At the outset, you should know that this route has caused pain in most that have tried it. Sierra clubbers call it the "dog route". Snwburd has this to say: "Learn to use ice tools and climb one of the chutes in early season from South Lake. Don't take this route unless you're a masochist (which I happen to be). It cannot be emphasized enough just how much this route starting from the bottom of the Thompson-Powell Col really sucks. " Still interested? OK, read on.
The SW Face can be accessed from LeConte Canyon (Big Pete Meadow) in Kings Canyon NP, or from the eastside trailhead at Lake Sabrina (via the Thompson-Powell Col). Since most people come from Sabrina, I will describe that approach:
Follow the Sabrina basin trail from the dam at Lake Sabrina (9,128') and follow it to Blue Lake. At Blue Lake, keep heading south towards Baboon Lakes. The trail can be difficult to follow through here, and kind of disappears 400 feet below Baboon Lakes. Just keep aiming up to the obvious bench that holds the lakes. Skirt the Baboon Lakes on the east side and follow the inlet stream up towards Sunset Lake. If you are camping, Baboon and Sunset Lakes are nice spots. If you are not camping at Sunset Lake, then do not follow the stream up to the lake. Instead, follow the right hand fork of this stream when it branches just above Baboon Lakes and follow it up to the saddle NW of Sunset Lake (between Peak 12,486' and unnamed point 11,680'+).
Contour above the NW shore of Sunset Lake and aim for the snowfield on the other side of the lake (which may melt out later in the season -- see note below). The route should be obvious from here up to the Thompson Glacier. Once at the moraine, you will see Thompson on the left and Point Powell on the right. In between are two broad chutes, and a very steep and long couloir on the right. The couloir is the NE couloir of Point Powell and leads to the summit plateau of that peak. The middle (higher) chute is the Thompson-Powell Col. You'll be lucky if you are here in the early season when snow reaches to the top. Otherwise, the top part of the route to the col is filled with nasty scree and loose rock.
[Note: Snwburd reports that in later season (mid-August 2003), the easy snowclimb from Sunset Lake is "a messy climb ... up 1000ft of steep moraine that cascade[s] down from the Thompson-Powell glacier above." He also reports that above this point, there is "a quarter mile boulder field that need[s] to be crossed before [you] reach the glacier. Ugh! Ugh! The glacier we found in deteriorating condition. Global warming seems to be doing a number on the glacier and it is disappearing quickly."]
Snwburd adds the following from his August 2003 trip: The route up to the glacier was quite pleasant. Some notes on that: Before Donkey Lake, the map shows two trails splitting heading above Blue Lake. We found only one trail. It crosses the main stream which we thought was the fork going to Donkey Lake. It isn't - follow this trail across the stream and up to Baboon Lakes. It's a fine use trail. Once at Baboon Lakes, follow Rich's recommendation to go around the east side of the lakes (there is a spectacular flower display in this area). Then, the key is not to go to Sunset Lake but take Rich's (and Secor's) suggestion of a high bench to the right (west). This has good footing and very little loose rock. There is a tarn up here above Sunset lake that would make a good camp site. Once above Sunset Lake, look south at the incredibly steep and horrible morraine spilling down from the glacier above. Now look at the rocky buttress splitting it in the middle. This is key. It looks difficult, but never more than easy class 3 - absolutely delightful climbing, avoiding all the steep morraine. This can be followed up and then a bit to the right around the huge boulder field at the top. If you do it right, you should only have a hundred yards of the boulders to cross until you reach the glacier.
From the Thompson-Powell Col, drop down the south side a few hundred feet and start heading east. Here's where it gets tricky. Snwburd says not to climb the first chute, which is Class 3+ and leads not the summit, but to the west ridge. Instead, you will need to cross over to the other side of a fairly prominent buttress that comes down from the summit ridge of Thompson (seen on the map at the red x). On the other side of this buttress, a chute filled with ugly loose rock leads up to the summit plateau. The summit has an awesome view.
Snwburd's report from August 2003 highlights some of the difficulties in routefinding here: "We regrouped at the col and looked south down the other side. Nothing but loose rock all around. Secor says to drop down about 200ft to find the SW Chute up to Thompson's summit plateau. Bad advice. After dropping down more than that, we traversed east as advised and aimed for the chute in front of us. It turned out class 3+ and loose, and took us up to the West Ridge instead of the plateau. No problem, Secor describes the ridge route as class 3. More bad advice. Like on Gabb before, there's no way this thing is class 3. Not even class 4. I was struggling to get around a gendarme hanging my ass out on a 75 degree granite block. Michael suggested I use better judgement, and besides, there was no way they were going to follow me. Back down the slope we went until we could cross the buttress on the right into the next chute which turned out to be the right one. We struggled up the loose chute to the plateau. Others have described this as a thoroughly unenjoyable part of the climb. We agreed."
If approaching from the west, head up towards the basin that holds unnamed Lake 12,140'+. From here, you will see the chutes leading to the summit plateau described above.
Ice axe and crampons are very nice to have if approaching from the east side. The snowfields leading up to the Thompson Glacier are much easier to climb with crampons, and if coming in early season, they are pretty much required equipment for gaining the col.
If you have information about this route that doesn't pertain to any of the other sections, please add it here.