The statistics of fog and low ceilings at Pendleton are discussed in relation to the topographic situation, prevailing winds, type of fog process, etc. The explanations require careful attention to topography. Nov. to Jan. is the foggy season; radiation, prefrontal, and advection are the chief types, but postfrontal and upslope fog also occur. Typical situations for each are illustrated. The forecasting by use of Brunt's radiation equation or the methods of George has not yet been satisfactorily worked out; some forecasting rules are cited however.

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*Paper read at the Seattle Meeting, June 1940.