On the morning of July 17th, 2008 a volcanic cloud passed over the Pacific Northwest. It was apparent on the morning visible satellite imagery. This cloud wasn't volcanic ash, but Sulphur Dioxide (SO2). The volcanic cloud appears as the faint west-to-east bands of clouds from the ocean and extending over Washington. Note that it looks similar to the wildfire smoke near Northern California. Okmok erupted on the afternoon of July 12th in the Aleutian Islands. The cloud from this eruption has meandered around in the Gulf of Alaska for the past 5 days before being caught up in the jet stream and pushed into the Pacific Northwest. In the satellite loop below, note how the cloud becomes less visible as the sun continues to rise (the loop starts at sunrise and ends at 9am PDT).

The image loop below is an Infrared Satellite loop on the afternoon/evening of July 12th. The bright red/pink area over the central Aleutian Islands is the ash cloud from the Okmok eruption.