An effort to improve marine stratus forecasts using satellite cloud climatologies for the Eureka, CA region

A major challenge for the National Weather Service (NWS) Eureka, CA office is the prediction of the formation and burn off of the marine stratus and fog that forms along the northwest California coast. To aid in this forecast, cloud cover climatologies over the region have been derived from GOES West imagery for May through September for 1999-2009. Each set of hourly cloud frequency of occurrence composites was derived using a differencing method between channel 4 (10.7 µm), and channel 2 (3.9 µm), with additional checks using the visible channel during daylight hours. The composites are then stratified using daily marine layer depth (MLD) for the Eureka area at 1200 UTC. This value is determined using the GIS system in the Eureka office. The composites are scheduled to be added to the Eureka office's GFE and AWIPS system in May 2010, and will be tested during the 2010 summer fog and stratus season. Preliminary results from these tests will be presented along with selected composites.