I saw this bird in a residential garden along the Russian River in Healdsburg. I didn't hear any vocalization, and identifying silent migrant Empidonax flycatchers is a dubious business, so I originally posted with a question mark on the ID. Better birders than I confirmed that it is indeed a Willow Flycatcher. Identifying marks include an all-white throat, broad all-orange lower mandible, gray-brown upperparts, and a scanty eye-ring.