terminals and for limited nearby areas. Forecasts of five days' duration are sought using a frequently observed sequence of synoptic events. Methods in use were reviewed. The synoptic approach, emphasizing sea–air relationships, has produced the most promising results at this time. This approach led to the method called LIBS (Leipper inversion base statistics), which is described in some detail. It is the only known method that attempts to meet the objective chosen. There are strong indications that the LIBS method is applicable to situations along the California, Oregon, and Washington coasts. Case studies are presented for Monterey, California. Further research is encouraged.

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