Cirque Forepeak avalanche

Date/heure de l'avalanche

mardi 13 février 2024 à 18 h 00

Estimation de l'heure d’occurrence de l’avalanche

< 12 heures

Nombre d'avalanches dans ce rapport

2 à 5

Taille de l’avalanche

2.5

Épaisseur de la plaque

30cm

Largeur de la plaque

25m

Longueur d'écoulement de l'avalanche

450m

Caractère de l'avalanche

• Plaque profonde et persistante
• Plaque à vent

Type d'élément déclencheur

Skieur

Sous-type d'élément déclencheur

À distance

Distance du déclenchement à distance

5m

Versant de la zone de départ

• S

Bande d'altitude de la zone de départ

• Alpin

Altitude de la zone de départ

2 770m

Inclinaison de la zone de départ

45°

Altitude de la zone de dépôt

2 320m

Type de cristaux de la couche fragile

• Givre de profondeur
• Grains à faces planes

Croûte près d'une couche fragile

Oui

Exposition au vent

Pente sous le vent

Couverture forestière

Pente dégagée

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.