Sara Goeking

Logan » Logan River » Bunch Grass » White Pine Knob

White Pine Knob

8,700'

East

40°

Skier

Unintentionally Triggered

Soft Slab

Persistent Weak Layer

Facets

4'

50'

150'

Avalanche #1 (trigger unknown): We stayed at the yurt Saturday and Sunday nights. The snow and winds started Saturday evening and didn't stop until Monday morning/early afternoon, and for a good portion of this multi-day storm the snow fell as graupel. Visibility was less than 1/4 mile. We stuck to low-angle slopes near Chicken Hill and White Pine Knob, and on Sunday the storm snow was pretty consistent and super fast. Sunday afternoon at about 4:45 pm we skied the ridge off the south side of the Knob, taking care to avoid the gut to skier's left. Partway down the ridge visibility cleared enough that we could see a 2-3' crown in the center/top of the Knob's southeast-facing gut. The slide was about 75' wide and traveled about 200' with mostly 2' chunks in the debris (which we couldn't see until Monday). It's possible that we triggered it remotely from the top of the Knob - we did hear several collapses during our hike - but because it looked like there was some new snow on top of the bed, we thought it was probably a natural slide. A photo of the slide in the gut of White Pine Knob on Sunday the 12th. Visibility was really bad but you can see the crown and the top of the debris.

Avalanche #2 (skier triggered): Late Monday morning we headed back to the Knob for a repeat of the low-angle south shoulder. Near the saddle between the Knob and Chicken Hill, we turned left and dropped into the yurt drainage. One skier descended the saddle on the same 25-degree slope that the group rode on Sunday. The second skier's line was slightly farther north/left from that line, and on his second turn a fracture immediately propagated across the 40-degree cliffs on the right flank of the gut. The crown was about 50' wide. The soft slab broke into small pieces and picked up speed quickly, going through a small aspen stand and snapping saplings as it traveled about 150' downslope. The skier who triggered the slide was directly below but managed to ski down and to the side before getting caught.

Tracey Frescino took the other two photos of the slide that we triggered today (the 13th). In the side view, you can just barely see the tracks of the skier that triggered the slide, just past the brush in the foreground. In the big view pic, those same tracks are on the far left, almost out of the picture. Those pics show some fairly big blocks near the top, but most of the slab broke into small pieces and slid into the little aspen stand at the bottom of the last photo. ***Both slides failed on early season facets very near the ground.