This past Saturday is the first time I've seen a Yellow Warbler in Oregon. I saw a couple in Minnesota last Summer while visiting my sister. I probably saw about five of them at Fernhill Wetlands. As with most Warblers, they are hard to get a good shot as they don't sit still and are always in amongst the branches.
The warbler I saw in Minnesota had very faint lines across its belly compared to the ones I saw on Saturday.