Carolyn,
I don't have a copy of the Bird of Washington in front of me unfortunately,
but I'll piece together a bit of info from what I have in front of me since
I haven't seen anyone respond with it yet. I'm far from an expert, but
hopefully my information is accurate.

To put it simply, they are rare, but expected annually in western
Washington. They are probably our most common rare warbler species.

While Palm Warbler's main migration corridor and breeding grounds occur far
east of Washington, a small number of birds end up along the west coast
during fall migration. The occurrence seems to increase as you get farther
south you get with Oregon and California receiving more birds than
Washington. They seem to stick close to the coast and have been recorded in
every Washington county with marine coastline.

Birds of North America states it the following way:
"Palm Warblers are rare transients throughout w. North America where they
are observed in greatest numbers along the West Coast. Numbers reaching the
Pacific Coast in fall are variable. An exceptional ?invasion? occurred in
the fall of 1993 when >125 were found in the Oregon?Washington region,
nearly 900 were found in n. California (about 3 times the previous record
high), and >150 were found in s. California (far more than usual) (McCaskie
1994, Tweit and Gilligan 1994, Yee et al. 1994). Following that major fall
flight, unusual numbers lingered in the winter, including 2 birds that
overwintered successfully as far north as the Queen Charlotte Is., British
Columbia (Siddle 1994). Almost all Palm Warblers observed in w. North
America are Western Palm Warblers (see Systematics: subspecies, above).
Yellow Palm Warbler has only been recorded as a transient in small numbers
west of the Appalachian Mtns."

Josh Adams (Who arrived at the spot ten minutes after the warbler departed
and left ten minutes before it returned this afternoon)
Lynnwood, WA
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman1.u.washington.edu/pipermail/tweeters/attachments/20131211/e705cd11/attachment.htm