Following is a 2003 writeup from the Northwest Mountaineering Journal on the lines:
“Poster Peak”, East-Northeast Buttresses, New Routes
Poster Peak is shown on the Washington Pass quad as point 7565’, located one mile southeast of the Early Winters Spires. It is the terminating high point of the long but mostly flat ridge extending toward Copper Point from the Early Winters massif. The locals named the peak, which is very striking from most angles, after it was used on a ski poster and everyone wanted to know where it was.
In the summer of 2003, Poster Peak saw ascents by two probable new routes.
Larry Goldie and Blue Bradley climbed the leftmost of the two prominent east-northeast buttresses, as seen from Highway 20 just below the hairpin turn. This high-quality moderate route makes for a great day out, with a one-hour approach. It traverses onto the nose of the buttress from the left on a broad ledge 200 feet up and left from the toe. From there, staying true to the ridge crest on delightful, sound rock will take one right to the summit in about 12 pitches, with the most difficult near the summit at 5.7. This route is of higher quality than the often overcrowded South Arete of South Early Winters Spire. Consider it a good alternative on a busy summer day. Descent is by walk-off to the south and down to the base of the route. Its name is tentatively “Blue Buttress.”
Grade III 5.7.
Steve House free-soloed the rightmost of the two east-northeast buttresses in 45 minutes. The climbing is less continuous than on Blue Buttress, but is 5.9 at its hardest. Protection is a bit hard to find in spots. Staying on the crest as much as possible takes one up several steps and across two significant notches. The route begins in a shallow depression on down-sloping, awkward climbing for the first pitch. Two pins are fixed on the first pitch. Subsequent parties have reported as many as 17 roped pitches. The climbing quality is lower than that of the Blue Buttress. Descent is same as for above.
Grade III 5.9.
This is a somewhat obscure route, so there is very little information on it. As such, I thought I might put some in here.
Approach the base of House Buttress the same way that you might approach Blue's Buttress. The toe of the House Buttress is approximately a hundred meters north of the base of Blue's Buttress.
In theory there are two pins on the first pitch. We never found these pins. They are likely on a direct start to the buttress, which we bypassed.
To climb the route, make your way up to the base of the buttress and then contour around to the left. There are several fifth class options that could be made instead of this third class option.
Climb the ridge crest, choosing the best line until you reach a small notch. There could be snow at this point, especially early in the season. I used an ice axe here to chop steps across a short exposed area on the snow. If you're wearing boots, it wouldn't be a big deal to cross this area, but if approach shoes or rock shoes, an ice axe is an important tool to have on hand.
After crossing the gully, the rock quality deteriorates and there is less protection available. The combination of limited protection and poor rock make this area the crux. Continue up toward the ridge crest. Once on the crest the rock quality gets substantially better and there is more protection.
After you reach the ridge crest the climbing become pleasant again as you slowly work your way to the top.
This line could be as many as seventeen roped pitches, or a handful of roped pitches and some simulclimbing, or just a big simulclimb. It all depends on how comfortable you are on fourth and low fifth-class rock, with an occasional 5.7 move thrown in.
To descend the peak, drop off the short southwest ridge to an easy scramble. Continue down southeast to the obvious short couloir. Drop down the couloir and contour back around to the base of the route.
The House Buttress is a very cool little line and well worth any climber's time...
--Jason D. Martin