Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Galen Weld
Observation Date:
March 4, 2023
Submitted:
March 4, 2023
Zone or Region:
Snoqualmie Pass
Activity:
Skiing/Snowboarding
Location:
Thunder Creek/Slot Couloir

Triggered Avalanches

Did you trigger any avalanches? 
Yes
Was it intentional? 
No
Avalanche Type:
Soft Slab
Size:
Size 1: Relatively harmless to people
Elevation:
start zone ~5400 ft
Aspect:
NW
Comments:
Skier-triggered soft slab on steep, convex roll in the Slot Couloir where it widens at approx. 5,400 feet. Crown ~30 feet wide, 3-6 inches deep, ran ~200 vertical feet entraining some additional snow but did not propagate more widely or step down below the uppermost layer in the snowpack. The avalanche triggered a short distance above the skier, who was able to ski off the slide without incident.

Signs of Unstable Snow

Did you see shooting cracks? 
Yes, Isolated
Did you experience collapsing or whumpfing? 
No

Observations

We headed up Mount Snoqualmie today and enjoyed unusual solitude and great skiing conditions - perhaps everyone was across the valley at Vertfest? Our original plan was to head up to the summit to ski the north slope, but strong winds above treeline caused us to adjust our plans to stay on more pleasant, sheltered aspects.

We skied to the standard Thunder Creek/Slot exit. Out of the trees, the south facing slopes near the exit were fairly wind-affected, while the exit couloir was quite wind loaded, with winds coming across the south slopes from the SE. We dropped a small chunk of cornice (~5ft x 3 ft x 3 ft) into the exit couloir, which sent some sluff running ~100 vertical feet down the slope, but did not trigger and slab avalanches. We skied down into the Thunder Creek basin, then spent the rest of the day skiing the fans below the Snot and Slot, as well as poking up a short distance into both couloirs. Skiing conditions were excellent, and in more sheltered slopes in the couloirs, we observed frequent yet small shooting cracks while making kick turns, as well as isolated very small skier triggered slabs.

The largest avalanche we observed was a D1 soft slab at approx. 5,400 feet in the wider part of the bottom of the Slot, which I triggered while skiing over a steep convex roll. The crown was ~30 feet wide and 3-6 inches deep, and ran ~200 vertical feet down the couloir. All activity we witnessed was isolated to the top ~3-6 inches, the uppermost layer in the snowpack.

Media

Crown of skier triggered avalanche in the Slot Couloir.
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