Exploring the timing of fog formation and dissipation over the San Francisco Bay area using satellite cloud composites

Cloud cover composites over the San Francisco Bay area have been derived from GOES 10 imagery for May through October for 1999-2003. Each set of hourly composites was derived using a differencing method between channel 4 (10.7 mm), and channel 2 (3.9 mm), with additional checks using the visible channel during daylight hours. The composites are then stratified using various combinations of parameters, including near surface wind speed, wind direction, humidity, and others from surface observations and the NCEP reanalysis data base. From these composites, the effect of the various parameters on the timing of fog formation and dissipation in the region are studied. Relevancy of this work for the Monterey NWS Forecast Office will be presented along with selected results.