The objective of this study is to develop classification equations to forecast the daily probability of occurrence of marine fog at selected locations on the west coast of the United States, using parameters easily obtainable from upper-air soundings and surface observations. In order to achieve this objective a computerized stepwise linear discriminant analysis program is extensively employed. Data input consists of surface and radiosonde observations for the five-year period 1 July 1968 to 30 June 1973 at three U.S. west coast stations, namely San Diego and Oakland, California and Quillayute, Washington. Tables showing the number of fog and no-fog cases, the classification functions, and the percentages of correct fog and no-fog discrimination are presented for each station. The most capable fog/no-fog discrimination parameters are discussed for each set of classification equations. Test results for the San Diego equations using a three-year independent data set are also shown. (Author).

Using transient ship observations, a hypothetical five phase Marine Fog Development (MFD) Model was applied to four actual cases of summer marine fog during 1973 along the central California coast. The MFD Model incorporates a phase zero or synoptic phase and a proposed Coastal Convergence Zone (CCZ) concept into previous West Coast fog models. Phase zero describes the synoptic conditions that establish the marine layer over the coastal regions and explains the presence of low stratus over cast which normally exists prior to fog development cases. The CCZ concept defines a transition zone in which warm dry continental air converges with cool moist marine air and denotes the seaward extent of coastal influence. The location of the transitory CCZ is dependent upon the strength of offshore flow of continental air from the coastal region. The location where this flow meets the prevailing northwesterlies becomes the most likely site of marine fog formation. Selected synoptic scale meteorological parameters were examined and incorporated with transient ship and coastal station observations. This appeared to be an effective technique for tracking the CCZ and identifying fog phase development. (Author).

Marine fog forecasts during the summer period in the North Pacific are not made presently with any acceptable degree of accuracy. Objective fog development models exist and are used with some success for localized coastal regions of the western U.S.; scarcity of accurate data has hindered creation of a reliable open-ocean model. The Eulerian single-station approach, utilizing a segment of the complete accurate data of Ocean Weather Station Papa (50N, 145W) is applied in this study to an objective marine fog forecasting model. The time-series study of significant atmospheric variables at OWS Papa, when coupled with a chronological synoptic overview, delineates accurately fog/no fog sequences in the summer months of 1973 and 1977. Actual observed fog situations are evaluated by the general model and presented in relation to open-ocean fog indices, NOAA 5 satellite coverage and synoptic history. The open-ocean forecast model is tested on an independent data set for the month of July 1975 at OWS Papa, with favorable results. The research delineates four required indices that must all be positive to forecast fog. These indices, when plotted daily in the region of OWS Papa allow a single station to predict, with some confidence out to twenty-four hours, the occurrence of advection fog. (Author).

Surface visibility data for selected stations on the central California coast in 1973 are analyzed. Radiosonde data from Oakland for the same period are used to derive meteorological indices. The year is divided into fog-related seasons, summer and winter, based on fog occurrence on the coast; and the seasonal and daily fluctuations of the indices are examined. A fog development model for the summer is formulated and compared to actual fog cases. In the winter, with far fewer coastal fog observations, the frequent occurrence of frontal passages prevents a standard development model from being formulated and compared. Four Oakland soundings are compared with four radiosondes taken at NPS Monterey, and the Oakland Soundings are found to closely approximate coastal conditions on these days. (Author).