Sam and I had each made visits to the burn late last fall, and found small numbers of Black-backed Woodpeckers. Our trip on Sunday turned up one Black-backed as well as a bunch of other species uncommon in King County - numerous House Wrens, several Rock Wrens, Western Bluebird, Nashville Warbler. Details in this eBird checklist: https://ebird.org/pnw/checklist/S70453519. There is tons of interesting habitat in the area, with a great variety of tree sizes and burn intensities interspersed with clearcuts.
As of Sunday, the road to the burn was snow-covered at its high point along Sawmill Ridge, so getting there required a substantial hike along the forest service road. In a few weeks the snow should melt off, though there is a deteriorating wash-out along FR 7030 on the way there, which may close the road entirely if it is not fixed soon. To get there, follow FR 7030 north from FR 70 for 4 miles to the T and turn left towards Kelly Butte. Immediately turn right instead of continuing straight toward Kelly Butte, and follow the road for an additional 3.3 mile until a smaller road breaks off downhill to the left. This smaller road takes you into the burn. Google maps directions to the eBird checklist above will get you most of the way there. Barring snow and the wash-out, the road is driveable all the way to the burn.
I'm posting this in hopes that it spurs other folks to explore this spot. I think it has great potential for additional birds more typical of the east side of the Cascades. And if anyone does head up there, I would love to hear about it.