Kelsey and I were looking for a single-day moderate alpine climbing objective and settled on Mount Thomson having looked at it a number of times from the Kendall Katwalk but never having been all the way back to do it. We left Seattle around 6:30am and were leaving the car a bit after 7:30am.
Our approach was reasonably quick, getting to the Katwalk for a snack in a little over 2 hours and then pressing on past Ridge Lake and then to Bumblebee Pass in a little over 3 hours from the car. We got a good look at the mountain from here and could see a party on the high slabs. We dropped down past a campsite and then started the lollipop, ascending talus and scree that looked worse than it was (for the most part) up to the West Ridge notch 4 hours and 8.5 miles from the car.
We geared up here and spent a couple of minutes looking around the base of the ridge and up the ridge thinking that it looked improbably steep for low 5th class, but as soon as we got onto the rock just left of the ridge crest to start and then on the crest shortly thereafter, we found very moderate terrain which was plenty comfortable to climb in our approach shoes with a light single rack. We decided to simul-climb with our 8mm 60m rope doubled up and this worked reasonably well, combining the three pitches of 5th class into two simul blocks.
The slab section afforded some great views of Mount Rainier on what was a brilliantly clear day. We scampered across and realized after a short stop shy of the next rock face that there was a tree belay tucked all the way up against it. We moved our belay here and then Kelsey finished the climb up to the final ridge. We put the rope in the backpack from here and scrambled to the top, savoring the great views at about 2pm.
We quickly hit a traffic jam on the descent and decided that at least the first rappel was easily down-climbable, so we did that. The next rappel looked a bit more loose and exposed, so we took the rope out for it since we were waiting regardless. The next rap was an easy down-climb. We scooted past the two other parties once everyone was off rappel and then began the slog out.
We stopped at Ridge Lake for a quick dip, which was marvelous and refreshed us for at least the next couple of miles. From the Kendall Katwalk down felt interminable, with the 18 miles adding up to some serious foot and leg pain, but it all faded quickly with a burger at Commonwealth shortly thereafter. It was about an 11 hour 15 minute round trip for us. Nice to be back on rock after a long time!