This is definately an Empidonax Sp. indicated by the yellowish breast/belly and a suggestion of an eye right. WWPW would be darker and lack the yellow colouring,
As for which empid, this is more difficult to determine as Bill, Chin and Head Shape are obsured. We can look at primary projection as a supporting field mark.
I would guess Pacific Slope Flycatcher as bird has a eye ring (just can't see the teardrop mark at the back of the eye), maybe a Hatch Year Pacific Slope as the wingbars appear orange'ish.
Need to see a bit more of the bird to be certain.