For skiers attempting to descend the steepest lines in the world’s great mountain ranges, seasonality of the sport does not apply. Every month of the year, big lines are in play somewhere in the world, and top-level ski alpinists, like Swiss Gilles Sierro, know where to look. One of those magical times in Sierro’s home mountains is in early June.

IFMGA-certified Sierro hails from Hérémence in the Swiss Valais, a region that’s a virtual gold mine of iconic 3- and 4,000-meter [9- to 14,000-foot] peaks. On Friday, June 6, Sierro, along with photographer David Carlier, completed a new line on the north face of 11,969-foot Blanche de Perroc. The next day, Sierro, accompanied by Andreas Fransson and one client, made a descent of the Marinelli Couloir, a legendary 8,000-foot run on the Italian (east) side of Monte Rosa. This descent of the Marinelli came on the one-year anniversary of Sierro’s first descent on the 14,291-foot Dent Blanche via the Swiss Direct, one of the more notable firsts in this heavily trafficked mountain range in years.

I caught up with Sierro to ask about his recent successes, what it takes to pull off goals like this, and where he’s looking in the future.

Drew Tabke: So, compare this new line on the Blanche de Perroc to the line you and your friends established on the Dent Blanche last year.
Gilles Sierro: Well, the Dent Blanche line is longer and more sustained, plus you have to deal with the altitude. But on the Perroc, the blind roll at the top is seriously intimidating and the max exposure and difficulty come right at the top of the face. Plus, there are two crux rock passages on the Perroc that might be more technical than what we skied on the Dent Blanche.

DT: Did you make rappels to complete both of these lines?
GS: We rappelled for about 40 meters on the Dent Blanche last year. On the Perroc I didn’t need the rope—I prefer to ski the entire route if possible, so I was really happy about that.

Swiss Direct of Dent Blanche

In 2013, Sierro and two others completed a first descent on the infamous Dent Blanche via the Swiss Direct route, giving inspiration for his first descent of the Blanche de Perroc exactly one year later. PHOTO: Manu Rivaud

DT: When did you begin planning to attempt this face?
GS: I made an attempt back in 2010 and I’ve been waiting for good conditions for another try since then. This year when David Carlier and I headed out, our first aim was just to get some artistic skiing shots in the area. I knew in the back of my mind that a storm last Wednesday might have put good snow cover on the face, making another attempt feasible. When we got closer and I saw the how good conditions on the wall looked, I told David the artsy shoot might have to wait.

DT: And so you decided to go for it?
GS: Yes. We both climbed to the top. I stayed as close to the possible ski line as possible to constantly check conditions and see if it was skiable. After two hours, we were both on the summit. David downclimbed the upper slopes and shot photos while I skied. He clicked in to skis on a lower ridge and joined me on the remainder of the face.

Blanche de Perroc

The north-facing route Sierro and Carlier skied from the Blanche de Perroc summit.

DT: How was the snow?
GS: The skiing was awesome on the top with almost powdery snow on the blind roll. Then loose, recrystallized snow on rocks with patches of white ice in between that I had to make sure I didn’t hit. The bottom was nice and chalky, then from the face down to the valley was corn o’clock!

DT: So are you running out of projects? There aren’t too many un-skied steep north faces in your part of the world.
GS: I’m never running out! I have one or two good ones in sight, though it might take a few years before the right conditions form. Or not, you never know.

DT: Do you think you’ll keep skiing this year or was this it?
GS: Well it’s going to be hard to beat these two days with a first descent one day and the mythical Marinelli the next. But as you know, the skis never go away—they’re ready for when the conditions appear. Some of the mountains I am checking out are at their best ski potential in September and October.

Editor’s note: This past April, author Drew Tabke spent a week skiing with Sierro in Arolla, Switzerland, just one valley west of the Blanche de Perroc. Check out their adventures in a feature story that will appear in the September 2014 issue of POWDER, hitting newsstands August 8.