Everything you need to know about North Sister
Here's the scoop on how to climb North Sister late-season, after all snow has melted.
In a year of typical snowfall, this period is usually between mid-August and mid-September.
As of 2013 I've climbed this peak 6 times, early season with snow and late season without.
While many people say they prefer snow, I think the chances of success and overall safety are increased by climbing it after the snow is gone.
The multiple pitch, spicy 45 degree+ hard snow traverses are transformed into easy class 2 and 3 scree scrambles that take a few minutes for the competent Cascades scree aficionado.
This beta is for the standard SW Ridge route with a team of six or more. North Sister is often climbed late-season with no rope, no pro, and in running shoes by those comfortable on unstable scree. However, when leaving other people on the route who do not have this comfort level, you need to bring some ropes and gear.
Suggested gear: two ropes (60m preferred). Four or five small cams. I like Metolius: 1 red, 2 yellow, 1 orange, 1 blue. Slings and biners for each cam. One cordelette.
Hexes, tricams, and stoppers are not needed.
1) Pole Creek trailhead (elevation 5,300 ft) to lower Hayden Glacier Camp (7,200 ft). About 5 miles and 1,900 foot vertical gain.
2) Obsidian trailhead (4,800 ft) to camp at Arrowhead Lake (6,900 ft). About 5.7 miles and 2,100 foot vertical gain.
Pros and cons: Pole Creek approach is slightly shorter and faster. Obsidian approach and the Arrowhead Lake camp is much more scenic Obsidian requires a permit (in 2013 $6) that you need to reserve far in advance.
Take your pick.
The rest of this trip report assumes the Obsidian trailhead. Both approaches use the Southwest Ridge as the main ascent route.
Approach hike via Obsidian trailhead
Hike a gentle ascent on a well-graded trail through trees. Cross lava field after about 3.5 miles. On the far side of lava field, cross a small creek. About 100 meters past the creek is a fork in the trail. Take the left fork. (In 2013, this left fork was marked “Minnie Scott Spring”.) Ascend a steeper trail with a creek on your left for about 0.8 miles to a junction with the Pacific Crest Trail. Take a right on this junction and hike about another 0.8 miles on the PCT. A large horseshoe shaped crumbling bench will come into view on your left. Arrowhead Lake is on top of this bench. You will see an obvious climbers trail cutting left off the PCT, across a meadow and small creek, and up the valley to the left of the buttress. Take this trail up the valley about 15 min, then ascend right up to the top of the bench when it's safe to do so. Enjoy the nice campsites around the lake.
Click on all photos to bring up a larger original (with legible text)
Ascent route from Arrowhead Lake to base of SW Ridge
A reasonable climber’s trail ascends from the Arrowhead Lake bench up to a large rock protrusion called the Black Fin. Climb up just to the right of the Black Fin, and then take a right and scramble over alternating sections of boulders and snowfield until you get to the pass between North and Middle sister. This route skirts the upper reaches of the Collier Glacier to the west. If you have crampons, ice axes, and glacier gear, you can get onto the Collier from the Black Fin for a slightly faster approach. However, in late-season, I've never carried this type of glacier travel gear, and therefore want to avoid any kind of crevasses.
This photo shows the ascent route from Arrowhead Lake up toward the Black Fin. There is a decent climbers trail up through here that you can follow in the dark.
Gain the SW Ridge
You now have to deal with a little bit of scree groveling to get up onto the Southwest Ridge. Possibly the best way to do this is on the slightly blocky, rock section to the right of the red band is seen in the photo below. It's not much fun anyway you do it, but once you get on the ridge proper the climbers trail is actually pretty decent. (When you descend, the red gravel in the middle is wonderful scree skiing and definitely where you want to be!)
This is probably the least fun section of the whole route on North Sister - gaining the Southwest Ridge from the upper Collier Glacier. This is a few hundred vertical feet of some pretty loose sand/gravel/scree. Just put your head down and go for it.
Looking up the Southwest Ridge
Once you gain the actual Ridge and get past the evil scree, it's actually a pretty pleasant walk for about 10 min. until you start traversing toward the summit block.
Get to the summit block
Once on top of the Southwest Ridge, you have a series of easy traverses followed by short gully climbs to get you over to the actual main summit block. The photo below should pretty much say it all. Be very mindful of rockfall from your teammates when you're in the sections marked in blue. These gullies are very loose.
