[EBB Sightings] Possible Blackpoll Warbler at Joaquin Miller Park

I spent an hour this morning before work (9/24) birding a foggy
Joaquin Miller Park along the hill west of the Woodminster Theater.
The highlight was an unusual warbler that I was surprised to find
foraging on the ground with some Dark-eyed Juncos in a grassy area
near the public restrooms and fire ring.  The bird was seen for about
30 seconds with binoculars at a distance of about 20 feet.  My field
notes (without looking at any guides) were as follows:  A warbler with
a thin bill and with the head and upperparts showing a uniform
greenish-yellow color.  The facial pattern and head color reminded me
of an Orange-crowned Warbler, with a faint split eye ring and
supercilium.  The underparts were lighter than the upperparts and were
generally a dingy cream color.  I didn't see any bright yellow at all
on the underparts.  Unfortunately, I never got a good look at the
underside of the tail.  The most striking feature of this bird were
the blackish wings with a pair of thick white wing bars.  The bird was
soon flushed into the nearby trees and I didn't have time to try and
refind it before work.  I don't have any experience with this species
and I'm not sure I saw it well enough for a positive ID.  Comments are
welcome.  Just posting the observation in case anyone else is headed
out there today...

Ken Schneider