Cirque Forepeak avalanche

Avalanche date/time

Tuesday, February 13, 2024 at 18:00

Estimated occurrence time of avalanche

Less than 12 hours ago

Number of avalanches in this report

2 to 5

The size of avalanche

2.5

Slab thickness

30cm

Slab width

25m

Run length

450m

Avalanche Character

• Deep persistent slab
• Wind slab

Trigger type

Skier

Trigger subtype

Remote

Remote trigger distance

5m

Start zone aspect

• S

Start zone elevation band

• Alpine

Start zone elevation

2,770m

Start zone incline

45°

Runout zone elevation

2,320m

Weak layer crystal type

• Depth hoar
• Facets

Crust near weak layer

Yes

Wind exposure

Lee slope

Vegetation cover

Open slope

While traversing on top of a narrow alpine ridge feature a member of our party remote triggered a sz. 2-2.5 avalanche that ran roughly 400-500m downslope, with a crown that varied between 10-60cm and had a propagation width of roughly 25m. We then pushed a bit further and intentionally triggered a second slightly smaller avalanche on the adjacent feature. Needless to say the snow was touchy in this steep and rocky terrain. Both avalanches initiated on what looked to be the late Dec. melt freeze-sun crust layer just off the ground and then stepped down in spots to scrub the ground where the well preserved depth hoar was located. It is suspected that this feature has previously released and reloaded given the limited snow depths in a lee feature. Snow depth in thinner spots near the ridge consisted of roughly a 5cm windslab overtop 10cm facets, with a 5cm melt-freeze crust on top of 10cm of depth hoar. The perfect avalanche recipe when mixed with steep terrain!

Lower on the route between 2300-2700m we also observed shooting cracks and whumpfing in lower angled and wind affected terrain.