Here is an annotated photo with a complete route across the upper summit Ridge. I think the text pretty much says it all. Feel free to save this onto your smart phone or print it out for your North Sister trip. (Click the photo for a larger image.)
Note that in section number six, you traverse for about 200 meters on the East of the summit ridge. Enjoy the spectacular views down to the Thayer Glacier.
Section number seven is the first of what could be roped technical climbing. In early-season this is a steep (45 degrees+) snowbowl with a L O N G runout. However, in late-season, this is easy class two scree for about 100 meters.
Section number eight: the so-called Terrible Traverse. With snow, most people like to have four pickets and maybe an ice screw to protect this. When the snow is gone, it's pretty easy third class scree, but with about 30 feet to cross of a nasty gully/runout. Less confident climbers will appreciate having a fixed line here. An anchors can be made at a large boulder at the start of the traverse, using two small cams (yellow and orange Metolius).
A close-up, annotated photo of the North Sister summit block. A common mistake here is to head up the gully to the left, or north of the Bowling Alley. It's marked here with a red X - avoid this area!
Here's a climbers view of the start of the so-called "Terrible Traverse" on North sister in late-season. When this is snow-covered, it can be a pitch or two of 50° alpine ice which will require your full attention. However, in late-season when the snow is gone, it's an easy third class scramble. There is a brief section with a bad runout, so larger climbing teams will probably want a fixed rope across it. Use several small cams for anchors at either end. (As mentioned in some of my previous photos, please avoid the common mistake of ascending the gully with the red X marks.)
The rope can be fixed on the far end with a single well-placed yellow Metolius cam. If you have a large team of people, bring two ropes and leave one of them fixed on this section for the return trip. A 50 m rope works fine here.
Be mindful of random mountain rockfall from above on this section, and have people cross it quickly. More confident climbers will not need a rope on this section.
At the end of the terrible traverse, the angle eases up and you can get off the rope. Traverse about another 50 m to the base of a reasonably solid rock buttress. This is the base of the bowling alley. Note the red X area left of the bowling alley. This is probably the place where most people make a route finding mistake by going up this gully. This is not the correct route! You may see some slings of to the left of this gully. Those are slings from people either bailing or coming up North Ridge.
Entrance to the bowling alley on North sister. This is a fourth class step of about 30 feet. It's pretty easy to solo, but with a larger group you probably want a fixed rope.
About a 30 foot ledge/step gets you into the bowling alley. Protect this area with a fixed rope. A 60 m rope will make it from here to the boulder in the middle of the bowling alley. This can be protected with a red 1 inch cam.
(Alternatively, there are some small pockets on the left side of the bowling alley below the boulder that take a small cam. I placed a bomber yellow red hybrid alien there on my last trip.)
Here's a climber entering the lower bowling alley on a fixed line. A 60 m rope reaches the large boulder in the center of the bowling alley. A red Metolius cam protects this nicely.
Once in the bowling alley, get your climb team off to the left in what I call the alcove. It's a large bowl shaped area that can hold the entire climb team, and keep them out of the way of any rockfall. Get your whole team to this point before you start climbing above this area.
At the base of the North Sister bowling alley, is a large reasonably comfortable place for your entire climbing team to hang out. I call it the alcove. It will probably be in the shade and a little chilly, but it's out of the way of almost any rockfall.
In the alcove, there is one point that I found for a belay anchor, a nice threaded hole in the rock.
Chockstone anchor point at the base of Bowling Alley. This is about the only decent place to anchor a rope in the entire lower section.
Once your climb team is all in the alcove, you start to lead the final pitch. I prefer to run it out to the big boulder in the middle of the bowling alley, place a single red Metolius cam for gear, and then run it out to the lower rap anchor, clip that for pro, and then head up to the upper rappel anchor and fix the rope here. Have everyone climb on a friction knot on the fixed line, and you are on the summit ridge, congratulations.
Leading the bowling alley.The big boulder in the middle offers the single best gear placement, about a 1 inch cam. This reasonably solid fourth class, and this section is often soloed. The top of the pitch is the rappel slings.
The actual summit, slightly to the north, is made a better rock and is not as steep as it first appears. Be sure to have everyone out of the bowling alley and on the summit ridge before anyone traverses over to the true summit. There are loads of rocks on this short traverse, and any of them they get kicked loose will go right down the middle of the bowling alley and nail anyone unfortunate enough to still be there.